Study On Data Correction Method Of Compact Gamma Camera Based On Flat Crystal

Now most of the research on gamma ray imaging at home and abroad uses crystal array crystals or plate crystals to combine with position sensitive photomultiplier tubes to form detectors.In the development of multifunctional gamma cameras,detectors are often required to be able to use different sizes of pinhole/coding plate collimators.The crystal matrix crystal does not apply due to the limitation of the lattice unit size.The detector module composed of flat crystals has the advantages of lower cost,higher light collection efficiency,high sensitivity,continuous sampling,and strong expansion ability.It is more suitable for application in multifunctional gamma cameras.However,plate crystals are affected by boundary conditions,thickness,electronic positioning algorithms,and other factors,and they can not always avoid the problem of edge compression effects.Therefore,data correction must be carried out.In this paper,the position correction method and the homogeneity correction method are proposed for the characteristics of the flat crystal detector responding to scintillation events.In nonlinear correction,a Gaussian distribution model of detector response to photons is established,and a new scale device is developed.By means of the calibration device,38*38 points position scale on the flat detector is completed.Through a series of steps,such as center location finding,segmentation algorithm,area marking,are used to generate the flat crystal data lookup table.At last a mapping relationship between ray event occur location of plate crystal and photon receive position of imaging picture is established.In the uniformity correction,in order to make the different locations of the detector respond to the scintillation event uniformly,the raw data accumulation graph is obtained by a long-time field test and generate the coefficient table by normalization.The two tables are read by the software system background,respectively,to complete the data position and uniformity correction,and generate the radiation image.A small gamma camera consisting of a flat crystal detector is placed in the radiation field,and the original data is collected by radiation experiments.The original data is processed using position correction and homogeneity correction methods respectively.The results show that the data correction method can effectively alleviate the image distortion caused by edge compression effect of the flat crystal detector,improve the imaging effect,and verify the correctness of the method.Then the data correction method is applied to a small gamma camera system,and the optical image and radiation image are fused using the method of proportional scaling transformation based on the feature points.Then two kinds of collimators are used to experiment in the radiation field.The measurement results show that the gamma camera system composed of flat crystal detectors can locate the hot spot position information,and the correctness of the data correction method is proved again.