Calculation algorithms and penumbra: Underestimation of dose in organs at risk in dosimetry audits

Hughes, Jeremy; Lye, Jessica; Kadeer, F.; Alves, Andrew; Shaw, Maddison; Supple, Jeremy; Keehan, Stephanie; Gibbons, Francis; Lehmann, Jöerg; Kron, Tomas

doi:10.1002/mp.15123

Cited by 11 publications

(8 citation statements)

References 23 publications

(57 reference statements)

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“…First, treatment planning systems are known to underestimate the collimator scatter and scatter from other components of the beam line, which directly affect the out-of-field dose calculations. Therefore, for organs further away from the target, the dose discrepancies increased, in accordance with the previous studies [14,15]. Second, in the treatment planning process, manual contouring was done to delineate the organs and structures of interest.…”

Section: Deterministic Effects and Stochastic Effects Of The Fetussupporting

confidence: 71%

Assessment of Fetal Dose and Health Effect to the Fetus from Breast Cancer Radiotherapy during Pregnancy

Suwanbut

Liamsuwan

Nantajit

et al. 2022

Life

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Decision for radiotherapy during the first trimester of pregnancy may occur, as patients may not realize their pregnancy at the very early stage. Since radiation dose can affect fetal development, the aim of this study was to evaluate fetal dose and associated deterministic effects and risks to the fetus from breast cancer radiotherapy of an 8-week pregnant patient. PHITS (Particle and Heavy Ion Transport code System) Monte Carlo simulation and the J-45 computational pregnancy phantom were used to simulate breast cancer radiotherapy from a 6 MV TrueBeam linear accelerator using the three dimensional-conformal radiotherapy (3D-CRT) technique with a prescribed dose to the planning target volume (PTV) of 50 Gy. Once the fetal dose was evaluated, the occurrence of the deterministic effects and risks for developing stochastic effects in the fetus were assessed using the recommendations of NCRP Report No. 174, AAPM Report No. 50, and ICRP Publication 84. The fetal dose was evaluated to be 3.37 ± 2.66 mGy, suggesting that the fetus was expected to have no additional deterministic effects, while the risks for developing cancer and malfunctions were similar to that expected from exposure to background radiation. The comparison with the other studies showed that accurate consideration of fetal position and size was important for dose determination in the fetus, especially at the early pregnancy stage when the fetus is very small.

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Section: Deterministic Effects and Stochastic Effects Of The Fetussupporting

confidence: 71%

Assessment of Fetal Dose and Health Effect to the Fetus from Breast Cancer Radiotherapy during Pregnancy

Suwanbut

Liamsuwan

Nantajit

et al. 2022

Life

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“…Moreover, comparing to the study by Sarkar et al 18 where the analyses were compared in MIM, the dosimetric endpoints in this current work were obtained in each TPS, which avoided further partial volume interpolation in a different software. Maximum dose in the spinal cord in our study was on average lower by 1.17% in AXB than AAA, which is consistent with the results of the spine study by Hughes et al, 15 where they found the plans calculated in AXB were on average 4.5% colder than AAA when comparing the maximum dose in the spinal cord. Overall, comparing to our clinical plans, the relative differences for all algorithms had an average of 1.73% (−10.36% to 13.21%) for the tumor metrics and −0.93% (−9.87%−10.95%) for Dmax of the spinal cord.…”

Section: Dose Calculation Algorithmssupporting

confidence: 92%

“…Dose algorithm calculation comparisons were of particular interest in heterogeneity and complex tissue interfaces, such as spine, 2 , 5 , 15 lung, 16 , 17 , 18 and HN. 19 , 20 Khan et al.…”

Section: Discussionmentioning

confidence: 99%

The dosimetric impact of titanium implants in spinal SBRT using four commercial treatment planning algorithms

Liu

Cho

Magnelli

et al. 2023

J Applied Clin Med Phys

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To evaluate the dosimetric impact of titanium implants in spine SBRT using four dose calculation algorithms. Twenty patients with titanium implants in the spine treated with SBRT without density override (DO) were selected. The clinical plan for each patient was created in Pinnacle and subsequently imported into Eclipse (AAA and AcurosXB) and Raystation (CC) for dose evaluation with and without DO to the titanium implant. We renormalized all plans such that 90% of the tumor volume received the prescription dose and subsequently evaluated the following dose metrics: (1) the maximum dose to 0.03 cc (Dmax), dose to 99% (D99%) and 90% (D90%) of the tumor volume; (2) Dmax and volumetric metrics of the spinal cord. For the same algorithm, plans with and without DO had similar dose distributions. Differences in Dmax, D99% and D90% of the tumor were on average <2% with slightly larger variations up to 5.58% in Dmax using AcurosXB. Dmax of the spinal cord for plans calculated with DO increased but the differences were clinically insignificant for all algorithms (mean: 0.36% ± 0.7%). Comparing to the clinical plans, the relative differences for all algorithms had an average of 1.73% (−10.36%–13.21%) for the tumor metrics and −0.93% (−9.87%–10.95%) for Dmax of the spinal cord. A few cases with small tumor and spinal cord volumes, dose differences of >10% in both D99% and Dmax of the tumor, and Dmax of the spinal cord were observed. For all algorithms, the presence of titanium implants in the spine for most patients had minimal impact on dose distributions with and without DO. For the same plan calculated with different algorithms, larger differences in volumetric metrics of >10% could be observed, impacted by dose gradient at the plan normalization volume, tumor volumes, plan complexity, and partial voxel volume interpolation.

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“…An instructive literature has grown which reports on investigations of the patterns of failures observed over the IROC-H experience with external E2E audits [52,93,140,[142][143][144][145][146][147][148]. Throughout the IROC-H audits, program failures have consistently been identified with issues in the physics domain, even daily output variations have contributed to unsuccessful E2E phantom irradiation [144].…”

Section: Lessons Learned From Past Radiation Therapy E2e Testingmentioning

confidence: 99%

End-to-End QA in Radiation Therapy Quality Management

Schreiner

2023

J. Phys.: Conf. Ser.

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End-to-End (E2E) testing is a method originating from computer science that is designed to determine whether an application communicates as required with hardware, networks, databases, and other applications. This paper is to advocate that the quality management (QM) of modern radiation therapy (RT) would benefit from more regular use of E2E based quality assurance (QA) in the local clinic. The argument is that modern RT delivery is performed through some process linked by a chain of interdependent stages and actions mediated by complex interchanges during the patient’s treatment. These actions along the chain are often modified due to decisions by clinical staff who are interpreting information acquired along the process. While physics QA can validate that each of these steps are technically achievable (e.g., through machine QA) such conventional QA does not guarantee that the overall process is being carried out as planned even when it has been described by a well-defined protocol and delivered by well-trained staff. The paper briefly reviews the changes in programmatic design as RT has become more complex, the associated changes in RT QM, and some past examples of E2E testing in RT clinics, usually performed during the implementation of some new RT technique or during external audits of the clinic’s practice. The paper then makes the case for increased E2E QA based on the lessons learned from this experience and ends with some suggestions for implementing effective and sustainable E2E testing in a clinic’s QM program.

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Calculation algorithms and penumbra: Underestimation of dose in organs at risk in dosimetry audits

Cited by 11 publications

References 23 publications

Assessment of Fetal Dose and Health Effect to the Fetus from Breast Cancer Radiotherapy during Pregnancy

Assessment of Fetal Dose and Health Effect to the Fetus from Breast Cancer Radiotherapy during Pregnancy

The dosimetric impact of titanium implants in spinal SBRT using four commercial treatment planning algorithms

End-to-End QA in Radiation Therapy Quality Management

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