PII S0360-3016(99)00477-0 CLINICAL INVESTIGATION Prostate NEEDLE DISPLACEMENT DURING HDR BRACHYTHERAPY IN THE TREATMENT OF PROSTATE CANCER STEVEN J. DAMORE, M.D., A.M. NISAR SYED, M.D., F.R.C.S., 1 AJMEL A. PUTHAWALA, M.D., F.A.C.R., AND ANIL SHARMA,PH.D., D.R.P. Department of Radiation Oncology, Long Beach Memorial Medical Center, Long Beach, CA Purpose: We used clinical patient data to examine implant displacement between high dose rate (HDR) brachytherapy fractions for prostate cancer to determine its impact on treatment delivery. Materials and Methods: We analyzed the verification films taken prior to each fraction for 96 consecutive patients treated with HDR brachytherapy boosts as part of their radiation therapy for definitive treatment of organ-confined prostate cancer at our institution. Patients were treated with 18 –24 Gy in 4 fractions of HDR delivered in 40 hours followed by 36 –39.6 Gy external beam radiation to the prostate. We determined the mean and maximum displacement distances of marker seeds placed in the prostate and of the implanted needles between HDR fractions. Results: Mean and maximum displacement distances between fractions were documented up to 7.6 mm and 28.5 mm, respectively, for the implant needles and 3.6 mm and 11.4 mm, respectively, for the gold marker seeds. All displacement of implant needles occurred in the caudal direction. At least 1 cm caudal displacement of needles occurred prior to 15.5% all fractions. Manual adjustment of needles was required prior to 15% of fractions, and adjustment of the CLP only was required in 24%. Most of the displacement for both the marker seeds and needles occurred between the first and second fractions. Conclusions: There is significant caudal displacement of interstitial implant needles between HDR fractions in our prostate cancer patients. Obtaining verification films and making adjustments in the treatment volume prior to each fraction is necesary to avoid significant inaccuracies in treatment delivery. © 2000 Elsevier Science Inc. Prostate cancer, Brachytherapy, High dose rate, Interstitial implant. INTRODUCTION Brachytherapy is being used increasingly either as a boost treatment or as monotherapy in the treatment of organ- confined prostate cancer in the U.S. This has been made possible by advances in transrectal ultrasound-guided nee- dle placement and computer treatment planning systems, which have increased the accuracy and ease of source placement and dose distribution (1–3). Several investigators have published results using permanent seed brachytherapy implants that compare well with prostatectomy and external beam radiation therapy for early, low-grade lesions (4 –9). Results for larger, more aggressive lesions with this modal- ity have been less impressive, making proper patient selec- tion a requirement for successful permanent seed brachy- therapy (6,10). At Long Beach Memorial Medical Center, we have integrated transperineal temporary interstitial im- plants using Ir-192 in the management of prostate cancer for the last 20 years. In our experience, advantages of tempo- rary interstitial implants over permanent seed implants in- clude the ability to implant the entire circumference of the prostate gland (including the proximal seminal vesicles, the base of the prostate, and any extracapsular extension), en- compass larger tumors, and precisely conform the dose distribution to the gland and the tumor with relatively ho- mogeneous coverage of the target volume (11,12). These may translate into a higher probability of delivering a tu- moricidal dose and minimizing the risk of complications, especially for large tumors that invade the capsule and seminal vesicles. Ir-192 also delivers a higher dose rate than I-125 and Paladium-103, avoiding the potential decreased efficacy in the treatment of high-grade lesions inherent with lower dose rate permanent seed implants. Our results and technique using low dose rate Ir-192 temporary implants have been published elsewhere (13–16). Recent technological advances have made the use of high dose rate (HDR) radiation more precise and appealing. HDR brachytherapy uses dosimetric optimization to achieve dose distributions that are more conformal than low dose rate temporary implants or external beam therapy, thus minimiz- ing dose to normal tissues. Our dose optimization technique Reprint requests to: Steven J. Damore, M.D., Department of Radiation Oncology, Long Beach Memorial Medical Center, 2801 Atlantic Avenue, Long Beach, CA 90806. Tel: (562) 933-0300; Fax: (562) 933-0301; E-mail: sjdamore@memnet.org 1 Senior Author: A.M. Nisar Syed, M.D.; Tel: (562) 933-0300. Accepted for publication 14 October 1999. Int. J. Radiation Oncology Biol. Phys., Vol. 46, No. 5, pp. 1205–1211, 2000 Copyright © 2000 Elsevier Science Inc. Printed in the USA. All rights reserved 0360-3016/00/$–see front matter 1205