Strategies to tackle the challenges of external beam radiotherapy for liver tumors

Table 3 Summary of dose constraints by number of fractions

Organ at risk	3 fraction (RAS trial[102])	5 fraction (RTOG 1112[103])	QUANTEC (1.8-2 Gy per fraction)[104]	Toxicity
Liver excluding CTV	700 mL < 15 Gy	V 10 < 70%	D mean < 30 Gy	Radiation induced liver dysfunction
Esophagus	D 1 mL < 21 Gy	D 0.5 mL < 32 Gy	V 35 < 50%	Esophagitis
Stomach	D 1 mL < 21 Gy	D 0.5 mL < 30 Gy	D 100 < 35 Gy	Ulceration
Kidney	D 35% < 15 Gy	D mean < 10 Gy	D mean < 28 Gy (1.8-2 Gy per fraction)	Renal dysfunction
Bowel and duodenum	D 1 mL < 21 Gy	D 0.5 mL < 30 Gy	D 45 < 195 cc	Enteritis/fistula
Spinal cord	Dmax < 18 Gy	D 0.5 mL < 25 Gy	Dmax = 45	Myelopathy
Heart	D 1 mL, 30 Gy	D 30 mL < 30 Gy	V 25 < 10%	Pericarditis

CTV: Clinical target volume.