Defining the "Hostile Pelvis" for Intensity Modulated Radiation Therapy: The Impact of Anatomic Variations in Pelvic Dimensions on Dose Delivered to Target Volumes and Organs at Risk in Patients With High-Risk Prostate Cancer Treated With Whole Pelvic Rad

The aim of this study was to evaluate the impact of variations in pelvic dimensions on the dose delivered to the target volumes and the organs at risk (OARs) in patients with high-risk prostate cancer (PCa) to be treated with whole pelvic radiation therapy (WPRT) in an attempt to define the hostile pelvis in terms of intensity modulated radiation therapy (IMRT).

In 45 men with high-risk PCa to be treated with WPRT, the target volumes and the OARs were delineated, the dose constraints for the OARs were defined, and treatment plans were generated according to the Radiation Therapy Oncology Group 0924 protocol. Six dimensions to reflect the depth, width, and height of the bony pelvis were measured, and 2 indexes were calculated from the planning computed tomographic scans. The minimum dose (Dmin), maximum dose (Dmax), and mean dose (Dmean) for the target volumes and OARs and the partial volumes of each of these structures receiving a specified dose (VD) were calculated from the dose-volume histograms (DVHs). The data from the DVHs were correlated with the pelvic dimensions and indexes.

According to an overall hostility score (OHS) calculation, 25 patients were grouped as having a hospitable pelvis and 20 as having a hostile pelvis. Regarding the OHS grouping, the DVHs for the bladder, bowel bag, left femoral head, and right femoral head differed in favor of the hospitable pelvis group, and the DVHs for the rectum differed for a range of lower doses in favor of the hospitable pelvis group.

Pelvimetry might be used as a guide to define the challenging anatomy or the hostile pelvis in terms of treatment planning for IMRT in patients with high-risk PCa to be treated with WPRT.

International journal of radiation oncology, biology, physics. 2015 Mar 25 [Epub]

Eda Yirmibeşoğlu Erkal, Sinan Karabey, Ayşegül Karabey, Mutlu Hayran, Haldun Şükrü Erkal

Department of Radiation Oncology, Kocaeli University Faculty of Medicine, Kocaeli, Turkey. Electronic address: eyirmibesoglu@yahoo. com. , Department of Radiation Oncology, Kocaeli University Faculty of Medicine, Kocaeli, Turkey. , Department of Radiation Oncology, Kocaeli State Hospital, Kocaeli, Turkey. , Department of Preventive Oncology, Hacettepe University Cancer Institute, Ankara, Turkey. , Department of Radiation Oncology, Sakarya University Faculty of Medicine, Sakarya, Turkey.

PubMed

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