Research On Quality Control Method Of Rotation Center Drift For Double Probe SPECT

Single photon emission computed tomography(SPECT)is an important imaging instrument for nuclear medicine.The image quality of tomographic reconstruction is not only related to its reconstruction method,but also related to the mechanical properties of its probe.The SPECT center of rotation(COR)is an important indicator of the mechanical performance of SPECT.If the center of rotation drift occurs,the spatial resolution of the tomographic image will be reduced,and even artifacts will appear,which will affect the clinician’s diagnosis.Therefore,some international organizations and China’s national standards have developed quality control standards or technical reports on the rotation center drift detection.However,there are two methods for calculating the rotation center drift value in these standards and reports.One is the curve fitting method,another is the arithmetic averaging method,and the difference between the two calculation methods is not known.Secondly,the number of 99mTc point sources used in each standard and report is different,and the placement method is also inconsistent.The operation of multiple 99mTc point sources not only increases the complexity of detection,but also increases the dose burden of the inspectors.The purpose of this study is to study the dual-probe SPECT rotation center drift quality control method.First,compare the curve fitting method with the arithmetic average method to calculate the difference of the rotation center drift;then,according to the 99mTc point source placed in different regions of the probe,study the spatial region.The effect on the drift value of the center of rotation;finally verifying whether the center of rotation drift could be quality controlled using a 99mTc point source.To lay the foundation for the improvemeIt of relevant domestic quality control indicators in the future,and provide experience for follow-up work.In this study,three point-source combinations were used for experiments,namely"one-point source combination","three-point source combination" and "five-point source combination".Each combination was calculated by "curve fitting method" and "arithmetic averaging method".Comparison of curve fitting method and arithmetic average method:under the"one-point source combination","three-point source combination" and "five-point source combination",the curve fitting method and the arithmetic average method were used to calculate respectively.The multi-group results calculated by the method were paired t-test,and the differences were not statistically significant(P>0.05).The experimental results indicate that the difference between the two methods is not statistically significant.The effect of the spatial region on the drift value of the center of rotation:the experiment was performed using "three-point source combination" and "five-point source combination",regardless of point source on the probe center or off center area,center of rotation drift value of absolute deviation is within±0.1 mm,and the calculated value of the off center area is not significantly larger than the central area,or the calculated value of the central area is significantly larger than the off center area,and the spatial region is rotated.The calculation of the center drift value has no effect.Verification of the "One-Source Combination" method for detecting the rotation of the center of rotation:Paired t-test and bland-altman consistency analysis were performed on the results of the "one-point source combination","three-point source combination" and "five-point source combination" with the results of the manufacturers respectively.The paired t-test results showed no statistical significance(P>0.05),and the results of the three combined detection methods were consistent with the results of the manufacturers.The experimental results indicate that the "one-point source combination" and the "three-point source combination" and the "five-point source combination" can correctly detect the rotation center drift of the dual-probe SPECT device.However,in the experimental operation,the point source is prepared by the radionuclide 99mTc,the "one-point source combination" method,because only one 99mTc point source needs to be prepared,the operation time is the shortest,and the radiation dose received by the tester is the lowest.The results of this study show that there is no statistically significant difference between the curve fitting method and the arithmetic mean method in calculating the rotation center drift value;the spatial region has little effect on the rotation center drifi value;a 99mTc point source can perform quality control detection on the double probe spect rotation center drift.And its operation method is simpler and safer.I hope this research can provide certain reference and technical support for the development of relevant standards in China.