Efficacy and Safety of Low-Dose Iodine Plaque Brachytherapy for Juxtapapillary Choroidal Melanoma.

PURPOSE: To evaluate low- vs high-dose plaque brachytherapy for juxtapapillary choroidal melanoma. DESIGN: Retrospective interventional case series. METHODS: Setting: Single institution. STUDY POPULATION: Forty-seven patients with juxtapapillary choroidal melanoma. INTERVENTION: Iodine-125 plaque brachytherapy. Eyes were divided into apex low-dose (LD) and high-dose (HD) groups (≤ or > median apex dose 84.35 Gy). Main outcome measures were time to distant failure, local failure, death, enucleation, radiation retinopathy, optic neuropathy, and best-corrected visual acuity (BCVA). RESULTS: Freedom from distant failure rates were 96% and 95% in apex LD and HD groups at 5 years and 77% and 95% at 10 years, respectively (P = .84). Freedom from local failure rates were 90% in the apex LD group vs 89% in the HD group at 5 and 10 years (P = .96). Apex LD and HD groups did not differ for time to death or enucleation. Five- and 10-year freedom from radiation retinopathy and optic neuropathy rates were higher in the apex LD than HD group. Loss of ≥3 BCVA lines, final BCVA 20/40 or better, and final BCVA 20/200 or worse were more favorable in the 5 mm LD compared to HD group. Visual acuity outcomes did not differ between apex LD and HD groups. CONCLUSIONS: Low-dose iodine-125 plaque brachytherapy (67.5-81 Gy at tumor apex) provides safe and effective tumor control for juxtapapillary choroidal melanoma and may be associated with reduced radiation toxicity. Larger trials are needed to determine the optimal therapeutic dose for juxtapapillary choroidal melanoma.

Uveal melanoma treated with iodine-125 episcleral plaque: an analysis of dose on disease control and visual outcomes.

PURPOSE: To investigate, in the treatment of uveal melanomas, how tumor control, radiation toxicity, and visual outcomes are affected by the radiation dose at the tumor apex. METHODS AND MATERIALS: A retrospective review was performed to evaluate patients treated for uveal melanoma with (125)I plaques between 1988 and 2010. Radiation dose is reported as dose to tumor apex and dose to 5 mm. Primary endpoints included time to local failure, distant failure, and death. Secondary endpoints included eye preservation, visual acuity, and radiation-related complications. Univariate and multivariate analyses were performed to determine associations between radiation dose and the endpoint variables. RESULTS: One hundred ninety patients with sufficient data to evaluate the endpoints were included. The 5-year local control rate was 91%. The 5-year distant metastases rate was 10%. The 5-year overall survival rate was 84%. There were no differences in outcome (local control, distant metastases, overall survival) when dose was stratified by apex dose quartile (<69 Gy, 69-81 Gy, 81-89 Gy, >89 Gy). However, increasing apex dose and dose to 5-mm depth were correlated with greater visual acuity loss (P=.02, P=.0006), worse final visual acuity (P=.02, P<.0001), and radiation complications (P<.0001, P=.0009). In addition, enucleation rates were worse with increasing quartiles of dose to 5 mm (P=.0001). CONCLUSIONS: Doses at least as low as 69 Gy prescribed to the tumor apex achieve rates of local control, distant metastasis-free survival, and overall survival that are similar to radiation doses of 85 Gy to the tumor apex, but with improved visual outcomes.

Commissioning of Varian ring & tandem HDR applicators: reproducibility and interobserver variability of dwell position offsets.

Studies have shown that source dwells within Varian's HDR CT/MR compatible ring applicators can deviate from intended positions by several millimeters. Quantifying this offset is an important part of commissioning. The aims of this study were to: 1) determine the reproducibility of the offset, 2) study the interobserver variation in the offset's measurement, and 3) quantify the dosimetric impact of the offset. Offsets were measured for four ring applicators: two 30°, one 45°, and one 60°. Dwell positions were measured five times for each ring to determine the reproducibility of source positioning. Experiments were done to compare two separate source wires, as well as different time points within a single source wire's lifecycle. Data were analyzed by three independent observers. To quantify the dosimetric impact of the offset, a treatment plan was generated using BrachyVision. The dose to point A, and the D(2cc) metric for rectum and bladder were calculated with and without the offset. For the 45° and 60° rings, measured offsets were 3.0 mm and 3.6 mm, respectively. The 30° ring showed substantial variation in distal dwell positions (maximum difference between the five experiments of 2.9 mm). Subsequent testing of a replacement ring showed an offset of 2.4 mm that was more reproducible. Offsets varied less than 1 mm between different source wires, and changed less than 1 mm over the course of a source wire's lifecycle. When comparing observers, the average range in a measurement of a dwell position was 0. 5 mm (σ = 0.2 mm, max 1.3 mm). The offset resulted in dose variations to point A, bladder, and rectum of less than 1%, 2%, and 5%, respectively. Results indicate that Varian rings can show systematic and random offsets of more than 3 mm. Some can be considered defective and should be replaced. Each applicator should be individually commissioned and reproducibility should be confirmed with multiple tests.

Renal shielding and dosimetry for patients with severe systemic sclerosis receiving immunoablation with total body irradiation in the scleroderma: cyclophosphamide or transplantation trial.

PURPOSE: To describe renal shielding techniques and dosimetry in delivering total body irradiation (TBI) to patients with severe systemic sclerosis (SSc) enrolled in a hematopoietic stem cell transplant protocol. METHODS AND MATERIALS: The Scleroderma: Cyclophosphamide or Transplantation (SCOT) protocol uses a lymphoablative preparative regimen including 800 cGy TBI delivered in two 200-cGy fractions twice a day before CD34(+) selected autologous hematopoietic stem cell transplantation. Lung and kidney doses are limited to 200 cGy to protect organs damaged by SSc. Kidney block proximity to the spinal cord was investigated, and guidelines were developed for acceptable lumbar area TBI dosing. Information about kidney size and the organ shifts from supine to standing positions were recorded using diagnostic ultrasound (US). Minimum distance between the kidney blocks (dkB) and the lumbar spine region dose was recorded, and in vivo dosimetry was performed at several locations to determine the radiation doses delivered. RESULTS: Eleven patients were treated at our center with an anteroposterior (AP)/posteroanterior (PA) TBI technique. A 10% to 20% dose inhomogeneity in the lumbar spine region was achieved with a minimum kidney block separation of 4 to 5 cm. The average lumbar spine dose was 179.6 ± 18.1 cGy, with an average dkB of 5.0 ± 1.0 cm. Kidney block shield design was accomplished using a combination of US and noncontrast computerized tomography (CT) or CT imaging alone. The renal US revealed a wide range of kidney displacement from upright to supine positions. Overall, the average in vivo dose for the kidney prescription point was 193.4 ± 5.1 cGy. CONCLUSIONS: The dose to the kidneys can be attenuated while maintaining a 10% to 20% dose inhomogeneity in the lumbar spine area. Kidneys were localized more accurately using both US and CT imaging. With this technique, renal function has been preserved, and the study continues to enroll patients.