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Objective Assessment of Spine Phantom Using Various 3D Printers for Patient Specific QA in SBRT: A Feasibility Study

T Suh

S Lee1,2*, T Suh1,2 , M Kim1,2 , M Lee1,2 , S Park1,2 , J Song1,2 , J Sohn3 , (1) Dept. of Biomedical Engineering, College of Medicine, The Catholic University of Korea, Seoul,(2) Research Institute of Biomedical Engineering, The Catholic University of Korea, Seoul, (3) Case Western University, Cleveland, OH


PO-BPC-Exhibit Hall-3 (Saturday, March 5, 2016)  Room: Exhibit Hall

Purpose: Radiation therapy oncology group (RTOG) 0631 suggest different planning method in spine stereotactic body radiation therapy (SBRT) according to location of cancer owing to its distinct shape. The purpose of this study is to verify dosimetric accuracy of delivered dose in spine SBRT as highly precise radiotherapy depending on cancer position using dedicated spine phantom based on 3d printer.

Materials and Methods: The phantom was designed to evaluate delivered dose by three different cancer positions located in vertebral body, encircling the spinal cord, and the posterior spinous process supplied by RTOG 0631. Furthermore, the phantom was made to enable film to insert between two slabs of the phantom to verify the dosimetric effects and accuracy of dose distributions. For 3d printing, the phantom modeling was performed by various software applications such as SEG3D, ImageVis3D, Meshmixer, Solid works and CAD based on spine CT images. There are many kinds of 3d printing methods depending on materials, printing time, or printing cost. Developed phantom can verify two classes according to printing method: (i) direct light projection (DLP) method (ii) polyjet method. These printing methods are using same material as acrylic polymer, the density of which is 1.39 g/ml similar with the density of spine.

Results: The Hounsfield unit (HU) value of the acquired CT images was different in accordance with 3d printing method despite same material. Average HU values of DLP and polyjet method were 148.97 and 109.54 in same region of interest (ROI). The HU value of former method was similar with that of patient spine CT, which is 163.07.

Conclusion: The developed phantom especially using DLP method can be utilized as spine SBRT dosimetry research. Our study was able to confirm that the phantom was indeed similar with HU value of human spine as well as its shape.

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