Kim J H, Choi Y, Joo K S, Sihn B S, Chong J W, Kim S E, Lee K H, Choe Y S, Kim B T
Department of Nuclear Medicine, Samsung Medical Center, Seoul, Korea.
Phys Med Biol. 2000 Nov;45(11):3481-8. doi: 10.1088/0031-9155/45/11/326.
We have developed a small scintillation camera dedicated to breast imaging and have evaluated the performance of the system. In order to increase the limited field of view (FOV) determined by the size of a position-sensitive photomultiplier tube (PSPMT), the imaging characteristics of a diverging hole collimator (DHC) were also investigated. The small scintillation camera system consists of an NaI(Tl) crystal (60 mm x 60 mm x 6 mm) coupled to a Hamamatsu R3941 PSPMT, a resistor chain circuit, preamplifiers, nuclear instrument modules, an analogue to digital converter and a PC for control and display. The intrinsic energy resolution of the system was 12.9% FWHM at 140 keV. The spatial resolution was measured using a line-slit mask and 99mTc point sources and was 3.1 mm FWHM. The intrinsic sensitivity of the system was approximately 162 counts/s kBq(-1). The DHC made it possible to image a larger FOV (75 x 75 mm2 at the surface of collimator) than a parallel-hole collimator (60 x 60 mm2). The system sensitivity obtained using the DHC gradually decreased with distance (3% at 1 cm, 6% at 2 cm and 9% at 3 cm). The results demonstrate that the system developed in this study could be utilized clinically to image malignant breast tumours. A DHC can be employed to expand the FOV of the system confined by the size of PSPMT with a modest compromise in the performance of the system.
我们开发了一款专门用于乳腺成像的小型闪烁相机，并对该系统的性能进行了评估。为了扩大由位置敏感光电倍增管（PSPMT）尺寸所决定的有限视野（FOV），我们还研究了发散孔准直器（DHC）的成像特性。小型闪烁相机系统由一块与滨松R3941型PSPMT耦合的碘化钠（铊）晶体（60毫米×60毫米×6毫米）、一个电阻链电路、前置放大器、核仪器模块、一个模数转换器以及一台用于控制和显示的个人计算机组成。该系统在140keV时的固有能量分辨率为半高宽（FWHM）的12.9%。使用线缝掩模和99mTc点源测量的空间分辨率为半高宽3.1毫米。该系统的固有灵敏度约为162计数/秒·kBq⁻¹。与平行孔准直器（60×60毫米²）相比，DHC能够对更大的视野（准直器表面为75×75毫米²）进行成像。使用DHC获得的系统灵敏度随着距离逐渐降低（1厘米处为3%，2厘米处为6%，3厘米处为9%）。结果表明，本研究中开发的系统可用于临床乳腺恶性肿瘤成像。DHC可用于扩大受PSPMT尺寸限制的系统视野，同时在系统性能上有适度的折衷。
