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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]

Image-guided adaptive brachytherapy (IGABT) is the standard of care for patients with cervical cancer. The objective of this study was to compare the treatment outcomes and adverse effects of computed tomography (CT)-guided and magnetic resonance imaging (MRI)-guided scenarios. Data of patients with cervical cancer treated using external beam radiotherapy followed by IGABT from 2012 to 2016 were retrospectively reviewed. CT-guided IGABT was compared with the three modes of MRI-guided IGABT: pre-brachytherapy (MRI Pre-BT) without applicator insertion for fusion, planning MRI with applicator in-place in at least 1 fraction (MRI ≥1Fx), and MRI in every fraction (MRI EveryFx). Patient characteristics, oncologic outcomes, and late radiation toxicity were analyzed using descriptive, survival, and correlation statistics. Overall, 354 patients were evaluated with a median follow-up of 60 months. The 5-year overall survival (OS) rates were 61.5%, 65.2%, 54.4%, and 63.7% with CT-guided, MRI PreBT, MRI ≥1Fx, and MRI EveryFx IGABT, respectively with no significant differences (p = 0.522). The 5-year local control (LC) rates were 92.1%, 87.8%, 80.7%, and 76.5% (p = 0.133), respectively, with a significant difference observed between the CT-guided and MRI ≥1Fx (p = 0.018). The grade 3–4 late gastrointestinal toxicity rates were 6% in the CT-guided, MRI ≥1Fx, and MRI EveryFx, and 8% in MRI PreBT. The grade 3–4 late genitourinary toxicity rates were 4% in the CT-guided, 2% in MRI PreBT, 1% in MRI ≥1Fx, and none in MRI EveryFx. No significant differences were observed in the oncologic and toxicity outcomes among MRI PreBT, MRI ≥1Fx, and MRI EveryFx. CT-guided IGABT yielded an acceptable 5-year OS, LC, and toxicity profile compared with all MRI scenarios and is a potentially feasible option in resource-limited settings. • CT-only IGABT was comparable to all MRI-guided scenarios. • No significant differences established among MRI Pre-BT, MRI ≥1Fx, and MRI EveryFx. • Utility of CT and MRI could be personalised based on availability of resources. [ABSTRACT FROM AUTHOR]