(Sunday, 7/14/2019)
Room: ePoster Forums
Purpose: This study a) compares the delivery quality assurance (DQA) results of commercially available dosimetric systems (ionization chamber and EBT film, MapCHECK, ArcCHECK, and dosimetry check [DC] software) for helical tomotherapy (HT) cases, and b) investigates the feasibility of pretreatments using the MapCHECK, ArcCHECK, and DC for HT instead of using ionization chambers and EBT films.
Methods: Sixty-five HT-treated patients were considered. Absolute point dose differences, profiles, and gamma passing rates evaluated agreements between calculated and measured data, and allowed comparisons of the outcomes of the four DQA devices in various clinical cases. Gamma analyses were performed based on the 3%/3-mm and 2%/2-mm criteria. Pearson correlation coefficients (r) were calculated between plan parameters and either absolute point dose differences or gamma passing rates.
Results: The calculated and measured point doses were within ±5%. On average, the gamma passing rates of the four tested DQA devices were >94% (3%/3 mm) and >81% (2%/2 mm). Strongest correlations were observed for: a) absolute point dose differences and plan parameters (ion chamber measurement and field width, r = -0.882 and p = 0.000 in brain cases), b) gamma passing rates and plan parameters (DC measurements in spine cases with 2%/2 mm (r = -0.861, p = 0.001), and ArcCHECK measurements and the modulation factor in spine cases with 3%/3 mm (r = -0.786, p = 0.004).
Conclusion: We showed that the MapCHECK, ArcCHECK, and DC systems are suitable patient-specific QA compared to film dosimetry systems for DQA in HT.
Keywords
Quality Assurance, Radiation Detectors, Tomotherapy
Taxonomy
TH- External beam- photons: Quality Assurance - IMRT
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