Usability and accuracy of high-resolution detectors for daily quality assurance for robotic radiosurgery

Current Directions in Biomedical Engineering

Poppe Björn¹  Stelljes Tenzin Sonam¹  Damme Marie-Christin²  Loutfi-Krauss Britta³  Ramm Ulla³  Siebert Frank-Andre⁴  Chan Mark KH⁴  Blanck Oliver⁴ 

[1] Carl von Ossietzky Universität, Universitätsklinik für Medizinische Strahlenphysik, Campus Pius Hospital, Georgstraße 12, 26121 Oldenburg, Germany;Technische Universität Ilmenau, Gustav-Kirchhoff-Platz 2, 98693 Ilmenau, Germany;Universitäts-klinikum Frankfurt, Klinik für Strahlentherapie und Onkologie, Theodor-Stern-Kai 7, 60590 Frankfurt, Germany;Universitätsklinikum Schleswig-Holstein, Klinik für Strahlentherapie, Arnold-Heller-Straße 3, 24105 Kiel, Germany;

关键词: cyberknife;    robotic radiosurgery;    automatic quality assurance;    high-resolution arrays;    gafchromic film;   

DOI  :  10.1515/cdbme-2017-0057

来源: DOAJ

【 摘 要 】

For daily CyberKnife QA a Winston-Lutz-Test (Automated-Quality-Assurance, AQA) is used to determine sub-millimeter deviations in beam delivery accuracy. This test is performed using gafchromic film, an extensive and user-dependent method requiring the use of disposables. We therefore analyzed the usability and accuracy of high-resolution detector arrays. We analyzed a liquid-filled ionization-chamber array (Octavius 1000SRS, PTW, Germany), which has a central resolution of 2.5mm. To test sufficient sensitivity, beam profiles with robot shifts of 0.1mm along the arrays' axes were measured. The detected deviation between the shifted and central profile were compared to the real robot's position. We then compared the results to the SRS-Profiler (SunNuclear, USA) with 4.0mm resolution and to the Nonius (QUART, Germany), a single-line diode detector with 2.8mm resolution. Finally, AQA variance and usability were analyzed performing a number of AQA tests over time, which required the use of specially designed fixtures for each array, and the results were compared to film. Concerning sensitivity, the 1000SRS detected the beam profile shifts with a maximum difference of 0.11mm (mean deviation = 0.03mm) compared to the actual robot shift. The Nonius and SRS-Profiler showed differences of up to 0.15mm and 0.69mm with mean deviation of 0.05mm and 0.18mm, respectively. Analyzing the variation of AQA results over time, the 1000SRS showed a comparable standard deviation to film (0.26mm vs. 0.18mm). The SRS-Profiler and the Nonius showed a standard deviation of 0.16mm and 0.24mm, respectively. The 1000SRS seems to provide equivalent accuracy and sensitivity to the gold standard film when performing daily AQA tests. Compared to other detectors in our study the sensitivity as well as the accuracy of the 1000SRS appears to be superior and more user-friendly. Furthermore, no significant modification of the standard AQA procedure is required when introducing 1000SRS for CyberKnife AQA.

【 授权许可】

Unknown