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Evaluation of a two-dimensional small field measurement array for stereotactic radiotherapy plan quality assurance
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J. Gao   , H. Wei , X. Nie , J. Yang , S. Zhang , H. Li , Z. Liang |
| Cancer Center, Hubei Key Laboratory of Precision Radiation Oncology, Institute of Radiation Oncology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei 430022, China , 987542214@qq.com |
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Abstract: (14 Views) |
Background: This study aimed to assess a two dimensional (2D) small field detector array for quality assurance (QA) in stereotactic radiotherapy (SRT), verify its key dosimetric properties, and evaluate its clinical performance for patient specific SRT plan verification. Materials and Methods: The myQA® SRS system comprises a 140 × 120 mm CMOS detector matrix with 400μm resolution, housed in a cylindrical ABS phantom. Tests included dose linearity, field size dependence, and beam angular response; clinical utility was validated via patient specific measurements. The detector’s sensitivity to deliberately introduced MLC positional shifts was also examined by simulating systematic MLC offsets and comparing measured doses with planned values. Results: The basic characteristic test of the detector met the recommended specifications. The maximum deviation in detector signal relative to baseline readings was 0.5 %. The detector exhibited excellent dose linearity (R² = 1). Output factors agreed within 1.5 % compared with ionization chamber (IC) measurements for field sizes above 1 cm. Angular dependence was evaluated by comparing calculated and measured relative doses, and a lookup table (LUT) was established and validated. For clinical patient plans, the detector yielded an average gamma pass rate of 97.8 % ± 1.3 % under the 3 %/1 mm criterion. The detector was sensitive to systematic MLC offsets larger than 0.2 mm at 3 %/1 mm. Conclusion: The myQA® SRS detector is validated as a reliable tool for stereotactic radiotherapy plan QA, capable of providing high resolution real time dosimetric results. |
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| Keywords: Radiometry, quality assurance, stereotactic body radiotherapy, stereotactic radiosurgery. |
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Full-Text [PDF 1210 kb]
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Type of Study: Original Research |
Subject:
Radiation Biology
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