Action Levels on Dose and Anatomic Variation for Adaptive Radiation Therapy Using Daily Offline Plan Evaluation: Preliminary Results

Zhang, Baoshe; Lee, Sung‐Woo; Chen, Shifeng; Zhou, Jinghao; Prado, K; D’Souza, W; Yi, B

doi:10.1016/j.prro.2018.08.006

Cited by 8 publications

(10 citation statements)

References 21 publications

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“…The accuracy of DIR methods affect the estimates of dose accumulation for both the target dose and the organ dose; one group found consistent correlations between the accuracy of the regions of interest deformation and discrepancies in dose accumulation . Another group addressed how to accommodate dosimetric variations resulting from anatomic changes during the course of treatments using daily CBCT . They found that a dose difference of 5% or anatomic variation at a Pearson correlation coefficient of 0.75 indicate practical “action levels” for replanning for the given data sets.…”

Section: Discussionmentioning

confidence: 98%

Quantifying the accuracy of deformable image registration for cone‐beam computed tomography with a physical phantom

Liu

Williamson

et al. 2019

J Applied Clin Med Phys

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Purpose: Kilo-voltage cone-beam computed tomography (CBCT) is widely used for patient alignment, contour propagation, and adaptive treatment planning in radiation therapy. In this study, we evaluated the accuracy of deformable image registration (DIR) for CBCT under various imaging protocols with different noise and patient dose levels.Methods: A physical phantom previously developed to facilitate end-to-end testing of the DIR accuracy was used with Varian Velocity v4.0 software to evaluate the performance of image registration from CT to CT, CBCT to CT, and CBCT to CBCT. The phantom is acrylic and includes several inserts that simulate different tissue shapes and properties. Deformations and anatomic changes were simulated by changing the rotations of both the phantom and the inserts. CT images (from a head and neck protocol) and CBCT images (from pelvis, head and "Image Gently" protocols) were obtained with different image noise and dose levels. Large inserts were filled with Mobil DTE oil to simulate soft tissue, and small inserts were filled with bone materials. All inserts were contoured before the DIR process to provide a ground truth contour size and shape for comparison. After the DIR process, all deformed contours were compared with the originals using Dice similarity coefficient (DSC) and mean distance to agreement (MDA). Both large and small volume of interests (VOIs) for DIR volume selection were tested by simulating a DIR process that included whole patient image volume and clinical target volumes (CTV) only (for CTVs propagation). Results:For cross-modality DIR registration (CT to CBCT), the DSC were >0.8 and the MDA were <3 mm for CBCT pelvis, and CBCT head protocols. For CBCT to CBCT and CT to CT, the DIR accuracy was improved relative to the cross-modality tests. For smaller VOIs, the DSC were >0.8 and MDA <2 mm for all modalities. Conclusions:The accuracy of DIR depends on the quality of the CBCT image at different dose and noise levels.Wu and Liu contributed equally.---

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Section: Discussionmentioning

confidence: 98%

Quantifying the accuracy of deformable image registration for cone‐beam computed tomography with a physical phantom

Liu

Williamson

et al. 2019

J Applied Clin Med Phys

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“…There are no established criteria, which correlates the clinical decision making for resimulation and replanning with the outcomes. Recent study by Zhang et al 19 retrospectively investigated some patients in their clinic with and without an intervention of ART. Greater than 5% difference in the dose to the CTV or <0.75 Pearson correlation coefficient of the CTV was found to be the action level related to the clinical decision made for ART 20 .…”

Section: Discussionmentioning

confidence: 99%

“…Further monitoring for the trend in the SPC or resimulation for ART could be determined. The action levels for an ART intervention can be established by statistical, biological, or clinical significance 19 . The control chart provides a statistical yet objective baseline for clinicians to consider any necessary interventions along the course of treatment.…”

Section: Discussionmentioning

confidence: 99%

Adaptive radiotherapy based on statistical process control for oropharyngeal cancer

Wang¹,

Xue²,

Chen³

et al. 2020

J Applied Clin Med Phys

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Purpose The purpose of this study is to quantify dosimetric changes throughout the delivery of oropharyngeal cancer treatment and to investigate the application of statistical process control (SPC) for the management of significant deviations during the course of radiotherapy. Methods Thirteen oropharyngeal cancer patients with daily cone beam computed tomography (CBCT) were retrospectively reviewed. Cone beam computed tomography images of every other fraction were imported to the Velocity software and registered to planning CT using the 6 DOF (degrees of freedom) couch shifts generated during patient setup. Using Velocity “Adaptive Monitoring” module, the setup‐corrected CBCT was matched to planning CT using a deformable registration. Volumes and dose metrics at each fraction were calculated and rated with plan values to evaluate interfractional dosimetric variations using a SPC framework. T‐tests between plan and fraction volumes were performed to find statistically insignificant fractions. Average upper and lower process capacity limits (UCL, LCL) of each dose metric were derived from these fractions using conventional SPC guidelines. Results Gross tumor volume (GTV) and organ at risk (OAR) volumes in the first 13 fractions had no significant changes from the pretreatment planning CT. The GTV and the parotid glands subsequently decreased by 10% at the completion of treatment. There were 3–4% increases in parotid mean doses, but no significant differences in dose metrics of GTV and other OARs. The changes were organ and patient dependent. Control charts for various dose metrics were generated to assess the metrics at each fraction for individual patient. Conclusions Daily CBCT could be used to monitor dosimetric variations of targets and OARs resulting from volume changes and tissue deformation in oropharyngeal cancer radiotherapy. Treatment review with the guidance of a SPC tool allows for an objective and consistent clinical decision to apply adaptive radiotherapy.

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“…Additionally, quarterly RTT peer-review rounds for challenging IGRT cases has been implemented for continuous practice improvements. Processes to reconstruct delivered radiotherapy doses are also being developed, using dose re-calculation on CBCT and deformable dose accumulation, to quantify the dosimetric impact of anatomic variations [30]. These efforts, combined with standardized reporting language by RTTs, will streamline clinical decision-making regarding adaptation for routine CBCT-guided radiotherapy.…”

Section: Discussionmentioning

confidence: 99%

Patterns of practice of adaptive re-planning for anatomic variances during cone-beam CT guided radiotherapy

Stankiewicz

Rosewall

et al. 2019

Technical Innovations & Patient Support in Radiation Oncolo

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Purpose: Substantial, unanticipated anatomic variances during cone-beam CT (CBCT)-guided radiotherapy can potentially impact treatment accuracy and clinical outcomes. This study assessed patterns of practice of CBCT variances reported by RTTs and subsequent interventions for multiple-disease sites. Methods: A chart review was conducted at a large cancer centre for patients treated with daily online CBCT-guided radiotherapy. Patients selected for review were identified via RTT-reported variances that then triggered offline multidisciplinary assessment. Cases were categorized by the type of anatomic variance observed on CBCT and any further interventions recorded such as unscheduled adaptive replanning. Results: Over a 1-year period, 287 variances from 261 patients were identified (6.2% of the 4207 patients treated with daily CBCT-guided radiotherapy), most often occurring within the first 5 fractions of the treatment course. Of these variances, 21% (59/287) were re-planned and 3.5% (10/287) discontinued treatment altogether. Lung was the most frequent disease-site (27% of 287 variances) reported with IGRT-related variances although head and neck and sarcoma were most frequently re-planned (19% of 59 re-plans for each site). Technical or clinical rationales for re-planning were not routinely documented in patient medical records. All disease-sites had numerous categories of variances. Three of the four most frequent categories were for tumor-related changes on CBCT, and the re-planning rate was highest for tumor progression at 25%. Normal tissue variances were the second most frequency category, and replanned in 14% of those cases. Conclusion: RTTs identified a wide range of anatomic variances during CBCT-guided radiotherapy. In a minority of cases, these substantially altered the care plan including ad hoc adaptive re-planning or treatment discontinuation. Improved understanding of the clinical decisions in these cases would aid in developing more routine, systematic adaptive strategies.

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Action Levels on Dose and Anatomic Variation for Adaptive Radiation Therapy Using Daily Offline Plan Evaluation: Preliminary Results

Cited by 8 publications

References 21 publications

Quantifying the accuracy of deformable image registration for cone‐beam computed tomography with a physical phantom

Quantifying the accuracy of deformable image registration for cone‐beam computed tomography with a physical phantom

Adaptive radiotherapy based on statistical process control for oropharyngeal cancer

Patterns of practice of adaptive re-planning for anatomic variances during cone-beam CT guided radiotherapy

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