MRI-Based Radiotherapy Planning to Reduce Rectal Dose in Excess of Tolerance

Table 1

Rectal volume exposed to high dose radiation.

	CT	MRI		value
Rx to prostate only
Median cc (IQR)
V70	9.3 (7.0, 10.2)	4.9 (4.1, 7.8)	2.1 (0.5, 5.3)	<0.001
V75	7.2 (5.6, 8.0)	3.8 (3.1, 5.7)	1.6 (0.7, 4.1)	<0.001
V80	4.0 (3.0, 4.8)	2.1 (1.5, 3.2)	0.9 (0.3, 2.6)	<0.001
Rx to prostate + 1 cm SVs
Median cc (IQR)
V70	10.9 (9.4, 11.6)	6.7 (5.4, 9.3)	2.7 (0.4, 5.2)	0.007
V75	8.5 (7.0, 9.1)	4.7 (4.1, 7.0)	1.7 (−0.1, 4.3)	0.005
V80	4.6 (3.7, 5.8)	2.7 (2.2, 4.3)	0.9 (0.2, 3.0)	0.003

V70, volume of organ that receives 70 Gy or higher; V75, volume of organ that receives 75 Gy or higher; V80, volume of organ that receives 80 Gy or higher; IQR, interquartile range; cc, cubic centimeters.