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Pediatric intracranial arteriovenous malformations (AVM) have a greater cumulative lifetime risk of rupture than adults. While obliteration after radiation occurs in a dose-dependent manner, increasing radiation doses also pose a higher risk of adverse radiation effects (ARE). Radiosurgery is effective in adults, but less is known about the efficacy and safety of robotic radiosurgery for pediatric intracranial AVMs. We performed a retrospective review of consecutive pediatric patients with AVMs at a single institution with minimum follow-up of 1.75 years who underwent robotic radiosurgery between 2005 and 2021 with one of 3 radiosurgery dosing schedules: 1) single-stage unfractionated, 2) single-stage fractionated, 3) volumetrically multi-staged treatment. Cox proportional hazards regression models were performed to identify predictors of AREs and obliteration. 95 patients (age:1-21 years, M:F 50:45) with 100 intracranial AVMs were identified for analysis. Median follow-up time was 4.5 years (range = 1.75-15.25 years). Forty-four (46.3%) patients presented with ruptured AVMs. The mean AVM volume was 10.0 cm3 ± 11.88 (range = 0.11-71.86 cm3). Most had Spetzler-Martin grade III (36.2%) and IV (31.9%). The overall rate of total obliteration was 52.6% (78.8% in single-stage unfractionated, 24.2% in single-stage fractionated, and 10% in multi-staged treatment) with a median obliteration time of 3.25 years (2.8- 4.1 years). Partial obliteration was achieved in 23.2% (17.3% in single-stage unfractionated, 30.3% in single-stage fractionated, and 30% in multi-staged treatment). In the univariate analysis, higher obliteration rate was associated with small volume (hazard ratio; HR = 0.876, 0.812 – 0.945) (P = 0.001), lower Spetzler-Martin grade (HR = 0.437, 0.320 – 0.597) (P = <0.001), and higher single-fraction equivalent dose (HR = 1.160, 1.020 – 1.198) (P = 0.015), respectively. Pretreatment hemorrhages were found in 51 patients (59.6 % in unfractionated, 45.5 % in fractionated, and 50% in multi-staged treatment). Thirteen patients experienced hemorrhage in the post-treatment period (3.8% in unfractionated, 12% in fractionated, and 60% in staged treatment). AREs were found in 31.6% of patients, many of whom (50%) had deep subcortical lesions. Male gender and V12Gy correlated with AREs (HR = 0.447, 0.199 – 1.004) (P = 0.051) and (HR = 1.020, 1.000 – 1.041) (P = 0.053), respectively. Single-fraction radiosurgery is very effective in treating smaller pediatric AVMs with obliteration rates of 79%. While single-stage fractionated treatment was less effective in achieving total obliteration (24%), this approach significantly reduced the posttreatment hemorrhage rate by at least half. Unfortunately, only 10% of AVMs in the multi-staged cohort were obliterated and post-treatment hemorrhage rates were not reduced. AVMs located in deeper cortical regions and those with higher Spetzler-Martin grade remain challenging. [ABSTRACT FROM AUTHOR]

In this article, we comment on the article by Ono et al . We focus specifically on the carbon ion radiotherapy studies and the method to calculate the dosing schedule. While photon hypofractionated radiotherapy in prostate cancer has demonstrated improvement in tumor control with reduced gastrointestinal toxicity compared to conventional radiotherapy, carbon ion radiotherapy (CIRT) offers additional physical and biological advantages. Recent findings, including those from Ono et al , have established new dose constraints of CIRT for prostate cancer treatment and risk factors for rectal bleeding. Due to limited data on CIRT dosing, this study underscores the need for more research to refine dose calculation methods and better understand their effects on clinical outcomes., Competing Interests: Conflict-of-interest statement: All the authors report no relevant conflicts of interest for this article., (©The Author(s) 2024. Published by Baishideng Publishing Group Inc. All rights reserved.)

Introduction: This study compared the predictive ability of radiation-induced cataract between maximum point dose of the lens (Lens Dmax) ≥7 Gy, mean lens dose (Lens Dmean) ≥7 Gy, Lens Dmax ≥10 Gy, and Lens Dmean ≥10 Gy., Methods: Patients aged 3-18 years received cranial irradiation or radiation therapy at head and neck area between January 2010 and December 2019 at our institute were included. Patients without baseline and/or follow-up eye examination were excluded. Receiver operating characteristic (ROC) curves identified potential predictors and Cox regression analysed correlations between potential factors and cataract occurrence., Results: Sixty-three patients (122 eyes) were analysed. Cataracts were detected in 14 eyes (11.5%). Median follow-up time was 4 years (range 0.5-10 years), with cataract developing in a median of 2.5 years (range 0.3-7 years). Three patients (21.4%) developed grade ≥3 cataract. Lens Dmean ≥10 Gy was associated with cataract formation., Conclusion: Lens Dmean ≥10 Gy showed the highest ability for predicting radiation-induced cataract in paediatric patients. Net reclassification improvement (NRI) suggested that changing lens dose constraint from Dmax <7 Gy to Dmean <10 Gy would miss 7% of cataract cases but avoid 28% of unnecessary restrictions. Adopting a mean lens dose <10 Gy was suggested as a constraint for lens dose., (© 2024 The Author(s). Journal of Medical Imaging and Radiation Oncology published by John Wiley & Sons Australia, Ltd on behalf of Royal Australian and New Zealand College of Radiologists.)