Dose Comparison of Treatment Plans Using Different Ir-192 Sources and Treatment Planning Systems for Intracavitary HDR Brachytherapy / 의학물리

For HDR intracavitary brachytherapy with ovoids and a tandem, we compared the dose discrepancy of treatment plans using two different Ir-192 sources (microSelectron, Varian) and generated on two different treatment planning systems (PLATO, BrachyVision). The treatment plans of ten patient treated from Oct. 2007 to Jan. 2008 were selected for these comparisons. For the comparison of dose calculation using different sources, the average discrepancies were -0.91+/-0.09%, 0.27+/-0.07%, 0.22+/-0.39%, and 0.88+/-0.37% in total treatment time and at B-point and ICRU bladder and rectum reference point, respectively. Comparing the two systems, the average dose discrepancies between treatment planning programs were -0.22+/-0.42%, -0.25+/-0.29%, -0.23+/-0.63%, and -0.17+/-0.76%, and the average dose discrepancies between positioning methods (PLATO with film and BrachyVision with digitial image) were -0.61+/-0.59%, -0.77+/-0.45%, -0.72+/-1.70%, and 0.35+/-2.82% at A-point, B-point, and ICRU bladder and rectum reference points, respectively. The rectal dose discrepancies between two systems were reached 5.87%. The difference in the dwell position expected by each TPS are mainly affected by the differences in the positioning method in TPSs and have an effect on dose calculations of rectal and bladder located in AP direction.

Preliminary Results of Concurrent Chemotherapy and Radiation Therapy using High-dose-rate Brachytherapy for Cervical Cancer / 대한방사선종양학회지

PURPOSE: To determine the efficacy and safety of concurrent chemotherapy and radiation therapy with high-dose-rate brachytherapy for cervical cancer. MATERIALS AND METHODS: From January 2001 to December 2002, 30 patients with cervical cancer were treated with concurrent chemotherapy (cisplatin and 5-FU) and definitive radiation therapy. The median age was 58 (range 34~74) year old. The pathology of the biopsy sections was squamous cell carcinoma in 29 patients and one was adenocarcinoma. The distribution to FIGO staging system was as follows: stage IB, 7 (23%); IIA, 3 (10%); IIB, 12 (40%); IIIA, 3 (10%); IIIB, 5 (17%). All patients received pelvic external beam irradiation (EBRT) to a total dose of 45~50.4 Gy (median: 50.4 Gy) over 5~5.5 weeks. Ir-192 HDR intracavitary brachytherapy (ICBT) was given after a total dose of 41.4 Gy. HDR-ICBT was performed twice a week, with a fraction point A dose of 4 Gy and median dose to point A was 28 Gy (range: 16~32 Gy) in 7 fractions. The median cumulative biologic effective dose (BED) at point A (EBRT+ICBT) was 88 Gy10 (range: 77~94 Gy10). The median cumulative BED at ICRU 38 reference point (EBRT+ICBT) was 131 Gy3 (range: 122~140 Gy3) at point A, 109 Gy3 (range: 88~125 Gy3) at the rectum and 111 Gy3 (range: 91~123 Gy3) at the urinary bladder. Cisplatin (60 mg/m2) and 5-FU (1,000 mg/m2) was administered intravenously at 3 weeks interval from the first day of radiation for median 5 (range: 2~6) cycles. The assessment was performed at 1 month after completion of radiation therapy by clinical examination and CT scan. The median follow-up time was 36 months (range: 8~50 months). RESULTS: The complete response rate after concurrent chemoradiation therapy was 93.3%. The 3-yr actuarial pelvic control rate was 87% and 3-yr actuarial overall survival and disease-free survival rate was 93% and 87%, respectively. The local failure rate was 13% and distant metastatic rate was 3.3%. The crude rate of minor hematologic complications (RTOG grade 1-2) occurred in 3 patients (10%) and one patient had suffered from severe leukopenia (RTOG grade 4) during concurrent treatment. Acute minor enterocolitis (RTOG grade 1-2) occurred in 11 patients (37%) and one patient (3%) was suffered from colon perforation during radiation therapy. Late colitis of RTOG grade 1 occurred in 5 patients (15%). Acute cystitis of RTOG grade 1 occurred in 12 patients (40%) and late cystitis of RTOG grade 2 occurred in one patient (3%). No treatment related death was seen. CONCLUSION: The results of this study suggest that the concurrent chemoradiation therapy with HDR brachytherapy could be accepted as an effective and safe treatment for cervical cancer.

Independent Verification Program for High-Dose-Rate Brachytherapy Treatment Plans / 대한방사선종양학회지

PURPOSE: The planning of High-Dose-Rate (HDR) brachytherapy treatments are becoming individualized and more dependent on the treatment planning system. Therefore, computer software has been developed to perform independent point dose calculations with the integration of an isodose distribution curve display into the patient anatomy images. MATERIALS AND METHODS: As primary input data, the program takes patients' planning data including the source dwell positions, dwell times and the doses at reference points, computed by an HDR treatment planning system (TPS). Dosimetric calculations were performed in a 10x12x10 cm3 grid space using the Interstitial Collaborative Working Group (ICWG) formalism and an anisotropy table for the HDR Iridium-192 source. The computed doses at the reference points were automatically compared with the relevant results of the TPS. The MR and simulation film images were then imported and the isodose distributions on the axial, sagittal and coronal planes intersecting the point selected by a user were superimposed on the imported images and then displayed. The accuracy of the software was tested in three benchmark plans performed by Gamma-Med 12i TPS (MDS Nordion, Germany). Nine patients' plans generated by Plato (Nucletron Corporation, The Netherlands) were verified by the developed software. RESULTS: The absolute doses computed by the developed software agreed with the commercial TPS results within an accuracy of 2.8% in the benchmark plans. The isodose distribution plots showed excellent agreements with the exception of the tip region of the source's longitudinal axis where a slight deviation was observed. In clinical plans, the secondary dose calculations had, on average, about a 3.4% deviation from the TPS plans. CONCLUSION: The accurate validation of complicate treatment plans is possible with the developed software and the quality of the HDR treatment plan can be improved with the isodose display integrated into the patient anatomy information.

Remote After Loading HDR Brachytherapy for female Urethral Cancer / 대한치료방사선과학회지

In our institution, a 76-year-old woman with primary urethral carcinoma was treated with remote afterloading high dose rate (HDR) interstitial brachytherapy using micro selectron Ir-192. In this paper, authors described the technical aspect of remote afterloading HDR interstitial brachytherapy for female urethal cancer.