Preliminary experience with intensity modulated radiation therapy for abdominopelvic tumor sites: a comparison with 3D radiotherapy plans

Purpose. To report our preliminary experience using intensity modulated radiation therapy (IMRT) in abdominopelvic tumors and to compare IMRT and three-dimensional conformal radiotherapy (3D-CRT) plans for various pelvic sites. Materials and methods. Nine IMRT procedures were performed in 8 patients between June 2000 and June 2001. Tumor diagnosis was rectal carcinoma in 5 (local relapses in 4 and primary in 1), prostate cancer in 2, soft tissue sarcoma in 1, and paravertebral relapse from endometrial carcinoma in 1. Six patients received concurrent chemotherapy. Exhaustive dosimetric verification was performed in all procedures. Results. Average fraction delivery lasted 30–45 minutes. Acute tolerance was excellent in all patients, with only one case of dermatitis grade 2 observed. Planning target volume coverage was satisfactory with a median of 101% (range 97–103). Planning comparison of 3D-CRT and IMRT revealed an ICRU point dose percentage for small bowel of 64% versus 42%, for bladder 78% versus 22%, for rectum 58% versus 29% and for spinal cord 34% versus 20%. Conclusions. This preliminary experience shows that, with IMRT, the median dose received by small bowel, bladder, rectum and spinal cord is substantially less than seen with 3D-CRT and should reduce the morbidity of abdominal-pelvic irradiation, thereby allowing delivery of a higher dose to the tumor.