Source displacement during the cardiac cycle in coronary endovascular brachytherapy.

PURPOSE: Preliminary clinical trials employing catheter-based endovascular brachytherapy show promising results in reducing restenosis after coronary intervention. Failure analysis of these studies showed a significant number of failures at the treatment margin. It is hypothesized that one of the possible causes for marginal failure is the longitudinal seed movement during the brachytherapy procedure. In this study a quantitative analysis was performed to determine the magnitude of the source displacement during the cardiac cycle. METHODS AND MATERIALS: Cine-angiograms of the Iridium-192 (Ir-192) active source seeds or dummy source seeds in place were reviewed frame by frame for 30 patients enrolled from various clinical trials using the Cordis catheter delivery system with a Ir-192 seed ribbon. The proximal and distal source points were measured in reference to branching vessels closest to the respective seed during the contrast phase of the cine-angiogram. The two frames showing the maximum source displacement were captured. After appropriate demagnification, longitudinal source displacement was measured. The data were tabulated for proximal vs. distal ends and for different coronary vessels. RESULTS: The longitudinal source displacement is significant with overall mean and standard deviation of 1.1 and 0.8 mm, respectively. The range is from 0.0 to 5.4 mm. CONCLUSION: The contribution of source movement should be included into the treatment length to avoid "geographic miss" and the subsequent marginal failure.

High dose rate transperineal interstitial brachytherapy for cervical cancer: high pelvic control and low complication rates.

PURPOSE: To report the clinical outcome for cervical carcinoma treated with external beam pelvic radiotherapy and interstitial high dose rate (IS-HDR) brachytherapy. METHODS AND MATERIALS: Between July 1991 and June 1996, 62 patients with locally advanced stage cervical carcinoma or early stage carcinoma that precluded satisfactory tandem and ovoid insertion were treated. Most patients received 36 Gy (range: 25 Gy-45 Gy) external beam radiotherapy (EBRT) to the pelvis prior to brachytherapy implant. EBRT was continued, with central shielding, to a dose of 50 Gy to the pelvic sidewalls. HDR Iridium-192 brachytherapy was given in 6 fractions of 5.5 to 6.0 Gy. The mean follow-up was 40 months. RESULTS: Stage distribution was: Stage IB (12), Stage IIA (1), Stage IIB (26), Stage IIIA (6), Stage IIIB (13), and Stage IVA (4). The overall local tumor control was 94%. Local control rates by FIGO stage were Stage I (12/12) 100%, Stage II (25/27) 93%, Stage III (18/19) 95%, and Stage IV (3/4) 75%. The regional pelvic control rates were overall 81%, Stage I (12/12) 100%, Stage II (22/27) 81%, Stage III (15/19) 79%, and Stage IV (1/4) 25%. Distant metastasis developed in 20 patients (32%). The actuarial 5-year disease-free survival was for all patients 48%, Stage I 81%, Stage II 47%, Stage III 39%, and Stage IV O%. Grade 3-4 delayed morbidity resulting from treatment, occurred in 6.5% (4/62) of patients. A fistula without local recurrence occurred in 1.6% (1/62) patients. CONCLUSIONS: We report excellent local and regional pelvic control results using a 6 fraction IS-HDR brachytherapy protocol for cervical carcinoma. The incidence of severe complications is low and suggests that a consistent brachytherapy technique and multiple HDR fractions are therapeutically advantageous to patients treated for cervical carcinoma.