Room: AAPM ePoster Library
Purpose: For late-effects studies, we use 3D age-scaling factors (ASFs) to scale our in-house DICOM computational phantom to patients’ ages at time of radiation therapy (RT); each body region is uniquely scaled to account for non-uniform growth. Since these age-based factors do not consider patient variations at each age, we aimed to generate additional ASFs to account for patients in different height percentiles. The new ASFs corresponds to U.S. population (male-based) heights reported by Center for Disease Control and Prevention (CDC).
Methods: We used 5th, 25th, 50th, 75th, and 95th CDC percentile-heights for ages 1, 3, 5 10, 15 and 18 years. At each age and percentile-height, we calculated the ratio of CDC percentile-height to the height of our DICOM phantom. We then multiplied each ratio to the DICOM-ASFs to create new CDC-ASFs for each body-region (head, neck, trunk, legs, and arms). The CDC-ASFs were used to produce all body regions and three organs (heart, colon and liver).
Results: We plotted the CDC-ASFs and evaluated how they changed with age for each body region and in each direction (superior-inferior, anterior-posterior, and left-right). All CDC-ASFs increased with age except for those of the head. For the head CDC-ASFs, a decrease is observed between ages 3 and 5 years. For the organs, we evaluated how the application of the CDC-ASFs changed the volume of each organ. Our DICOM in-house phantom organs had similar volumes as those scaled with the 50th percentile-height CDC-ASFs.
Conclusion: We generated ASFs from the percentile-heights reported by CDC for each body region to generate percentile-height specific DICOM phantoms. Next, we will use these CDC-ASFs to create DICOM phantoms of a user-selected height. Future plans include adding ASFs based on CDC percentile-heights for females.