Comparison of Organs at Risk Dose in Conventional (2-Dimensional) and Conformal (3-Dimensional) Radiotherapy of Seminoma

The aim of this study was to predict and compare the dose received by normal critical organs in radiotherapy of stage one seminoma in conventional (2-dimensional or 2D) and conformal (3-dimensional or 3D) methods.
Conventional treatment was designed based on bony anatomy, and conformal treatment based on vessels and nodal anatomy, for 10 patients with 6-MV photon and total dose of 25 Gy. Dose distribution of inside and outside of field was measured (with the profiler system) and calculated (with a treatment planning system).
Findings: Mean received dose was 5.58 and 7.16, 20.67 and 19.29, 5.20 and 3.19, 9.73 and 6.43, 5.96 and 7.60 Gy for kidneys, pancreas, liver, stomach, and colon in conventional and conformal methods, respectively. For organs out of the field, mean received dose was 1.55 and 1.48 Gy for right and left kidneys in conventional and conformal methods, respectively. Moreover, the mean received dose by testis was 7 and 6 cGy in conventional and conformal methods, respectively.
In conformal treatment method, due to more accurate design of target volume, probability of recurrence was less, and the damage to kidneys and colon was predicted more.