ObjectiveTo investigate the potential to reduce the cochlear dose with robotic photon radiosurgery or intensity-modulated proton therapy planning for vestibular schwannomas.Materials and... Show moreObjectiveTo investigate the potential to reduce the cochlear dose with robotic photon radiosurgery or intensity-modulated proton therapy planning for vestibular schwannomas.Materials and MethodsClinically delivered photon radiosurgery treatment plans were compared to five cochlear-optimized plans: one photon and four proton plans (total of 120). A 1x12 Gy dose was prescribed. Photon plans were generated with Precision (Cyberknife, Accuray) with no PTV margin for set-up errors. Proton plans were generated using an in-house automated multi-criterial planning system with three or nine-beam arrangements, and applying 0 or 3 mm robustness for set-up errors during plan optimization and evaluation (and 3 % range robustness). The sample size was calculated based on a reduction of cochlear Dmean > 1.5 Gy(RBE) from the clinical plans, and resulted in 24 patients.ResultsCompared to the clinical photon plans, a reduction of cochlear Dmean > 1.5 Gy(RBE) could be achieved in 11/24 cochlear-optimized photon plans, 4/24 and 6/24 cochlear-optimized proton plans without set-up robustness for three and nine-beam arrangement, respectively, and in 0/24 proton plans with set-up robustness. The cochlea could best be spared in cases with a distance between tumor and cochlea. Using nine proton beams resulted in a reduced dose to most organs at risk.ConclusionCochlear dose reduction is possible in vestibular schwannoma radiosurgery while maintaining tumor coverage, especially when the tumor is not adjacent to the cochlea. With current set-up robustness, proton therapy is capable of providing lower dose to organs at risk located distant to the tumor, but not for organs adjacent to it. Consequently, photon plans provided better cochlear sparing than proton plans. Show less
Objective: In vestibular schwannoma patients, a loss of signal intensity (SI) on T2-weighted magnetic resonance imaging (MRI) has been reported within the ipsilateral labyrinth. The purpose of this... Show moreObjective: In vestibular schwannoma patients, a loss of signal intensity (SI) on T2-weighted magnetic resonance imaging (MRI) has been reported within the ipsilateral labyrinth. The purpose of this study was to quantitatively evaluate the occurrence and course of this intensity loss in relation to proton radiotherapy and its possible association with hearing loss. Study Design: Retrospective chart review. Setting: Tertiary referral center. Patients: Patients who received proton therapy for a vestibular schwannoma and underwent at least two high-resolution T2-weighted cisternographic sequence (constructive interference in steady state/fast imaging employing steady-state acquisition/DRIVE) MRIs and audiometry assessments. Main Outcome Measures: Relative T2 SIs from the vestibules and basal/apical cochlear turns of the labyrinth, bilaterally.ResultsNinety-five MRI scans from 34 patients were included. The apical turn of the ipsilateral cochlea showed a lower mean cochlear SI than on the contralateral side (+/- 3.5 versus 5.0). The mean relative cochlear SI did not significantly change after proton radiotherapy. The ipsilateral vestibule showed a higher SI than the cochlea. The relative mean cochlear SI was not directly correlated to (the degree of) hearing loss before or after proton radiotherapy, nor did it predict future hearing loss. Conclusion: The relative mean cochlear SI on cisternographic T2-MRI in vestibular schwannoma patients is diminished on the treated side, when compared with the ipsilateral vestibule and the contralateral cochlea/vestibule. The SI of the ipsilateral cochlea does not further decrease after proton radiotherapy and seems to be related to the tumor rather than the therapy. The diminished cochlear SI does not correlate with subsequent loss of hearing. Show less
Objective: To assess the efficacy and toxicity of proton radiotherapy in vestibular schwannoma. Study Design: Retrospective chart review and volumetric MRI-analyses. Setting: Tertiary referral... Show moreObjective: To assess the efficacy and toxicity of proton radiotherapy in vestibular schwannoma. Study Design: Retrospective chart review and volumetric MRI-analyses. Setting: Tertiary referral center. Patients: Vestibular schwannoma patients treated with protons between 2003 and 2018. Intervention: Proton radiotherapy. Main Outcome Measures: Tumor control was defined as not requiring salvage treatment. Progressive hearing loss was defined as a decrease in maximum speech discrimination score below the 95% critical difference in reference to the pretreatment score. Hearing assessment includes contralateral hearing and duration of follow-up. Dizziness and/or unsteadiness and facial and trigeminal nerve function were scored. Patients who had surgery prior to proton radiotherapy were separately assessed. Results: Of 221 included patients, 136 received single fraction and 85 fractionated proton radiotherapy. Actuarial 5-year local control rate was 96% (95% CI 90-98%). The median radiological follow-up was 4.5 years. Progressive postirradiation speech discrimination score loss occurred in 42% of patients with audiometric follow-up within a year. Facial paresis was found in 5% (usually mild), severe dizziness in 5%, and trigeminal neuralgia in 5% of patients receiving protons as primary treatment. Conclusions: Proton radiotherapy achieves high tumor control with modest side effects aside from hearing loss in vestibular schwannoma patients. Limited and heterogeneous outcome reporting hamper comparisons to the literature. Potential sequelae of radiation therapy impacting vestibular function, cognitive function, and quality of life warrant further evaluation. Subgroups that benefit most from proton radiotherapy should be identified to optimize allocation and counterbalance its costs. Show less
Patients with locally advanced cervical cancer (LACC) treated with chemoradiation often experience hematologic toxicity (HT), as chemoradiation can induce bone marrow (BM) suppression. Studies on... Show morePatients with locally advanced cervical cancer (LACC) treated with chemoradiation often experience hematologic toxicity (HT), as chemoradiation can induce bone marrow (BM) suppression. Studies on the relationship between BM dosimetric parameters and clinically significant HT might provide relevant indices for developing BM sparing (BMS) radiotherapy techniques. This systematic review studied the relationship between BM dose and HT in patients with LACC treated with primary cisplatin-based chemoradiation. A systematic search was conducted in Embase, Medline, and Web of Science. Eligibility criteria were treatment of LACC-patients with cisplatin-based chemoradiation and report of HT or complete blood cell count (CBC). The search identified 1346 papers, which were screened on title and abstract before two reviewers independently evaluated the full-text. 17 articles were included and scored according to a selection of the TRIPOD criteria. The mean TRIPOD score was 12.1 out of 29. Fourteen studies defining BM as the whole pelvic bone contour (PB) detected significant associations with V10 (3/14), V20 (6/14), and V40 (4/11). Recommended cut-off values were V10 > 95-75%, V20 > 80-65%, and V40 > 37-28%. The studies using lower density marrow spaces (PBM) or active bone marrow (ABM) as a proxy for BM only found limited associations with HT. Our study was the first literature review providing an overview of articles evaluating the correlation between BM and HT for patients with LACC undergoing cisplatin-based chemoradiation. There is a scarcity of studies independently validating developed prediction models between BM dose and HT. Future studies may use PB contouring to develop normal tissue complication probability models. (c) 2021 The Author(s). Published by Elsevier B.V. Radiotherapy and Oncology 164 (2021) 128-137 This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/). Show less
Proton therapy offers an attractive alternative to conventional photon-based radiotherapy in low grade glioma patients, delivering radiotherapy with equivalent efficacy to the tumour with less... Show moreProton therapy offers an attractive alternative to conventional photon-based radiotherapy in low grade glioma patients, delivering radiotherapy with equivalent efficacy to the tumour with less radiation exposure to the brain. In the Netherlands, patients with favourable prognosis based on tumour and patient characteristics can be offered proton therapy. Radiation-induced neurocognitive function decline is a major concern in these long surviving patients. Although level 1 evidence of superior clinical outcome with proton therapy is lacking, the Dutch National Health Care Institute concluded that there is scientific evidence to assume that proton therapy can have clinical benefit by reducing radiation-induced brain damage. Based on this decision, proton therapy is standard insured care for selected low grade glioma patients. Patients with other intracranial tumours can also qualify for proton therapy, based on the same criteria. In this paper, the evidence and considerations that led to this decision are summarised. Additionally, the eligibility criteria for proton therapy and the steps taken to obtain high-quality data on treatment outcome are discussed. (C) 2020 The Author(s). Published by Elsevier B.V. Show less
Objective Vestibular schwannomas are benign tumors that are often managed by radiotherapy. Minimizing long-term toxicity is paramount for a population that remains at normal life expectancy and at... Show moreObjective Vestibular schwannomas are benign tumors that are often managed by radiotherapy. Minimizing long-term toxicity is paramount for a population that remains at normal life expectancy and at risk for loss of quality of life for years if not decades. Whereas current radiotherapy standard utilizes photon radiation, proton radiotherapy characteristics may enable a reduction of toxicity by reducing the volume of collateral irradiated healthy tissue. A systematic review was conducted to assess tumor control and short- and long-term sequelae after proton irradiation. Methods Studies that reported on treatment outcomes of proton radiotherapy in vestibular schwannoma patients were included. Results Five peer-reviewed retrospective series met the inclusion criteria. Quality of the studies varied from low to good. There were 276 unique patients described. Tumor control rates ranged from 85 to 100% (radiological median follow-up of 2.2-7.4 years). Hearing loss rates, defined as losing Gardner Robertson class I/II hearing, showed an weighted crude average 52% (depending on follow-up duration). The weighted averages for post-irradiation facial and trigeminal neuropathy were 5% and 4%, respectively. The risk of neuropathy seems to decrease with lower radiation dosages. Conclusion Proton irradiation for vestibular schwannomas achieves high tumor control rates, equivalent to photon irradiation. Reported cranial nerve preservation rates vary, partly due to an apparent selection bias with a high percentage of patients with clinical symptoms prior to treatment. Results of cranial nerve function preservation, quality of life, and cognitive functioning are currently insufficiently reported. In addition, advances in proton radiotherapy technology warrant re-evaluation of current techniques and protocols for the management of vestibular schwannomas. Show less
Boer, P. de; Schoot, A.J.A.J. van de; Westerveld, H.; Smit, M.; Buist, M.R.; Bel, A.; ... ; Stalpers, L.J.A. 2018
The aim of the study was to investigate the potential clinical benefit from both target tailoring by excluding the tumour-free proximal part of the uterus during image-guided adaptive radiotherapy ... Show moreThe aim of the study was to investigate the potential clinical benefit from both target tailoring by excluding the tumour-free proximal part of the uterus during image-guided adaptive radiotherapy (IGART) and improved dose conformity based on intensity-modulated proton therapy (IMPT).The study included planning CTs from 11 previously treated patients with cervical cancer with a > 4-cm tumour-free part of the proximal uterus on diagnostic magnetic resonance imaging (MRI). IGART and robustly optimised IMPT plans were generated for both conventional target volumes and for MRI-based target tailoring (where the non-invaded proximal part of the uterus was excluded), yielding four treatment plans per patient. For each plan, the V-15Gy, V-30Gy, V-45Gy and D-mean for bladder, sigmoid, rectum and bowel bag were compared, and the normal tissue complication probability (NTCP) for >= grade 2 acute small bowel toxicity was calculated.Both IMPT and MRI-based target tailoring resulted in significant reductions in V-15Gy, V-30Gy, V-45Gy and D-mean for bladder and small bowel. IMPT reduced the NTCP for small bowel toxicity from 25% to 18%; this was further reduced to 9% when combined with MRI-based target tailoring. In four of the 11 patients (36%), NTCP reductions of > 10% were estimated by IMPT, and in six of the 11 patients (55%) when combined with MRI-based target tailoring. This > 10% NTCP reduction was expected if the V-45Gy for bowel bag was > 275 cm(3) and > 200 cm(3), respectively, during standard IGART alone.In patients with cervical cancer, both proton therapy and MRI-based target tailoring lead to a significant reduction in the dose to surrounding organs at risk and small bowel toxicity. Show less
Arts, T.; Breedveld, S.; Jong, M.A. de; Astreinidou, E.; Tans, L.; Keskin-Cambay, F.; ... ; Hoogeman, M.S. 2017
