ESTRO 37 Abstract book

ESTRO 37

S580

and 3 years. Acute toxicity was dermatitis G1 in 30% and G2 in 23%. Late effects were hypopigmentation or atrophy in 44.8%, telangiectasia in 20.6% and hyperpigmentation in 13.8%. Cosmetic outcome was registered in 25 cases, and it was considered good or excellent in 88%. Conclusion HDR contact brachytherapy is a good alternative to treat skin carcinomas on flat surfaces with good local control and acceptable cosmetic outcome. The hypofractionated scheme three times a week and right applicators tolerance, allows for a better compliance in elderly people. PO-1032 CT-guided interstitial BT of pulmonary malignomas. Retrospective analysis of 174 patients. P. Hass 1 , F. Sieber 1 , C. Willich 2 , M. Seidensticker 3 , T. Brunner 1 , J. Ricke 4 , K. Mohnike 5 1 University Hospital Magdeburg, Radiation Oncology, Magdeburg, Germany 2 University Hospital Jena, Radiation Oncology and Radiooncology, Jena, Germany 3 Ludwig-Maximilians-University, Clinical Radiology, Munich, Germany 4 Ludwig-Maximilians-University, Clinival Radiology, Munich, Germany 5 DTZ am Frankfurter Tor, Center for Radiology, Berlin, Germany Purpose or Objective Studies of recent years have shown that hypo- fractionated stereotactic radiation treatments of localized NSCLC and lung metastases can lead to high local control rates and thus also the chance to improve the overall prognosis. This study analyzed side effects and effectiveness as well as results of an alternative radiotherapeutic method. Material and Methods A retrospective analysis of 174 patients with metastases (156 patients, 89.6%) or primary NSCLC (18 patients, 10.4%) were treated with CT-guided interstitial HDR- brachytherapy (HDR-BT) in the period 03/2006-01/2015. A total of 359 lung malignomas were treated in 276 predominantly single-time brachytherapies. The number of malignomas ablated per single-time therapy was median 1 (1-7). Depending on the size of the lesion median 2 BT catheters (1-11) were administered. 56% of the metastatic patients suffered from a Colorectal Carcinoma (CRC), further 18% from renal cell carcinomas, mammary carcinomas and malignant melanomas. The tumor diameters varied between 5-134mm (median 18mm).The malignomas were irradiated with PTV enclosing single doses between 1.7-29.7 Gy (median 20.5 Gy). Patients received regular follow-up at intervals of 3, 6, 9 and 12 months after intervention, including contrast enhanced CT of the thorax. Side effects were recorded according to CTCAE criteria, survival data calculated using the Kaplan-Meier method. Results The local control rate (LCR) after 12 months was 77%, the 1-year overall survival (OS) 78%, the median OS 22.8 months.In the subgroup analysis, there are partially significant differences between the examined histological types (metastases of squamous cell carcinomas, adenocarcinomas, malignant melanomas, kidney cell carcinomas and other entities in the local control rate after 12 months (44%, 77%, 88%, 100%, 96%). As a result of the catheter application local bleeding occurred in 6 cases (2.2%, 1x °3 [CTCAE], promptly controlled by

Figure 2: Reconstructed prostate volume utilising an in- house automatic segmentation and rendering software

Conclusion BrachyView has demonstrated the reconstruction of 100% of the seeds for the LDR patient plan. Co-registration of seed positions and a 3D prostate volume has also been successful. 74% of the seed positions have been reconstructed within 1.5 mm of discrepancy and 95% within 2 mm. The larger discrepancies noted in the x direction can possibly be attributed to a slight rotation of the pinhole collimator. With the implementation of a system that can mechanically fix the TRUS and BrachyView probes to the same stager, it is expected current uncertainties will be minimised. PO-1031 High-dose-rate contact brachytherapy to treat skin carcinomas on flat surfaces J.L. Guinot 1 , M. Tamarit 1 , V. Gonzalez-Perez 2 , M. Peña 1 , L. Oliver 2 , M. Santos 1 , M. Tortajada 1 , L. Arribas 1 1 Fundación Instituto Valenciano de Oncologia, Department of Radiation Oncology, Valencia, Spain 2 Fundación Instituto Valenciano de Oncologia, Department of Radiation Physics, Valencia, Spain Purpose or Objective We present our results with Ir-192 high-dose-rate (HDR) contact brachytherapy (BT) to treat skin carcinomas on flat surfaces. Material and Methods From 2000 to 2016 forty two skin carcinomas in 39 patients were treated with HDR contact brachytherapy employing Freiburg flaps, or customised flaps with plastic tubes on bolus or wax moulds for the skull (Fig 1-2). Mean age was 80 years (range 64-103 years). BT was radical in 20 cases with a maximum tumour thickness of 3 mm; BT was adjuvant in 22 cases after surgery, due to a positive surgical margin in 11 cases, close margin ≤ 1mm in 6, perineural involvement in 4 cases and one with free margins but histology with areas of sarcomatoid carcinoma. Treatment included 26 cases of squamous cell carcinomas (SCC) 15 basal cell carcinoma (BCC) and one Merkel carcinoma. A fractionation of three times a week was chosen, at 3-4Gy per fraction to a total dose of 48-57 Gy in most cases. Large areas of the skull were treated at 2-2.5Gy daily. Prescription was at 3-4mm under the skin Two local recurrences appeared after a mean follow-up of 43 months. The 2 and 3-year actuarial local control rate was 96.6% and 92% (100% for adjuvant cases, and 92.2 and 85.7% for radical BT). No difference was found between SCC and BCC. Two cases of SCC presented regional failure, with 2 and 3-year actuarial regional control rate of 96.2% and 89.7% for SCC and 100% for BCC. Cause-specific survival was 96.6% and 91.7% at 2 surface. Results