SU1405819A1 - Transmission/emission computing tomograph - Google Patents

Abstract

The invention relates to the field of computational trmography, and more specifically to transmission-emission type combined tomographs. The goal is to increase speed by increasing the efficiency of gamma-quanta registration from the active isotope introduced into the studied object of the radio. In the tomograph carried out collimation-free spatial

Description

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Selection of gamma-quanta using a set of semiconductor detectors and a strip scintillator 5, spaced from the specified set and with its ends optically conjugated with a photomultiplier 6 and 7. The photomultiplier circuit 6 and 7 includes power selection circuits 8 and 9 and blocks 10 and 11 of the formation scintillation linear coordinate signal. Signals with detekto1

The invention relates to computational tomography, namely to transmission-emission computational tomographs.

The purpose of the invention is to increase the speed by increasing the efficiency of gamma quanta detection from the radioactive isotope introduced into the object under study.

The ce line shows the functional diagram of the transmission-emission computational tomograph.

The transmission-emission computed tomograph contains a source of 1 fan X-ray beam, a holder 2 of the object under study 3, a linear set of semiconductor detectors 4.1–4.N, a strip scintilla tor 5 with photoelectronic smart

residents (PMTs) 6 and 7 at the ends схему energy selection circuit 8 for gamma quanta energy, energy selection circuit 9, x-ray quanta energy, linear scintillation coordinate generating unit 10 from gamma quanta with a resolution input to which the output is connected Circuits 8, block 11 of forming a linear scintillation coordinate signal from X-ray quanta, a series-parallel converter 12 connected to the output of a block to 10, amplifiers 13.1-13.N ,. connected to the detectors 4.1-4.N, additional circuits, N energy selection g 1m-quanta, matrix memory 15, polling unit 16, computing unit 17 processing the corresponding gamma-quanta of signals

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The ditch 4.1-4 “Dials through additional circuits 14., N of the energy selection of gamma quanta arrive at the columns of the matrix memory 15, the coordinate signal from the block 10 through the parallel-serial converter 12 to the rows of memory 15, each cell of which corresponds to a certain gamma-ray trajectory, 1 hp f-ly, J il.

a computing unit 18 for processing the corresponding x-ray quanta signals, a combination unit 19 and a display unit 20.

The tomograph works as follows.

Semiconductor detectors 4.1-4.N have a thickness such that the energy losses of gamma-quanta and rtgene quanta in their material are relatively small. In the object under study 3, a radioactive isotope is introduced into the solution, which is distributed through its organs. The intensity of the x-ray beam of source 1 is set in such a way that the number of x-ray quanta in the code from the object under study is commensurate with the number of gamma-quanta exiting in the same directions.

Thus, when registering radiation, the quanta of both x-ray and gamma radiation, which cause scintillation, are incident on the strip scintillator 5. The nature of the resulting scintillation is discriminated by the energy selection circuits 8 and 9, which control the units 10 and 11 of generating the linear coordinates of the scintillations. If the scintillation originated under the action of a gamma quantum, the energy selection circuit 8 generates a signal at the resolution input of the block 10, the output of which produces a signal proportional to the coordinate of the corresponding scintillation in the strip scintillator 5. If the scintillation

occurred under the action of an x-ray quantum, then the signal of the linear scintillation coordinate forms a block 11 under the action of a resolution signal from the circuit 9 of the energy selection of x-ray quanta. Since X-ray radiation propagates directionally, the scintillation coordinate of the x-ray quantum unambiguously corresponds to the trajectory of its passage in the object under study 3

Gamma quanta coming out of the object under study do not have an unambiguous directionality, the linear scintillation coordinate cannot unambiguously characterize the trajectory of gamma photon emission from object 3, However, before it hits the strip scintillant 5, the gamma quantum hits one of the detectors 4 .. 1.4 -N, the signal from which is amplified by the corresponding of amplifiers 13.1-13.N, passes through the circuit 14.1-14.N of the energy selection of gamma quanta, which are necessary for filtering out signals caused by x-ray quanta, and p The corresponding column input of the matrix memory 15. In turn, the linear coordinate signal of the corresponding scintillation from the output of the block 10 is fed to the input of the series-parallel converter 12, which generates a signal

cash on its output, which corresponds to the value of the specified linear coordinates. This signal is supplied to the row address input of the Matrix memory 15. Thus, a unit is stored in the memory cell located at the crossroads indicated with the column and the row (memory cells operate in the counting mode), i.e. the position of each cell in the matrix memory 15 uniquely corresponds to a certain gamma-quantum trajectory in the plane under investigation. After completing the required amount of information, the source 1 assembly is a detector system from a linear set of 4.1-4.N detectors and a strip scintilator 5 with a PMT 6 and 7 is rotated to a predetermined angle by means of a mechanism (not shown) and the measurement cycle is repeated. At the time of rotation, the polling block 16 reads the contents of the matrix memory 15 into the computation block 17. At the end of all the cycles

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measurements in the required angular range, blocks 17 and 18 form, in a known manner, the signals needed to restore the transmission and emission images of the object layer 3. These signals are combined by block 19 and a combined transmission emission image is displayed on the screen of display unit 20.

The effectiveness of the solution described is that when gamma quanta are detected, their spatial selection is absent using collimators, which leads to large losses of gamma quanta being recorded. More complete registration of the object leaving the object under study. gamma radiation causes a reduction in the total research time.

Claims (2)

1. Transmission emission computed tomography containing a source of a fan x-ray beam, a detection system, a holder of the object under study, a mechanism for relative rotation of the assembly, a source of a fan x-ray beam, energy selection schemes of the detection system for X-ray and gamma quanta 5 computing processing units signals corresponding to x-ray and gamma-quanta, and a display unit with the means of combining the signals generated by computing blocks In order to improve speed by increasing the efficiency of detecting gamma quanta from the radioisotope introduced into the object under study, the detection system contains a linear set of semiconductor detectors and a strip scintidator spaced from it, the ends of which are optically conjugated by photomultiplier tubes, the tomograph is used to block the formation of a signal of the linear coordinate caused by gamma quantum and. an x-ray scintillation quantum with enable or disable inputs connected by working inputs to the outputs of photomultipliers, to which the inputs of the energy selector circuit are also connected means of forming and storing signals of gamma-ray trajectories and additional schemes for the energetic selection of gamma-quanta, moreover, | 1, the gamma and x-ray energy selection circuits are connected to enable or disable inputs of linear scintillation coordinate signal generation units, additional energy selection circuits are connected to linear type semiconductor detectors, and the means for generating and storing signals of gamma quanta trajectories are included one side between the linear scintillation coordinate generation unit from gamma quanta and additional energy selection circuits and on the other hand us computing unit processing the respective signals of the gamma quanta, and the output signal generating unit linear coordinates of scintillation rentgeno058196 Vskih quanta is connected to the input of the computational processing unit for the signals corresponding to the X-ray quanta. 2. A tomograph according to claim 1, of tl and h a-ya and so that the means of forming and storing signals of gamma-ray trajectories contain a sequential-parallel converter, a matrix memory and a polling unit, and the input serial-parallel converter connected to the output of the signal conditioning unit 15 linear scintillation coordinates from gamma quanta, the address inputs of one coordinate of the matrix memory are associated with the outputs of the series-parallel converter, the address inputs 20 of the other coordinate are with additional energy selection circuits, and the interrogator is connected between the memory. and a computing unit processing the corresponding gamma-quanta 25 signals there.