The Use of Rectal Balloon During the Delivery of Intensity Modulated Radiotherapy (IMRT) for Prostate Cancer

• DOI: 10.1097/00130404-200211000-00012
• Publication Date: 2008-05-04T08:52:34Z
• Authors: Bin S. Teh; John E. McGary; Lei Dong; Wei-Yuan Mai; L. Steve Carpenter; Hsin H. Lu; J. Kam Chiu; Shiao Y. Woo; Walter H. Grant; E. Brian Butler
• Keywords: Isocenter

PURPOSE The purpose of this study was to investigate the role a rectal balloon for prostate immobilization and toxicity reduction in patients receiving dose-escalated intensity-modulated radiotherapy cancer. PATIENTS AND METHODS Patients with localized cancer who were undergoing treated prone position, immobilized customized Vac-Lok bag (MED-TEC, Orange City, IA). A 100 cc air used immobilize prostate. displacements measured using computed tomography (CT)-CT fusion on 10 received radioactive seed implant before radiotherapy. They scanned twice weekly during 5 weeks radiotherapy, breathing studies also performed. Rectal evaluated by use Radiation Therapy Oncology Group scoring patients. mean dose 76 Gy over 35 fractions (2.17-Gy fraction size). Dose-volume histogram rectum assessed. film phantom constructed simulate 4-cm diameter cavity that created balloon. Kodak XV2 films (Rochester NY) measure compare distribution without cavity. 1.25 delivered at isocenter 15-MV photons NOMOS Peacock system MIMiC treatment delivery (Sewickley, PA). RESULTS anterior-posterior lateral minimal, order measurement uncertainty (∼1 mm). standard deviation superior-inferior displacement 1.78 mm. Breathing showed no organ normal when place. profile very favorable: 83% (83/100) had complaint, 11% 6% grade 1 2 toxicity, respectively. analysis revealed all patients, more than 25% 70 or greater. As visualized dosimetry, air-tissue interface approximately 15% lower an built up rapidly so mm, differential 8% 5%, dosimetric coverage depth posterior wall essentially equal, DISCUSSION significantly reduces motion. Prostate thus allows safer smaller planning target volume margin. It has helped spare anterior (by its effects) reduced high-dose radiation distension). All these factors may have further contributed decreased achieved despite escalation higher-than-conventional size.