{"classes":[{"categories":[{"measurements":[{"groupId":"OG000","spread":"27","value":"60"}]}]}],"denomUnitsSelected":"Scans","denoms":[{"counts":[{"groupId":"OG000","value":"53"}],"units":"Participants"},{"counts":[{"groupId":"OG000","value":"134"}],"units":"Scans"}],"description":"Measures will be analyzed for intermediate risk participants who receive proton beam therapy (PBT) and who consent. This objective aims to assess the feasibility of using post-proton beam therapy (PBT) positron emission tomography (PET) as an in-vivo dosimetric and distal edge verification system in this patient population. To quantify the decay in signal, 134 scans from 53 patients were analyzed by recording the mean activation value (MAV), the average recorded PET signal from activation, within the target volume. With each patient being given the same dose, the percent standard deviation in the MAV can serve as a quantitative representation of signal loss due to radioactive decay.","dispersionType":"Standard Deviation","groups":[{"description":"Patients with M0 medulloblastoma or nodular desmoplastic histology with less than a GTR, other histologic diagnoses with no metastatic disease","id":"OG000","title":"Intermediate Risk Group"}],"paramType":"MEAN","populationDescription":"Intermediate risk patients treated at St. Jude were eligible to receive proton beam therapy through referral to the University of Florida Proton Therapy Institute. Patients electing to receive PBT and post-treatment PET scans after the delivery of one treatment beam were included in the analysis.","reportingStatus":"POSTED","timeFrame":"Up to 3 times during RT consolidation","title":"Percent of PET Scans With Loss of Signal Intensity","type":"SECONDARY","typeUnitsAnalyzed":"Scans","unitOfMeasure":"mean activation value (MAV)"}