Small field output factor measurement and verification for CyberKnife robotic radiotherapy and radiosurgery system using 3D polymer gel, ionization chamber, diode, diamond and scintillator detectors, Gafchromic film and Monte Carlo simulation

Kafi, Abdullah Al; Arib, Mehenna; Moussa, A.; Alzorkany, F.; Shehadeh, Mamoun; Yusof, Mohd Fahmi Mohd; Moftah, Belal

doi:10.1016/j.apradiso.2022.110576

Cited by 2 publications

(6 citation statements)

References 100 publications

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“…Furthermore, Al Kafi et al demonstrated that PTW Diode (TM 60016), PTW Diamond (TM 60003), Exradin W1, and Exradin W2 detectors produced output factors with 1%−2% differences for nominal cone sizes between 0.5 and 5.0 cm. 20 In that study, the measured data were in good agreement with Monte Carlo simulated field output factors. Each radiation detection system that measures dosimetric parameters for small fields has advantages and limitations.…”

Section: Discussionsupporting

confidence: 57%

“…Previously, a few other groups have published small field dosimetry data with applications to radiosurgery. For CyberKnife system, Al Kafi et al concluded micro-ionization chambers, diodes, and scinsuitable for small field output factor measurements, 20 whereas Francescon et al demonstrated variations in output factors up to 9%, as measured by microchambers. 49 For the ZAP-X system, Weidlich et al showed that peripheral dose fall-off measurements depend on the type of detector used (e.g., microSilicon diode, microDiamond, film, etc.…”

Section: Discussionmentioning

confidence: 99%

“…20 These factors can cause variation in dose measurements (e.g., due to variations in measured output factors) of up to 30%, negatively impacting the overall treatment efficacy and patient safety. 20 To address the issue of accurate and consistent clinical reference dosimetry, several protocols have been developed over the years, including the widely adopted Task Group (TG) report TG-51, its predecessor TG-21, and TG-155 by the American Association of Physicists in Medicine (AAPM), as well as the Technical Report Series (TRS) TRS-398 from the International Atomic Energy Agency (IAEA), and TRS-483, a joint report from the AAPM and IAEA. [21][22][23][24][25] TG-51 is specifically for what are referred to as "standard" radiation fields, but TG-155 and TRS-483 can be applied to small field scenarios.…”

Section: Introductionmentioning

confidence: 99%

“…Common to all radiosurgical systems, small fields or field segments are used to deliver radiation. Determination of dose for small fields presents a significant technical challenge because of high‐dose gradients, lack of charged particle equilibrium, partial occlusion of the radiation source, and detector volume averaging effects 20 . These factors can cause variation in dose measurements (e.g., due to variations in measured output factors) of up to 30%, negatively impacting the overall treatment efficacy and patient safety 20 .…”

Section: Introductionmentioning

confidence: 99%

“…Determination of dose for small fields presents a significant technical challenge because of high‐dose gradients, lack of charged particle equilibrium, partial occlusion of the radiation source, and detector volume averaging effects 20 . These factors can cause variation in dose measurements (e.g., due to variations in measured output factors) of up to 30%, negatively impacting the overall treatment efficacy and patient safety 20 . To address the issue of accurate and consistent clinical reference dosimetry, several protocols have been developed over the years, including the widely adopted Task Group (TG) report TG‐51, its predecessor TG‐21, and TG‐155 by the American Association of Physicists in Medicine (AAPM), as well as the Technical Report Series (TRS) TRS‐398 from the International Atomic Energy Agency (IAEA), and TRS‐483, a joint report from the AAPM and IAEA 21–25 .…”

Section: Introductionmentioning

confidence: 99%

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Accurate machine‐specific reference and small‐field dosimetry for a self‐shielded neuro‐radiosurgical system

Jermain,

Muir,

McEwen

et al. 2024

Medical Physics

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BackgroundThe newly available ZAP‐X stereotactic radiosurgical system is designed for the treatment of intracranial lesions, with several unique features that include a self‐shielding, gyroscopic gantry, wheel collimation, non‐orthogonal kV imaging, short source‐axis distance, and low‐energy megavoltage beam. Systematic characterization of its radiation as well as other properties is imperative to ensure its safe and effective clinical application.PurposeTo accurately determine the radiation output of the ZAP‐X with a special focus on the smaller diameter cones and an aim to provide useful recommendations on quantification of small field dosimetry.MethodsSix different types of detectors were used to measure relative output factors at field sizes ranging from 4 to 25 mm, including the PTW microSilicon and microdiamond diodes, Exradin W2 plastic scintillator, Exradin A16 and A1SL ionization chambers, and the alanine dosimeter. The 25 mm cone served as the reference field size. Absolute dose was determined with both TG‐51‐based dosimetry using a calibrated PTW Semiflex ion chamber and measurements using alanine dosimeters.ResultsThe average radiation output factors (maximum deviation from the average) measured with the microDiamond, microSilicon, and W2 detectors were: for the 4 mm cone, 0.741 (1.0%); for the 5 mm cone: 0.817 (1.0%); for the 7.5 mm cone: 0.908 (1.0%); for the 10 mm cone: 0.946 (0.4%); for the 12.5 mm cone: 0.964 (0.2%); for the 15 mm cone: 0.976 (0.1%); for the 20 mm cone: 0.990 (0.1%). For field sizes larger than 10 mm, the A1SL and A16 micro‐chambers also yielded consistent output factors within 1.5% of those obtained using the microSilicon, microdiamond, and W2 detectors. The absolute dose measurement obtained with alanine was within 1.2%, consistent with combined uncertainties, compared to the PTW Semiflex chamber for the 25 mm reference cone.ConclusionFor field sizes less than 10 mm, the microSilicon diode, microDiamond detector, and W2 scintillator are suitable devices for accurate small field dosimetry of the ZAP‐X system. For larger fields, the A1SL and A16 micro‐chambers can also be used. Furthermore, alanine dosimetry can be an accurate verification of reference and absolute dose typically measured with ion chambers. Use of multiple suitable detectors and uncertainty analyses were recommended for reliable determination of small field radiation outputs.

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Section: Discussionsupporting

confidence: 57%

Section: Discussionmentioning

confidence: 99%