Evaluation of a new secondary dose calculation software for Gamma Knife radiosurgery

Prusator, Michael T.; Zhao, Tianyu; Kavanaugh, James; Santanam, Lakshmi; Dise, Joe; Goddu, S; Mitchell, Timothy J.; Zoberi, Jacqueline E.; Kim, Sang Woo; Mutic, Sasa; Knutson, Nels C.

doi:10.1002/acm2.12794

Cited by 5 publications

(7 citation statements)

References 17 publications

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“…Accurately calculating dose near the skull surface and for gamma angles other than 90° is particularly challenging. Newer GSR independent‐check software packages employ more realistic approximations in many of these areas and appear to be more accurate than previous products 82 . Based on experience, this task group suggests a tolerance level of 3% and an action level of 5%.…”

Section: Treatment Process Quality Assurancementioning

confidence: 99%

“…Newer GSR independent-check software packages employ more realistic approximations in many of these areas and appear to be more accurate than previous products. 82 Based on experience, this task group suggests a tolerance level of 3% and an action level of 5%. If the action level is exceeded, the user is advised to check the input data for both the treatment planning and independent-check calculations.…”

Section: Independent Check Of Dose Calculationmentioning

confidence: 99%

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Recommendations on the practice of calibration, dosimetry, and quality assurance for gamma stereotactic radiosurgery: Report of AAPM Task Group 178

et al. 2021

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The American Association of Physicists in Medicine (AAPM) formed Task Group 178 (TG-178) to perform the following tasks: review in-phantom and in-air calibration protocols for gamma stereotactic radiosurgery (GSR), suggest a dose rate calibration protocol that can be successfully utilized with all gamma stereotactic radiosurgery (GSR) devices, and update quality assurance (QA) protocols in TG-42 (AAPM Report 54, 1995) for static GSR devices. The TG-178 report recommends a GSR dose rate calibration formalism and provides tabulated data to implement it for ionization chambers commonly used in GSR dosimetry. The report also describes routine mechanical, dosimetric, and safety checks for GSR devices, and provides treatment process quality assurance recommendations. Sample worksheets, checklists, and practical suggestions regarding some QA procedures are given in appendices. The overall goal of the report is to make recommendations that help standardize GSR physics practices and promote the safe implementation of GSR technologies.

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Section: Treatment Process Quality Assurancementioning

confidence: 99%

Section: Independent Check Of Dose Calculationmentioning

confidence: 99%

Recommendations on the practice of calibration, dosimetry, and quality assurance for gamma stereotactic radiosurgery: Report of AAPM Task Group 178

et al. 2021

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“…However, MRI intensities do not possess a calibrated scale; the MRI signal depends on the density of protons and the tissue’s relaxation properties, and not on the electron density like in a CT scan [ 8 , 9 ]. Currently, MRI-only based RT remains cumbersome and is limited to gamma knife therapy, with limited dosimetric planification using the TMR10 algorithm [ 10 ].…”

Section: Introductionmentioning

confidence: 99%

Dosimetric Validation of a GAN-Based Pseudo-CT Generation for MRI-Only Stereotactic Brain Radiotherapy

Bourbonne

Jaouen

Hognon

et al. 2021

Cancers

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Purpose: Stereotactic radiotherapy (SRT) has become widely accepted as a treatment of choice for patients with a small number of brain metastases that are of an acceptable size, allowing for better target dose conformity, resulting in high local control rates and better sparing of organs at risk. An MRI-only workflow could reduce the risk of misalignment between magnetic resonance imaging (MRI) brain studies and computed tomography (CT) scanning for SRT planning, while shortening delays in planning. Given the absence of a calibrated electronic density in MRI, we aimed to assess the equivalence of synthetic CTs generated by a generative adversarial network (GAN) for planning in the brain SRT setting. Methods: All patients with available MRIs and treated with intra-cranial SRT for brain metastases from 2014 to 2018 in our institution were included. After co-registration between the diagnostic MRI and the planning CT, a synthetic CT was generated using a 2D-GAN (2D U-Net). Using the initial treatment plan (Pinnacle v9.10, Philips Healthcare), dosimetric comparison was performed using main dose-volume histogram (DVH) endpoints in respect to ICRU 91 guidelines (Dmax, Dmean, D2%, D50%, D98%) as well as local and global gamma analysis with 1%/1 mm, 2%/1 mm and 2%/2 mm criteria and a 10% threshold to the maximum dose. t-test analysis was used for comparison between the two cohorts (initial and synthetic dose maps). Results: 184 patients were included, with 290 treated brain metastases. The mean number of treated lesions per patient was 1 (range 1–6) and the median planning target volume (PTV) was 6.44 cc (range 0.12–45.41). Local and global gamma passing rates (2%/2 mm) were 99.1 CI95% (98.1–99.4) and 99.7 CI95% (99.6–99.7) respectively (CI: confidence interval). DVHs were comparable, with no significant statistical differences regarding ICRU 91′s endpoints. Conclusions: Our study is the first to compare GAN-generated CT scans from diagnostic brain MRIs with initial CT scans for the planning of brain stereotactic radiotherapy. We found high similarity between the planning CT and the synthetic CT for both the organs at risk and the target volumes. Prospective validation is under investigation at our institution.

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“…The performance of earlier versions of the secondary dose calculation program RadCalc has been investigated for various types of treatment machines 18–20 . RadCalc now offers dose calculation on the patient geometry using a Monte Carlo algorithm, which, to the best of our knowledge, has not yet been thoroughly investigated.…”

Section: Introductionmentioning

confidence: 99%

Sensitivity and specificity of secondary dose calculation for head and neck treatment plans

Wegener,

Abu Rashed,

Sauer

et al. 2023

J Applied Clin Med Phys

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PurposeSecondary dose calculation (SDC) with an independent algorithm is one option to perform plan‐specific quality assurance (QA). While measurement‐based QA can potentially detect errors in plan delivery, the dose values are typically only compared to calculations on homogeneous phantom geometries instead of patient CT data. We analyzed the sensitivity and specificity of an SDC software by purposely introducing different errors and determined thresholds for optimal decisions.MethodsThirty head and neck VMAT plans and 30 modifications of those plans, including errors related to density and beam modelling, were recalculated using RadCalc with a Monte Carlo algorithm. Decision thresholds were obtained by receiver operating characteristics (ROC) analysis. For comparison, measurement‐based QA using the ArcCHECK phantom was carried out and evaluated in the same way.ResultsDespite optimized decision thresholds, none of the systems was able to reliably detect all errors. ArcCHECK analysis using a 2%/2 mm criterion with a threshold of 91.1% had an area under the curve (AUC) of 0.80. Evaluating differences in recalculated and planned DVH parameter of the target structures in RadCalc with a 2% threshold an AUC of 0.86 was achieved. Out‐of‐field deviations could be attributed to weaknesses in the beam model.ConclusionsSecondary dose calculation with RadCalc is an alternative to established measurement‐based phantom QA. Different tools catch different errors; therefore, a combination of approaches should be preferred.

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Evaluation of a new secondary dose calculation software for Gamma Knife radiosurgery

Cited by 5 publications

References 17 publications

Recommendations on the practice of calibration, dosimetry, and quality assurance for gamma stereotactic radiosurgery: Report of AAPM Task Group 178

Recommendations on the practice of calibration, dosimetry, and quality assurance for gamma stereotactic radiosurgery: Report of AAPM Task Group 178

Dosimetric Validation of a GAN-Based Pseudo-CT Generation for MRI-Only Stereotactic Brain Radiotherapy

Sensitivity and specificity of secondary dose calculation for head and neck treatment plans

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