High dose-rate brachytherapy of prostate cancer utilising Iridium-192 after-loading technique: Technical and methodological aspects

Abstract

Abstract. The aim of this study was to focus on certain characteristic problems associated with Iridium-192 high dose-rate brachytherapy in combination with external beam radiation therapy (EBRT) in the treatment of patients with localised prostate cancer. Over a period of 16 years, >2,000 patients with prostate cancer have been treated in Sweden with a combination of two fractions of 10 Gy Ir-192 HDR-BT and 50 Gy of fractionated EBRT. Although this treatment is usually well tolerated, there are biological and technical factors to be considered before and during the treatment of the patient to avoid side effects or under-treatment of the target volume. Some of the problems facing the doctors are transducer stability, needle deviation, target definition, target motion, pubic arch interference, concomitant diseases and tolerance doses for different organs at risk. These problems are discussed and possible solutions are presented in this study. IntroductionProstate cancer is the most common malignancy afflicting Swedish men (1,2). Annually, more than 9,000 new cases are diagnosed (3). Although health controls have been ardently discussed during recent years, no screening programmes have as yet been initiated in Scandinavia (4,5). Radiotherapy and radical prostatectomy are generally regarded as the two chief modalities suitable for curative intent treatment (6-12). The results of treatment by these modalities are equivalent, but the acute and long-term side effects which develop after the definitive treatment of prostate cancer differ. The main side effects after surgery are impotence and incontinence, while proctitis, colitis and cystitis are seen after radiotherapy (13).The advantage of brachytherapy (BT) is the short irradiation range. This minimises the dose to organs at risk in the neighbourhood of the target, even though therapy requires that the irradiation source is placed inside or very near the target.Prostate BT was first reported by Pasteau in 1911 (14). The complication rate was high, probably due to the application of the source through the urethra. In the years that followed, the treatment of prostate cancer has focused on radical prostatectomy and external beam radiation therapy (EBRT). However, two different techniques for obtaining a more homogeneous dose distribution in the prostate, which reduce the frequency of side effects, were reported by Flocks in 1964 (15), by Carlton (16) and by Whitmore et al in 1972 (17). These techniques utilized permanent implants of low doserate (LDR) Gold-198 and Iodine-125 isotopes, respectively. These reports resulted in a renaissance for prostate BT. In 1977, Court and Chassangne (18) began treating prostate cancer with after-loading techniques, and since then several reports have been published (13,14,(19)(20)(21)(22)(23)(24)(25)(26)(27)(28). Although the data presented were encouraging, no randomised study has been published, and there are criticisms concerning some of the BT treatment studies (29,30). Randomised clinical trials are planned by national groups...

The impact of prostate volume changes during external-beam irradiation in consequence of HDR brachytherapy in prostate cancer treatment

“…Until today, the best timing of HDR brachytherapy and external-beam irradiation in a combined-treatment setting remains unclear and there is still no consensus in the literature regarding the dosage of the external-beam radiotherapy, the number and dosage of the brachytherapy fractions, and the definition of the target volumes [2,3,8,[10][11][12][13]17].…”

Secondary malignancies following radiotherapy for prostate cancer

“…Brachytherapy, or interstitial radiation therapy, is an alternative treatment option for prostate cancer patients, particularly for those with lessaggressive features, although the role of brachytherapy still continues to evolve. Brachytherapy can be delivered by a variety of isotopes such as I-125 and Ir-192 [Henry et al 2010;Edgren et al 2006].…”

Gold marker displacement due to needle insertion during HDR-brachytherapy for treatment of prostate cancer: A prospective cone beam computed tomography and kilovoltage on-board imaging (kV-OBI) study

“…High-dose-rate (HDR)-brachytherapy is a highly precise option in prostate cancer treatment to deliver high doses of radiation to the prostate as a boost to percutaneous irradiation, as monotherapy in the primary treatment setting or as salvage therapy [6-16]. In the combined treatment setting various fractionation schedules and implant timing schedules of the HDR-brachytherapy have been described [17-21].…”