日本放射線技術学会雑誌
Online ISSN : 1881-4883
Print ISSN : 0369-4305
ISSN-L : 0369-4305
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SPECTにおける新しいコントラスト分解能評価用ファントム
市川 肇小野口 昌久島田 秀樹加藤 豊大
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2012 年 68 巻 1 号 p. 111-116

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Objectives: We have designed a phantom to evaluate acquisition and reconstruction parameters using contrast transfer function (CTF). The goal of this study was to evaluate the accuracy of the phantom for contrast resolution. Methods: The phantom consisted of spaced (0–14 mm, 1 mm intervals) pairs of cubic containers (5 mm wide, 20 mm long, and 50 mm high). The phantom’s accuracy was examined by comparing a real value of a measured count profile using the phantom with a theoretical value obtained by the line spread function (LSF) using a line source. A SPECT acquisition was 256×256 matrix (pixel size: 0.9×0.9 mm2), 360 degrees at 30 s/view. The radius of rotation was set to 15 cm, and the types of collimators were low energy high resolution (LEHR) and low middle energy general purpose (LMEGP). Reconstructions were performed with filtered backprojection and ordered subsets expectation maximization method (10 iterations, 10 subsets) with collimator-detector response correction. Results: The actual measured count profile and CTF accorded closely with the theoretical one. Discussion: The line pair (LP) phantom, obtained with smaller pixels, was really accurate. The size of cubic containers poses as a minimal problem for accurately evaluating the contrast resolution and plotted counts profile. Conclusions: This phantom could be a useful method for evaluating acquisition and reconstruction parameters in SPECT.

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© 2012 公益社団法人 日本放射線技術学会
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