Biologic Dose and Imaging Changes in Pediatric Brain Tumor Patients Receiving Spot Scanning Proton Therapy
Our institution utilizes both biologic and standard dose models in spot scanning proton treatment planning. This analysis examines the rates of post-treatment radiologic change as detected on post-treatment MRI scans, and toxicities for pediatric brain tumor patients treated during the first year of our institution ’s experience. Our novel biologic dose model was found to demonstrate greater volumetric overlap with the post-treatment radiologic changes, than the standard dose model.
(European Society for Radiotherapy and Oncology (ESTRO)) A comparison of three types of radiotherapy for children's brain tumors suggests that a type of proton therapy called pencil beam scanning offers the best hope of preserving cognitive functions.
ConclusionsThe complexity of illustrated cases demonstrates the need for a multidisciplinary board evaluation to reach a more accurate diagnosis.
Conclusions: our results suggest that in PBS proton therapy range shifter (RS) need to be used with extreme caution when planning the treatment with an analytical algorithm due to potentially great discrepancies between the planned dose and the dose delivered to the patients, also in case of brain tumours where this issue could be underestimated. Our results also suggest that a MC evaluation of the dose has to be performed every time the RS is used and, mostly, when it is used with large air gaps and beam directions tangential to the patient surface. . PMID: 29726402 [PubMed - as supplied by publisher]
Limited clinical data in children treated with pencil beam scanning proton therapy for a brain tumor are available. We retrospectively analyzed our pediatric patients and reviewed magnetic resonance imaging changes after proton therapy, to assess the rate of radiation necrosis and white matter lesions. Overall, children treated with PBS proton therapy demonstrated a low prevalence of symptomatic radiation necrosis and white matter lesions, compared to similar cohorts treated with either proton or photon radiation therapy.
To assess the rate of radiation necrosis (RN) and white matter lesions (WMLs) in pediatric patients with primary brain tumors treated with pencil beam scanning (PBS) proton therapy (PT) with or without concomitant chemotherapy at the PSI.
DISCUSSION: Fractionated irradiation of exposed target volumes (e.g., subcutaneous tumor model or brain) can be realized with the suggested method being used for daily positioning and range determination. Robust registration of X-ray and proton radiography images allows for the irradiation of tumor entities that require conventional computed tomography (CT)-based planning, such as orthotopic lung or brain tumors, similar to conventional patient treatment. PMID: 28835182 [PubMed - as supplied by publisher]
CONCLUSIONS: Dose escalation can be achieved with IMRT, VMAT and IMPT while respecting normal tissue constraints, yet with IMPT being most favorable. PMID: 28464742 [PubMed - in process]
Abstract Target coverage and organ-at-risk sparing were compared for 22 pediatric patients with primary brain tumors treated using two distinct nozzles in pencil beam scanning (PBS) proton therapy. Consecutive patients treated at our institution using a PBS-dedicated nozzle (DN) were replanned using a universal nozzle (UN) beam model and the original DN plan objectives. Various cranial sites were treated among the patients to prescription doses ranging from 45 to 54 Gy. Organs at risk (OARs) evaluated were patient-dependent; 15 unique OARs were analyzed, all of which were assessed in at least 10 patients. Clinical...
In conclusion, when pencil beam spot sizes are large, the addition of apertures to sharpen the penumbra decreases the in-field radiation-induced secondary cancer risk. There is a slight increase in out-of-field cancer risk as a result of neutron scatter from the aperture, but this risk is by far outweighed by the in-field risk benefit from using an aperture with a large PBS spot size. In general, the risk for developing a second malignancy in out-of-field organs for PBS remains much lower compared to PPT even if apertures are being applied. PMID: 26605679 [PubMed - as supplied by publisher]
Target coverage and organ-at-risk sparing were compared for 22 pediatric patients with primary brain tumors treated using two distinct nozzles in pencil beam scanning (PBS) proton therapy. Consecutive patients treated at our institution using a PBS-dedicated nozzle (DN) were replanned using a universal nozzle (UN) beam model and the original DN plan objectives. Various cranial sites were treated among the patients to prescription doses ranging from 45 to 54 Gy. Organs at risk (OARs) evaluated were patient-dependent; 15 unique OARs were analyzed, all of which were assessed in at least 10 patients. Clinical target volume (CT...