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Wallmark J, Josefsson M, Wiberg M. Efficiency Analysis of Item Response Theory Kernel Equating for Mixed-Format Tests. APPLIED PSYCHOLOGICAL MEASUREMENT 2023; 47:496-512. [PMID: 38027462 PMCID: PMC10664743 DOI: 10.1177/01466216231209757] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/01/2023]
Abstract
This study aims to evaluate the performance of Item Response Theory (IRT) kernel equating in the context of mixed-format tests by comparing it to IRT observed score equating and kernel equating with log-linear presmoothing. Comparisons were made through both simulations and real data applications, under both equivalent groups (EG) and non-equivalent groups with anchor test (NEAT) sampling designs. To prevent bias towards IRT methods, data were simulated with and without the use of IRT models. The results suggest that the difference between IRT kernel equating and IRT observed score equating is minimal, both in terms of the equated scores and their standard errors. The application of IRT models for presmoothing yielded smaller standard error of equating than the log-linear presmoothing approach. When test data were generated using IRT models, IRT-based methods proved less biased than log-linear kernel equating. However, when data were simulated without IRT models, log-linear kernel equating showed less bias. Overall, IRT kernel equating shows great promise when equating mixed-format tests.
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Affiliation(s)
| | | | - Marie Wiberg
- Department of Statistics, USBE, Umeå University, Sweden
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2
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Kweon DC. Radiation exposure in cone beam CT measured using a MOSFET and RPLGD dosimeter and Monte Carlo simulation in phantom. JOURNAL OF X-RAY SCIENCE AND TECHNOLOGY 2023:XST230026. [PMID: 37248944 DOI: 10.3233/xst-230026] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
BACKGROUND Due to the wide application of the cone beam computed tomography (CBCT) in clinical practice, it is important to assess radiation dose of CBCT more accurately and efficiently in different clinical applications. OBJECTIVE This study aims to calculate effective and absorbed doses in CBCT measured in an anthropomorphic phantom using computer-based Monte Carlo (PCXMC) software, and to conduct comparative evaluations of MOSFET (metal- oxide- semiconductor field-effect transistor) and radiophotoluminescence glass dosimeters (RPLGD). METHODS Effective and absorbed organ doses are compared with those obtained using MOSFET and RPLGD dosimetry in an anthropomorphic phantom given the same exposure settings. Effective and absorbed organ doses from CBCT during scout and main projections are calculated using PCXMC and PCXMCRotation software, respectively. RESULTS The mean effective dose from CBCT calculated using PCXMC software is 233.8μSv, while the doses calculated using dosimetry (MOSFET and RPLGD) are 266.67μSv and 268.78μSv, respectively. The X-ray source variation is 0.79%. The prescription limits based on the Friedman test for MOSFET and RPLGD pre-points (i.e., in an analytical analysis of diagnostic names in CBCT) are not statistically significant. The calculated correlation coefficient between MOSFET- and RPLGD-derived absorbed dose values with respect to a field of view CBCT parameter of 17×13.5 mm is r = 0.8623. CONCLUSIONS The study demonstrates that the PCXMC software may be used as an alternative to MOSFET and RPLGD dosimetry for effective and absorbed organ dose estimation in CBCT conducted with a large FOV in an anthropomorphic phantom.
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Affiliation(s)
- Dae Cheol Kweon
- Department of Radiological Science, Shinhan University, Uijeongbu, Republic of Korea
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Derikvand AM, Bagherzadeh S, MohammadSharifi A, Khoshgard K, AllahMoradi F. Estimation of cancer risks due to chest radiotherapy treatment planning computed tomography (CT) simulations. RADIATION AND ENVIRONMENTAL BIOPHYSICS 2023; 62:269-277. [PMID: 37129707 DOI: 10.1007/s00411-023-01025-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/14/2022] [Accepted: 03/28/2023] [Indexed: 05/03/2023]
Abstract
The objective of our study was to determine organ doses to estimate the lifetime attributable risk (LAR) of cancer incidence related to chest tomography simulations for Radiotherapy Treatment Planning (RTTP) using patient-specific information. Patient data were used to calculate organ doses and effective dose. The effective dose (E) was calculated by two methods. First, to calculate effective dose in a standard phantom, the collected dosimetric parameters were used with the ImPACT CT Patient Dosimetry Calculator and E was calculated by applying related correction factors. Second, using the scanner-derived Dose Length Product, LARs were computed using the US National Academy of Sciences (BEIR VII) model for age- and sex-specific risks at each exposure. DLP, CTDIvol, and scan length were 507 ± 143 mGy.cm, 11 ± 4 mGy, and 47 ± 7 cm, respectively. The effective dose was 10 ± 3 mSv using ImPACT patient dosimetry calculator software and 9 ± 2 mSv using the scanner-derived Dose Length Product. The LAR of cancer incidence for all cancers, all solid cancers and leukemia were 65 ± 29, 62 ± 27, 7 ± 2 cases per 100,000 individuals, respectively. Radiation exposure from the usage of CT for radiotherapy treatment planning (RTTP) causes non-negligible increases in lifetime attributable risk. The results of this study can be used as a guide by physicians to implement strategies based on the As Low As Reasonably Achievable (ALARA) principle that lead to a reduction dose without sacrificing diagnostic information.
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Affiliation(s)
- Afsaneh Mir Derikvand
- Department of Medical Physics, Kermanshah University of Medical Sciences, Kermanshah, Iran
| | - Saeed Bagherzadeh
- Department of Medical Physics, Faculty of Medicine, Tarbiat Modares University, Tehran, Iran
| | - Ali MohammadSharifi
- Clinical Research Development Center, Shahid Modarres Educational Hospital, Shahid Beheshti University of Medical Science, Tehran, Iran
| | - Karim Khoshgard
- Department of Medical Physics, School of Medicine, Kermanshah University of Medical Sciences, Kermanshah, Iran
| | - Fariba AllahMoradi
- Department of Medical Physics, Kermanshah University of Medical Sciences (KUMS), Building No. 1Shahid Beheshti Boulevard, Kermanshah, 6715847141, Iran.
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Shubayr N, Alashban Y. Estimation of radiation doses and lifetime attributable risk of radiation-induced cancer in the uterus and prostate from abdomen pelvis CT examinations. Front Public Health 2023; 10:1094328. [PMID: 36699908 PMCID: PMC9868812 DOI: 10.3389/fpubh.2022.1094328] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2022] [Accepted: 12/21/2022] [Indexed: 01/12/2023] Open
Abstract
Computed tomography (CT) scans are one of the most common radiation imaging modalities, and CT scans are rising steadily worldwide. CT has the potential to enhance radiography practice, but it also has the risk of drastically increasing patient doses. One CT procedure for the abdomen pelvis (AP) area can expose a patient's prostate or uterus to a substantial radiation dose, leading to concerns about radiation-induced cancer. This study aimed to estimate organ doses of the uterus and prostate and evaluate the lifetime attributable risk (LAR) of cancer incidence and mortality resulting from AP CT examinations. This retrospective study included 665 patients, of which 380 (57%) were female, and 285 (43%) were male. Data were collected from the picture archiving and communication system for AP CT procedures and exposure parameter data. Organ doses for the uterus and prostate were calculated using National Cancer Institute CT (NCICT) software. Based on the risk models proposed by the BEIR VII report, the calculated organ doses were used to estimate the LAR of prostate and uterus cancer incidence and mortality due to radiation exposure from AP CT procedures. The mean effective dose resulting from AP CT for females and males was 5.76 ± 3.22 (range: 1.13-12.71 mSv) and 4.37 ± 1.66 mSv (range: 1.36-8.07 mSv), respectively. The mean organ dose to the uterus was 10.86 ± 6.09 mGy (range: 2.13-24.06 mGy). The mean organ dose to the prostate was 7.00 ± 2.66 mGy (range: 2.18-12.94 mGy). The LAR of uterus and prostate cancer incidence was 1.75 ± 1.19 cases and 2.24 ± 1.06 cases per 100,000 persons, respectively. The LAR of cancer mortality rates from uterus and prostate cancers were 0.36 ± 0.22 and 0.48 ± 0.18 cases per 100,000 persons, respectively. The LAR of prostate and uterus cancer occurrence and mortality from radiation doses with AP CT procedures was low but not trivial. Therefore, efforts should be made to lower patient doses while retaining image quality. Although the minimization of the patient's radiation dose must guide clinical practice, the estimated slight increase in risk could aid in easing fears regarding well-justified AP CT procedures.
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Affiliation(s)
- Nasser Shubayr
- Department of Diagnostic Radiography Technology, College of Applied Medical Sciences, Jazan University, Jazan, Saudi Arabia,*Correspondence: Nasser Shubayr ✉
| | - Yazeed Alashban
- Radiological Sciences Department, College of Applied Medical Sciences, King Saud University, Riyadh, Saudi Arabia
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Happonen E, Husso M, Matikka H. Effect of MOSFET dosimeters' calibration method on calibration factors and radiation doses measured with the dosimeters in radiology. Biomed Phys Eng Express 2022; 8. [PMID: 35354122 DOI: 10.1088/2057-1976/ac6292] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2022] [Accepted: 03/30/2022] [Indexed: 11/11/2022]
Abstract
MOSFET dosimeters have widely been used to measure radiation doses caused by x-rays. When using the MOSFET dosimeters, calibration factors (CFs) have a direct effect on reliability of dose measurements. The aim of this paper was to study the effect of various calibration methods on the CFs of the MOSFET dosimeters. The CFs were measured on clinical digital x-ray angiography (XA) and computed tomography (CT) devices using a calibrated CT ionization chamber and a standard polymethyl methacrylate (PMMA) phantom. The measurements were conducted by having the dosimeters (1) in air, (2) on the surface of the PMMA phantom and (3) inside the phantom. A statistically significant difference was seen between the CFs measured on the XA and CT devices. The CFs measured on the CT device were 20%-165% higher than those measured with the XA device (p < 0.001) in every calibration geometry. Furthermore, the calibration geometry had a notable effect on the CFs on CT. The CFs on the surface of the phantom were 18%-25% higher than in air (p < 0.05), and the CFs inside the phantom were 32%-39% smaller than in air (p < 0.05). These results suggest that the calibration of the MOSFET dosimeters should be conducted with the same device that is used in actual dose measurements. Also, the scattering conditions and the calibration geometry should be similar in the calibration and subsequent dose measurements.
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Affiliation(s)
- Emilia Happonen
- Department of Applied Physics, University of Eastern Finland, 70210 Kuopio, Finland
| | - Minna Husso
- Diagnostic Imaging Center, Kuopio University Hospital, 70210 Kuopio, Finland
| | - Hanna Matikka
- Diagnostic Imaging Center, Kuopio University Hospital, 70210 Kuopio, Finland
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Bryce-Atkinson A, de Jong R, Bel A, Aznar MC, Whitfield G, van Herk M. Evaluation of Ultra-low-dose Paediatric Cone-beam Computed Tomography for Image-guided Radiotherapy. Clin Oncol (R Coll Radiol) 2020; 32:835-844. [PMID: 33067079 DOI: 10.1016/j.clon.2020.09.011] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2020] [Revised: 09/11/2020] [Accepted: 09/29/2020] [Indexed: 01/01/2023]
Abstract
AIMS In image-guided radiotherapy, daily cone-beam computed tomography (CBCT) is rarely applied to children due to concerns over imaging dose. Simulating low-dose CBCT can aid clinical protocol design by allowing visualisation of new scan protocols in patients without delivering additional dose. This work simulated ultra-low-dose CBCT and evaluated its use for paediatric image-guided radiotherapy by assessment of image registration accuracy and visual image quality. MATERIALS AND METHODS Ultra-low-dose CBCT was simulated by adding the appropriate amount of noise to projection images prior to reconstruction. This simulation was validated in phantoms before application to paediatric patient data. Scans from 20 patients acquired at our current clinical protocol (0.8 mGy) were simulated for a range of ultra-low doses (0.5, 0.4, 0.2 and 0.125 mGy) creating 100 scans in total. Automatic registration accuracy was assessed in all 100 scans. Inter-observer registration variation was next assessed for a subset of 40 scans (five scans at each simulated dose and 20 scans at the current clinical protocol). This subset was assessed for visual image quality by Likert scale grading of registration performance and visibility of target coverage, organs at risk, soft-tissue structures and bony anatomy. RESULTS Simulated and acquired phantom scans were in excellent agreement. For patient scans, bony atomy registration discrepancies for ultra-low-dose scans fell within 2 mm (translation) and 1° (rotation) compared with the current clinical protocol, with excellent inter-observer agreement. Soft-tissue registration showed large discrepancies. Bone visualisation and registration performance reached over 75% acceptability (rated 'well' or 'very well') down to the lowest doses. Soft-tissue visualisation did not reach this threshold for any dose. CONCLUSION Ultra-low-dose CBCT was accurately simulated and evaluated in patient data. Patient scans simulated down to 0.125 mGy were appropriate for bony anatomy set-up. The large dose reduction could allow for more frequent (e.g. daily) image guidance and, hence, more accurate set-up for paediatric radiotherapy.
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Affiliation(s)
- A Bryce-Atkinson
- Division of Cancer Sciences, School of Medical Sciences, Faculty of Biology, Medicine and Health, The University of Manchester, Manchester, UK.
| | - R de Jong
- Department of Radiation Oncology, Amsterdam University Medical Center, University of Amsterdam, Amsterdam, the Netherlands
| | - A Bel
- Department of Radiation Oncology, Amsterdam University Medical Center, University of Amsterdam, Amsterdam, the Netherlands
| | - M C Aznar
- Division of Cancer Sciences, School of Medical Sciences, Faculty of Biology, Medicine and Health, The University of Manchester, Manchester, UK; Clinical Trial Service Unit, Nuffield Department of Population Health, University of Oxford, Oxford, UK
| | - G Whitfield
- Manchester Academic Health Science Centre, The Christie NHS Foundation Trust, Manchester, UK; The Children's Brain Tumour Research Network, The University of Manchester, Royal Manchester Children's Hospital, Manchester, UK
| | - M van Herk
- Division of Cancer Sciences, School of Medical Sciences, Faculty of Biology, Medicine and Health, The University of Manchester, Manchester, UK
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CT Angiography Findings Predictive of Kidney Injury in Chronic Aortic Dissection. AJR Am J Roentgenol 2020; 214:1409-1416. [PMID: 32286876 DOI: 10.2214/ajr.19.21877] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
OBJECTIVE. The purpose of this study was to compare the volume alteration and effective renal plasma flow of kidneys supplied by false lumens (FLs) with those of kidneys supplied by true lumens (TLs), to show the discrepancy in perfusion between the two lumens. We sought to corroborate malperfusion of FL-supplied kidneys with imaging characteristics observed on CT angiography. MATERIALS AND METHODS. A retrospective analysis was conducted using prospectively collected data for 87 patients with a diagnosis of residual chronic aortic dissection between 2005 and 2013 who had one kidney perfused by a TL and the other kidney perfused by a FL. RESULTS. Overall, at follow-up, FL-supplied kidneys had a mean (± SD) effective renal plasma flow (117.5 ± 42.6 vs 146.6 ± 41.0 mL/min; p = 0.004) and volume (131.1 ± 37.1 vs 146.5 ± 33.3 cm3; p = 0.004) that were lower than those of TL-supplied kidneys. Multivariate analysis revealed the presence of a proximal major inlet (odds ratio, 0.306; 95% CI, 0.103-0.910; p = 0.033) and large FL area (odds ratio, 0.104; CI, 0.012-0.880; p = 0.038) as factors protecting against malperfusion of FL-supplied kidneys. In patients with dissected renal arteries, the FL-supplied kidney had low effective renal plasma flow (mean, 88.5 ± 26.8 vs 149.6 ± 43.5 mL/min; p = 0.004) and diminished volume (mean, 120.4 ± 30.4 vs 152.3 ± 24.6 cm3; p = 0.001). CONCLUSION. In the present study, kidneys perfused by FLs showed decreased volume and reduced effective renal plasma flow during follow-up, particularly those kidneys with dissected renal arteries, a small FL area at the renal level, and lack of a proximal major inlet. Further studies are warranted to identify the clinical relevance of malperfusion in FL-supplied kidneys.
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Shkumat NA, Brashdi YA, Volodina S, Parra D, Connolly BL. Dosimetric Feasibility of Cone-Beam CT in Pediatric Image-Guided Retrograde Gastrostomy Tube Insertions. Can Assoc Radiol J 2020; 71:68-74. [DOI: 10.1177/0846537119885680] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
Purpose: Cone-beam computed tomography (CBCT) in interventional radiology allows volumetric imaging with open patient access. This work aimed to assess radiation dose metrics of CBCT in simulated image-guided retrograde gastrostomy (IGRG) tube insertions in pediatric anthropomorphic phantoms and to compare them to measured radiation dose metrics obtained using fluoroscopy during clinical IGRG tube insertions in children. Methods: Radiation dose indices obtained from radiation dose structured reports of fluoroscopic IGRG tube insertions were retrospectively evaluated in a consecutive cohort of 30 children. Dose indices were fractionated into 3 clinical stages for each procedure ( planning, insertion, and confirmation). These 3 stages in 30 patients (3 × 30 = 90 patient stages) were compared to dose indices measured from 4 CBCT acquisition protocols acquired in pediatric phantoms. Results: The mean proportion of radiation dose during planning, insertion, and confirmation was 35%, 38% and 27%, with mean reference-point air kerma (range) measured to be 1.0 (0.02-6.0) mGy, 0.9 (0.03-4.1) mGy, and 0.7 (0.04-3.7) mGy, respectively. Cone-beam computed tomography dose varied greatly depending on technical parameters and protocol selection, ranging from 0.7 to 39.3 mGy. In 19% of patient stages, the most dose-sparing CBCT protocol evaluated on phantoms delivered less radiation than the radiation dose indices recorded from patient’s fluoroscopy. Conclusions: From a dosimetric perspective, radiation delivered in CBCT can vary widely, yet can be appreciably low. With appropriate CBCT protocol selection, the radiation dose delivered may be sufficiently low to warrant consideration for use, if clinically needed during difficult IGRG tube insertions, and satisfy the interventionalist’s benefit–risk assessment.
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Affiliation(s)
- Nicholas A. Shkumat
- Department of Diagnostic Imaging, The Hospital for Sick Children, Toronto, Ontario, Canada
- Department of Medical Imaging, University of Toronto, Toronto, Ontario, Canada
| | - Yahya Al Brashdi
- Department of Diagnostic Imaging, The Hospital for Sick Children, Toronto, Ontario, Canada
- Department of Medical Imaging, University of Toronto, Toronto, Ontario, Canada
| | - Sabina Volodina
- Department of Diagnostic Imaging, The Hospital for Sick Children, Toronto, Ontario, Canada
| | - Dimitri Parra
- Department of Diagnostic Imaging, The Hospital for Sick Children, Toronto, Ontario, Canada
- Department of Medical Imaging, University of Toronto, Toronto, Ontario, Canada
| | - Bairbre L. Connolly
- Department of Diagnostic Imaging, The Hospital for Sick Children, Toronto, Ontario, Canada
- Department of Medical Imaging, University of Toronto, Toronto, Ontario, Canada
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Jakl L, Marková E, Koláriková L, Belyaev I. Biodosimetry of Low Dose Ionizing Radiation Using DNA Repair Foci in Human Lymphocytes. Genes (Basel) 2020; 11:genes11010058. [PMID: 31947954 PMCID: PMC7016656 DOI: 10.3390/genes11010058] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2019] [Revised: 12/17/2019] [Accepted: 12/24/2019] [Indexed: 02/04/2023] Open
Abstract
Purpose: Ionizing radiation induced foci (IRIF) known also as DNA repair foci represent most sensitive endpoint for assessing DNA double strand breaks (DSB). IRIF are usually visualized and enumerated with the aid of fluorescence microscopy using antibodies to γH2AX and 53BP1. This study analyzed effect of low dose ionizing radiation on residual IRIF in human lymphocytes to the aim of potential biodosimetry and possible extrapolation of high-dose γH2AX/53BP1 effects to low doses and compared kinetics of DSB and IRIF. We also analyzed whether DNaseI, which is used for reducing of clumps, affects the IRIF level. Materials and Methods: The cryopreserved human lymphocytes from umbilical cord blood (UCB) were thawed with/without DNaseI, γ-irradiated at doses of 0, 5, 10, and 50 cGy and γH2AX/53BP1 foci were analyzed 30 min, 2 h, and 22 h post-irradiation using appropriate antibodies. We also analyzed kinetics of DSB using PFGE. Results: No significant difference was observed between data obtained by γH2AX foci evaluation in cells that were irradiated by low doses and data obtained by extrapolation from higher doses. Residual 53BP1 foci induced by low doses significantly outreached the data extrapolated from irradiation by higher doses. 53BP1 foci induced by low dose-radiation remain longer at DSB loci than foci induced by higher doses. There was no significant effect of DNaseI on DNA repair foci. Conclusions: Primary γH2AX, 53BP1 foci and their co-localization represent valuable markers for biodosimetry of low doses, but their usefulness is limited by short time window. Residual γH2AX and 53BP1 foci are more useful markers for biodosimetry in vitro. Effects of low doses can be extrapolated from high dose using γH2AX residual foci while γH2AX/53BP1 foci are valuable markers for evaluation of initial DSB induced by ionizing radiation. Residual IRIF induced by low doses persist longer time than those induced by higher doses.
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Affiliation(s)
- Lukáš Jakl
- Correspondence: ; Tel.: +421-2-59327321; Fax: +421-2-59327305
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Ma GMY, Dmytriw AA, Patel PA, Shkumat N, Krings T, Shroff MM, Muthusami P. Quantitative color-coded digital subtraction neuroangiography for pediatric arteriovenous shunting lesions. Childs Nerv Syst 2019; 35:2399-2403. [PMID: 31280353 DOI: 10.1007/s00381-019-04289-8] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/27/2019] [Accepted: 06/30/2019] [Indexed: 12/11/2022]
Abstract
BACKGROUND Several complex pediatric neurovascular conditions are amenable to endovascular treatment. Given the unique anatomical and physiological challenges in children, there is an ongoing need for tools and techniques that provide accurate information for treatment planning, while minimizing exposure to ionizing radiation and contrast. This is more so for neonates and infants with high-flow arteriovenous (AV) shunts that are challenging to assess using conventional techniques. OBJECTIVE In this brief report, we describe, through representative cases, the potential role of quantitative color-coded digital subtraction angiography (qDSA) in neuroendovascular procedures in children with high-flow AV shunting lesions. METHODS Images were obtained using an ArtisQ biplane system (Siemens Healthineers, Erlangen, Germany). Post-processing was performed at a dedicated workstation (Syngo, Siemens) using the iFlow module to generate color-coded maps of individual digital subtraction angiography runs. CONCLUSION Color-coded qDSA provides real-time quantitative information in high-flow AV shunting neurovascular lesions. This can potentially help direct treatment choices, optimize endovascular treatment protocols, monitor outcomes, and determine treatment end points.
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Affiliation(s)
- Grace M Y Ma
- Image Guided Therapy, Department of Diagnostic Imaging, Department of Medical Imaging, Hospital for Sick Children, University of Toronto, 555 University Ave, Toronto, ON, M5S, Canada.
| | - Adam A Dmytriw
- Image Guided Therapy, Department of Diagnostic Imaging, Department of Medical Imaging, Hospital for Sick Children, University of Toronto, 555 University Ave, Toronto, ON, M5S, Canada
- Division of Neuroradiology, Joint Department of Medical Imaging, Toronto Western Hospital, University Health Network, University of Toronto, Toronto, Ontario, Canada
| | - Premal A Patel
- Wellcome / EPSRC Centre for Interventional and Surgical Sciences (WEISS), University College London, Bloomsbury, London, WC1E 6BT, UK
- Radiology Department, Great Ormond Street Hospital for Children, London, UK
| | - Nicholas Shkumat
- Image Guided Therapy, Department of Diagnostic Imaging, Department of Medical Imaging, Hospital for Sick Children, University of Toronto, 555 University Ave, Toronto, ON, M5S, Canada
| | - Timo Krings
- Division of Neuroradiology, Joint Department of Medical Imaging, Toronto Western Hospital, University Health Network, University of Toronto, Toronto, Ontario, Canada
| | - Manohar M Shroff
- Image Guided Therapy, Department of Diagnostic Imaging, Department of Medical Imaging, Hospital for Sick Children, University of Toronto, 555 University Ave, Toronto, ON, M5S, Canada
| | - Prakash Muthusami
- Image Guided Therapy, Department of Diagnostic Imaging, Department of Medical Imaging, Hospital for Sick Children, University of Toronto, 555 University Ave, Toronto, ON, M5S, Canada
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Kuo TT, Huang CY, Chen PL, Chen IM, Shih CC. Impact of Renal Artery Stent-Graft Placement on Renal Function in Chronic Aortic Dissection. J Vasc Interv Radiol 2019; 30:979-986. [PMID: 30982639 DOI: 10.1016/j.jvir.2018.12.015] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2018] [Revised: 12/09/2018] [Accepted: 12/11/2018] [Indexed: 01/03/2023] Open
Abstract
PURPOSE To evaluate the effect of renal stent-graft placement on kidney function and size alternation in chronic aortic dissection. MATERIALS AND METHODS Twenty-five consecutive patients with chronic aortic dissection after thoracic endovascular aortic repair who underwent renal stent-graft placement between January 2015 and December 2016 were retrospectively reviewed. Forty-three patients with chronic aortic dissection who received thoracic endovascular aortic repair in the same period were reviewed as a control group for kidney volume comparison. RESULTS Twenty-five stent-grafts were deployed over 25 renal arteries. Overall renal function was assessed by the slope of the regression line constructed from the plots of creatinine clearance versus time within 2 years after the procedure (-0.2810 vs -0.3146 mL/min-1/mo-1, P = .868), kidney volume at 12 months (129.4 ± 40.9 vs 137.0 ± 44.2 cm2, P = .193) and effective renal plasma flow at 6 months (106.3 ± 46.9 vs 124.4 ± 55.5 mL/min, P = .050) and was not significantly deteriorated. Seven treated patients (87.5%) with a renal artery supplied by a false lumen had a decrease in kidney volume, as did 14 patients (56%) in the control group (P = .206). Three patients with a dissected renal artery (75%) in the stent-graft group had an increase in kidney volume compared with 1 patient (11.1%) in the control group (P = .052). CONCLUSIONS Occlusion of the re-entry tear by a stent-graft in the renal artery remains a safe strategy to promote false lumen thrombosis. The stent-graft poses a potential risk of reducing the kidney volume in kidneys supplied by the false lumen but may provide a positive effect in kidney volume with a concomitant dissected renal artery in chronic aortic dissection.
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Affiliation(s)
- Tzu-Ting Kuo
- Division of Cardiovascular Surgery, Department of Surgery, Taipei Veterans General Hospital, Taiwan; Department of Medicine, School of Medicine, National Yang Ming University, No. 201, Section 2, Shipai Road, Beitou District, Taipei City, Taiwan
| | - Chun-Yang Huang
- Division of Cardiovascular Surgery, Department of Surgery, Taipei Veterans General Hospital, Taiwan; Department of Medicine, School of Medicine, National Yang Ming University, No. 201, Section 2, Shipai Road, Beitou District, Taipei City, Taiwan
| | - Po-Lin Chen
- Division of Cardiovascular Surgery, Department of Surgery, Taipei Veterans General Hospital, Taiwan; Department of Medicine, School of Medicine, National Yang Ming University, No. 201, Section 2, Shipai Road, Beitou District, Taipei City, Taiwan
| | - I-Ming Chen
- Division of Cardiovascular Surgery, Department of Surgery, Taipei Veterans General Hospital, Taiwan; Institute of Clinical Medicine, School of Medicine, National Yang Ming University, No. 201, Section 2, Shipai Road, Beitou District, Taipei City, Taiwan
| | - Chun-Che Shih
- Division of Cardiovascular Surgery, Department of Surgery, Taipei Veterans General Hospital, Taiwan; Institute of Clinical Medicine, School of Medicine, National Yang Ming University, No. 201, Section 2, Shipai Road, Beitou District, Taipei City, Taiwan.
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12
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Malik DES, Fida M, Sukhia RH. Correlation between radiographic parameters for the prediction of palatally impacted maxillary canines. J Orthod 2019; 46:6-13. [DOI: 10.1177/1465312518823012] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Objective: This study aimed to identify radiographic parameters on routine orthopantomograms to aid in early diagnosis of palatally impacted canines. Design: Split-mouth case-control study. Setting: Single-centre university dental hospital. Methods: Thirty-three individuals with palatally impacted canines and non-impacted contra-lateral teeth were recruited. Radiographic variables angle A, angle B, angle C, distance D, sector class and depth of vertical impaction were measured for both groups. Mann–Whitney U test and Spearman’s correlation coefficient were used to analyse significant differences and association between variables with sector class and depth of vertical impaction, respectively. Logistic regression analysis determined radiographic parameters as predictors of palatal impaction. Results: Significant differences were seen between sector class, depth of vertical impaction and the radiographic parameters between cases and controls ( P ⩽ 0.001). For cases, strong correlation was found for angle C between the impacted canine and occlusal plane (r = −0.28, P = 0.022) and perpendicular distance D of impacted canine to the occlusal plane (r = 0.81, P ⩽ 0.001) with the depth of vertical impaction. Logistic regression analysis showed the odds of canine impaction increase with an increase in angle B and angle C. Conclusions: Our study showed that greater depth of vertical impaction, sector class, increased perpendicular distance and reduced angulation from occlusal plane resulted in palatal impaction of permanent maxillary canines. The odds of palatal canine impaction increase nearly twofold with every 10 increase in angle B and angle C.
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Affiliation(s)
- Durr e Shahwar Malik
- Section of Dentistry, Department of Surgery, The Aga Khan University Hospital, Karachi, Pakistan
| | - Mubassar Fida
- Section of Dentistry, Department of Surgery, The Aga Khan University Hospital, Karachi, Pakistan
| | - Rashna Hoshang Sukhia
- Section of Dentistry, Department of Surgery, The Aga Khan University Hospital, Karachi, Pakistan
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Lee KH, Jeong HG, Kwak EJ, Park W, Kim KD. Ultrasound Guided Free Gingival Graft: Case Report. J ORAL IMPLANTOL 2018; 44:385-388. [DOI: 10.1563/aaid-joi-d-17-00298] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Affiliation(s)
- Kang-Hee Lee
- Department of Advanced General Dentistry, College of Dentistry, Yonsei University, Seoul, Korea
| | - Ho-Gul Jeong
- Department of Oral and Maxillofacial Radiology, College of Dentistry, Yonsei University, Seoul, Korea
| | | | - Wonse Park
- Department of Advanced General Dentistry, College of Dentistry, Yonsei University, Seoul, Korea
| | - Kee-Deog Kim
- Department of Advanced General Dentistry, College of Dentistry, Yonsei University, Seoul, Korea
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Bagherzadeh S, Jabbari N, Khalkhali HR. Estimation of lifetime attributable risks (LARs) of cancer associated with abdominopelvic radiotherapy treatment planning computed tomography (CT) simulations. Int J Radiat Biol 2018. [PMID: 29528791 DOI: 10.1080/09553002.2018.1450536] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
PURPOSE The present study attempts to calculate organ-absorbed and effective doses for cancer patients to estimate the possible cancer induction and cancer mortality risks resulting from 64-slice abdominopelvic computed tomography (CT) simulations for radiotherapy treatment planning (RTTP). MATERIAL AND METHODS A group of 70 patients, who underwent 64-slice abdominopelvic CT scan for RTTP, voluntarily participated in the present study. To calculate organ and effective doses in a standard phantom of 70 kg, the collected dosimetric parameters were used with the ImPACT CT Patient Dosimetry Calculator. Patient-specific organ dose and effective dose were calculated by applying related correction factors. For the estimation of lifetime attributable risks (LARs) of cancer incidence and cancer-related mortality, doses in radiosensitive organs were converted to risks based on the data published in Biological Effects of Ionizing Radiation VII (BEIR VII). RESULTS The mean ± standard deviation (SD) of the effective dose for males and females were 13.87 ± 2.37 mSv (range: 9.25-18.82 mSv) and 13.04 ± 3.42 mSv (range: 6.99-18.37 mSv), respectively. The mean ± SD of LAR of cancer incidence was 35.34 ± 13.82 cases in males and 34.49 ± 9.63 cases in females per 100,000 persons. The LAR of cancer mortality had the mean ± SD value of 15.38 ± 4.25 and 16.72 ± 3.87 cases per 100,000 persons in males and females respectively. CONCLUSION Increase in the LAR of cancer occurrence and mortality due to abdominopelvic treatment planning CT simulation is noticeable and should be considered.
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Affiliation(s)
- Saeed Bagherzadeh
- a Department of Medical Physics, School of Medicine , Urmia University of Medical Sciences , Urmia , Iran
| | - Nasrollah Jabbari
- b Solid Tumor Research Center , Urmia University of Medical Sciences , Urmia , Iran
| | - Hamid Reza Khalkhali
- c Patient Safety Research Center, Department of Biostatistics and Epidemiology , Urmia University of Medical Sciences , Urmia , Iran
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Böning G, Lüdemann WM, Chapiro J, Jonczyk M, Hamm B, Günther RW, Gebauer B, Streitparth F. Clinical Experience with Real-Time 3-D Guidance Based on C-Arm-Acquired Cone-Beam CT (CBCT) in Transjugular Intrahepatic Portosystemic Stent Shunt (TIPSS) Placement. Cardiovasc Intervent Radiol 2018. [PMID: 29541837 DOI: 10.1007/s00270-018-1877-4] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
PURPOSE The aim of this study was to evaluate the feasibility of cone-beam computed tomography (CBCT)-based real-time 3-D guidance of TIPSS placement and its positioning compared to standard guiding methods. MATERIALS AND METHODS In a prospective, randomized, consecutive study design from 2015 to 2017, we included 21 patients in the CBCT guided group and 15 patients in the ultrasound (US) guided group. The prospective groups were compared in terms of success rate of intervention, portal vein puncture/procedure time, number of puncture attempts and applied dose. We furthermore retrospectively analyzed the last 23 consecutive cases with fluoroscopic guided portal vein puncture in terms of success rate, procedure time and applied dose, as it has been the standard method before US guidance. RESULTS The median number of puncture attempts (CBCT: n = 2, US: n = 4, p = 0.249) and the mean puncture time (CBCT: 32 ± 45 min, US: 36 ± 45 min, p = 0.515) were not significantly different. There were furthermore no significant differences in the mean time needed for the total TIPSS procedure (CBCT: 115 ± 52 min, US: 112 ± 41 min, fluoroscopy: 110 ± 33 min, p = 0.996). The mean applied dose of the complete procedure also showed no statistically significant differences (CBCT: 563 ± 289 Gy·cm2, US: 322 ± 186 Gy·cm2, fluoroscopy: 469 ± 352 Gy·cm2, p = 0.069). There were no image guidance related complications. CONCLUSION Real-time 3-D needle guidance based on CBCT is feasible for TIPSS placement. In terms of puncture attempts, duration and dose, CBCT guidance was not inferior to the control groups and may be a valuable support for interventionists in TIPSS procedures.
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Affiliation(s)
- Georg Böning
- Department of Radiology, Charité - Universitätsmedizin Berlin, Augustenburger Platz 1, 13353, Berlin, Germany.
| | - Willie M Lüdemann
- Department of Radiology, Charité - Universitätsmedizin Berlin, Augustenburger Platz 1, 13353, Berlin, Germany
| | - Julius Chapiro
- Department of Radiology and Biomedical Imaging, Yale School of Medicine, 330 Cedar St, New Haven, CT, 06520, USA
| | - Martin Jonczyk
- Department of Radiology, Charité - Universitätsmedizin Berlin, Augustenburger Platz 1, 13353, Berlin, Germany
| | - Bernd Hamm
- Department of Radiology, Charité - Universitätsmedizin Berlin, Augustenburger Platz 1, 13353, Berlin, Germany
| | - Rolf W Günther
- Department of Radiology, Charité - Universitätsmedizin Berlin, Augustenburger Platz 1, 13353, Berlin, Germany
| | - Bernhard Gebauer
- Department of Radiology, Charité - Universitätsmedizin Berlin, Augustenburger Platz 1, 13353, Berlin, Germany
| | - Florian Streitparth
- Department of Radiology, Charité - Universitätsmedizin Berlin, Augustenburger Platz 1, 13353, Berlin, Germany
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Yang CC, Yu PC, Ruan JM, Chen YC. Optimizing the target detectability of cone beam CT performed in image-guided radiation therapy for patients of different body sizes. J Appl Clin Med Phys 2018. [PMID: 29516610 PMCID: PMC5978665 DOI: 10.1002/acm2.12306] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Purpose The target detectability of cone beam computed tomography (CBCT) performed in image‐guided radiation therapy (IGRT) was investigated to achieve sufficient image quality for patient positioning over a course of treatment session while maintaining radiation exposure from CBCT imaging as low as reasonably achievable (ALARA). Methods Body CBCT scans operated in half‐fan mode were acquired with three different protocols: CBCTlowD, CBCTmidD, and CBCThighD, which resulted in weighted CT dose index (CTDIw) of 0.36, 1.43, and 2.78 cGy, respectively. An electron density phantom that is 18 cm in diameter was covered by four layers of 2.5‐cm‐thick bolus to simulate patients of different body sizes. Multivariate analysis was used to examine the impact of body size, radiation exposure, and tissue type on the target detectability of CBCT imaging, quantified as contrast‐to‐noise ratio (CNR). Results CBCTmidD allows sufficient target detection of adipose, breast, muscle, liver in a background of water for normal‐weight adults with cross‐sectional diameter less than 28 cm, while CBCThighD is suitable for adult patients with larger body sizes or body mass index over 25 kg/m2. Once the cross‐sectional diameter of adult patients is larger than 35 cm, the CTDIw of CBCT scans should be higher than 2.78 cGy to achieve required CNR. As for pediatric and adolescent patients with cross‐sectional diameter less than 25 cm, CBCTlowD is able to produce images with sufficient target detection. Conclusion The target detectability of soft tissues in default CBCT scans may not be sufficient for overweight or obese adults. Contrary, pediatric and adolescent patients would receive unnecessarily high radiation exposure from default CBCT scans. Therefore, the selection of acquisition parameters for CBCT scans optimized according to patient body size was proposed to ensure sufficient image quality for daily patient positioning in radiation therapy while achieving the ALARA principle.
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Affiliation(s)
- Ching-Ching Yang
- Department of Medical Imaging and Radiological Sciences, Tzu-Chi University of Science and Technology, Hualien, Taiwan
| | - Pei-Chieh Yu
- Department of Radiation Oncology, Cathay General Hospital, Taipei, Taiwan.,School of Medicine, China Medical University, Taichung, Taiwan
| | - Jau-Ming Ruan
- Department of Radiation Oncology, Cathay General Hospital, Taipei, Taiwan
| | - Yu-Cheng Chen
- Department of Radiation Oncology, Cathay General Hospital, Taipei, Taiwan
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Shkumat NA, Shroff MM, Muthusami P. Radiation Dosimetry of 3D Rotational Neuroangiography and 2D-DSA in Children. AJNR Am J Neuroradiol 2018; 39:727-733. [PMID: 29496725 DOI: 10.3174/ajnr.a5568] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2017] [Accepted: 12/28/2017] [Indexed: 11/07/2022]
Abstract
BACKGROUND AND PURPOSE The benefit-risk assessment concerning radiation use in pediatric neuroangiography requires an extensive understanding of the doses delivered. This work evaluated the effective dose of 3D rotational angiography in a cohort of pediatric patients with complex neurovascular lesions and directly compared it with conventional 2D-biplane DSA. MATERIALS AND METHODS Thirty-three 3D rotational angiography acquisitions were acquired in 24 pediatric patients (mean age, 10.4 years). When clinically indicated, following 2D-biplane DSA, 3D rotational angiography was performed with 1 of 3 technical protocols (2 subtracted, 1 unsubtracted). The protocols consisted of 1 factory and 2 customized techniques, with images subsequently reconstructed into CT volumes for clinical management. Raw projections and quantitative dose metrics were evaluated, and the effective dose was calculated. RESULTS All 3D rotational angiography acquisitions were of diagnostic quality and assisted in patient management. The mean effective doses were 0.5, 0.12, and 0.06 mSv for the factory-subtracted, customized-subtracted, and customized-unsubtracted protocols, respectively. The mean effective dose for 2D-biplane DSA was 0.9 mSv. A direct intraprocedural comparison between 3D and 2D acquisitions indicated that customized 3D rotational angiography protocols delivered mean relative doses of 9% and 15% in unsubtracted and subtracted acquisitions, respectively, compared with biplane DSA, whereas the factory subtracted protocol delivered 68%. CONCLUSIONS In pediatric neuroangiography, the effective dose for 3D rotational angiography can be significantly lower than for 2D-biplane DSA and can be an essential adjunct in the evaluation of neurovascular lesions. Additionally, available 3D rotational angiography protocols have significant room to be tailored for effectiveness and dose optimization, depending on the clinical question.
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Affiliation(s)
- N A Shkumat
- From the Department of Diagnostic Imaging (N.A.S., M.M.S., P.M.), The Hospital for Sick Children, Toronto, Ontario, Canada .,Department of Medical Imaging (N.A.S., M.M.S., P.M.), University of Toronto, Toronto, Ontario, Canada
| | - M M Shroff
- From the Department of Diagnostic Imaging (N.A.S., M.M.S., P.M.), The Hospital for Sick Children, Toronto, Ontario, Canada.,Department of Medical Imaging (N.A.S., M.M.S., P.M.), University of Toronto, Toronto, Ontario, Canada
| | - P Muthusami
- From the Department of Diagnostic Imaging (N.A.S., M.M.S., P.M.), The Hospital for Sick Children, Toronto, Ontario, Canada.,Department of Medical Imaging (N.A.S., M.M.S., P.M.), University of Toronto, Toronto, Ontario, Canada
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Xu J, Hwang S, Lee H, Chin H. Relationship of renal morphology on 3-dimensional ultrasonography with renal pathologic findings and outcome in biopsy-proven nephropathy. Exp Ther Med 2017; 15:2088-2096. [DOI: 10.3892/etm.2017.5626] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2017] [Accepted: 10/19/2017] [Indexed: 11/05/2022] Open
Affiliation(s)
- Jianwei Xu
- Department of Internal Medicine, 12303 Seoul National University Bundang Hospital, Seongnam, Gyeonggi 13620, Republic of Korea
| | - Sung Hwang
- Department of Radiology, 12303 Seoul National University Bundang Hospital, Seongnam, Gyeonggi 13620, Republic of Korea
| | - Hak Lee
- Department of Radiology, 12303 Seoul National University Bundang Hospital, Seongnam, Gyeonggi 13620, Republic of Korea
| | - Ho Chin
- Department of Internal Medicine, 12303 Seoul National University Bundang Hospital, Seongnam, Gyeonggi 13620, Republic of Korea
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Abstract
There are several special situations in which urinary lithiasis presents management challenges to the urologist. An in-depth knowledge of the pathophysiology, unique anatomy, and treatment options is crucial in order to maintain good health in these patients. In this review, we summarize the current literature on the management of the following scenarios: bladder stones, stones in bowel disease, during pregnancy, in association with renal anomalies, with skeletal deformities, in urinary diversions, and in children.
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Eslami E, Barkhordar H, Abramovitch K, Kim J, Masoud MI. Cone-beam computed tomography vs conventional radiography in visualization of maxillary impacted-canine localization: A systematic review of comparative studies. Am J Orthod Dentofacial Orthop 2017; 151:248-258. [DOI: 10.1016/j.ajodo.2016.07.018] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2015] [Revised: 07/01/2016] [Accepted: 07/01/2016] [Indexed: 11/25/2022]
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Kim S, Alaei P. Implementation of full/half bowtie filter models in a commercial treatment planning system for kilovoltage cone-beam CT dose estimations. J Appl Clin Med Phys 2016; 17:153-164. [PMID: 27074480 PMCID: PMC5874958 DOI: 10.1120/jacmp.v17i2.5988] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2015] [Revised: 12/03/2015] [Accepted: 11/30/2015] [Indexed: 11/23/2022] Open
Abstract
The purpose of this study was to implement full/half bowtie filter models in a com-mercial treatment planning system (TPS) to calculate kilovoltage (kV) cone-beam CT (CBCT) doses of Varian On-Board Imager (OBI) kV X-ray imaging system. The full/half bowtie filter models were created as compensators in Pinnacle TPS using MATLAB software. The physical profiles of both bowtie filters were imported and hard-coded in the MATLAB system. Pinnacle scripts were written to import bowtie filter models into Pinnacle treatment plans. Bowtie filter-free kV X-ray beam models were commissioned and the bowtie filter models were validated by analyzing the lateral and percent-depth-dose (PDD) profiles of anterior/posterior X-ray beams in water phantoms. A CT dose index (CTDI) phantom was employed to calculate CTDI and weighted CTDI values for pelvis and pelvis-spotlight CBCT protocols. A five-year-old pediatric anthropomorphic phantom was utilized to evaluate absorbed and effective doses (ED) for standard and low-dose head CBCT protocols. The CBCT dose calculation results were compared to ion chamber (IC) and Monte Carlo (MC) data for the CTDI phantom and MOSFET and MC results for the pediatric phantom, respectively. The differences of lateral and PDD profiles between TPS calculations and IC measurements were within 6%. The CTDI and weighted CTDI values of the TPS were respectively within 0.25 cGy and 0.08 cGy compared to IC measurements. The absorbed doses ranged from 0 to 7.22 cGy for the standard dose CBCT and 0 to 1.56 cGy for the low-dose CBCT. The ED values were found to be 36-38 mSv and 7-8 mSv for the standard and low-dose CBCT protocols, respectively. This study demonstrated that the established full/half bowtie filter beam models can produce reasonable dose calculation results. Further study is to be performed to evaluate the models in clinical situations.
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Woldu SL, Thoreson GR, Okhunov Z, Ghandour R, Rothberg MB, RoyChoudhury A, Kim HH, Bozoghlanian M, Newhouse JH, Helmy MA, Badani KK, Landman J, Cadeddu JA, McKiernan JM. Comparison of Renal Parenchymal Volume Preservation Between Partial Nephrectomy, Cryoablation, and Radiofrequency Ablation Using 3D Volume Measurements. J Endourol 2015; 29:948-55. [DOI: 10.1089/end.2014.0866] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
Affiliation(s)
- Solomon L. Woldu
- Department of Urology, Columbia University Medical Center, New York, New York
| | - Gregory R. Thoreson
- Department of Urology, University of Texas Southwestern Medical Center, Dallas, Texas
| | - Zhamshid Okhunov
- Department of Urology, University of California Irvine Medical Center, Irvine, California
| | - Rashed Ghandour
- Department of Urology, Columbia University Medical Center, New York, New York
| | - Michael B. Rothberg
- Department of Urology, Columbia University Medical Center, New York, New York
| | - Arindam RoyChoudhury
- Department of Biostatistics, Columbia University Medical Center, New York, New York
| | - Helen H.R. Kim
- Department of Radiology, University of California Irvine Medical Center, Irvine, California
| | - Mari Bozoghlanian
- Department of Radiology, University of California Irvine Medical Center, Irvine, California
| | - Jeffrey H. Newhouse
- Department of Radiology, Columbia University Medical Center, New York, New York
| | - Mohammad A. Helmy
- Department of Radiology, University of California Irvine Medical Center, Irvine, California
| | - Ketan K. Badani
- Department of Urology, Columbia University Medical Center, New York, New York
| | - Jamie Landman
- Department of Urology, University of California Irvine Medical Center, Irvine, California
| | - Jeffrey A. Cadeddu
- Department of Urology, University of Texas Southwestern Medical Center, Dallas, Texas
| | - James M. McKiernan
- Department of Radiology, University of California Irvine Medical Center, Irvine, California
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Koivisto JH, Wolff JE, Kiljunen T, Schulze D, Kortesniemi M. Characterization of MOSFET dosimeters for low-dose measurements in maxillofacial anthropomorphic phantoms. J Appl Clin Med Phys 2015; 16:266–278. [PMID: 26219008 PMCID: PMC5690001 DOI: 10.1120/jacmp.v16i4.5433] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2014] [Revised: 03/10/2015] [Accepted: 03/14/2015] [Indexed: 11/23/2022] Open
Abstract
The aims of this study were to characterize reinforced metal-oxide-semiconductor field-effect transistor (MOSFET) dosimeters to assess the measurement uncertainty, single exposure low-dose limit with acceptable accuracy, and the number of exposures required to attain the corresponding limit of the thermoluminescent dosimeters (TLD). The second aim was to characterize MOSFET dosimeter sensitivities for two dental photon energy ranges, dose dependency, dose rate dependency, and accumulated dose dependency. A further aim was to compare the performance of MOSFETs with those of TLDs in an anthropomorphic phantom head using a dentomaxillofacial CBCT device. The uncertainty was assessed by exposing 20 MOSFETs and a Barracuda MPD reference dosimeter. The MOSFET dosimeter sensitivities were evaluated for two photon energy ranges (50-90 kVp) using a constant dose and polymethylmethacrylate backscatter material. MOSFET and TLD comparative point-dose measurements were performed on an anthropomorphic phantom that was exposed with a clinical CBCT protocol. The MOSFET single exposure low dose limit (25% uncertainty, k = 2) was 1.69 mGy. An averaging of eight MOSFET exposures was required to attain the corresponding TLD (0.3 mGy) low-dose limit. The sensitivity was 3.09 ± 0.13 mV/mGy independently of the photon energy used. The MOSFET dosimeters did not present dose or dose rate sensitivity but, however, presented a 1% decrease of sensitivity per 1000 mV for accumulated threshold voltages between 8300 mV and 17500 mV. The point doses in an anthropomorphic phantom ranged for MOSFETs between 0.24 mGy and 2.29 mGy and for TLDs between 0.25 and 2.09 mGy, respectively. The mean difference was -8%. The MOSFET dosimeters presented statistically insignificant energy dependency. By averaging multiple exposures, the MOSFET dosimeters can achieve a TLD-comparable low-dose limit and constitute a feasible method for diagnostic dosimetry using anthropomorphic phantoms. However, for single in vivo measurements (<1.7 mGy) the sensitivity is too low.
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Kornerup JS, Brodin P, Birk Christensen C, Björk-Eriksson T, Kiil-Berthelsen A, Borgwardt L, Munck Af Rosenschöld P. Use of PET/CT instead of CT-only when planning for radiation therapy does not notably increase life years lost in children being treated for cancer. Pediatr Radiol 2015; 45:570-81. [PMID: 25378209 DOI: 10.1007/s00247-014-3197-4] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/16/2013] [Revised: 07/03/2014] [Accepted: 08/13/2014] [Indexed: 01/09/2023]
Abstract
BACKGROUND PET/CT may be more helpful than CT alone for radiation therapy planning, but the added risk due to higher doses of ionizing radiation is unknown. OBJECTIVE To estimate the risk of cancer induction and mortality attributable to the [F-18]2-fluoro-2-deoxyglucose (FDG) PET and CT scans used for radiation therapy planning in children with cancer, and compare to the risks attributable to the cancer treatment. MATERIALS AND METHODS Organ doses and effective doses were estimated for 40 children (2-18 years old) who had been scanned using PET/CT as part of radiation therapy planning. The risk of inducing secondary cancer was estimated using the models in BEIR VII. The prognosis of an induced cancer was taken into account and the reduction in life expectancy, in terms of life years lost, was estimated for the diagnostics and compared to the life years lost attributable to the therapy. Multivariate linear regression was performed to find predictors for a high contribution to life years lost from the radiation therapy planning diagnostics. RESULTS The mean contribution from PET to the effective dose from one PET/CT scan was 24% (range: 7-64%). The average proportion of life years lost attributable to the nuclear medicine dose component from one PET/CT scan was 15% (range: 3-41%). The ratio of life years lost from the radiation therapy planning PET/CT scans and that of the cancer treatment was on average 0.02 (range: 0.01-0.09). Female gender was associated with increased life years lost from the scans (P < 0.001). CONCLUSION Using FDG-PET/CT instead of CT only when defining the target volumes for radiation therapy of children with cancer does not notably increase the number of life years lost attributable to diagnostic examinations.
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Affiliation(s)
- Josefine S Kornerup
- Section of Radiotherapy, Department of Oncology, Rigshospitalet, Blegdamsvej 9, 2100, Copenhagen, Denmark,
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Dosimetric feasibility of magnetic resonance imaging-guided tri-cobalt 60 preoperative intensity modulated radiation therapy for soft tissue sarcomas of the extremity. Pract Radiat Oncol 2015; 5:350-356. [PMID: 25749215 DOI: 10.1016/j.prro.2015.01.007] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2014] [Revised: 12/08/2014] [Accepted: 01/19/2015] [Indexed: 11/20/2022]
Abstract
PURPOSE The purpose of this study was to investigate the dosimetric differences of delivering preoperative intensity modulated radiation therapy (IMRT) to patients with soft tissue sarcomas of the extremity (ESTS) with a teletherapy system equipped with 3 rotating (60)Co sources and a built-in magnetic resonance imaging and with standard linear accelerator (LINAC)-based IMRT. METHODS AND MATERIALS The primary study population consisted of 9 patients treated with preoperative radiation for ESTS between 2008 and 2014 with LINAC-based static field IMRT. LINAC plans were designed to deliver 50 Gy in 25 fractions to 95% of the planning target volume (PTV). Tri-(60)Co system IMRT plans were designed with ViewRay system software. RESULTS Tri-(60)Co-based IMRT plans achieved equivalent target coverage and dosimetry for organs at risk (long bone, skin, and skin corridor) compared with LINAC-based IMRT plans. The maximum and minimum PTV doses, heterogeneity indices, and ratio of the dose to 50% of the volume were equivalent for both planning systems. One LINAC plan violated the maximum bone dose constraint, whereas none of the tri-(60)Co plans did. CONCLUSIONS Using a tri-(60)Co system, we were able to achieve equivalent dosimetry to the PTV and organs at risk for patients with ESTS compared with LINAC-based IMRT plans. The tri-(60)Co system may be advantageous over current treatment platforms by allowing PTV reduction and by elimination of the additional radiation dose associated with daily image guidance, but this needs to be evaluated prospectively.
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Zhang H, Ouyang L, Huang J, Ma J, Chen W, Wang J. Few-view cone-beam CT reconstruction with deformed prior image. Med Phys 2014; 41:121905. [DOI: 10.1118/1.4901265] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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Effect of dose reduction on image registration and image quality for cone-beam CT in radiotherapy. Strahlenther Onkol 2014; 191:192-200. [DOI: 10.1007/s00066-014-0750-x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2014] [Accepted: 09/02/2014] [Indexed: 10/24/2022]
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Koivisto J, Schulze D, Wolff J, Rottke D. Effective dose assessment in the maxillofacial region using thermoluminescent (TLD) and metal oxide semiconductor field-effect transistor (MOSFET) dosemeters: a comparative study. Dentomaxillofac Radiol 2014; 43:20140202. [PMID: 25143020 PMCID: PMC4240264 DOI: 10.1259/dmfr.20140202] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2014] [Revised: 07/11/2014] [Accepted: 08/19/2014] [Indexed: 11/05/2022] Open
Abstract
OBJECTIVES The objective of this study was to compare the performance of metal oxide semiconductor field-effect transistor (MOSFET) technology dosemeters with thermoluminescent dosemeters (TLDs) (TLD 100; Thermo Fisher Scientific, Waltham, MA) in the maxillofacial area. METHODS Organ and effective dose measurements were performed using 40 TLD and 20 MOSFET dosemeters that were alternately placed in 20 different locations in 1 anthropomorphic RANDO(®) head phantom (the Phantom Laboratory, Salem, NY). The phantom was exposed to four different CBCT default maxillofacial protocols using small (4 × 5 cm) to full face (20 × 17 cm) fields of view (FOVs). RESULTS The TLD effective doses ranged between 7.0 and 158.0 µSv and the MOSFET doses between 6.1 and 175.0 µSv. The MOSFET and TLD effective doses acquired using four different (FOV) protocols were as follows: face maxillofacial (FOV 20 × 17 cm) (MOSFET, 83.4 µSv; TLD, 87.6 µSv; -5%); teeth, upper jaw (FOV, 8.5 × 5.0 cm) (MOSFET, 6.1 µSv; TLD, 7.0 µSv; -14%); tooth, mandible and left molar (FOV, 4 × 5 cm) (MOSFET, 10.3 µSv; TLD, 12.3 µSv; -16%) and teeth, both jaws (FOV, 10 × 10 cm) (MOSFET, 175 µSv; TLD, 158 µSv; +11%). The largest variation in organ and effective dose was recorded in the small FOV protocols. CONCLUSIONS Taking into account the uncertainties of both measurement methods and the results of the statistical analysis, the effective doses acquired using MOSFET dosemeters were found to be in good agreement with those obtained using TLD dosemeters. The MOSFET dosemeters constitute a feasible alternative for TLDs for the effective dose assessment of CBCT devices in the maxillofacial region.
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Affiliation(s)
- J Koivisto
- 1 Department of Physics, University of Helsinki, Helsinki, Finland
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Yan H, Zhen X, Cerviño L, Jiang SB, Jia X. Progressive cone beam CT dose control in image-guided radiation therapy. Med Phys 2014; 40:060701. [PMID: 23718579 DOI: 10.1118/1.4804215] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
PURPOSE Cone beam CT (CBCT) in image-guided radiotherapy (IGRT) offers a tremendous advantage for treatment guidance. The associated imaging dose is a clinical concern. One unique feature of CBCT-based IGRT is that the same patient is repeatedly scanned during a treatment course, and the contents of CBCT images at different fractions are similar. The authors propose a progressive dose control (PDC) scheme to utilize this temporal correlation for imaging dose reduction. METHODS A dynamic CBCT scan protocol, as opposed to the static one in the current clinical practice, is proposed to gradually reduce the imaging dose in each treatment fraction. The CBCT image from each fraction is processed by a prior-image based nonlocal means (PINLM) module to enhance its quality. The increasing amount of prior information from previous CBCT images prevents degradation of image quality due to the reduced imaging dose. Two proof-of-principle experiments have been conducted using measured phantom data and Monte Carlo simulated patient data with deformation. RESULTS In the measured phantom case, utilizing a prior image acquired at 0.4 mAs, PINLM is able to improve the image quality of a CBCT acquired at 0.2 mAs by reducing the noise level from 34.95 to 12.45 HU. In the synthetic patient case, acceptable image quality is maintained at four consecutive fractions with gradually decreasing exposure levels of 0.4, 0.1, 0.07, and 0.05 mAs. When compared with the standard low-dose protocol of 0.4 mAs for each fraction, an overall imaging dose reduction of more than 60% is achieved. CONCLUSIONS PINLM-PDC is able to reduce CBCT imaging dose in IGRT utilizing the temporal correlations among the sequence of CBCT images while maintaining the quality.
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Affiliation(s)
- Hao Yan
- Center for Advanced Radiotherapy Technologies and Department of Radiation Medicine and Applied Sciences, University of California San Diego, La Jolla, California 92037-0843, USA
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Oh JS, Koea JB. Radiation risks associated with serial imaging in colorectal cancer patients: Should we worry? World J Gastroenterol 2014; 20:100-109. [PMID: 24415862 PMCID: PMC3885998 DOI: 10.3748/wjg.v20.i1.100] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/28/2013] [Revised: 07/31/2013] [Accepted: 08/09/2013] [Indexed: 02/06/2023] Open
Abstract
To provide an overview of the radiation related cancer risk associated with multiple computed tomographic scans required for follow up in colorectal cancer patients. A literature search of the PubMed and Cochrane Library databases was carried out and limited to the last 10 years from December 2012. Inclusion criteria were studies where computed tomographic scans or radiation from other medical imaging modalities were used and the risks associated with ionizing radiation reported. Thirty-six studies were included for appraisal with no randomized controlled trials. Thirty-four of the thirty-six studies showed a positive association between medical imaging radiation and increased risk of cancer. The radiation dose absorbed and cancer risk was greater in children and young adults than in older patients. Most studies included in the review used a linear, no-threshold model to calculate cancer risks and this may not be applicable at low radiation doses. Many studies are retrospective and ensuring complete follow up on thousands of patients is difficult. There was a minor increased risk of cancer from ionizing radiation in medical imaging studies. The radiation risks of low dose exposure (< 50 milli-Sieverts) are uncertain. A clinically justified scan in the context of colorectal cancer is likely to provide more benefits than harm but current guidelines for patient follow up will need to be revised to accommodate a more aggressive approach to treating metastatic disease.
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Fahimian BP, Zhao Y, Huang Z, Fung R, Mao Y, Zhu C, Khatonabadi M, DeMarco JJ, Osher SJ, McNitt-Gray MF, Miao J. Radiation dose reduction in medical x-ray CT via Fourier-based iterative reconstruction. Med Phys 2013; 40:031914. [PMID: 23464329 DOI: 10.1118/1.4791644] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
PURPOSE A Fourier-based iterative reconstruction technique, termed Equally Sloped Tomography (EST), is developed in conjunction with advanced mathematical regularization to investigate radiation dose reduction in x-ray CT. The method is experimentally implemented on fan-beam CT and evaluated as a function of imaging dose on a series of image quality phantoms and anonymous pediatric patient data sets. Numerical simulation experiments are also performed to explore the extension of EST to helical cone-beam geometry. METHODS EST is a Fourier based iterative algorithm, which iterates back and forth between real and Fourier space utilizing the algebraically exact pseudopolar fast Fourier transform (PPFFT). In each iteration, physical constraints and mathematical regularization are applied in real space, while the measured data are enforced in Fourier space. The algorithm is automatically terminated when a proposed termination criterion is met. Experimentally, fan-beam projections were acquired by the Siemens z-flying focal spot technology, and subsequently interleaved and rebinned to a pseudopolar grid. Image quality phantoms were scanned at systematically varied mAs settings, reconstructed by EST and conventional reconstruction methods such as filtered back projection (FBP), and quantified using metrics including resolution, signal-to-noise ratios (SNRs), and contrast-to-noise ratios (CNRs). Pediatric data sets were reconstructed at their original acquisition settings and additionally simulated to lower dose settings for comparison and evaluation of the potential for radiation dose reduction. Numerical experiments were conducted to quantify EST and other iterative methods in terms of image quality and computation time. The extension of EST to helical cone-beam CT was implemented by using the advanced single-slice rebinning (ASSR) method. RESULTS Based on the phantom and pediatric patient fan-beam CT data, it is demonstrated that EST reconstructions with the lowest scanner flux setting of 39 mAs produce comparable image quality, resolution, and contrast relative to FBP with the 140 mAs flux setting. Compared to the algebraic reconstruction technique and the expectation maximization statistical reconstruction algorithm, a significant reduction in computation time is achieved with EST. Finally, numerical experiments on helical cone-beam CT data suggest that the combination of EST and ASSR produces reconstructions with higher image quality and lower noise than the Feldkamp Davis and Kress (FDK) method and the conventional ASSR approach. CONCLUSIONS A Fourier-based iterative method has been applied to the reconstruction of fan-bean CT data with reduced x-ray fluence. This method incorporates advantageous features in both real and Fourier space iterative schemes: using a fast and algebraically exact method to calculate forward projection, enforcing the measured data in Fourier space, and applying physical constraints and flexible regularization in real space. Our results suggest that EST can be utilized for radiation dose reduction in x-ray CT via the readily implementable technique of lowering mAs settings. Numerical experiments further indicate that EST requires less computation time than several other iterative algorithms and can, in principle, be extended to helical cone-beam geometry in combination with the ASSR method.
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Affiliation(s)
- Benjamin P Fahimian
- Department of Radiation Oncology, Stanford University, Stanford, California 94305, USA
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Page M, Florescu C, Johnstone L, Habteslassie D, Ditchfield M. Paediatric urological investigations--dose comparison between urology-related and CT irradiation. Pediatr Radiol 2013; 43:846-50. [PMID: 23381302 DOI: 10.1007/s00247-013-2635-z] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/07/2012] [Revised: 12/04/2012] [Accepted: 12/19/2012] [Indexed: 01/02/2023]
Abstract
BACKGROUND Urological investigation in children frequently involves high radiation doses; however, the issue of radiation for these investigations receives little attention compared with CT. OBJECTIVE To compare the radiation dose from paediatric urological investigations with CT, which is commonly regarded as the more major source of radiation exposure. MATERIALS AND METHODS We conducted a retrospective audit in a tertiary paediatric centre of the number and radiation dose of CT scans, micturating cystourethrography exams and urological nuclear medicine scans from 2006 to 2011. This was compared with radiation doses in the literature and an audit of the frequency of these studies in Australia. RESULTS The tertiary centre audit demonstrated that the ratio of the frequency of urological to CT examinations was 0.8:1 in children younger than 17 years. The ratio of the radiation dose of urological to CT examinations was 0.7:1. The ratio in children younger than 5 years was 1.9:1. In Australia the frequency of urological procedures compared with CT was 0.4:1 in children younger than 17 years and 3.1:1 in those younger than 5 years. The ratio of radiation-related publications was 1:9 favouring CT. CONCLUSION The incidence and radiation dose of paediatric urological studies is comparable to those of CT. Nevertheless the radiation dose of urological procedures receives considerably less attention in the literature.
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Affiliation(s)
- Mark Page
- Diagnostic Imaging, Southern Health, 246 Clayton Road, Melbourne, Australia, 3168
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Sykes JR, Lindsay R, Iball G, Thwaites DI. Dosimetry of CBCT: methods, doses and clinical consequences. ACTA ACUST UNITED AC 2013. [DOI: 10.1088/1742-6596/444/1/012017] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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Koivisto J, Kiljunen T, Tapiovaara M, Wolff J, Kortesniemi M. Assessment of radiation exposure in dental cone-beam computerized tomography with the use of metal-oxide semiconductor field-effect transistor (MOSFET) dosimeters and Monte Carlo simulations. Oral Surg Oral Med Oral Pathol Oral Radiol 2013; 114:393-400. [PMID: 22862982 DOI: 10.1016/j.oooo.2012.06.003] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2012] [Revised: 05/28/2012] [Accepted: 06/01/2012] [Indexed: 10/28/2022]
Abstract
OBJECTIVES The aims of this study were to assess the organ and effective dose (International Commission on Radiological Protection (ICRP) 103) resulting from dental cone-beam computerized tomography (CBCT) imaging using a novel metal-oxide semiconductor field-effect transistor (MOSFET) dosimeter device, and to assess the reliability of the MOSFET measurements by comparing the results with Monte Carlo PCXMC simulations. STUDY DESIGN Organ dose measurements were performed using 20 MOSFET dosimeters that were embedded in the 8 most radiosensitive organs in the maxillofacial and neck area. The dose-area product (DAP) values attained from CBCT scans were used for PCXMC simulations. The acquired MOSFET doses were then compared with the Monte Carlo simulations. RESULTS The effective dose measurements using MOSFET dosimeters yielded, using 0.5-cm steps, a value of 153 μSv and the PCXMC simulations resulted in a value of 136 μSv. CONCLUSIONS The MOSFET dosimeters placed in a head phantom gave results similar to Monte Carlo simulations. Minor vertical changes in the positioning of the phantom had a substantial affect on the overall effective dose. Therefore, the MOSFET dosimeters constitute a feasible method for dose assessment of CBCT units in the maxillofacial region.
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Affiliation(s)
- J Koivisto
- Department of Physics, University of Helsinki, Helsinki, Finland.
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Roihuvuo-Leskinen H, Lahdes-Vasama T, Niskanen K, Rönnholm K. The association of adult kidney size with childhood vesicoureteral reflux. Pediatr Nephrol 2013; 28:77-82. [PMID: 22932995 DOI: 10.1007/s00467-012-2274-x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/01/2011] [Revised: 06/21/2012] [Accepted: 07/03/2012] [Indexed: 12/13/2022]
Abstract
BACKGROUND We used ultrasound to measure kidney volumes in adults with a history of childhood vesicoureteral reflux (VUR) and assessed whether total renal volume, small kidney size or the thickness of the upper pole correlated with renal function or hypertension. METHODS The kidneys of 123 adults were studied by ultrasound, calculating their volumes using an ellipsoid formula normalised to body surface area (Vol(N)). The thickness of the upper pole parenchyma and the number of small kidneys (<80% of normal volume) were recorded. Blood pressure measurements and laboratory tests were also performed. RESULTS Kidneys with a history of VUR were 12% smaller than those without known VUR (p < 0.05), and those with prior dilating VUR were 16% smaller than those with non-dilating VUR (p < 0.05). There was a moderate correlation (r = 0.42, p < 0.05) between total Vol(N) and GFR values in the total patient series. Thirteen percent of the patients had a moderate decrease in kidney function. The occurrence of hypertension and proteinuria was not affected by either kidney size or a thin upper pole. CONCLUSIONS Total Vol(N) in ultrasound in early adulthood could probably predict possible renal deterioration in later life. The occurrence of one small kidney was a common finding and seemed not to affect the prevalence of proteinuria or hypertension.
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Affiliation(s)
- Hanna Roihuvuo-Leskinen
- Department of Pediatric Surgery, Tampere University Hospital, PSHP, L09b, P.O. Box 2000, 33521 Tampere, Finland.
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Qiu Y, Moiseenko V, Aquino-Parsons C, Duzenli C. Equivalent doses for gynecological patients undergoing IMRT or RapidArc with kilovoltage cone beam CT. Radiother Oncol 2012; 104:257-62. [DOI: 10.1016/j.radonc.2012.07.007] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2011] [Revised: 07/05/2012] [Accepted: 07/08/2012] [Indexed: 11/17/2022]
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Yan H, Cervino L, Jia X, Jiang SB. A comprehensive study on the relationship between the image quality and imaging dose in low-dose cone beam CT. Phys Med Biol 2012; 57:2063-80. [PMID: 22459913 DOI: 10.1088/0031-9155/57/7/2063] [Citation(s) in RCA: 63] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
While compressed sensing (CS)-based algorithms have been developed for the low-dose cone beam CT (CBCT) reconstruction, a clear understanding of the relationship between the image quality and imaging dose at low-dose levels is needed. In this paper, we qualitatively investigate this subject in a comprehensive manner with extensive experimental and simulation studies. The basic idea is to plot both the image quality and imaging dose together as functions of the number of projections and mAs per projection over the whole clinically relevant range. On this basis, a clear understanding of the tradeoff between the image quality and imaging dose can be achieved and optimal low-dose CBCT scan protocols can be developed to maximize the dose reduction while minimizing the image quality loss for various imaging tasks in image-guided radiation therapy (IGRT). Main findings of this work include (1) under the CS-based reconstruction framework, image quality has little degradation over a large range of dose variation. Image quality degradation becomes evident when the imaging dose (approximated with the x-ray tube load) is decreased below 100 total mAs. An imaging dose lower than 40 total mAs leads to a dramatic image degradation, and thus should be used cautiously. Optimal low-dose CBCT scan protocols likely fall in the dose range of 40-100 total mAs, depending on the specific IGRT applications. (2) Among different scan protocols at a constant low-dose level, the super sparse-view reconstruction with the projection number less than 50 is the most challenging case, even with strong regularization. Better image quality can be acquired with low mAs protocols. (3) The optimal scan protocol is the combination of a medium number of projections and a medium level of mAs/view. This is more evident when the dose is around 72.8 total mAs or below and when the ROI is a low-contrast or high-resolution object. Based on our results, the optimal number of projections is around 90 to 120. (4) The clinically acceptable lowest imaging dose level is task dependent. In our study, 72.8 mAs is a safe dose level for visualizing low-contrast objects, while 12.2 total mAs is sufficient for detecting high-contrast objects of diameter greater than 3 mm.
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Affiliation(s)
- Hao Yan
- Center for Advanced Radiotherapy Technologies and Department of Radiation Medicine and Applied Sciences, University of California, San Diego, La Jolla, CA 92037-0843, USA
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Stock M, Palm A, Altendorfer A, Steiner E, Georg D. IGRT induced dose burden for a variety of imaging protocols at two different anatomical sites. Radiother Oncol 2012; 102:355-63. [DOI: 10.1016/j.radonc.2011.10.005] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2011] [Revised: 09/23/2011] [Accepted: 10/16/2011] [Indexed: 10/15/2022]
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Zanca F, Demeter M, Oyen R, Bosmans H. Excess radiation and organ dose in chest and abdominal CT due to CT acquisition beyond expected anatomical boundaries. Eur Radiol 2011; 22:779-88. [DOI: 10.1007/s00330-011-2332-y] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2011] [Revised: 09/12/2011] [Accepted: 09/18/2011] [Indexed: 10/15/2022]
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Chang ML, Hou JK. Cancer risk related to gastrointestinal diagnostic radiation exposure. Curr Gastroenterol Rep 2011; 13:449-457. [PMID: 21833692 DOI: 10.1007/s11894-011-0214-8] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Exposure to ionizing radiation is associated with an increased risk of cancer. With the growing use of diagnostic imaging studies, there is concern for increasing the risk of radiation associated malignancy of the gastrointestinal tract. The purpose of this review is to summarize the existing literature for risk of gastrointestinal malignancy after ionizing radiation exposure from diagnostic imaging studies. Estimates of organ specific effective doses of radiation vary widely based on the method of measurement and patient factors. Most of the current data are based on calculations of organ effective doses from anthropomorphic phantoms and estimated cancer risk based on radiation exposure from environmental sources. Radiation associated cancer risk is dependent on both the cumulative radiation dose and the radiosensitivity of the particular organ. The majority of radiation exposure and risk associated with gastrointestinal malignancy comes from CT scans, especially of the abdomen/pelvis. Of the abdominal organs, the colon carries the highest lifetime attributable risk of radiation associated malignancy. The attributable risk of malignancy for an individual diagnostic imaging study is low, but measurable, and therefore imaging studies without radiation such as MRI and ultrasound should be considered, especially in patients who require repeated imaging studies. There is a shortage of epidemiological data and an absence of prospective data with adequate follow-up to describe accurate risk estimates of gastrointestinal cancers after diagnostic imaging. More studies are needed to better determine the risks of malignancy from diagnostic imaging.
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Affiliation(s)
- Mimi L Chang
- Department of Medicine, Section of Gastroenterology and Hepatology, Baylor College of Medicine, 1709 Dryden Road, Suite 8.40, MS: BCM 620, Houston, TX 77030, USA
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Comparison of esophageal screen findings on videofluoroscopy with full esophagram results. Head Neck 2011; 34:264-9. [DOI: 10.1002/hed.21727] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/14/2010] [Indexed: 11/07/2022] Open
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