Dosimetric comparison of organs at risk with three-dimensional conformal radiation, intensity-modulated radiation and volumetric-modulated arc therapy in cervical cancer: a cross sectional study

Abstract

Three-dimensional conformal radiation therapy (3DCRT), intensity-modulated radiation therapy (IMRT) and volumetric-modulated arc therapy (VMAT) are the three main radiotherapy treatment techniques for cervical cancer. Whether either technique significantly reduces the radiation exposure to organs at risk remains unclear. We dosimetrically compared the irradiated volumes of bone marrow, bladder and rectum in cervical cancer patients using 3DCRT, IMRT and VMAT techniques in those patients with FIGO stage IIIB cervical cancer, receiving chemo irradiation at our institute. A total of 10 patients were dosimetrically compared. Significant reduction in V10, V20, V30, V40, V50 Gy of bone marrow was observed with IMRT and VMAT when compared to 3DCRT. Similar results were seen with V20, V30, V40, V50 Gy of bladder, and V40, V50 Gy of rectum. While comparing IMRT and VMAT, statistically significant dose reduction was noted in V20 Gy of bone marrow and V20 and V30 Gy of bladder with VMAT. When compared with 3DCRT the use of IMRT and/or VMAT reduced the radiation exposure to bone marrow, bladder, and rectum volumes at various radiation dose levels. VMAT can further reduce the radiation exposure to bone marrow and bladder when compared with IMRT. Thus, we propose the use of VMAT in cervical cancer to reduce the OAR toxicities.

Dosimetric comparison of irradiated small bowel volume with intensity modulated radiotherapy and volumetric modulated arc therapy in adjuvant pelvic radiation therapy for endometrial carcinoma

“…2 The change in treatment technique from two dimensional radiotherapy (2DRT) to three dimensional conventional radiotherapy (3DCRT) to IMRT and VMAT have led to reduction in acute and late small bowel toxicities. [7][8][9] In majority of the studies which used inverse planning, instead of individual SB loops, entire peritoneal cavity which includes SB and surrounding peritoneal space was contoured and constraints were given to BB which resulted in reducing acute and late bowel toxicity. [6][7][8] Though QUANTEC recommended SB V15 Gy <120 cc for <10% of acute grade 3 toxicity, most of the centres and clinical trials used to contour BB and gave QUANTEC recommendation of BB V45 Gy <195 cc.…”