SU1599871A1 - Reverse projection device for producing object image in computerized tomography - Google Patents

Abstract

The invention relates to computed tomography using X-rays and can be used for image processing in quantitative introscopic studies of the internal structures of objects in medical and technical applications. The aim of the invention is to improve the performance of image processing. This is achieved by simultaneously processing each new projection simultaneously with all segments. The device comprises a projection address generator, N segments of the image storage unit, N segments 3 of the image processing unit, a control unit. Each segment 2 contains an address shaper 5, a projection memory block 6, a multiplier 7, a weight function shaper 8, adders 9, 10, 11, and registers 12, 13. 5 ill.

Description

The invention relates to imaging tomography using x-ray radiation and can be used for image processing in quantitative inroscopic studies of the internal structures of objects under study in medical and technical applications.

The purpose of the invention is to improve the performance of image processing.

Figure 1 shows the overall structural scheme of the proposed device; 2 is a block diagram of one image processing segment of a device; FIG. 3 is a block diagram of the projection address generator; Fig. 4 is a block diagram of the control unit; FIG. 3 shows geometrical relationships arising from movement across the image segment during processing.

The device (Fig. 1) contains the projection address generator 1, the n segments of the image storage unit 2, and the image processing segments 3, the control unit 4.

The image processing segment 3 (FIG. 2) contains the address generator 5, a projection memory block 6, a multiplier 7, a weight function generator 8, an adder 9, registers 10, 11, and adders 12 and 13. The projection address generator 1 (FIG. 3) contains two buffer registers 14, two buffer registers 15, two buffer registers 16, two adders 17, counters 18, 19 and two buffer registers 20 and two switches 21.

The control unit 4 (Fig. 4) contains counters 22, 23 and a shift register 24.

Geometric relationships (Figs are represented by the following parameters: A ;, c; - the initial values of the addresses of the i-ro segment of the image; iAy; AB - the increment of addresses for the next image element in the row;

Resov to go to the first image element of the next line.

The device works as follows.

Each new projection is processed: the batu immediately after it arrives from the measurement setup at the same time by all segments 3 of the device. With

five

0

five

0

five

0

45

50

55

In this case, each segment 3 runs on its own memory segment 2. Before starting the reverse projection, the registers 10 and 11 of each segment 3 load the values of the start addresses of each segment of the image. In the shaper 8 of the weighting function and in the shaper 5 of the address, the values of the weighting correction function and the values of the projection addresses are loaded.

Thereafter, the projection is loaded into all the blocks 6 of the memory of the projections of the segments 3. After that, the back projection operation begins. For this, address generator 1 causes the values of addresses A and B to move along the image line (Fig. 5). Values A and B enter segments 3, where they are summed up in adders 12 and 13 with values defining the start addresses coming from registers 10 and 11. The resulting values are fed to the inputs of drivers 5 and 8, where, based on the incoming values A and B The table defines the weighting function and the address for block 6 of the projection memory of this segment 3.

Based on the incoming address in blocks 6, the projection value is selected and fed to multiplier 7, where it is multiplied with the value of the weight function and fed to the adder 9. In the adder 9, the resulting value is summed with the value previously available (or zero at the beginning of the reverse: projection :) at X, j Y; in the image memory block segment. The result of the sum is sent to the same address X, Y, back to memory block 2. The values of X, -, Y; the image elements enter segments 3 from control unit 4. Thus, the reverse projection operation is produced with 3 devices synchronously in all segments.

After the projection operation is completed, at Xj, Y; The control unit 4 assigns the values of the addresses X ;. This happens until all the values Xj, Y; are passed, defining the line in the image segment (Fig. 5). After completing the passage of the line control block 4

gives the values of X ;, Y ;, corresponding to the next line in the image segment of the memory block.

Address generator 1 contains the values of A. And B corresponding to the given line. The process of backward projection is repeated for the given line. This happens until all the lines of the image segments are passed. After this, the reverse projection process ends. After all the projections are measured and processed in segments 2 of the image storage unit, a cross-section image of the object under study is formed, which through the image data line goes sequentially from each memory segment to the monitor and is visualized as a single image.

The address generator 1 operates as follows.

Before processing, registers 14, 15, 20 load the values (YES, TLDs), (iAx, LVX), (AO, BO) for all projection angles. After this, during reverse projection, the counters 18 and 19 begin to count the pulses coming from the control unit 4, corresponding to the transition to each new picture element. At the same time, on the arrival of each new pulse, the values A and B stored in registers 20 are added in adders 17 the values of iA X and utBx stored in registers 15. Thus, during the transition to each new element of the image the values of the addresses A and B are updated. After one line has passed, which is determined by counters 18 and 19, the values A and B are added to the values 17 and uB, u from registers 14 and a transition is made to the new row of the matrix images. To add these values, the switches 21 are switched to the state corresponding to the connection of the input of adders 17 to the registers 14. Then the summation is performed in the adder 17 again with the values stored in J 1 C in the registers 15. This happens until all image matrix for a given projection angle.

The control unit 4 functions as follows.

to

15

0

five

0

five

0

five

0

five

Counting pulses from the reference oscillator are fed to the shift register 24, which creates a comb of pulses with a predetermined delay corresponding to the response time of the various blocks included in the device, and are used by these blocks as gates and buttons when executing operations. At the same time, the pulses td arrive at the input of the counters 23 and 22, determined by the address of the pixel addresses X and Y for the image segments 2j.

When moving to a new projection angle, the values (Hell, Be), (& A & B & K), (& A & & Bwi) are taken from the buffers, corresponding to this projection angle. This happens until the data processing is completed.

Claims (1)

Invention Formula A rear projection device for acquiring an image of an object in computational tomography, comprising a projection address generator, a control unit, an image storage unit and n image processing segments, each segment containing an address generator, the output of which is connected to the address input of the projection memory unit whose output is connected with the first input of the multiplier, the second input of which is connected to the output of the weight function generator, and the output with the first input of the first adder, the input of the control unit is input the start house of the device, the first clock of the control unit is connected to the control inputs of the address shaper and the weighting function, the second clock output of the control unit is connected to the control input of the projection memory, the third clock output of the control unit is connected to the control input of the multiplier 11, output The image storage unit is an information output of the device, characterized in that, in order to increase the image processing performance, the image storage unit is made in n segments, the first and The address addresses of each i-ro | Segment of the image storage unit are connected to the first and second outputs of setting the image element coordinates of the control unit, the fourth clock output of which is connected to the control input of the i-ro segment of the image storage unit, information output and input which are connected respectively to the second input and output of the first adder of the i-ro image processing segment, the i-th image processing segment further comprises two registers and the second and third adders, with the output of the second adder Connected to the first address input of the address maker of the i-ro image processing segment, the second address input of which is connected to the input of the imaging unit of the weighting function of the i-ro image segment image processing and with the output of the third adder, the control input of which is connected to the control input of the second adder and the fifth clock output of the control unit, the sixth clock output of which is connected to the control inputs of the first and second registers, information inputs are respectively connected to the first and second outputs of the projection address generator and with the first information inputs of the second and third adders, the second information inputs of which are connected respectively to the codes of the first and second regis tr. fPuB. A b ig. 3