| 1. |
- Gasic, D., et al.
(författare)
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Retrospective estimation of heart and lung doses in pediatric patients treated with spinal irradiation
- 2018
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Ingår i: Radiotherapy and Oncology. - : Elsevier BV. - 0167-8140. ; 128:2, s. 209-213
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Tidskriftsartikel (refereegranskat)abstract
- Background and purpose: The purpose of this study was to investigate whether treatment information from medical records can be used to estimate radiation doses to heart and lungs retrospectively in pediatric patients receiving spinal irradiation with conventional posterior fields. Material and methods: An algorithm for retrospective dosimetry in children treated with spinal irradiation was developed in a cohort of 21 pediatric patients with available CT-scans and treatment plans. We developed a multivariable linear regression model with explanatory variables identifiable in case note review for retrospective estimation of minimum, maximum, mean and V-10%-V-80% doses to the heart and lungs. Doses were estimated for both linear accelerator (Linac) and Co-60 radiation therapy modalities. Results: Age and spinal field width were identified as statistically significant predictors of heart and lung doses in multivariable analyses (p < 0.01 in all models). Models showed excellent predictive performance with R-2 = 0.70 for mean heart dose and 0.79 for mean lung dose, for Linac plans. In leave-one-out cross-validation analysis the average difference between predicted and actual mean heart dose was 6.7% and 7.6% of the prescription dose for Linac and Co-60 plans, respectively, and 5.2% and 4.9% for mean lung dose. Due to the small sample size and large inter-patient variation in heart and lung dose, prospective studies validating these findings are highly warranted. Conclusions: The models presented here provide retrospective estimates of heart and lung doses for historical cohorts of pediatric patients, thus facilitating studies of long-term adverse effects of radiation. (C) 2018 Elsevier B.V. All rights reserved.
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| 2. |
- Gram, D., et al.
(författare)
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Residual positioning errors and uncertainties for pediatric craniospinal irradiation and the impact of image guidance
- 2020
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Ingår i: Radiation Oncology. - : Springer Science and Business Media LLC. - 1748-717X. ; 15:1
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Tidskriftsartikel (refereegranskat)abstract
- Background Optimal alignment is of utmost importance when treating pediatric patients with craniospinal irradiation (CSI), especially with regards to field junctions and multiple isocenters and techniques applying high dose gradients. Here, we investigated the setup errors and uncertainties for pediatric CSI using different setup verification protocols. Methods A total of 38 pediatric patients treated with CSI were identified for whom treatment records and setup images were available. The setup images were registered retrospectively to the reference image using an automated tool and matching on bony anatomy, subsequently, the impact of different correction protocols was simulated. Results For an action-level (AL)-protocol and a non-action level (NAL)-protocol, the translational residual setup error can be as large as 24 mm for an individual patient during a single fraction, and the rotational error as large as 6.1 degrees. With daily IGRT, the maximum setup errors were reduced to 1 mm translational and 5.4 degrees rotational versus 1 mm translational and 2.4 degrees rotational for 3- and 6- degrees of freedom (DoF) couch shifts, respectively. With a daily 6-DoF IGRT protocol for a wide field junction irradiation technique, the residual positioning uncertainty was below 1 mm and 1 degrees for translational and rotational directions, respectively. The largest rotational uncertainty was found for the patients' roll even though this was the least common type of rotational error, while the largest translational uncertainty was found in the patients' anterior-posterior-axis. Conclusions These results allow for informed margin calculation and robust optimization of treatments. Daily IGRT is the superior choice for setup of pediatric patients treated with CSI, although centers that do not have this option could use the results presented here to improve their margins and uncertainty estimates for a more accurate treatment alignment.
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| 3. |
- Gram, D., et al.
(författare)
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The risk of radiation-induced neurocognitive impairment and the impact of sparing the hippocampus during pediatric proton cranial irradiation
- 2023
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Ingår i: Acta Oncologica. - : Informa UK Limited. - 0284-186X .- 1651-226X. ; 62:2, s. 134-140
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Tidskriftsartikel (refereegranskat)abstract
- Background and purposeHippocampus is a central component for neurocognitive function and memory. We investigated the predicted risk of neurocognitive impairment of craniospinal irradiation (CSI) and the deliverability and effects of hippocampal sparing. The risk estimates were derived from published NTCP models. Specifically, we leveraged the estimated benefit of reduced neurocognitive impairment with the risk of reduced tumor control.Material and methodsFor this dose planning study, a total of 504 hippocampal sparing intensity modulated proton therapy (HS-IMPT) plans were generated for 24 pediatric patients whom had previously received CSI. Plans were evaluated with respect to target coverage and homogeneity index to target volumes, maximum and mean dose to OARs. Paired t-tests were used to compare hippocampal mean doses and normal tissue complication probability estimates.ResultsThe median mean dose to the hippocampus could be reduced from 31.3 Gy(RBE) to 7.3 Gy(RBE) (p < .001), though 20% of these plans were not considered clinically acceptable as they failed one or more acceptance criterion. Reducing the median mean hippocampus dose to 10.6 Gy(RBE) was possible with all plans considered as clinically acceptable treatment plans. By sparing the hippocampus to the lowest dose level, the risk estimation of neurocognitive impairment could be reduced from 89.6%, 62.1% and 51.1% to 41.0% (p < .001), 20.1% (p < .001) and 29.9% (p < .001) for task efficiency, organization and memory, respectively. Estimated tumor control probability was not adversely affected by HS-IMPT, ranging from 78.5 to 80.5% for all plans.ConclusionsWe present estimates of potential clinical benefit in terms of neurocognitive impairment and demonstrate the possibility of considerably reducing neurocognitive adverse effects, minimally compromising target coverage locally using HS-IMPT.
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