Absolute calibration of the Gamma Knife<sup>®</sup>
 Perfexion™ and delivered dose verification using EPR/alanine dosimetry

Hornbeck, Amaury; Garcia, Tristan; Cuttat, M.; Jenny, C.

doi:10.1118/1.4873686

Cited by 6 publications

(5 citation statements)

References 16 publications

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“…The agreement between the ionization chamber and TLDs was within 1% and confirms the accuracy of dose delivery and calculation. This aligns with the findings of McDonald et al (2011), Hornbeck et al (2014 and Zeverino et al (2017), who demonstrated <1% agreement with independent verifications. Although 15 and 25 mm are small fields, they are well within the established size range for performing accurate measurements with suitable small field designated ion chambers as listed in IAEA TRS 483 (Stasi et al 2004, Palmans et al 2018.…”

Section: Discussionsupporting

confidence: 90%

“…Other papers have described the device and initial planning abilities but not a comprehensive description of the commissioning process (Mutaf et al 2013. We have followed a process similar to that previously reported for devices such as the Gamma Knife Perfexion (Ma et al 2009, Hornbeck et al 2014 and Icon (Zeverino et al 2017); however, this treatment delivery system has characteristics that are different from the Gamma Knife and required detailed analysis.…”

Section: Discussionmentioning

confidence: 99%

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Commissioning and acceptance guide for the GammaPod

et al. 2019

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The GammaPod breast treatment device has been introduced to provide stereotactic radiation therapy to the breast to patients in the prone position. The GammaPod, using a stereotactic coordinate system, dynamically delivers dose to the target by rotating 25 non-overlapping Co-60 beams while the patient’s breast is translated continuously in three axes on the couch during delivery. From simulation to treatment, the patient’s breast is immobilized using mild negative pressure (150 mm Hg below atmospheric pressure) through a device-specific dual-cup system with stereotactic fiducials. This technology can be used for boost, multi-fraction partial-breast steterotactic body radiotherapy (SBRT), or single-fraction stereotactic radiosurgery (SRS). This paper reports the commissioning of the system for clinical use. The GammaPod device has four major subsystems: mechanical, dosimetric, radiation safety, and safety interlocks. Detailed methods for testing each subsystem have been identified and quantified. Mechanical systems include couch motion and accuracy along with couch sag. Dosimetric tests include absolute dose calibration, dose profiles, timer error, and plan verifications. Radiation safety includes room and wall surveys, along with device leakage measurements. Safety interlocks deal with power systems, immobilization, and treatment interrupts. The absolute dose rate of the 25 mm collimator was determined using TG-21 dosimetry protocol. The relative output factor for the 15 mm collimator was 0.94. The difference of the full-width-at-half-maximum of the single shot of the 25 mm collimator between the treatment planning system and the measurement was 0.2 mm. All interlocks were found to perform correctly, and the shield was within state and Nuclear Regulatory Commission limits. The items and techniques for commissioning the GammaPod have been developed and tested using the methods reported here.

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Section: Discussionsupporting

confidence: 90%

Section: Discussionmentioning

confidence: 99%

Commissioning and acceptance guide for the GammaPod

et al. 2019

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“…However, studies have been conducted to test the precision of EPR/alanine dosimetry for use in the therapeutic dose ranges [3]. The advanced radiotherapy beam modalities and applications that have been verified using alanine dosimetry include intensity modulated radiotherapy (IMRT); electron, proton, carbon ion, and neutron beams radiotherapy; tomotherapy [4]; gamma knife [5]; cyberknife [6]; brachytherapy [7]; small field dosimetry [8]; in vivo dosimetry [9]; electron arc therapy treatment planning verification [10]; total body irradiation [11]; and blood irradiation [12]. In addition, the EPR/alanine dosimetry was used in national audits of radiotherapy centers in other countries, such as the UK [13] and Italy [14].…”

Section: Introductionmentioning

confidence: 99%

Verification of the pure alanine in PMMA tube dosimeter applicability for dosimetry of radiotherapy photon beams: a feasibility study

Al-Karmi

Ayaz

Al-Enezi

et al. 2015

Australas Phys Eng Sci Med

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Alanine dosimeters in the form of pure alanine powder in PMMA plastic tubes were investigated for dosimetry in a clinical application. Electron paramagnetic resonance (EPR) spectroscopy was used to measure absorbed radiation doses by detection of signals from radicals generated in irradiated alanine. The measurements were performed for low-dose ranges typical for single-fraction doses often used in external photon beam radiotherapy. First, the dosimeters were irradiated in a solid water phantom to establish calibration curves in the dose range from 0.3 to 3 Gy for 6 and 18 MV X-ray beams from a clinical linear accelerator. Next, the dosimeters were placed at various locations in an anthropomorphic pelvic phantom to measure the dose delivery of a conventional four-field box technique treatment plan to the pelvis. Finally, the doses measured with alanine dosimeters were compared against the doses calculated with a commercial treatment planning system (TPS). The results showed that the alanine dosimeters have a highly sensitive dose response with good linearity and no energy dependence in the dose range and photon beams used in this work. Also, a fairly good agreement was found between the in-phantom dose measurements with alanine dosimeters and the TPS dose calculations. The mean value of the ratios of measured to calculated dose values was found to be near unity. The measured points in the in-field region passed dose-difference acceptance criterion of 3% and those in the penumbral region passed distance-to-agreement acceptance criterion of 3 mm. These findings suggest that the pure alanine powder in PMMA tube dosimeter is a suitable option for dosimetry of radiotherapy photon beams.

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“…The absorbed dose rate measured inside a plastic phantom is passed to the LGP and used as the absorbed dose rate in water without any correction. The errors from this substitution have been analyzed, and some alternatives were suggested …”

Section: Introductionmentioning

confidence: 99%

“…The errors from this substitution have been analyzed, and some alternatives were suggested. [10][11][12][13][14] Error occurs because the TMR10 algorithm disregards the inhomogeneity of the materials inside a patient's head. To correct this error, a convolution algorithm that employs the electron-density information of computed tomography (CT) images was added to the LGP.…”

Section: Introductionmentioning

confidence: 99%

Verification of dose profiles generated by the convolution algorithm of the gamma knife^® radiosurgery planning system

2017

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The measured accuracies of the dose distributions calculated by the convolution algorithm of the LGP were within the clinically acceptable range (GIPR ≥ 96.9%) for various configurations of collimator size, location, direction of calculation plane, and number of shots. Due to the intrinsic asymmetry in the dose distribution along the z-axis, the treatment plan should also be verified in coronal or sagittal plane.

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Absolute calibration of the Gamma Knife^® Perfexion™ and delivered dose verification using EPR/alanine dosimetry

Abstract: This paper shows there is a good agreement between the new calibration method and the currently used one. There is also a good agreement between the calculated and delivered doses especially for Gammaplan v10.

Cited by 6 publications

References 16 publications

Commissioning and acceptance guide for the GammaPod

Commissioning and acceptance guide for the GammaPod

Verification of the pure alanine in PMMA tube dosimeter applicability for dosimetry of radiotherapy photon beams: a feasibility study

Verification of dose profiles generated by the convolution algorithm of the gamma knife^® radiosurgery planning system

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Absolute calibration of the Gamma Knife® Perfexion™ and delivered dose verification using EPR/alanine dosimetry

Abstract: This paper shows there is a good agreement between the new calibration method and the currently used one. There is also a good agreement between the calculated and delivered doses especially for Gammaplan v10.

Cited by 6 publications

References 16 publications

Commissioning and acceptance guide for the GammaPod

Commissioning and acceptance guide for the GammaPod

Verification of the pure alanine in PMMA tube dosimeter applicability for dosimetry of radiotherapy photon beams: a feasibility study

Verification of dose profiles generated by the convolution algorithm of the gamma knife® radiosurgery planning system

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Product

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Absolute calibration of the Gamma Knife^® Perfexion™ and delivered dose verification using EPR/alanine dosimetry

Verification of dose profiles generated by the convolution algorithm of the gamma knife^® radiosurgery planning system