Software for Analysis Characteristics of Radiation Fields

Vysoká přesnost dodání předepsané dávky do cílového léčebného objemu tkáně je základním požadavkem všech radioterapeutických aplikací zdrojů ionizujícího záření. V rámci Systému řízení (dle zákona 263/2016 Sb.) musí mít každé radioterapeutické pracoviště vypracovány metodiky zkoušek provozní stálosti, které jsou posuzovány Státním úřadem pro jadernou bezpečnost (SÚJB). Pravidelné měření a hodnocení parametrů radiačního pole je součást zkoušek provozní stálosti lineárního urychlovače. V této diplomové práci se zabývám problematikou zkoušek provozní stálosti, které vychází z požadavků Onkologického oddělení Nemocnice České Budějovice a.s., konkrétně testování velikosti radiačního pole a koincidenci světelného / radiačního pole. Na základě analýzy charakteristik radiačních polí a dosavadních postupů měsíčních zkoušek je navržen software na automatizaci vyhodnocování měsíčních testů, které se vyhodnocují manuálně. Vytvořený software je následně testován na reálných datech a postupně začleněn do provozu.The high accuracy of delivery of the prescribed dose to the target therapeutic tissue volume is a basic requirement of all radioterapeutic applications of ionizing radiation sources. Within the framework of the Quality Assurance Program, each radiotherapeutic station must have operational stability testing methodology developed by the State Office for Nuclear Safety. Regular measurement and evaluation of the radiation field parameters is part of the linear accelerator operational stability tests. In this diploma thesis I deal with the issues of operational stability tests, which are based on requirements of the Department of Oncology of the hospital Nemocnice České Budějovice a.s., specially the radiation field size testing and coincidence of the light / radiation field. Based on analysis of characteristics radiation fields and the current procedures of monthly tests, software is designed to automate the evaluation of monthly tests that are evaluated manually. The created software is then tested on real data and gradually integrated into operation.450 - Katedra kybernetiky a biomedicínského inženýrstvívýborn

Analysis of lung tumor motion in a large sample: patterns and factors influencing precise delineation of internal target volume

Purpose/Objective To evaluate lung tumor motion during respiration and to describe factors affecting the range and variability of motion in patients treated with stereotactic ablative radiation therapy. Methods and Materials Log file analysis from online respiratory tumor tracking was performed in 145 patients. Geometric tumor location in the lungs, tumor volume and origin (primary or metastatic), sex, and tumor motion amplitudes in the superior-inferior (SI), latero-lateral (LL), and anterior-posterior (AP) directions were recorded. Tumor motion variability during treatment was described using intrafraction/interfraction amplitude variability and tumor motion baseline changes. Tumor movement dependent on the tumor volume, position and origin, and sex were evaluated using statistical regression and correlation analysis. Results After analysis of >500 hours of data, the highest rates of motion amplitudes, intrafraction/interfraction variation, and tumor baseline changes were in the SI direction (6.0 ± 2.2 mm, 2.2 ± 1.8 mm, 1.1 ± 0.9 mm, and −0.1 ± 2.6 mm). The mean motion amplitudes in the lower/upper geometric halves of the lungs were significantly different (P15 mm were observed only in the lower geometric quarter of the lungs. Higher tumor motion amplitudes generated higher intrafraction variations (R=.86, P3 mm indicated tumors contacting mediastinal structures or parietal pleura. On univariate analysis, neither sex nor tumor origin (primary vs metastatic) was an independent predictive factor of different movement patterns. Metastatic lesions in women, but not men, showed significantly higher mean amplitudes (P=.03) and variability (primary, 2.7 mm; metastatic, 4.9 mm; P=.002) than primary tumors. Conclusion Online tracking showed significant irregularities in lung tumor movement during respiration. Motion amplitude was significantly lower in upper lobe tumors; higher interfraction amplitude variability indicated tumors in contact with mediastinal structures, although adhesion to parietal pleura did not necessarily reduce tumor motion amplitudes. The most variable lung tumors were metastatic lesions in women.Web of Science96475875