Quantified VMAT plan complexity in relation to measurement‐based quality assurance results

Nguyen, Michael; Chan, Grace

doi:10.1002/acm2.13048

Cited by 15 publications

(12 citation statements)

References 15 publications

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“…For example, treatment plans for the head and neck (H&N) are generally more complex than for the prostate 50 . The complexity of the treatment plan affects the accuracy of dose delivery, and a complex treatment plan increases failing points and decreases GPR 51–54 . It could also affect the accuracy of the gamma distribution synthesis and the GPR prediction of the GAN model.…”

Section: Discussionmentioning

confidence: 99%

“…50 The complexity of the treatment plan affects the accuracy of dose delivery, and a complex treatment plan increases failing points and decreases GPR. [51][52][53][54] It could also affect the accuracy of the gamma distribution synthesis and the GPR prediction of the GAN model. Our study showed that the sensitivity of failing points was increased with tighter tolerance.…”

Section: Discussionmentioning

confidence: 99%

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A synthesized gamma distribution‐based patient‐specific VMAT QA using a generative adversarial network

et al. 2023

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Background Artificial intelligence (AI)‐based gamma passing rate (GPR) prediction has been proposed as a time‐efficient virtual patient‐specific QA method for the delivery of volumetric modulation arc therapy (VMAT). However, there is a limitation that the GPR value loses the locational information of dose accuracy. Purpose The objective was to predict the failing points in the gamma distribution and the GPR using a synthesized gamma distribution of VMAT QA with a deep convolutional generative adversarial network (GAN). Methods The fluence maps of 270 VMAT beams for prostate cancer were measured using an electronic portal imaging device and analyzed using gamma evaluation with 3%/2‐mm, 2%/1‐mm, 1%/1‐mm, and 1%/0.5‐mm tolerances. The 270 gamma distributions were divided into two datasets: 240 training datasets for creating a model and 30 test datasets for evaluation. The image prediction network for the fluence maps calculated by the treatment planning system (TPS) to the gamma distributions was created using a GAN. The sensitivity, specificity, and accuracy of detecting failing points were evaluated using measured and synthesized gamma distributions. In addition, the difference between measured GPR (mGPR) and predicted GPR (pGPR) values calculated from the synthesized gamma distributions was evaluated. Results The root mean squared errors between mGPR and pGPR were 1.0%, 2.1%, 3.5%, and 3.6% for the 3%/2‐mm, 2%/1‐mm, 1%/1‐mm, and 1%/0.5‐mm tolerances, respectively. The accuracies for detecting failing points were 98.9%, 96.9%, 94.7%, and 93.7% for 3%/2‐mm, 2%/1‐mm, 1%/1‐mm, and 1%/0.5‐mm tolerances, respectively. The sensitivity and specificity were the highest for 1%/0.5‐mm and 3%/2‐mm tolerances, which were 82.7% and 99.6%, respectively. Conclusions We developed a novel system using a GAN to generate a synthesized gamma distribution‐based patient‐specific VMAT QA. The system is promising from the point of view of quality assurance in radiotherapy because it shows high performance and can detect failing points.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

A synthesized gamma distribution‐based patient‐specific VMAT QA using a generative adversarial network

et al. 2023

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“…For STD, the MCSv has a value around 0.172. The values in SW are among the lowest compared to those found in the literature 23,26–28 . While specific results may not be applied to other institutions, the results can be used to develop institute specific QA tools to aid in the treatment planning process.…”

Section: Discussionmentioning

confidence: 86%

“…In our study, 800 MUs seems to be a good compromise between a dosimetric plan of the same quality as the SO‐STD referential plan, a satisfactory pre‐treatment measurement and a modulation controlled by the MLC complexity metrics. Previous studies 23,26 of complexity metric correlations generally report weak to moderate correlations to QA results. For this study, the complexity metrics selected were used to describe the general MLC movement and aperture shape of treatments, not to determine a correlation with the pre‐processing QA.…”

Section: Discussionmentioning

confidence: 92%

Dosimetric comparison of VMAT standard optimization (SO) and multi‐criteria optimization (MCO) treatment plans with standard mode delivery (STD) or sliding window (SW) for head and neck cancer

Rolland

Favrel

Fau

et al. 2023

J Applied Clin Med Phys

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PurposeA new development on the RayStation treatment planning system (TPS) allows a plan to be planned by imposing a constraint on the leaf sequencing: all leaves move in the same direction before moving again in the opposite direction to create a succession of sliding windows (SWs). The study aims to investigate this new leaf sequencing, coupled with standard optimization (SO) and multi‐criteria optimization (MCO) and to compare it with the standard sequencing (STD).MethodsSixty plans were replanned for 10 head and neck cancer patients (two dose levels simultaneously SIB, 56 and 70 Gy in 35 fractions). All plans were compared, and a Wilcoxon signed‐rank test was performed. Pre‐processing QA and metrics of multileaf collimator (MLC) complexity were studied.ResultsAll methodologies met the dose requirements for the planning target volumes (PTVs) and organs at risk (OARs). SO demonstrates significantly best results for homogeneity index (HI), conformity index (CI), and target coverage (TC). SO‐SW gives best results for PTVs (D98% and D2%) but the differences between techniques are less than 1%. Only the D2%,PTV‐56 Gy is higher with both MCO methods. MCO‐STD offer the best sparing OARs (parotids, spinal cord, larynx, oral cavity). The gamma passing rates (GPRs) with 3%/3 mm criteria between the measured and calculated dose distributions are higher than 95%, slightly lowest with SW. The number of monitor units (MUs) and MLC metrics are higher in SW show a higher modulation.ConclusionsAll plans are feasible for the treatment. A clear advantage of SO‐SW is that the treatment plan is more straightforward to planning by the user due to the more advanced modulation. MCO stands out for its ease of use and will allow a less experienced user to offer a better plan than in SO. In addition, MCO‐STD will reduce the dose to the OARs while maintaining good TC.

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“…When developing standard plan protocols or class solutions, it is common practice to limit certain features within the planning system that might increase the plan complexity, which could result in low PSQA pass rates. 16,17 Figure 2 shows the frequency of plan features that the participating centers indicated were limited for IMRT and VMAT based on the impact that these have on the PSQA pass rates (Supporting Information, A4, A5). The most common limiting features reported were minimum segment size for IMRT and dose computation (spatial) resolution for VMAT.…”

Section: A | Policy and Proceduresmentioning

confidence: 99%

Survey of patient‐specific quality assurance practice for IMRT and VMAT

Chan

Chin²,

Abdellatif

et al. 2021

J Applied Clin Med Phys

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A first-time survey across 15 cancer centers in Ontario, Canada, on the current practice of patient-specific quality assurance (PSQA) for intensity modulated radiation therapy (IMRT) and volumetric modulated arc therapy (VMAT) delivery was conducted. The objectives were to assess the current state of PSQA practice, identify areas for potential improvement, and facilitate the continued improvement in standardization, consistency, efficacy, and efficiency of PSQA regionally. The survey asked 40 questions related to PSQA practice for IMRT/VMAT delivery. The questions addressed PSQA policy and procedure, delivery log evaluation, instrumentation, measurement setup and methodology, data analysis and interpretation, documentation, process, failure modes, and feedback. The focus of this survey was on PSQA activities related to routine IMRT/ VMAT treatments on conventional linacs, including stereotactic body radiation therapy but excluding stereotactic radiosurgery. The participating centers were instructed to submit answers that reflected the collective view or opinion of their department and represented the most typical process practiced. The results of the survey provided a snapshot of the current state of PSQA practice in Ontario and demonstrated considerable variations in the practice. A large majority (80%) of centers performed PSQA measurements on all VMAT plans. Most employed pseudo-3D array detectors with a true composite (TC) geometry. No standard approach was found for stopping or reducing frequency of measurements. The sole use of delivery log evaluation was not widely implemented, though most centers expressed interest in adopting this technology. All used the Gamma evaluation method for analyzing PSQA measurements; however, no universal approach was reported on how Gamma evaluation and pass determination criteria were determined. All or some PSQA results were reviewed regularly in twothirds of the centers. Planning related issues were considered the most frequent source for PSQA failures (40%), whereas the most frequent course of action for a failed PSQA was to review the result and decide whether to proceed to treatment.

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Quantified VMAT plan complexity in relation to measurement‐based quality assurance results

Cited by 15 publications

References 15 publications

A synthesized gamma distribution‐based patient‐specific VMAT QA using a generative adversarial network

A synthesized gamma distribution‐based patient‐specific VMAT QA using a generative adversarial network

Dosimetric comparison of VMAT standard optimization (SO) and multi‐criteria optimization (MCO) treatment plans with standard mode delivery (STD) or sliding window (SW) for head and neck cancer

Survey of patient‐specific quality assurance practice for IMRT and VMAT

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