Establishing action threshold for change in patient anatomy using <scp>EPID</scp> gamma analysis and <scp>PTV</scp> coverage for head and neck radiotherapy treatment

Ophelie, Piron; Varfalvy, Nicolas; Archambault, Louis

doi:10.1002/mp.13045

Cited by 18 publications

(19 citation statements)

References 40 publications

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“…Another group has used the gamma metric and cluster means analysis to detect head-and-neck patients who need replanning with a sensitivity of 0.84 and specificity of 0.80. 14 The improved correlation of the GDSA method suggests it may also be effective. However, a more in-depth analysis is needed to better characterize the correlation and find the sensitivity and specificity of detecting clinically relevant deviations.…”

Section: Discussionmentioning

confidence: 99%

“…10,12,13 In vivo EPID images analyzed with a gamma comparison have been used to monitor changes in patient anatomy which could trigger a plan adaptation. 14,15 These systems have been implemented to successfully detect errors and patient changes, but the relationship between in vivo metrics used and dosimetric parameters is still unclear. Because of this, tolerance levels have been empirically optimized based on clinical experience and can vary between treatment site and clinic.…”

Section: Introductionmentioning

confidence: 99%

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Using in vivo EPID images to detect and quantify patient anatomy changes with gradient dose segmented analysis

et al. 2020

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Purpose To investigate the utility of gradient dose segmented analysis (GDSA) in combination with in vivo electronic portal imaging device (EPID) images to predict changes in the PTV mean dose for patient cases. Also, we use the GDSA to retrospectively analyze patients treated in our clinic to assess deviations for different treatment sites and use time‐series data to observe any day‐to‐day changes. Methods In vivo EPID transit images acquired on the Varian Halcyon were analyzed for simulated errors in a phantom, including gas bubbles, weight loss, patient shifts, and an arm erroneously in the field. GDSA threshold parameters were tuned to maximize the coefficient of determination (R2) between GDSA metrics and the change in the PTV mean dose (Dmean) as estimated in a treatment planning system (TPS). Similarly for a gamma analysis, the gamma criteria were adjusted to maximize R2 between gamma pass rate and the change in the PTV Dmean from the TPS. The predictive accuracy of these models was tested on patient data measuring the mean and standard deviation of the difference in the predicted change in PTV Dmean and the change in PTV Dmean measured in the TPS. This analysis was extended retrospectively for every patient treated over a 23‐month period (n = 852 patients) to assess the range of expected deviations that occurred during routine clinical operation, as well as to assess any differences between treatment sites. Grouping patients treated on the same day, a time‐series analysis was performed to determine if GDSA metrics could add value in tracking machine behavior over time. Results For the phantom data, analyzing the errors, except for shifts, and comparing the change in PTV Dmean and GDSA mean, a maximal R2 = 0.90 was found for a dose threshold of 5% and gradient threshold of 3 mm. For the gamma approach a linear fit between the gamma pass rate for change in the PTV Dmean was assessed for different criteria, using the same image data. A maximal, R2 = 0.84 was found for a gamma criteria of 3%/3 mm, 45% lower dose threshold. For patient data, the predictive accuracy of the change in the PTV Dmean using the GDSA approach and the gamma approach was 0.09 ± 0.98 % and − 0.65 ± 2.21%, respectively. Comparing the two approaches the accuracy did not significantly differ (P = 0.38), whereas the precision of the GDSA prediction is significantly less (P < 0.001). The dosimetric impact of shifts was not detectable with either the GDSA or gamma approach. Analysis of all patients treated over 23 months showed that over 95% of fractions treated deviated from the first fraction by 2% or less. Deviations> 2% occurred most frequently for the later fractions of head‐and‐neck and lung treatments. Additionally, averaging the GDSA mean metric over all patients on a given treatment day showed that changes in the machine output on the order of 1% could be identified. Conclusions GDSA of in vivo EPID images is a useful technique for monitoring patient changes during the course of treatment, particularly weight loss and tumor shrinkage...

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Using in vivo EPID images to detect and quantify patient anatomy changes with gradient dose segmented analysis

et al. 2020

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“…Indeed, early changes in CBCT were correlated with late xerostomia in a retrospective analysis of 119 patients [68]. Dosimetric variations may also be estimated thanks to the use of electronic portal imaging device (EPID) [70]. However, ongoing randomized trials are necessary to demonstrate the benefits of ART in comparison to no-ART before using the technique in routine practice in patients with locally advanced HNC.…”

Section: Discussionmentioning

confidence: 99%

Adaptive radiotherapy for head and neck cancer

et al. 2018

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Introduction: Large anatomical variations can be observed during the treatment course intensitymodulated radiotherapy (IMRT) for head and neck cancer (HNC), leading to potential dose variations. Adaptive radiotherapy (ART) uses one or several replanning sessions to correct these variations and thus optimize the delivered dose distribution to the daily anatomy of the patient. This review, which is focused on ART in the HNC, aims to identify the various strategies of ART and to estimate the dosimetric and clinical benefits of these strategies. Material and methods: We performed an electronic search of articles published in PubMed/MEDLINE and Science Direct from January 2005 to December 2016. Among a total of 134 articles assessed for eligibility, 29 articles were ultimately retained for the review. Eighteen studies evaluated dosimetric variations without ART, and 11 studies reported the benefits of ART. Results: Eight in silico studies tested a number of replanning sessions, ranging from 1 to 6, aiming primarily to reduce the dose to the parotid glands. The optimal timing for replanning appears to be early during the first two weeks of treatment. Compared to standard IMRT, ART decreases the mean dose to the parotid gland from 0.6 to 6 Gy and the maximum dose to the spinal cord from 0.1 to 4 Gy while improving target coverage and homogeneity in most studies. Only five studies reported the clinical results of ART, and three of those studies included a non-randomized comparison with standard IMRT. These studies suggest a benefit of ART in regard to decreasing xerostomia, increasing quality of life, and increasing local control. Patients with the largest early anatomical and dose variations are the best candidates for ART. Conclusion: ART may decrease toxicity and improve local control for locally advanced HNC. However, randomized trials are necessary to demonstrate the benefit of ART before using the technique in routine practice.

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“…ROC analysis, however, requires a statistically significant size of error and no-error samples as input. The experimental acquisition of EPID measurements to produce such samples is typically a cumbersome process, which explains why there are only a few studies on the topic in the IVD literature [78] , [79] , [80] , [81] . Recently, use has been made of synthetic EPID images to eliminate the need for phantom error introduction and positioning [82] .…”

Section: Future Directions For Research Development and Clinical Pramentioning

confidence: 99%

In vivo dosimetry in external beam photon radiotherapy: Requirements and future directions for research, development, and clinical practice

Olaciregui-Ruiz

Beddar

Greer

et al. 2020

Physics and Imaging in Radiation Oncology

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External beam radiotherapy with photon beams is a highly accurate treatment modality, but requires extensive quality assurance programs to confirm that radiation therapy will be or was administered appropriately. In vivo dosimetry (IVD) is an essential element of modern radiation therapy because it provides the ability to catch treatment delivery errors, assist in treatment adaptation, and record the actual dose delivered to the patient. However, for various reasons, its clinical implementation has been slow and limited. The purpose of this report is to stimulate the wider use of IVD for external beam radiotherapy, and in particular of systems using electronic portal imaging devices (EPIDs). After documenting the current IVD methods, this report provides detailed software, hardware and system requirements for in vivo EPID dosimetry systems in order to help in bridging the current vendor-user gap. The report also outlines directions for further development and research. In vivo EPID dosimetry vendors, in collaboration with users across multiple institutions, are requested to improve the understanding and reduce the uncertainties of the system and to help in the determination of optimal action limits for error detection. Finally, the report recommends that automation of all aspects of IVD is needed to help facilitate clinical adoption, including automation of image acquisition, analysis, result interpretation, and reporting/documentation. With the guidance of this report, it is hoped that widespread clinical use of IVD will be significantly accelerated.

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Establishing action threshold for change in patient anatomy using EPID gamma analysis and PTV coverage for head and neck radiotherapy treatment

Cited by 18 publications

References 40 publications

Using in vivo EPID images to detect and quantify patient anatomy changes with gradient dose segmented analysis

Using in vivo EPID images to detect and quantify patient anatomy changes with gradient dose segmented analysis

Adaptive radiotherapy for head and neck cancer

In vivo dosimetry in external beam photon radiotherapy: Requirements and future directions for research, development, and clinical practice

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