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그림1) (a) A photograph in the treatment setup. (b) CT based (c) and tablet generated PC models of RANDO™ phantom.​

그림2) (a) The 3D model of a compensator, created by a computer aided design application, and (b) the 3D-printed shape of the compensator used to create a silicone mold for shaping the wax/tungsten powder mixture.​

Abstract

PURPOSE:

The purpose of total body irradiation (TBI) techniques is to deliver a uniform radiation dose to the entire volume of a patient's body. Due to variations in the thickness of the patient, it is difficult to produce such a uniform dose distribution throughout the body. In many techniques, a compensator is used to adjust the dose delivered to various sections of the patient. The current study aims to develop and validate an innovative method of using depth-sensing cameras and 3D printing techniques for TBI treatment planning and compensator fabrication.

METHODS:

A tablet with an integrated depth-sensing camera and motion tracking sensors was used to scan a RANDO™ phantom positioned in a TBI treatment booth to detect and store the 3D surface in a point cloud format. The accuracy of the detected surface was evaluated by comparing extracted body thickness measurements with corresponding measurements from computed tomography (CT) scan images. The thickness, source to surface distance, and off-axis distance of the phantom at different body section were measured for TBI treatment planning. A detailed compensator design was calculated to achieve a uniform dose distribution throughout the phantom. The compensator was fabricated using a 3D printer, silicone molding, and a mixture of wax and tungsten powder. In vivo dosimetry measurements were performed using optically stimulated luminescent detectors.

RESULTS:

The scan of the phantom took approximately 30 s. The mean error for thickness measurements at each section of phantom relative to CT was 0.48 ± 0.27 cm. The average fabrication error for the 3D-printed compensator was 0.16 ± 0.15 mm. In vivo measurements for an end-to-end test showed that overall dose differences were within 5%.

CONCLUSIONS:

A technique for planning and fabricating a compensator for TBI treatment using a depth camera equipped tablet and a 3D printer was demonstrated to be sufficiently accurate to be considered for further investigation.​ 

Author information

Lee MY1, Han B2, Jenkins C3, Xing L2, Suh TS1.​

1Department of Biomedical Engineering, College of Medicine, The Catholic University of Korea, Seoul 137-701, South Korea and Research Institute of Biomedical Engineering, College of Medicine, The Catholic University of Korea, Seoul 137-701, South Korea.

2Department of Radiation Oncology, Stanford University School of Medicine, Stanford, California 94305.

3Department of Radiation Oncology, Stanford University School of Medicine, Stanford, California 94305 and Department of Mechanical Engineering, Stanford University, Stanford, California 94305.