CN108760777B - Device and method for tracking focal point of bulb - Google Patents
Device and method for tracking focal point of bulb Download PDFInfo
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- CN108760777B CN108760777B CN201810268985.4A CN201810268985A CN108760777B CN 108760777 B CN108760777 B CN 108760777B CN 201810268985 A CN201810268985 A CN 201810268985A CN 108760777 B CN108760777 B CN 108760777B
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- G01N23/046—Investigating or analysing materials by the use of wave or particle radiation, e.g. X-rays or neutrons, not covered by groups G01N3/00 – G01N17/00, G01N21/00 or G01N22/00 by transmitting the radiation through the material and forming images of the material using tomography, e.g. computed tomography [CT]
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Abstract
The invention discloses a bulb focus tracking device and method, which comprises an X-ray inlet, wherein two tungsten gold sheets are arranged at the X-ray inlet, a slit is formed in each tungsten gold sheet, and a plurality of positioning pin holes are formed in each tungsten gold sheet.
Description
Technical Field
The invention relates to the field of detection, in particular to a device and a method for tracking a bulb focus.
Background
The anode target surface of the X-ray tube expands differently at different temperatures, so that the focal spot position shifts in the z-direction at different anode target temperatures. In the process of obtaining the X-ray bulb tube from cold to hot, the focal spot of a typical bulb tube is shifted by about 0.2-0.4 mm. When the X-ray tube is mounted on the rotating gantry of a CT, the focal spot of the tube will have a z-offset of about 0.1mm at different rotational speeds and gantry angles due to mechanical deformations of the rotating gantry and due to the different centrifugal forces to which the rotating shaft of the X-ray anode target is subjected. Therefore, most of the CT manufacturers are equipped with an automatic focal spot tracking function, so that the detector can be always irradiated with the X-ray in the local area while the focal spot is shifted. If the automatic focal spot tracking function is not configured, the opening of the front collimator is increased accordingly in order to prevent the front collimator opening from blocking X-rays under different focal spot shifts. The utilization of X-rays of a machine without an automatic focal spot tracking function is low, and particularly the utilization of small openings is much lower than the utilization of X-rays with an automatic focal spot tracking function. The current focus tracking design is complicated, the cost is high, and the tracking precision is limited by the alert motion.
Disclosure of Invention
Aiming at the defects of the prior art, the invention provides a device and a method for accurately positioning bulb focus tracking.
In order to achieve the purpose, the invention provides the following technical scheme: a method for tracking the focus of a bulb is characterized in that: the calibration needs to be carried out at different X-ray bulb tube temperatures, then a final calibration curve is obtained according to calibration data of the different bulb tube temperatures, and the steps at each X-ray bulb tube temperature are as follows;
(1) selecting an X-ray bulb tube temperature, selecting a certain opening of a front collimator, and enabling the collimator to shift n steps in the z direction, wherein the minimum shift and the shift step of each time are z0 and delta _ z respectively;
(2) performing a stationary X-ray exposure of the gantry at each offset position of an opening of the collimator selected in step (1);
(3) selecting the most central detector modules in the channel direction at each offset position of a certain opening of the collimator selected in the step (1); calculating the ratio ra of the numbers received by the 1 st row of detectors and the 2 nd row of detectors, and calculating the ratio rb of the numbers received by the m-th row of detectors and the m-1 st row of detectors;
(4) in all the offset positions of a certain opening of the collimator selected in the step (1), respectively interpolating and finding out collimator offset positions za and zb corresponding to ra =0.5 and rb = 0.5;
(5) calculating za according to the positions of za and zb, the distance between the collimator and the focal spot center and the distance between the collimator and the detector, wherein zb corresponds to the focal spot positions fza and fzb on the anode target, and the optimal offset position z = (za + zb)/2 of the collimator is calculated;
(6) calculating fz = (fza + fzb)/2 to obtain the focal spot position corresponding to the X-ray tube temperature point;
(7) the tracking detectors of the ray tracking module are divided into two rows in the z direction, when the X-ray is irradiated, the digital proportion t received by the two rows of tracking detectors is related to the position of a focal spot, and the mean value of t corresponding to the offset position of each collimator is calculated and recorded as rt under the current temperature of the X-ray bulb tube;
(8) if steps 1 to 7 have ternary arrays { (z1, fz1, rt1), (z2, fz2, rt2), …, (zk, fzk, rtk) } at k different bulb temperatures. Fitting z = sum (c _ n + rt ^ n) and fz = sum (d _ n + rt ^ n) by using a polynomial according to the array to obtain coefficients { c _1, c _2, … } and { d _1, d _2, … } which are coefficients of the calibration polynomial;
(9) in the real-time tracking part, rt mean value in a certain time interval is calculated, then collimator opening offset position z _ target of the target is calculated according to calibration formula z = sum (c _ n × rt ^ n), and then the collimator is moved from current offset position z _ current to z _ target position.
And (3) further, the exposure in the step (2) ensures that the X-ray bulb tube is always in a small range near the set temperature of the X-ray bulb tube, and data detected by the detector is collected.
The utility model provides a device that bulb focus was tracked, includes the X ray entry, the X ray entry is equipped with two tungsten gold pieces, be equipped with on the tungsten gold piece and crack.
Furthermore, a plurality of positioning pin holes are formed in the tungsten sheet.
In conclusion, the focus tracking design is separated from the alert, the focus tracking design is directly embodied at a ray inlet, the structure is simple, the positioning is accurate, the tracking imaging calculation is simple, the focus tracking can be better realized, and the scheme can carry out various detection and tracking on the focus of the ball tube in the X direction and the Z direction through opening designs in various directions and shapes.
Drawings
FIG. 1 is a schematic diagram of a bulb focus tracking device according to the present invention;
description of the labeling: 1. slotting; 2. a tungsten gold sheet; 3. a positioning pin hole.
Detailed Description
An embodiment of the apparatus and method for tracking the focus of a bulb according to the present invention is further described with reference to fig. 1.
A method for tracking the focus of a bulb is characterized in that: the calibration needs to be carried out at different X-ray bulb tube temperatures, then a final calibration curve is obtained according to calibration data of the different bulb tube temperatures, and the steps at each X-ray bulb tube temperature are as follows;
(1) selecting an X-ray bulb tube temperature, selecting a certain opening of a front collimator, and enabling the collimator to shift n steps in the z direction, wherein the minimum shift and the shift step of each time are z0 and delta _ z respectively;
(2) performing a stationary X-ray exposure of the gantry at each offset position of an opening of the collimator selected in step (1);
(3) at each offset position of an opening of the collimator selected in step (1), selecting the most central detector modules in the channel direction. Calculating the ratio ra of the numbers received by the 1 st row of detectors and the 2 nd row of detectors, and calculating the ratio rb of the numbers received by the m-th row of detectors and the m-1 st row of detectors;
(4) in all the offset positions of a certain opening of the collimator selected in the step (1), respectively interpolating and finding out collimator offset positions za and zb corresponding to ra =0.5 and rb = 0.5;
(5) calculating za according to the positions of za and zb, the distance between the collimator and the focal spot center and the distance between the collimator and the imaging detector, wherein zb corresponds to the focal spot positions fza and fzb on the anode target, and the optimal offset position z = (za + zb)/2 of the collimator is calculated;
(6) calculating fz = (fza + fzb)/2 to obtain the focal spot position corresponding to the X-ray tube temperature point;
(7) the tracking detectors of the ray tracking module are divided into two rows in the z direction, when the X-ray is irradiated, the digital proportion t received by the two rows of tracking detectors is related to the position of a focal spot, and the mean value of t corresponding to the offset position of each collimator is calculated and recorded as rt under the current temperature of the X-ray bulb tube;
(8) if steps 1 to 7 have ternary arrays { (z1, fz1, rt1), (z2, fz2, rt2), …, (zk, fzk, rtk) } at k different bulb temperatures. Fitting z = sum (c _ n + rt ^ n) and fz = sum (d _ n + rt ^ n) by using a polynomial according to the array to obtain coefficients { c _1, c _2, … } and { d _1, d _2, … } which are coefficients of the calibration polynomial;
(9) in the real-time tracking part, rt mean value in a certain time interval is calculated, then collimator opening offset position z _ target of the target is calculated according to calibration formula z = sum (c _ n × rt ^ n), and then the collimator is moved from current offset position z _ current to z _ target position.
Thus, a real-time pre-collimator tracking with X-ray focal spot movement is achieved, one possible variant is implemented when the opening offset position at the next instant is based on z _ target and the collimator movement response delay is z _ target + Delta _ z, Delta _ z can be determined experimentally based on the response delay of the system, and (z _ target-z).
And (3) further, the exposure in the step (2) ensures that the X-ray bulb tube is always in a small range near the set temperature of the X-ray bulb tube, and data detected by the detector is collected.
The utility model provides a device that bulb focus was tracked, includes the X ray entry, the X ray entry is equipped with two tungsten gold pieces 2, be equipped with on the tungsten gold piece and crack 1.
Further, a plurality of positioning pin holes 3 are formed in the tungsten sheet 2.
At an X-ray inlet, two very small tungsten gold sheets 2 are accurately fixed and are accurately positioned by positioning pin holes 3, the tungsten gold sheets 2 are provided with designed special-shaped slots 1, the slots are projected onto a detector during imaging, and focus tracking calculation is carried out according to imaging data.
The above description is only a preferred embodiment of the present invention, and the protection scope of the present invention is not limited to the above embodiments, and all technical solutions belonging to the idea of the present invention belong to the protection scope of the present invention. It should be noted that modifications and embellishments within the scope of the invention may occur to those skilled in the art without departing from the principle of the invention, and are considered to be within the scope of the invention.
Claims (2)
1. A method for tracking the focus of a bulb is characterized in that: the calibration needs to be carried out at different X-ray bulb tube temperatures, then a final calibration curve is obtained according to calibration data of the different bulb tube temperatures, and the steps at each X-ray bulb tube temperature are as follows;
(1) selecting an X-ray bulb tube temperature, selecting a certain opening of a front collimator, and enabling the collimator to shift n steps in the z direction, wherein the minimum shift and the shift step of each time are z0 and delta _ z respectively;
(2) performing a stationary X-ray exposure of the gantry at each offset position of an opening of the collimator selected in step (1);
(3) selecting the most central detector modules in the channel direction at each offset position of a certain opening of the collimator selected in the step (1);
calculating the ratio ra of the numbers received by the 1 st row of detectors and the 2 nd row of detectors, and calculating the ratio rb of the numbers received by the m-th row of detectors and the m-1 st row of detectors;
(4) in all the offset positions of a certain opening of the collimator selected in the step (1), respectively interpolating and finding out collimator offset positions za and zb corresponding to ra =0.5 and rb = 0.5;
(5) calculating za according to the positions of za and zb, the distance between the collimator and the focal spot center and the distance between the collimator and the detector, wherein zb corresponds to the focal spot positions fza and fzb on the anode target, and the optimal offset position z = (za + zb)/2 of the collimator is calculated;
(6) calculating fz = (fza + fzb)/2 to obtain the focal spot position corresponding to the X-ray tube temperature point;
(7) the tracking detectors of the ray tracking module are divided into two rows in the z direction, when the X-ray is irradiated, the digital proportion t received by the two rows of tracking detectors is related to the position of a focal spot, and the mean value of t corresponding to the offset position of each collimator is calculated and recorded as rt under the current temperature of the X-ray bulb tube;
(8) if steps 1 to 7 have ternary arrays { (z1, fz1, rt1), (z2, fz2, rt2), …, (zk, fzk, rtk) } at k different bulb temperatures; fitting z = sum (c _ n + rt ^ n) and fz = sum (d _ n + rt ^ n) by using a polynomial according to the array to obtain coefficients { c _1, c _2, … } and { d _1, d _2, … } which are coefficients of the calibration polynomial;
(9) in the real-time tracking part, rt mean value in a certain time interval is calculated, then collimator opening offset position z _ target of the target is calculated according to calibration formula z = sum (c _ n × rt ^ n), and then the collimator is moved from current offset position z _ current to z _ target position.
2. The method of claim 1, wherein: and (3) ensuring that the exposure in the step (2) ensures that the X-ray bulb tube is always in a small range near the set temperature of the X-ray bulb tube, and collecting data detected by a detector.
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| CN201810268985.4A CN108760777B (en) | 2018-03-29 | 2018-03-29 | Device and method for tracking focal point of bulb |
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Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
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| US5452720A (en) * | 1990-09-05 | 1995-09-26 | Photoelectron Corporation | Method for treating brain tumors |
| US5633907A (en) * | 1996-03-21 | 1997-05-27 | General Electric Company | X-ray tube electron beam formation and focusing |
| CN1268337A (en) * | 1999-03-31 | 2000-10-04 | 模拟技术公司 | Scanner for computerized tomograph using vertical floating focus |
| CN103839603A (en) * | 2012-11-27 | 2014-06-04 | Ge医疗系统环球技术有限公司 | CT collimator and CT system comprising same |
| CN106873302A (en) * | 2016-12-30 | 2017-06-20 | 成都信息工程大学 | A kind of method of detector longitudinal direction automatic tracing bulb focus radial imaging |
| CN107811647A (en) * | 2017-11-24 | 2018-03-20 | 上海联影医疗科技有限公司 | CT equipment, the X-ray detection X method with reference to detection device and radiographic source |
-
2018
- 2018-03-29 CN CN201810268985.4A patent/CN108760777B/en active Active
Patent Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5452720A (en) * | 1990-09-05 | 1995-09-26 | Photoelectron Corporation | Method for treating brain tumors |
| US5633907A (en) * | 1996-03-21 | 1997-05-27 | General Electric Company | X-ray tube electron beam formation and focusing |
| CN1268337A (en) * | 1999-03-31 | 2000-10-04 | 模拟技术公司 | Scanner for computerized tomograph using vertical floating focus |
| CN103839603A (en) * | 2012-11-27 | 2014-06-04 | Ge医疗系统环球技术有限公司 | CT collimator and CT system comprising same |
| CN106873302A (en) * | 2016-12-30 | 2017-06-20 | 成都信息工程大学 | A kind of method of detector longitudinal direction automatic tracing bulb focus radial imaging |
| CN107811647A (en) * | 2017-11-24 | 2018-03-20 | 上海联影医疗科技有限公司 | CT equipment, the X-ray detection X method with reference to detection device and radiographic source |
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