Assessment of organs-at-risk contouring practices in radiosurgery institutions around the world – The first initiative of the OAR Standardization Working Group

Sandström, Helena; Chung, Caroline; Jokura, Hidefumi; Torrens, Michael; Jaffray, David A.; Toma-Daşu, Iuliana

doi:10.1016/j.radonc.2016.10.014

Cited by 17 publications

(12 citation statements)

References 32 publications

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“…Both the intra‐ and inter‐observer OAR contour variation as well as the change in OARs over time results in a significant variation in the maximum dose estimates to the OARs. In previous studies, the inter‐observer variability contributed to a range of maximum doses to the optic apparatus equivalent to 70% of the prescribed dose in stereotactic radiosurgery . In our study, the range of dose differences to the optic chiasm ranged from −1500 to 1700 cGy for a 6000 cGy plan, corresponding to a variability range of 53% of the prescribed dose.…”

Section: Discussionsupporting

confidence: 49%

“…Delineation of OARs in the brain is detailed in guidelines such as those by Scoccianti et al and Niyazi et al However, despite such guidelines, inter‐observer variation in the delineation of OARs in the brain is significant . The agreement between manual ground truth contours and both the static and propagated contours in this work was greater than the inter‐observer agreement in the literature.…”

Section: Discussionmentioning

confidence: 71%

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Improved dosimetric accuracy with semi‐automatic contour propagation of organs‐at‐risk in glioblastoma patients undergoing chemoradiation

Lee

Stewart

Lee

et al. 2019

J Applied Clin Med Phys

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BackgroundWe study the changes in organs‐at‐risk (OARs) morphology as contoured on serial MRIs during chemoradiation therapy (CRT) of glioblastoma (GBM). The dosimetric implication of assuming non‐deformable OAR changes and the accuracy and feasibility of semi‐automatic OAR contour propagation are investigated.MethodsFourteen GBM patients who were treated with adjuvant CRT for GBM prospectively underwent MRIs on fractions 0 (i.e., planning), 10, 20, and 1 month post last fraction of CRT. Three sets of OAR contours — (a) manual, (b) rigidly registered (static), and (c) semi‐automatically propagated — were compared using Dice similarity coefficient (DSC) and Hausdorff distance (HD). Dosimetric impact was determined by comparing the minimum dose to the 0.03 cc receiving the highest dose (D0.03 cc) on a clinically approved reference, non‐adapted radiation therapy plan.ResultsThe DSC between the manual contours and the static contours decreased significantly over time (fraction 10: [mean ± 1 SD] 0.78 ± 0.17, post 1 month: 0.76 ± 0.17, P = 0.02) while the HD (P = 0.74) and the difference in D0.03cc did not change significantly (P = 0.51). Using the manual contours as reference, compared to static contours, propagated contours have a significantly higher DSC (propagated: [mean ± 1 SD] 0.81 ± 0.15, static: 0.77 ± 0.17, P < 0.001), lower HD (propagated: 3.77 ± 1.8 mm, static: 3.96 ± 1.6 mm, P = 0.002), and a significantly lower absolute difference in D0.03cc (propagated: 101 ± 159 cGy, static: 136 ± 243 cGy, P = 0.019).ConclusionsNonrigid changes in OARs over time lead to different maximum doses than planned. By using semi‐automatic OAR contour propagation, OARs are more accurately delineated on subsequent fractions, with corresponding improved accuracy of the reported dose to the OARs.

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Section: Discussionsupporting

confidence: 49%

Section: Discussionmentioning

confidence: 71%

Improved dosimetric accuracy with semi‐automatic contour propagation of organs‐at‐risk in glioblastoma patients undergoing chemoradiation

Lee

Stewart

Lee

et al. 2019

J Applied Clin Med Phys

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“…The observed differences in optic chiasm contouring may be due to the challenges in identifying the anatomical borders of the structure in relation to its transition into optic nerves anteriorly and optic tracts posteriorly. Similarly, Sanstrom et al reported large variability in the contouring of the optic chiasm in a study evaluating OAR contouring practices in international radiosurgery institutions [21]. In cases (e.g.…”

Section: Discussionmentioning

confidence: 94%

Glioma consensus contouring recommendations from a MR-Linac International Consortium Research Group and evaluation of a CT-MRI and MRI-only workflow

et al. 2020

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Introduction This study proposes contouring recommendations for radiation treatment planning target volumes and organs-at-risk (OARs) for both low grade and high grade gliomas. Methods Ten cases consisting of 5 glioblastomas and 5 grade II or III gliomas, including their respective gross tumor volume (GTV), clinical target volume (CTV), and OARs were each contoured by 6 experienced neuro-radiation oncologists from 5 international institutions. Each case was first contoured using only MRI sequences (MRI-only), and then re-contoured with the addition of a fused planning CT (CT-MRI). The level of agreement among all contours was assessed using simultaneous truth and performance level estimation (STAPLE) with the kappa statistic and Dice similarity coefficient. Results A high level of agreement was observed between the GTV and CTV contours in the MRI-only workflow with a mean kappa of 0.88 and 0.89, respectively, with no statistically significant differences compared to the CT-MRI workflow (p = 0.88 and p = 0.82 for GTV and CTV, respectively). Agreement in cochlea contours improved from a mean kappa of 0.39 to 0.41, to 0.69 to 0.71 with the addition of CT information (p < 0.0001 for both cochleae). Substantial to near perfect level of agreement was observed in all other contoured OARs with a mean kappa range of 0.60 to 0.90 in both MRI-only and CT-MRI workflows. Conclusions Consensus contouring recommendations for low grade and high grade gliomas were established using the results from the consensus STAPLE contours, which will serve as a basis for further study and clinical trials by the MR-Linac Consortium.

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“…Even with high-quality imaging, variability in target and normal tissue definition can result in wide variability in radiation treatment delivery, particularly for treatments that have higher conformality and precision such as radiosurgery [17][18][19]. Challenges in defining the gross tumor margin and clinical target margin for radiation planning have been a growing challenge in Radiation Oncology with increasing importance with the advent of inverse planning and increasingly conformal treatments, such as radiosurgery approaches.…”

Section: Special Focus Y Imaging and Imagination: Advances In Image-gmentioning

confidence: 99%

Image-guided radiation therapy: looking beyond what we currently see

Chung

Brock

2017

Future Oncol.

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Assessment of organs-at-risk contouring practices in radiosurgery institutions around the world – The first initiative of the OAR Standardization Working Group

Cited by 17 publications

References 32 publications

Improved dosimetric accuracy with semi‐automatic contour propagation of organs‐at‐risk in glioblastoma patients undergoing chemoradiation

Improved dosimetric accuracy with semi‐automatic contour propagation of organs‐at‐risk in glioblastoma patients undergoing chemoradiation

Glioma consensus contouring recommendations from a MR-Linac International Consortium Research Group and evaluation of a CT-MRI and MRI-only workflow

Image-guided radiation therapy: looking beyond what we currently see

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