A method to enhance 2D ion chamber array patient specific quality assurance for IMRT

Moreno, Rogelio Manuel Díaz; Venencia, C; Garrigo, E; Pipman, Y

doi:10.1007/s13246-016-0498-y

Cited by 4 publications

(2 citation statements)

References 27 publications

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“…At first glance, our results may seem unsurprising, and multiple previous studies have likewise noted similar coalescence procedure in ion chamber detectors 4,5,7,[9][10][11] . However, the current work is unique in that the SPC technique and PCA herein are used as a more reliable argumentation on the coalescence process in meliorating spatial resolution and sampling frequency.…”

Section: Discussionsupporting

confidence: 67%

Correlation between patient-specific quality assurance in volumetric modulated arc therapy and 2D dose image features

Yixiao

Hu²,

et al. 2023

Sci Rep

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In radiotherapy, air-filled ion chamber detectors are ubiquitously used in routine dose measurements for treatment planning. However, its use has been restricted by intrinsic low spatial resolution barriers. We developed one procedure for patient-specific quality assurance (QA) in arc radiotherapy by coalescing two adjacent measurement images into a single image to improve spatial resolution and sampling frequency, and investigated how different spatial resolutions affect the QA results. PTW 729 and 1500 ion chamber detectors were used for dosimetric verification via coalescing two measurements with 5 mm-couch shift and the isocenter, and only isocenter measurement, which we call coalescence and standard acquisition (SA). Statistical process control (SPC), process capability analysis (PCA), and receiver operating characteristic (ROC) curve were used to compare the performance of the two procedures in determining tolerance levels and identifying clinically relevant errors. By analyzing 1256 γ values calculated on interpolated data points, our results indicated that detector 1500 showed higher averages in coalescence cohorts at different tolerance criteria and the dispersion degrees were spread out smaller. Detector 729 yielded a slightly lower process capability of 0.79, 0.76, 1.10, and 1.34, but detector 1500 exhibited somewhat different results of 0.94, 1.42, 1.19, and 1.60 in magnitude. The results of SPC individual control chart showed that cases in coalescence cohorts with γ values lowering its lower control limit (LCL) were greater than those in SA cohorts for detector 1500. A combination of the width of multi-leaf collimator (MLC) leaf, the cross-sectional area of the single detector, and the spacing between adjacent detectors might lead to discrepancies in percent γ values across diverse spatial resolution scenarios. The accuracy of reconstructed volume dose is mainly determined by the interpolation algorithm used in dosimetric systems. The magnitude of filling factor in the ion chamber detectors determined its ability to detect dose deviations. SPC and PCA results indicated that coalescence procedure could detect more potential failure QA results than SA while enhancing action thresholds.

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Section: Discussionsupporting

confidence: 67%

Correlation between patient-specific quality assurance in volumetric modulated arc therapy and 2D dose image features

Yixiao

Hu²,

et al. 2023

Sci Rep

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“…These Life 2022, 12,1923 2 of 12 detectors have the following advantages: stability for a short time, dose linearity, and simple dose calibration. However, they have an average volume effect, poor spatial resolution, and require phantom setup time [6,10,11].…”

Section: Introductionmentioning

confidence: 99%

Clinical Efficacy of an Electronic Portal Imaging Device versus a Physical Phantom Tool for Patient-Specific Quality Assurance

Baek

Choi

Han

et al. 2022

Life

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Pre-treatment patient-specific quality assurance (QA) is critical to prevent radiation accidents. The electronic portal imaging device (EPID) is a dose measurement tool with good resolution and a low volume-averaging effect. EPIbeam—an EPID-based portal dosimetry software—has been newly installed in three institutions in Korea. This study evaluated the efficacy of the EPID-based patient-specific QA tool versus the PTW729 detector (a previously used QA tool) based on gamma criteria and planning target volume (PTV). A significant difference was confirmed through the R statistical analysis software. The average gamma passing rates of PTW729 and EPIbeam were 98.73% and 99.60% on 3 mm/3% (local), 96.66% and 97.91% on 2 mm/2% (local), and 88.41% and 74.87% on 1 mm/1% (local), respectively. The p-values between them were 0.015 (3 mm/3%, local), 0.084 (2 mm/2%, local), and less than 0.01 (1 mm/1%, local). Further, the average gamma passing rates of PTW 729 and EPIbeam according to PTV size were 99.55% and 99.91% (PTV < 150 cm3) and 97.91% and 99.28% (PTV > 150 cm3), respectively. The p-values between them were 0.087 (PTV < 150 cm3) and 0.036 (PTV > 150 cm3). These results confirm that EPIbeam can be an effective patient-specific QA tool.

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Evaluation of target autocrop function in nasopharyngeal carcinoma SIB IMRT plan

Duan

Zhou

2021

Phys Eng Sci Med

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A new target autocrop function was introduced in the Varian Eclipse™ treatment planning software (version 15.5 above). The study aimed to evaluate this new target autocrop impact on nasopharyngeal carcinoma (NPC) plan quality and delivery e ciency. MethodsRandomly 66 approved NPC simultaneous integrated boost (SIB) intensity modulated radiation therapy (IMRT) treatment plans were retrospectively studied. The manual cropping-based plans served as reference and were designed using sliding-window IMRT. Reference plans were re-optimized with identical planning parameters following the institutional clinical protocol except for the optimization objective of the manual cropping targets deleted. Additionally, each target within 5mm of another had one lower objective at 100% volume and one upper objective at 0% volume for the autocrop plans. Plan quality was assessed based on selected parameters, including TCP (tumor control probability), NTCP (normal tissue complication probability), conformality index (CI), homogeneity index (HI), and dose-volume characteristics. Additionally, the delivery e ciency, the total plan treatment time de ned as a sum of monitor units (MUs) for each treated eld, and delivery accuracy, γ passing rate of treatment plan quality assurance (QA) also were compared. ResultsBoth the manual cropping plans and the autocrop plans could be approved by an experienced oncologist.Overall, the autocrop plans could provide approximately a 13% reduction in linac MU while maintaining comparable plan quality, radiobiological ranking, and accuracy to that of the manual cropping plans. ConclusionsThe new target autocrop tip facilitated the SIB IMRT plans for nasopharyngeal cancer patients. The autocrop could guarantee the quality and delivery accuracy of the radiotherapy plan, improved the planning e ciency, treatment e ciency, and reduced machine wear and tear. It was a promising tool for optimal plan selection for NPC SIB IMRT.

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A method to enhance 2D ion chamber array patient specific quality assurance for IMRT

Cited by 4 publications

References 27 publications

Correlation between patient-specific quality assurance in volumetric modulated arc therapy and 2D dose image features

Correlation between patient-specific quality assurance in volumetric modulated arc therapy and 2D dose image features

Clinical Efficacy of an Electronic Portal Imaging Device versus a Physical Phantom Tool for Patient-Specific Quality Assurance

Evaluation of target autocrop function in nasopharyngeal carcinoma SIB IMRT plan

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