| 1. |
- Brodin, N Patrik, et al.
(författare)
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Radiobiological risk estimates of adverse events and secondary cancer for proton and photon radiation therapy of pediatric medulloblastoma.
- 2011
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Ingår i: Acta oncologica (Stockholm, Sweden). - 1651-226X. ; 50:6, s. 806-16
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Tidskriftsartikel (refereegranskat)abstract
- Abstract Introduction. The aim of this model study was to estimate and compare the risk of radiation-induced adverse late effects in pediatric patients with medulloblastoma (MB) treated with either three-dimensional conformal radiotherapy (3D CRT), inversely-optimized arc therapy (RapidArc(®) (RA)) or spot-scanned intensity-modulated proton therapy (IMPT). The aim was also to find dose-volume toxicity parameters relevant to children undergoing RT to be used in the inverse planning of RA and IMPT, and to use in the risk estimations. Material and methods. Treatment plans were created for all three techniques on 10 pediatric patients that have been treated with craniospinal irradiation (CSI) at our institution in 2007-2009. Plans were generated for two prescription CSI doses, 23.4 Gy and 36 Gy. Risk estimates were based on childhood cancer survivor data when available and secondary cancer (SC) risks were estimated as a function of age at exposure and attained age according to the organ-equivalent dose (OED) concept. Results. Estimates of SC risk was higher for the RA plans and differentiable from the estimates for 3D CRT at attained ages above 40 years. The risk of developing heart failure, hearing loss, hypothyroidism and xerostomia was highest for the 3D CRT plans. The risks of all adverse effects were estimated as lowest for the IMPT plans, even when including secondary neutron (SN) irradiation with high values of the neutron radiation weighting factors (WR(neutron)). Conclusions. When comparing RA and 3D CRT treatment for pediatric MB it is a matter of comparing higher SC risk against higher risks of non-cancer adverse events. Considering time until onset of the different complications is necessary to fully assess patient benefit in such a comparison. The IMPT plans, including SN dose contribution, compared favorably to the photon techniques in terms of all radiobiological risk estimates.
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| 2. |
- Sveistrup, Joen, et al.
(författare)
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Prospective assessment of urinary, gastrointestinal and sexual symptoms before, during and after image-guided volumetric modulated arc therapy for prostate cancer
- 2015
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Ingår i: Scandinavian journal of urology. - : Taylor & Francis. - 2168-1805 .- 2168-1813. ; 49:1, s. 58-69
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Tidskriftsartikel (refereegranskat)abstract
- Objective: The aim of this study was to prospectively assess the development of 24 urinary, gastrointestinal and sexual symptoms in patients with prostate cancer (PCa) during and after image-guided volumetric modulated arc therapy (IG-VMAT).Material and methods: A total of 87 patients with PCa participated in this study. The patients were asked to complete a modified version of the Prostate Cancer Symptom Scale (PCSS) questionnaire before radiotherapy (RT) (baseline), at the start of RT, at the end of RT and 1 year after RT. Changes in symptoms at the start of RT, at the end of RT and 1 year after RT compared to baseline were analysed by a mixed model analysis of repeated measurements with the following covariates: age, comorbidity, smoking and androgen deprivation therapy (ADT).Results: All urinary problems except for haematuria increased significantly at the end of RT compared to baseline. One year after RT, there was no longer any difference compared to baseline for any of the urinary symptoms. All gastrointestinal symptoms except for nausea increased significantly at the end of RT. One year after RT, patients also reported slightly higher degrees of stool frequency, bowel leakage, planning of toilet visits, flatulence, mucus, gastrointestinal bleeding and impact of gastrointestinal bother on daily activities compared to baseline. All sexual symptoms increased significantly at all times compared to baseline. The use of ADT was associated with worse sexual symptoms.Conclusions: IG-VMAT is a safe treatment for PCa, with few and mild changes in urinary and gastrointestinal symptoms 1 year after RT compared to baseline. Sexual symptoms deteriorated both during and after RT. The use of ADT was associated with worse sexual symptoms.
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| 3. |
- Wegdén, Marie, et al.
(författare)
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Nuclear microprobe analysis of the selective boron uptake obtained with BPA in brain tumour tissue
- 2004
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Ingår i: Nuclear Instruments & Methods in Physics Research. Section B: Beam Interactions with Materials and Atoms. - : Elsevier BV. - 0168-583X. ; 219-20, s. 67-71
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Tidskriftsartikel (refereegranskat)abstract
- The tumour selective ability of the boron compound boronophenylalanine (BPA), today used in Boron Neutron Capture Therapy in Sweden, has been investigated with the Lund Nuclear Microprobe. The tumour to tissue ratio of the boron concentration, as well as the location of boron within the cells, is critical for the efficiency of the therapy. It is desirable that the boron is accumulated as close as possible to the cell nucleus, since the alpha particles produced in the B-10(n,alpha)Li-7 reaction only have a range of about 10 microns, i.e. a cell diameter. The nuclear reaction B-11(p,alpha)2alpha, which has an especially high cross-section (300 mb) for 660 keV protons, has been used to analyse brain tissue from BPA-injected rats. Previous studies on other boron compounds have shown significant background problems when the alpha particles are detected in the backward direction. By a specially designed set-up, alpha particles in the forward and backward direction are detected simultaneously, and only the coincidences between the two directions are considered to be true boron events. In this way we could achieve excellent background suppression. The analysis shows that BPA indeed is tumour selective. Quantifications show a boron abundance of 150 +/- 20 ng/cm(2) in normal tissue and 567 70 ng/cm(2) in tumour tissue. If the rat is fed with L-dopa before the injection of BPA the uptake increases 3-4 times. The boron is homogeneously distributed in the cellular structure and no specific intracellular accumulation has been shown. (C) 2004 Elsevier B.V. All rights reserved.
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| 6. |
- af Rosenschöld, Per Munck, et al.
(författare)
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The MCNP Monte Carlo Program
- 2012. - 2nd
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Ingår i: Monte Carlo Calculations in Nuclear Medicine : Applications in Diagnostic Imaging - Applications in Diagnostic Imaging. - : Taylor & Francis. - 9781439841099 - 9781439841105 ; , s. 153-172
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Bokkapitel (refereegranskat)abstract
- Monte Carlo N-Particle (MCNP) is a Monte Carlo code package allowing coupled neutron, photon, and electron transport calculations. Also, the possibility of performing heavy charged particle transport calculations was recently introduced with the twin MCNPX code package. An arbitrary three-dimensional problem can be formulated through the use of surfaces defining building blocks (“cells” that are assigned density, material, and relevant cross-section tables. The source can be specified as point, surface, or volumes using generic or as a phase/space file.
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| 7. |
- Agn, Mikael, et al.
(författare)
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A modality-adaptive method for segmenting brain tumors and organs-at-risk in radiation therapy planning
- 2019
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Ingår i: Medical Image Analysis. - : Elsevier BV. - 1361-8415. ; 54, s. 220-237
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Tidskriftsartikel (refereegranskat)abstract
- In this paper we present a method for simultaneously segmenting brain tumors and an extensive set of organs-at-risk for radiation therapy planning of glioblastomas. The method combines a contrast-adaptive generative model for whole-brain segmentation with a new spatial regularization model of tumor shape using convolutional restricted Boltzmann machines. We demonstrate experimentally that the method is able to adapt to image acquisitions that differ substantially from any available training data, ensuring its applicability across treatment sites; that its tumor segmentation accuracy is comparable to that of the current state of the art; and that it captures most organs-at-risk sufficiently well for radiation therapy planning purposes. The proposed method may be a valuable step towards automating the delineation of brain tumors and organs-at-risk in glioblastoma patients undergoing radiation therapy.
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| 8. |
- Astradsson, Arnar, et al.
(författare)
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Cerebral infarction after fractionated stereotactic radiation therapy of benign anterior skull base tumors
- 2019
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Ingår i: Clinical and Translational Radiation Oncology. - : Elsevier BV. - 2405-6308. ; 15, s. 93-98
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Tidskriftsartikel (refereegranskat)abstract
- Background: The purpose of this study was to examine the occurrence of cerebral infarction (ischemic stroke), in a large combined cohort of patients with anterior skull base meningiomas, pituitary adenomas and craniopharyngiomas, after fractionated stereotactic radiation therapy (FSRT). Material and Methods: All patients, 18 years and older, with anterior skull base meningiomas, pituitary adenomas and craniopharyngiomas, treated with fractionated stereotactic radiation, in our center, from January 1999 to December 2015 were identified. In total 169 patients were included. The prescription dose to the tumor was 54 Gy for 164 patients (97%) and 46.0–52.2 Gy for 5 patients (3%). Cases of cerebral infarctions subsequent to FSRT were identified from the Danish National Patient Registry and verified with review of case notes. The rate of cerebral infarction after FSRT was compared to the rate in the general population with a one sample t-test after standardization for age and year. We explored if age, sex, disease type, radiation dose and dose per fraction was associated with increased risk of cerebral infarction using univariate Cox models. Results: At a median follow-up of 9.3 years (range 0.1–16.5), 7 of the 169 patients (4.1%) developed a cerebral infarction, at a median 5.7 years (range 1.2–11.5) after FSRT. The mean cerebral infarction rate for the general population was 0.0035 and 0.0048 for the FSRT cohort (p = 0.423). Univariate cox models analysis showed that increasing age correlated significantly with the cerebral infarction risk, with a hazard ratio of 1.090 (p = 0.013). Conclusion: Increased risk of cerebral infarction after FSRT of anterior skull base tumors was associated with age, similar to the general population. Our study revealed that FSRT did not introduce an excess risk of cerebral infarction.
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| 9. |
- Brodin, N Patrik, et al.
(författare)
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Hippocampal sparing radiotherapy for pediatric medulloblastoma: impact of treatment margins and treatment technique.
- 2014
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Ingår i: Neuro-oncology. - : Oxford University Press (OUP). - 1523-5866 .- 1522-8517. ; 16:4, s. 594-602
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Tidskriftsartikel (refereegranskat)abstract
- BackgroundWe investigated how varying the treatment margin and applying hippocampal sparing and proton therapy impact the risk of neurocognitive impairment in pediatric medulloblastoma patients compared with current standard 3D conformal radiotherapy.MethodsWe included 17 pediatric medulloblastoma patients to represent the variability in tumor location relative to the hippocampal region. Treatment plans were generated using 3D conformal radiotherapy, hippocampal sparing intensity-modulated radiotherapy, and spot-scanned proton therapy, using 3 different treatment margins for the conformal tumor boost. Neurocognitive impairment risk was estimated based on dose-response models from pediatric CNS malignancy survivors and compared among different margins and treatment techniques.ResultsMean hippocampal dose and corresponding risk of cognitive impairment were decreased with decreasing treatment margins (P < .05). The largest risk reduction, however, was seen when applying hippocampal sparing proton therapy-the estimated risk of impaired task efficiency (95% confidence interval) was 92% (66%-98%), 81% (51%-95%), and 50% (30%-70%) for 3D conformal radiotherapy, intensity-modulated radiotherapy, and proton therapy, respectively, for the smallest boost margin and 98% (78%-100%), 90% (60%-98%), and 70% (39%-90%) if boosting the whole posterior fossa. Also, the distance between the closest point of the planning target volume and the center of the hippocampus can be used to predict mean hippocampal dose for a given treatment technique.ConclusionsWe estimate a considerable clinical benefit of hippocampal sparing radiotherapy. In choosing treatment margins, the tradeoff between margin size and risk of neurocognitive impairment quantified here should be considered.
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| 10. |
- Brodin, N. Patrik, et al.
(författare)
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Modeling freedom from progression for standard-risk medulloblastoma : A mathematical tumor control model with multiple modes of failure
- 2013
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Ingår i: International Journal of Radiation Oncology, Biology, Physics. - : Elsevier BV. - 0360-3016. ; 87:2, s. 422-429
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Tidskriftsartikel (refereegranskat)abstract
- Purpose As pediatric medulloblastoma (MB) is a relatively rare disease, it is important to extract the maximum information from trials and cohort studies. Here, a framework was developed for modeling tumor control with multiple modes of failure and time-to-progression for standard-risk MB, using published pattern of failure data. Methods and Materials Outcome data for standard-risk MB published after 1990 with pattern of relapse information were used to fit a tumor control dose-response model addressing failures in both the high-dose boost volume and the elective craniospinal volume. Estimates of 5-year event-free survival from 2 large randomized MB trials were used to model the time-to-progression distribution. Uncertainty in freedom from progression (FFP) was estimated by Monte Carlo sampling over the statistical uncertainty in input data. Results The estimated 5-year FFP (95% confidence intervals [CI]) for craniospinal doses of 15, 18, 24, and 36 Gy while maintaining 54 Gy to the posterior fossa was 77% (95% CI, 70%-81%), 78% (95% CI, 73%-81%), 79% (95% CI, 76%-82%), and 80% (95% CI, 77%-84%) respectively. The uncertainty in FFP was considerably larger for craniospinal doses below 18 Gy, reflecting the lack of data in the lower dose range. Conclusions Estimates of tumor control and time-to-progression for standard-risk MB provides a data-driven setting for hypothesis generation or power calculations for prospective trials, taking the uncertainties into account. The presented methods can also be applied to incorporate further risk-stratification for example based on molecular biomarkers, when the necessary data become available.
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