Abstract

Background: Prostate cancer (PC) is the second most frequent malignancy in men beyond lung cancer. Modern radiation therapy techniques employ over 3D conformal radiotherapy has been widely used now a day.

Objectives: The study aimed to compare between hypofractionated radiotherapy with conventional radiotherapy in prostate cancer using VMAT technique and to investigate the dose delivered to organs at risk in prostate cancer treated with conventional and hypofractionated VMAT techniques.

Method: A prospective clinical and dosimetric study in radiotherapy, medical physics, and dosimetry. Forty patients diagnosed with proven PC will be treat with the VMAT technique. Two prescribed dose methods used for each patient, the first method is the conventional fractionation as VMAT-SEQ with a prescribed dose of 78 Gy delivered in 39 sessions (2 Gy per session), and the second method is the hypofractionated dose as VMAT-SIB with a prescribed dose of 60 Gy in 20 sessions (3 Gy per session).

Results: Forty patients with PC, the mean age (±SD) was 60.45 years (±8.77). The mean dose of rectum in sequential group was greater than SIB group with no significant difference (p=0.055). Regarding doses distribution at V80, V60 of rectum, the mean of sequential group was much lower than SIB group with a high significant difference (p<0.0001), while at V40 of rectum, the mean of sequential group was greater than SIB group with a high significant difference (p<0.0001). Regarding dose distribution at V45 of bowel, the mean of sequential group was greater than SIB group with a high significant difference (p<0.0001).

Conclusion: The SIB deliver lower doses to rectum, bladder, head of femurs, bowel and penile bulb than sequential planning. Hypofractionated achieve better PTV coverage, improved the dosimetry and decline the dose delivery time for targets. SIB Hypofractionated RT produce better coverage to the targets and better protection of OARs.