Siegel J A, Khan S H
Department of Radiation Oncology, Cooper Hospital/University Medical Center, Camden, New Jersey 08103, USA.
J Nucl Med. 1996 Mar;37(3):495-7.
The purpose of this study was to validate a previously reported body contour measurement using Compton backscatter sources with bremsstrahlung SPECT imaging.
Bremsstrahlung SPECT imaging was performed with 32P using a dual-headed camera system fitted with medium-energy, parallel-hole collimators. Two sources of 99mTc were placed directly on each collimator. Energy windows of 100 keV +/- 25% were used to image the 32P and also to record the Compton scatter from the 99mTc sources. Eleven patients enrolled in clinical Phase I therapeutic protocols were injected with 32P-chromic phosphate and SPECT images were acquired and reconstructed in the transaxial plane. The 32P distribution and the patient body contour were both visualized in these slices. The anteroposterior and lateral patient dimensions were measured by generating count profiles parallel to the anteroposterior and lateral body contour, respectively, at the midline in a transaxial slice. The distance in centimeters between the two centroids of each profile is representative of the anteroposterior and lateral dimensions and was determined for each patient. These anteroposterior and lateral dimensions were compared to the same distance measurements made in these patients by CT in an anatomically comparable transaxial slice. A cylindrical SPECT phantom was also studied to further validate the contour measurements.
The mean percent difference in the patient dimension measurements between SPECT and CT was -0.8% with a range of -8.5% to 9.9%. The percent difference between the known and SPECT measured dimensions in the cylindrical phantom was 0.5%.
The two external Compton scatter source method is accurate for determining the body contour.
本研究的目的是使用具有轫致辐射单光子发射计算机断层显像（SPECT）成像的康普顿背散射源来验证先前报道的身体轮廓测量方法。
使用配备中能平行孔准直器的双头相机系统，用³²P进行轫致辐射SPECT成像。将两个⁹⁹ᵐTc源直接放置在每个准直器上。使用100keV±25%的能量窗对³²P进行成像，并记录来自⁹⁹ᵐTc源的康普顿散射。11名参加临床I期治疗方案的患者注射了³²P - 磷酸铬，并采集SPECT图像并在横断面进行重建。在这些切片中同时显示³²P分布和患者身体轮廓。通过分别在横断面的中线处生成与前后和侧身体轮廓平行的计数剖面图来测量患者的前后和左右尺寸。每个剖面图的两个质心之间以厘米为单位的距离代表前后和左右尺寸，并针对每个患者进行确定。将这些前后和左右尺寸与在解剖学可比的横断面切片中通过CT对这些患者进行的相同距离测量进行比较。还研究了一个圆柱形SPECT体模以进一步验证轮廓测量。
SPECT和CT之间患者尺寸测量的平均百分比差异为 -0.8%，范围为 -8.5%至9.9%。圆柱形体模中已知尺寸和SPECT测量尺寸之间的百分比差异为0.5%。
双外部康普顿散射源方法在确定身体轮廓方面是准确的。
