全身用ポジトロン断層撮影装置(島津: SET-2400W)の2次元および3次元データ収集画像の分解能とカウント·リカバリ係数の測定

摘要

[目的]島津社製pET装置SET-2400Wの3次元画像の分解能とカウント·リカバリ係数を臨床検査条件画像より求め, 2次元画像と比較検討した. [方法と結果] 3次元画像は3DRP法とFORE法, 2次元画像は2D FBP法にて再構成した.断面内分解能はフィルタ·カットオフ周波数1.25cm'~（-1）にて2次元, 3次元画像共に断面中心10cm以内で約6~7mmFWHM, 20cmにおいて9mmFWHM以下であった.スライス半値幅は断面中心にて2D FBP5.8mm, 3DRP8.0mm, FORE6.8mmFWHMを示した.断面中心から6cmでのリカバリ係数は,直径10mmの円柱で2D FBP0.69, 3DRP0.72,FOREO.73,また球体では, 2D FBP0.52, 3DRP0.51, FORE0.53であった.[結論]臨床検査条件での2次元と3次元画像再構成画像の間に大きな差はなかった.We measured the resolution and count recovery coefficients (RC) of the SET-2400W whole-body PET scanner (Shimadzu Co., Japan) in the 2D and 3D clinical modes. Method: The 3D images were reconstructed by using the full 3D image reconstruction method (3-D reprojection algorithm: 3DRP) and the Fourier rebinning method (FORE). The 2D images were reconstructed with conventional filtered back-projection method (FBP). The measurements of resolution and recovery coefficient were according to JRIA (Japan Radioisotope Association) protocols. Results: The transaxial resolutions of all methods were better than 7 mm FWHM at a radius of 10 cm with 1.25 cm~(-1) cutoff frequency. The average slice width of 2D FBP, 3DRP and FORE are 5.8 mm, 8.0 mm and 6.8 mm respectively at the center of transaxial field of view. The RC values were measured in a range from 10 mm to 27 mm at 6 cm from the center with the cylindrical and spherical hot area phantoms. In all methods, RC values at 27 mm diameter were nearly 1.0 in both type of hot area. RC values at 10 mm diameter in 2D FBP, 3DRP and FORE of cylindrical hot area were 0.69, 0.72, 0.73 and those of spherical hot area were 0.52, 0.51,0.53 respectively. Conclusion: At the SET-2400W, resolution and recovery coefficient of 3D mode image under the clinical mode showed the value which did not differ from the 2D mode image.