Campbell D L, Peterson T E
Institute of Imaging Science, Vanderbilt University Medical Center, Nashville, TN, USA. Department of Physics and Astronomy, Vanderbilt University, Nashville, TN, USA.
Phys Med Biol. 2014 Nov 21;59(22):7059-79. doi: 10.1088/0031-9155/59/22/7059. Epub 2014 Oct 31.
We conducted simulations to compare the potential imaging performance for breast cancer detection with High-Purity Germanium (HPGe) and Cadmium Zinc Telluride (CZT) systems with 1% and 3.8% energy resolution at 140 keV, respectively. Using the Monte Carlo N-Particle (MCNP5) simulation package, we modelled both 5 mm-thick CZT and 10 mm-thick HPGe detectors with the same parallel-hole collimator for the imaging of a breast/torso phantom. Simulated energy spectra were generated, and planar images were created for various energy windows around the 140 keV photopeak. Relative sensitivity and scatter and the torso fractions were calculated along with tumour contrast and signal-to-noise ratios (SNR). Simulations showed that utilizing a ±1.25% energy window with an HPGe system better suppressed torso background and small-angle scattered photons than a comparable CZT system using a -5%/+10% energy window. Both systems provided statistically similar contrast and SNR, with HPGe providing higher relative sensitivity. Lowering the counts of HPGe images to match CZT count density still yielded equivalent contrast between HPGe and CZT. Thus, an HPGe system may provide equivalent breast imaging capability at lower injected radioactivity levels when acquiring for equal imaging time.
我们进行了模拟，以比较高纯度锗（HPGe）和碲化镉锌（CZT）系统在140 keV能量分辨率分别为1%和3.8%时检测乳腺癌的潜在成像性能。使用蒙特卡罗N粒子（MCNP5）模拟软件包，我们对5毫米厚的CZT探测器和10毫米厚的HPGe探测器进行建模，两者使用相同的平行孔准直器对乳房/躯干模型进行成像。生成模拟能谱，并针对140 keV光电峰周围的各种能量窗创建平面图像。计算相对灵敏度、散射和躯干分数以及肿瘤对比度和信噪比（SNR）。模拟表明，与使用-5%/+10%能量窗的类似CZT系统相比，使用HPGe系统的±1.25%能量窗能更好地抑制躯干背景和小角度散射光子。两个系统在统计学上提供了相似的对比度和SNR，HPGe具有更高的相对灵敏度。将HPGe图像的计数降低以匹配CZT计数密度，HPGe和CZT之间仍具有等效的对比度。因此，在相同成像时间采集时，HPGe系统在较低的注入放射性水平下可能提供等效的乳房成像能力。
