Room: Exhibit Hall | Forum 7
Purpose: In this study, we developed a novel anthropomorphic head and neck phantom with tissue heterogeneity using a personal three-dimensional (3D) printer for patient-specific quality assurance(QA)in intensity-modulated radiation therapy (IMRT).ã€€
Methods: Computed tomography (CT) images from head and neck cancer patients treated with IMRT were used. Using semi-automatic segmentation, 3D models of bone, soft tissue, and air-filled cavity were created. Multiple holes were incorporated into the 3D models to insert radiophotoluminescent glass dosimeters (RGDs), which enabled us to measure point dose in the phantom. The 3D model which was exported to a standard triangulated language format was imported to Slicer software to print the phantom using a 3D printer. For setting the 3D printer, polylactide was used for soft tissue with 100% infill. Bone was reproduced by pouring the plaster into the cavity created by the 3D printer. To accurately pour the plaster into the whole cavity, separate parts of the cavity were combined into a single continuous one, and the phantom was divided into two separate parts (right and left sides). Gamma analysis was performed for dose distributions calculated using CT images of the 3D-printed phantom and patient. Point dose was measured using seven RGDs distributed throughout the phantom.
Results: On visual inspection, CT image of the phantom was considerably similar to that of the patient. The average CT values for soft tissues and bones were 13.0Â±144.3 HU and 439.5Â±137.0 HU for the phantom and 12.1Â±124.5 HU and 771.5Â±405.3 HU for the patient, respectively. Gamma passing rate with 3%/3 mm criterion was 96.1% for the nine-field IMRT plan.
Conclusion: Our phantom had considerably similar CT values and dose distributions compared to those of the patients. Thus, it could be used for patient-specific QA in IMRT instead of a standard shape phantom.
Radiation Therapy, Phantoms, Dosimetry