Gamma analysis with a gamma criterion of 2%/1 mm for stereotactic ablative radiotherapy delivered with volumetric modulated arc therapy technique: a single institution experience

Kim, Jung-In; Chun, Minsoo; Wu, Hong‐Gyun; Chie, Eui Kyu; Kim, Hak Jae; Kim, Jin Ho; Park, Jong Min

doi:10.18632/oncotarget.18530

Cited by 11 publications

(15 citation statements)

References 30 publications

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“…This presented a challenge, because historically the Gamma Knife has been considered capable of delivering dose distributions accurately without the necessity of patient‐specific measurements. A number of reports have described PSQA for linac‐based SRS and SBRT . In general, these articles described results similar to those we achieved with our PSQA program.…”

Section: Discussionsupporting

confidence: 73%

“…Wen et al using a 3%/1 mm gamma criteria achieved an overall pass rate of 95% for linac‐based SRS/SBRT. Kim et al achieved an average gamma of 97.0 ± 2.5% for stereotactic ablative radiotherapy/volumetric‐modulated arc therapy (VMAT) with 2%/1‐mm criteria. Colodro et al achieved an average gamma pass rate of 92.7 ± 2.9% with 3%/1.5‐mm gamma criteria for VMAT SBRT.…”

Section: Discussionmentioning

confidence: 99%

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Development and validation of a comprehensive patient‐specific quality assurance program for a novel stereotactic radiation delivery system for breast lesions

Becker

Niu

Mutaf

et al. 2019

J Applied Clin Med Phys

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Purpose: The GammaPod is a dedicated prone breast stereotactic radiosurgery (SRS) machine composed of 25 cobalt-60 sources which rotate around the breast to create highly conformal dose distributions for boosts, partial-breast irradiation, or neo-adjuvant SRS. We describe the development and validation of a patient-specific quality assurance (PSQA) system for the GammaPod. Methods: We present two PSQA methods: measurement based and calculation based PSQA. The measurements are performed with a combination of absolute and relative dose measurements. Absolute dosimetry is performed in a single point using a 0.053-cc pinpoint ionization chamber in the center of a polymethylmethacrylate (PMMA) breast phantom and a water-filled breast cup. Relative dose distributions are verified with EBT3 film in the PMMA phantom. The calculationbased method verifies point doses with a novel semi-empirical independent-calculation software.Results: The average (± standard deviation) breast and target sizes were 1263 ± 335.3 cc and 66.9 ± 29.9 cc, respectively. All ion chamber measurements performed in water and the PMMA phantom agreed with the treatment planning system (TPS) within 2.7%, with average (max) difference of -1.3% (−1.9%) and −1.3% (−2.7%), respectively. Relative dose distributions measured by film showed an average gamma pass rate of 97.0 ± 3.2 when using a 3%/1 mm criteria. The lowest gamma analysis pass rate was 90.0%. The independent calculation software had average agreements (max) with the patient and QA plan calculation of 0.2% (2.2%) and −0.1% (2.0%), respectively. Conclusion:We successfully implemented the first GammaPod PSQA program.These results show that the GammaPod can be used to calculate and deliver the predicted dose precisely and accurately. For routine PSQA performed prior to treatments, the independent calculation is recommended as it verifies the accuracy of the planned dose without increasing the risk of losing vacuum due to prolonged waiting times.---

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Section: Discussionsupporting

confidence: 73%

Section: Discussionmentioning

confidence: 99%

Development and validation of a comprehensive patient‐specific quality assurance program for a novel stereotactic radiation delivery system for breast lesions

Becker

Niu

Mutaf

et al. 2019

J Applied Clin Med Phys

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“…Although the 2% /2 mm criterion remains widely used in clinical practice [ 35 , 36 ], no clear international guidelines exist. In the special setting of stereotactic ablative RT delivered by VMAT, a 2D global gamma analysis with a 2%/1 mm criterion provided promising results [ 37 ]. Comparison between such criteria and our workflow seemed to be of particular interest.…”

Section: Discussionmentioning

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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“…Several studies have reported that more stringent criteria (e.g., 2%/1 mm) may be useful for stereotactic radiotherapy owing to a higher sensitivity in the detection of delivery errors. Therefore, our model requires improvement to increase the MAE prediction accuracy in this range 25,26 …”

Section: Discussionmentioning

confidence: 99%

Improvement of deep learning prediction model in patient‐specific QA for VMAT with MLC leaf position map and patient's dose distribution

Tomori

Kimura

Kajikawa

et al. 2023

J Applied Clin Med Phys

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PurposeDeep learning‐based virtual patient‐specific quality assurance (QA) is a novel technique that enables patient QA without measurement. However, this method could be improved by further evaluating the optimal data to be used as input. Therefore, a deep learning‐based model that uses multileaf collimator (MLC) information per control point and dose distribution in patient's CT as inputs was developed.MethodsOverall, 96 volumetric‐modulated arc therapy plans generated for prostate cancer treatment were used. We developed a model (Model 1) that can predict measurement‐based gamma passing rate (GPR) for a treatment plan using data stored as a map reflecting the MLC leaf position at each control point (MLPM) and data of the dose distribution in patient's CT as inputs. The evaluation of the model was based on the mean absolute error (MAE) and Pearson's correlation coefficient (r) between the measured and predicted GPR. For comparison, we also analyzed models trained with the dose distribution in patient's CT alone (Model 2) and with dose distributions recalculated on a virtual phantom CT (Model 3).ResultsAt the 2%/2 mm criterion, MAE[%] and r for Model 1, Model 2, and Model 3 were 2.32% ± 0.43% and 0.54 ± 0.03, 2.70% ± 0.26%, and 0.32 ± 0.08, and 2.96% ± 0.23% and 0.24 ± 0.22, respectively; at the 3%/3 mm criterion, these values were 1.25% ± 0.05% and 0.36 ± 0.18, 1.57% ± 0.35% and 0.19 ± 0.20, and 1.39% ± 0.32% and 0.17 ± 0.22, respectively. This result showed that Model 1 exhibited the lowest MAE and highest r at both criteria of 2%/2 mm and 3%3 mm.ConclusionsThese findings showed that a model that combines the MLPM and dose distribution in patient's CT exhibited a better GPR prediction performance compared with the other two studied models.

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Gamma analysis with a gamma criterion of 2%/1 mm for stereotactic ablative radiotherapy delivered with volumetric modulated arc therapy technique: a single institution experience

Cited by 11 publications

References 30 publications

Development and validation of a comprehensive patient‐specific quality assurance program for a novel stereotactic radiation delivery system for breast lesions

Development and validation of a comprehensive patient‐specific quality assurance program for a novel stereotactic radiation delivery system for breast lesions

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

Improvement of deep learning prediction model in patient‐specific QA for VMAT with MLC leaf position map and patient's dose distribution

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