Dosimetric comparison between intensity modulated radiotherapy and three-dimensional conformal radiotherapy in adjuvant setting after radical cystectomy in high-risk urothelial bladder cancer

Objective: To compare the 4-field 3D conformal radiotherapy technique (3DCRT) to the intensity-modulated radiotherapy (IMRT) 9-field technique for adjuvant radiotherapy post radical cystectomy in high-risk urothelial bladder cancer cases. Patients and Methods: A dosimetric analysis of 11 urothelial bladder cancer patients who underwent radical cystectomy was performed. These patients were presented to the radiotherapy department, National Cancer Institute, Cairo, between 2018 and 2020 with adjuvant radiotherapy using the IMRT technique. Two plans were designed for each patient, one using 9-field IMRT and the second using 4-field 3DCRT. The two techniques were compared, including the PTV, bowel bag, rectum, neobladder, and pelvic bone marrow. Results: Comparing different DVHs, the planning target volume (PTV) was adequately covered in both plans, while the 9-field IMRT technique delivered significantly lower doses to OARs (bowel, rectum, and pelvic bone marrow). Conclusion: The IMRT technique incredibly spared the OARs more than that obtained by the 3DCRT technique, while both techniques covered the PTV adequately. The IMRT technique, through sparing OARs, was expected to decrease early and late radiation side effects