Characteristics of CCD Based Optical CT Scanner for Therapeutic Radiation Dosimetry

Jae Choon Lee; Ae Ran Kim; Young Hoon Ji; Soo-Il Kwon

doi:10.14316/pmp.2016.27.2.72

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Lee, Kim, Ji, and Kwon: Characteristics of CCD Based Optical CT Scanner for Therapeutic Radiation Dosimetry

Original Article

Progress in Medical Physics 2016;27(2):72-78.

Published online: 20 March 2016

DOI: https://doi.org/10.14316/pmp.2016.27.2.72

Characteristics of CCD Based Optical CT Scanner for Therapeutic Radiation Dosimetry

Jae Choon Lee^∗, Ae Ran Kim^∗, Young Hoon Ji^†, Soo-Il Kwon^‡

^∗Department of Medical Physics, Kyonggi University, Suwon, Korea

^†Korea Institute of Radiological and Medical Sciences, Seoul, Korea

^‡Department of ElectroPhysics, College of Natural Science, Kyonggi University, Suwon, Korea

Correspondence: Soo-Il Kwon (sikwon@kyonggi.ac.kr) Tel: 82-31-249-9618, Fax: 82-31-253-1165 cc This is an Open-Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/4.0) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.

Received 30 May 2016 Revised 3 June 2016 Accepted 4 June 2016

This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/3.0) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

A CCD camera and an LED light source were combined to fabricate a compact optical CT scanner for the therapeutic radiation dose evaluation of a polymer gel dosimeter. After the collimated beam emitted by the LED passed through aquarium, gel phantom, and telecentric lens, an image was collected by the CCD camera and reconstructed using MATLAB. By using a stepping motor and LabVIEW, the gel dosimeter was rotated at every 0.72^o, and the time for collecting 500 slice images per a revolution was within 20 min. At a spatial frequency of 4.5 lp/mm of the optical CT scanner, the modulation transfer function value was 72%. The linear correlation coefficient of the optical CT scanner for the polymer gel dosimeter was 0.987.

Keywords: Optical Computed Tomography Scanner, Polymer Gel, Dosimetry

References

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Fig. 1.

A schematic diagram of OCT Scanner (left) and a picture of OCT on the experiment (right).

Fig. 2.

Modulation Transfer Function curve. Spatial resolution for a optical CT system is measured to be 72% out to 4.5 lp/mm.

Fig. 3.

Projection image of a gel dosimeter irradiated with Cyberknife (1 Gy, 2 Gy and 3 Gy).

Fig. 4.

Dose response curve of a gel dosimeter measured by OCT scanner. The inset shows the linearity to 6 Gy and the linear correlation coefficient of r²=0.987.

Fig. 5.

Dose response curve of a gel dosimeter using MRI. The linear correlation coefficient is r²=0.997.

Fig. 6.

Percent Depth Dose distribution measured on the depth of central axis of a polymer gel dosimeter using 6 MV X-ray photon beam.

Fig. 7.

(a) Sinogram, (b) irradiated gel and (c) isodose distribution.

Fig. 8.

(a) A bear doll installed in PET container, (b) sagittal projection image (2,456×2,058 pixels, 16 bit), (c) sinogram, (d) line profile at the vertical black line of sinogram and (e) 3-dimensional rendering image.

Table 1.

Timing characteristics of OCT scanner.

Timing characteristics	Number of projections/revolution
Timing characteristics	100	500	1000
Time per slice	2.4 min/slice	2.5 min/slice	2.1 min/slice
Time per slice	2.4 min/slice	2.5 min/slice	2.1 min/slice
Scanning	.4 min	.20 min	.35 min
Reconstruction	.1 h	.2 h	.6 h
Overall	.1.5 h	.2.5 h	.10 h

Table 2.

A comparison of the dosimetric characteristics for OCT, X-ray CT, and MRI.

Modality	Linear Correlation Coefficient (^)	Time (min/slice)	Advantages	Disadvantages
OCT∗	0.987∗ (0∼6 Gy)	＜3	▶Fast time	▶Scattering
			▶Compact	▶Phantom size limitation
			▶Low cost
X-ray CT	0.990¹⁰⁾ (0∼6 Gy)	＜1⁹⁾	▶Easily accessible	▶low sensitivity
			▶Fast time	▶Extra x-ray
MRI	0.970¹¹⁾ (0∼14 Gy)	25¹⁶⁾	▶Good dose resolution	▶Temperature dependence
				▶Long time
				▶High cost

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