Maura Campitelli MD, Presenter: Nothing to Disclose

Chantal Dauphinot, Abstract Co-Author: Nothing to Disclose

Vincent Servois MD, Abstract Co-Author: Nothing to Disclose

Pascal Francois, Abstract Co-Author: Nothing to Disclose

Alexia Savignoni, Abstract Co-Author: Nothing to Disclose

Anne De La Rochefordiere, Abstract Co-Author: Nothing to Disclose

Corine Plancher, Abstract Co-Author: Nothing to Disclose

Severine Alran, Abstract Co-Author: Nothing to Disclose

Virginie Fourchotte, Abstract Co-Author: Nothing to Disclose

Paul Cottu, Abstract Co-Author: Nothing to Disclose

Purpose/Objective(s): To evaluate the dosimetric characteristics of intensity modulated radiotherapy, in comparison to 3-D conformal radiation therapy (3-D CRT), in the delivery of whole pelvic radiation therapy to patients with cervical cancer. Materials/Methods: Twelve women with cervical cancer undergoing intensity modulated whole pelvic radiation therapy (IM-WPRT) between September 2006 and September 2008 were selected for this analysis. Each patient underwent a planning CT scan and MRI in the supine position. Target volumes and organs at risk were contoured on matched images. The CTV consisted of the uterus/cervix, parametria, the whole vagina and the regional lymph nodes. The PTV was defined as the CTV with a 1-cm margin. The small bowel, bladder and rectum were considered for dosimetric evaluation. The median pelvic prescribed dose was 45 Gy [range 36-45], with the aim of covering 95% of the PTV with 95% of the prescription dose. Eight patients also received a pelvic boost (median dose 53 Gy [range 42-65]. A 5-field 20-MV, coplanar plan was created for both 3-D CRT and IMRT. They differed in gantry angles. Both plans were normalized to cover 100% of the PTV with the prescription dose. Dose volume histograms were created for the target volumes and the organs at risk, and used to compare both techniques. A Wilcoxon signed rank test was performed for statistical significance. Results: Mean doses to the OARs were all significantly lower in the IMRT plan than in 3-D CRT plan (p= 0.001). The median percent volumes of small bowel, rectum and bladder receiving the prescribed dose were 26.6% [range 0.90 - 83], 63% [range 6.5 - 95.2] and 94.6% [range 67.4 - 100] for IMRT and 39.5% [range 8 - 98.7], 92% [range 66 - 100] and 100% [range 93.2 - 100] for 3-D CRT. Concerning target coverage, no statistical differences were found in the median dose delivered to the 100% of the PTV between IMRT and 3-D CRT. IMRT median doses to the 95% of the PTV were lower than 3-D CRT (p= 0.01). However, for all the IMRT patients, the ICRU prescription criteria were respected. The maximal doses to the PTV were not statistically different between the two techniques. Conclusions: This was the first French comparative dosimetric study on IMRT in cervical cancer. We compared IMRT with a more conformal 5-field treatment plan instead of a four field box technique. Our results confirm that IMRT improves normal tissue sparing while providing similar target coverage than 3D-CRT, in cervical cancer patients. A phase 2 prospective trial will be undertaken to evaluate clinical outcomes in terms of local control and toxicities, when using IMRT.

Campitelli, M, Dauphinot, C, Servois, V, Francois, P, Savignoni, A, De La Rochefordiere, A, Plancher, C, Alran, S, Fourchotte, V, Cottu, P, Comparative Dosimetric Analysis of Intensity Modulated Whole Pelvic Radiation Therapy with 3-D Conformal Radiation Therapy for Cervical Cancer.  Radiological Society of North America 2009 Scientific Assembly and Annual Meeting, November 29 - December 4, 2009 ,Chicago IL. http://archive.rsna.org/2009/8500677.html