Sapienza University of Rome, Ph. D. Program in Morphogenesis & Tissue Engineering, Rome, Italy.
Department of Radiological Sciences, Oncology and Anatomical Pathology, Sapienza University of Rome, Rome, Italy.
Phys Med. 2019 Nov;67:155-165. doi: 10.1016/j.ejmp.2019.10.028. Epub 2019 Nov 8.
This study investigates a novel gamma tomosynthesis (GT) method based on a variable tilt-angle, parallel-hole collimator (VAPHC) which, mounting to a conventional gamma, is able to perform high-resolution three-dimensional imaging.
The VAPHC has the remarkable feature to be modular, consisting of independent collimation elements able to tilt according to variable angles [-45° to +45°]. Spatial resolutions were measured in reconstructed GT images using a point source at different source-to-collimator distances, while sensitivity was evaluated over the range of slant angles using a disk-source. Image contrast (IC) and contrast-to-noise-ratio (CNR) of sub-centimeters tumors were evaluated using a breast phantom containing a background activity and spheres filled with Tc to simulate lesions at two depths. Breast phantom GT images were compared with planar and circular-orbit SPECT acquisitions of equal scan-time.
Planar spatial resolutions range from 9 to 14 mm over a depth range of 6-10 cm; spatial resolution in depth dimension becomes two times greater than those in the other dimensions. The measured sensitivity decreases from 9 cps/μCi to 6 cps/μCi varying the slant angle from 5° to 45°. The measured IC and CNR of GT reconstructed images demonstrated that it was possible to improve the spatial resolution/sensitivity trade-off.
The proposed GT based VAPHC demonstrated the potential for superior spatial resolution and contrast compared to planar and SPECT acquisitions. A conventional gamma camera equipped with the VAPHC could be located at the minimum distance from the patient, thus improving detection, localisation and characterisation of sub-centimetre lesions.
本研究调查了一种基于可变倾斜角度平行孔准直器（VAPHC）的新型伽马断层合成（GT）方法，该准直器安装在传统伽马相机上，能够进行高分辨率三维成像。
VAPHC 的显著特点是模块化，由能够根据不同角度（-45°至+45°）倾斜的独立准直元件组成。使用点源在不同源-准直器距离下测量 GT 重建图像中的空间分辨率，同时使用盘源评估斜角范围内的灵敏度。使用包含背景活动和充满 Tc 的球体以模拟两个深度处的病变的乳房体模评估亚厘米肿瘤的图像对比度（IC）和对比度噪声比（CNR）。比较了包含背景活动和充满 Tc 的球体以模拟两个深度处的病变的乳房体模 GT 图像与平面和圆形轨道 SPECT 采集的图像。
平面空间分辨率在 6-10cm 的深度范围内从 9 到 14mm 不等；在深度方向上的空间分辨率是其他方向的两倍。从 5°到 45°，斜角从 9cps/μCi 降低到 6cps/μCi。测量的 IC 和 GT 重建图像的 CNR 表明，有可能改善空间分辨率/灵敏度的权衡。
与平面和 SPECT 采集相比，基于 VAPHC 的 GT 显示出具有更高空间分辨率和对比度的潜力。配备 VAPHC 的传统伽马相机可以放置在离患者最近的位置，从而提高对亚厘米病变的检测、定位和定性。
