“…In general, overestimated dose for OARs brings the dose distributions to the safer side, however, underdosage of tumours may be a consequence if the OAR is directly adjacent to the planning target volume and unintendedly included in the high-dose region on the basis of an incorrectly-defined volume [18] . Furthermore, variations in rectum volumes and the impact on rectal toxicity modelling has been investigated in a retrospective study where the same rectum definition as used for our curated volumes was included as one of 13 investigated OAR definitions [21] . This study found that the more distinct differences in DVH shapes between the OAR definitions related to volumes of 60–110 cm 3 , mean doses of 35–50 Gy, and maximum doses of 70–73 Gy (n = 163; 3D-CRT primary and salvage prostate cancer treatments; prescribed dose = 67–76 Gy).…”