CN105769231A - Ray tracing method of beam limiting device on axis Z - Google Patents
Ray tracing method of beam limiting device on axis Z Download PDFInfo
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- CN105769231A CN105769231A CN201610090289.XA CN201610090289A CN105769231A CN 105769231 A CN105769231 A CN 105769231A CN 201610090289 A CN201610090289 A CN 201610090289A CN 105769231 A CN105769231 A CN 105769231A
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- 208000019300 CLIPPERS Diseases 0.000 claims description 50
- 208000021930 chronic lymphocytic inflammation with pontine perivascular enhancement responsive to steroids Diseases 0.000 claims description 50
- 238000002591 computed tomography Methods 0.000 claims description 7
- 230000002159 abnormal effect Effects 0.000 claims description 3
- 238000010606 normalization Methods 0.000 claims description 3
- 230000006378 damage Effects 0.000 abstract description 2
- WFKWXMTUELFFGS-UHFFFAOYSA-N tungsten Chemical compound [W] WFKWXMTUELFFGS-UHFFFAOYSA-N 0.000 abstract 1
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- 241001269238 Data Species 0.000 description 4
- 210000000056 organ Anatomy 0.000 description 4
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- 239000006185 dispersion Substances 0.000 description 2
- 208000027418 Wounds and injury Diseases 0.000 description 1
- 238000001514 detection method Methods 0.000 description 1
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- 208000014674 injury Diseases 0.000 description 1
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- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
- A61B6/00—Apparatus or devices for radiation diagnosis; Apparatus or devices for radiation diagnosis combined with radiation therapy equipment
- A61B6/02—Arrangements for diagnosis sequentially in different planes; Stereoscopic radiation diagnosis
- A61B6/03—Computed tomography [CT]
- A61B6/032—Transmission computed tomography [CT]
- A61B6/035—Mechanical aspects of CT
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- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
- A61B6/00—Apparatus or devices for radiation diagnosis; Apparatus or devices for radiation diagnosis combined with radiation therapy equipment
- A61B6/02—Arrangements for diagnosis sequentially in different planes; Stereoscopic radiation diagnosis
- A61B6/03—Computed tomography [CT]
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- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
- A61B6/00—Apparatus or devices for radiation diagnosis; Apparatus or devices for radiation diagnosis combined with radiation therapy equipment
- A61B6/40—Arrangements for generating radiation specially adapted for radiation diagnosis
- A61B6/4021—Arrangements for generating radiation specially adapted for radiation diagnosis involving movement of the focal spot
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Abstract
The invention relates to a ray tracing method of a beam limiting device on the axis Z.The ray tracing method includes the steps that the beam limiting device reads detector data of all reference channels of each view of multiple layers of CT machines; the detector data is averagely divided into two groups in the Z-axis direction; average values and standard deviations of the two groups of detector data are calculated respectively; a normalized value of the standard deviations of the two groups of detector data is obtained; the fine adjustment distance of an opening of the beam limiting device on the axis Z is calculated according to the normalized value of the standard deviations; the standard deviation of the group A of detector data is compared with that of the group B of detector data, and the moving direction of the opening of the beam limiting device on the axis Z is determined; the beam limiting device controls two tungsten pieces to synchronously move the fine adjustment distance on the Z axis in the moving direction, and ray tracing of the beam limiting device on the Z axis is completed.The beam limiting device can be controlled to move in the Z-axis direction to trace X-ray sources, and meaningless X-ray damage is avoided.
Description
Technical field
The present invention relates to the technical field of radiodiagnosis, be specifically related to a kind of beam-defining clipper ray tracing method on Z axis.
Background technology
Computed tomograph scanner system (CT) is in scanning process, rotation shake and expanding with heat and contract with cold of anode target surface owing to producing the plate target of X ray can cause the skew of focus so that the X-ray beam generated at anode target surface 101 (focus), at Z axis, random skew occurs.X-ray beam is irradiated on detector 104 after the histoorgan 103 of beam-defining clipper opening 102 and human body.Even if small skew, after geometry amplifies, the bigger skew in spatial resolution also can be produced on human body/detector, referring to Fig. 4.These X-ray beams producing random skew in Z-direction can cause image quality decrease, indirectly causes insignificant x-ray bombardment.
Summary of the invention
It is an object of the invention to provide a kind of beam-defining clipper ray tracing method on Z axis, based on the beam-defining clipper in current CT system, beam-defining clipper mobile tracking x-ray source in the Z-axis direction can be controlled, make the X-ray bundle being irradiated on detector just cover required beamwidth.
It is an object of the invention to be realized by following technical proposals: a kind of beam-defining clipper ray tracing method on Z axis, the step of described ray trace includes:
A, beam-defining clipper read the detector data of all reference channels of each view of multi-Slice CT Scanner；
B, described detector data is divided into along Z-direction A group detector data and B group detector data；
C, calculate the meansigma methods of described A group detector data and the meansigma methods of described B group detector data respectively；
D, mean value calculation according to described A group detector data go out the standard variance of A group detector data, go out the standard variance of B group detector data according to the mean value calculation of described B group detector data；
E, the standard variance normalization of the standard variance of described A group detector data and described B group detector data, obtain standard variance normalized value；
F, calculate beam-defining clipper opening fine setting distance on Z axis according to described standard variance normalized value；The standard variance of the standard variance of described A group detector data Yu described B group detector data is compared, it is determined that beam-defining clipper opening moving direction on Z axis；
G, beam-defining clipper control two leaf according to described moving direction and finely tune distance on Z axis described in synchronizing moving, complete beam-defining clipper ray trace on Z axis.
Further, the standard variance of described A group detector data is more than the standard variance of described B group detector data, and beam-defining clipper opening moves to the direction at B group detector place on Z axis；The standard variance of described A group detector data is less than the standard variance of described B group detector data, and beam-defining clipper opening moves to the direction at A group detector place on Z axis.
Further, described reference channel is positioned at the outermost end often arranging detector.
Further, described reference channel can not be blocked in CT scan process, if be blocked, beam-defining clipper judges according to the CT empirical value of described reference channel, and abnormal to upper System Reports.
Further, described beam-defining clipper A/F remains unchanged in CT scan process.
The present invention compared with prior art has the advantage that
The present invention can accurately obtain the ray shake in Z-direction, and control beam-defining clipper mobile tracking x-ray source in the Z-axis direction, the X ray sent by x-ray source is precisely limited, and allows it just through the position and the organ that need scanning, reduces dosage suffered by patient to greatest extent.Thus realizing bulb focus, beam-defining clipper, detector keeps high consistency, it is to avoid meaningless X-ray injury.
Below in conjunction with the drawings and specific embodiments, the present invention is described in detail.
Accompanying drawing explanation
Fig. 1 is the ray trace schematic diagram of present pre-ferred embodiments；
Fig. 2 is the structural representation of beam-defining clipper；
Fig. 3 is x-ray focus tracking effect figure；
Fig. 4 is the schematic diagram of x-ray focus skew.
Detailed description of the invention
Referring to Fig. 1, Fig. 2, a kind of beam-defining clipper ray tracing method on Z axis, the step of described ray trace includes:
A, beam-defining clipper read the detector data of all reference channels 1 of each view of multi-Slice CT Scanner；
In the present embodiment, multi-Slice CT Scanner has 32 row's detectors, and often row's detector has 8 reference channels, 256 reference channels altogether.As shown in the table.
At least needing the reference channel having ray trace in the side often arranging detector, the quantity for multi-detector every layer reference channel is the amount doesn't matter, and quantity is more many, and the precision of control is more good.One view gathers all passages in detector once, including reference channel.
Further, described reference channel is positioned at the outermost end often arranging detector.
B, described detector data is divided into along Z-direction A group detector data and B group detector data；
In the present embodiment, by above-mentioned detector data along Z-direction, being divided into two groups from the center of Z axis, the 1st row the～the 16 row is set as A group, and A group detector data has 128；17th row the～the 32 row is set as B group, and B group detector data has 128.The data volume of two groups of detector datas is the same is all N=128.
C, calculate the meansigma methods of described A group detector data and the meansigma methods of described B group detector data respectively；
Mean_A=(data1+data2+…+dataN)÷N；
Mean_B=(dataN+1+dataN+2+…+data2N)÷N；N=128.
D, mean value calculation according to described A group detector data go out the standard variance of A group detector data, go out the standard variance of B group detector data according to the mean value calculation of described B group detector data；
σ _ A and σ _ B reflects the dispersion degree of two groups of detector datas.The measure value of dispersion degree is more big, illustrates that the diversity of these two groups of detector datas is more big, and deviation occurs in the position that its basic reason is exactly beam-defining clipper opening, thus causing that the ray entering detector both sides is not balanced.
When standard variance σ _ A and σ _ B relatively time, illustrate that the x-ray dose that two groups of reference channels of A, B accept is essentially the same.Beam-defining clipper controls the position of opening and just makes X ray through human organ and be irradiated on detector, it does not have X ray problem of which group deflection in A, B two groups occurs, and namely meaningless radiohazard does not occur the be irradiated to human organ of X ray.
E, the standard variance normalization of the standard variance of described A group detector data and described B group detector data, obtain standard variance normalized value；
G=(| σ _ A-σ _ B |) ÷ (σ _ A+ σ _ B).
F, calculate the beam-defining clipper opening 2 fine setting distance on Z axis according to described standard variance normalized value；The standard variance of the standard variance of described A group detector data Yu described B group detector data is compared, it is determined that the beam-defining clipper opening 2 moving direction on Z axis；
In the present embodiment, the standard variance of described A group detector data is more than the standard variance of described B group detector data, and beam-defining clipper opening is mobile to the direction (downwards) at B group detector place on Z axis；The standard variance of described A group detector data is less than the standard variance of described B group detector data, and beam-defining clipper opening is mobile to the direction (upwards) at A group detector place on Z axis.
σ _ A > σ _ B, then move to B group detector direction.
σ _ A < σ _ B, then move to A group detector direction.
G, beam-defining clipper control two leaf according to described moving direction and finely tune distance on Z axis described in synchronizing moving, complete beam-defining clipper ray trace on Z axis.
The standard variance normalized value of fine setting=two groups of detector datas of distance and the product of beam-defining clipper opening, Dist=G × W.The unit of beam-defining clipper opening actual size is as the criterion with control accuracy, generally in units of micron.
Beam-defining clipper should set A/F in advance before CT scan, and the A/F of beam-defining clipper remains unchanged in CT scan process.To beam-defining clipper openings of sizes control completed by motor and the code-disc of beam-defining clipper itself on the one hand, another aspect also to judge that whether the size in beam-defining clipper gap suitable by receiving the CT value of X ray from detector end reference channel.
Beam-defining clipper Main Function is to be any limitation as by the ray sent from x-ray source, allows it just through the human body and the organ that need scanning, reduces the dosage that patient is subject to as much as possible.
Referring to Fig. 2, the basic structure of beam-defining clipper has
A) 3: two parallel placements of self-movement leaf of leaf, the gap between two leaf parallel edges is the place of X ray traverse, and other local meeting be blocked by leaf.For different scanning demands, the size in gap can be adjusted by the relative motion of two leaf.
B) motor 4 and driving device: by actuating device, drags leaf motion.
C) encoder: the feedback device of leaf move distance.
D) stop: the extreme position of detection leaf motion.
E) actuating device: include slideway 5, slide block 6, leading screw 7, belt 8, motor drives leaf motion by actuating device.
Further, described reference channel can not be blocked in CT scan process, if be blocked, beam-defining clipper judges according to the CT empirical value of described reference channel, and abnormal to upper System Reports.
Referring to Fig. 3, arranging, 32, the test done in CT system, every 20 view do and once translate tracking adjustment.Transverse axis represents the number of view, and the longitudinal axis is the distance of translation tracking adjustment.It can be seen that the distance that the translation tracking adjustment initial stage adjusts is relatively larger, the distance adjusted after adjusting about 240～260 view just substantially shortens, and illustrates that beam-defining clipper has followed the tracks of the skew of x-ray focus.
The content of the present embodiment is only the present invention preferably detailed description of the invention; but protection scope of the present invention is not limited thereto; any those familiar with the art is in the technical scope of present disclosure; the change that can readily occur in or replacement, all should be encompassed within protection scope of the present invention.Therefore, protection scope of the present invention should be as the criterion with the protection domain of claims.
Claims (5)
1. the beam-defining clipper ray tracing method on Z axis, it is characterised in that: the step of described ray trace includes:
A, beam-defining clipper read the detector data of all reference channels of each view of multi-Slice CT Scanner；
B, described detector data is divided into along Z-direction A group detector data and B group detector data；
C, calculate the meansigma methods of described A group detector data and the meansigma methods of described B group detector data respectively；
D, mean value calculation according to described A group detector data go out the standard variance of A group detector data, go out the standard variance of B group detector data according to the mean value calculation of described B group detector data；
E, the standard variance normalization of the standard variance of described A group detector data and described B group detector data, obtain standard variance normalized value；
F, calculate beam-defining clipper opening fine setting distance on Z axis according to described standard variance normalized value；The standard variance of the standard variance of described A group detector data Yu described B group detector data is compared, it is determined that beam-defining clipper opening moving direction on Z axis；
G, beam-defining clipper control two leaf according to described moving direction and finely tune distance on Z axis described in synchronizing moving, complete beam-defining clipper ray trace on Z axis.
2. ray tracing method according to claim 1, it is characterised in that: the standard variance of described A group detector data is more than the standard variance of described B group detector data, and beam-defining clipper opening moves to the direction at B group detector place on Z axis；The standard variance of described A group detector data is less than the standard variance of described B group detector data, and beam-defining clipper opening moves to the direction at A group detector place on Z axis.
3. ray tracing method according to claim 1, it is characterised in that: described reference channel is positioned at the outermost end often arranging detector.
4. ray tracing method according to claim 1, it is characterised in that: described reference channel can not be blocked in CT scan process, if be blocked, beam-defining clipper judges according to the CT empirical value of described reference channel, and abnormal to upper System Reports.
5. ray tracing method according to claim 1, it is characterised in that: described beam-defining clipper A/F remains unchanged in CT scan process.
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| CN201610090289.XA CN105769231B (en) | 2016-02-18 | 2016-02-18 | A kind of ray tracing method of beam-defining clipper on Z axis |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN110123353A (en) * | 2019-05-29 | 2019-08-16 | 明峰医疗系统股份有限公司 | A kind of alignment schemes of detector module |
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| US4991189A (en) * | 1990-04-16 | 1991-02-05 | General Electric Company | Collimation apparatus for x-ray beam correction |
| JPH08243100A (en) * | 1995-03-10 | 1996-09-24 | Ge Yokogawa Medical Syst Ltd | Offset correction method and x-ray ct equipment |
| US20020021785A1 (en) * | 1999-08-27 | 2002-02-21 | Toth Thomas L. | Methods and apparatus for calibrating CT x-ray beam tracking loop |
| CN1352919A (en) * | 2000-11-09 | 2002-06-12 | Ge医疗系统环球技术有限公司 | Collimator control method and equipment, and x-ray CT equipment |
| JP2002238885A (en) * | 2001-02-02 | 2002-08-27 | Ge Medical Systems Global Technology Co Llc | Method and program for controlling position of x-ray focal point, and x-ray ct apparatus and x-ray tube |
| JP2003111754A (en) * | 2001-09-28 | 2003-04-15 | Ge Medical Systems Global Technology Co Llc | Gantry device in x-ray ct system and control method therefor |
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2016
- 2016-02-18 CN CN201610090289.XA patent/CN105769231B/en active Active
Patent Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4991189A (en) * | 1990-04-16 | 1991-02-05 | General Electric Company | Collimation apparatus for x-ray beam correction |
| JPH08243100A (en) * | 1995-03-10 | 1996-09-24 | Ge Yokogawa Medical Syst Ltd | Offset correction method and x-ray ct equipment |
| US20020021785A1 (en) * | 1999-08-27 | 2002-02-21 | Toth Thomas L. | Methods and apparatus for calibrating CT x-ray beam tracking loop |
| CN1352919A (en) * | 2000-11-09 | 2002-06-12 | Ge医疗系统环球技术有限公司 | Collimator control method and equipment, and x-ray CT equipment |
| JP2002238885A (en) * | 2001-02-02 | 2002-08-27 | Ge Medical Systems Global Technology Co Llc | Method and program for controlling position of x-ray focal point, and x-ray ct apparatus and x-ray tube |
| JP2003111754A (en) * | 2001-09-28 | 2003-04-15 | Ge Medical Systems Global Technology Co Llc | Gantry device in x-ray ct system and control method therefor |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN110123353A (en) * | 2019-05-29 | 2019-08-16 | 明峰医疗系统股份有限公司 | A kind of alignment schemes of detector module |
| CN110123353B (en) * | 2019-05-29 | 2022-12-30 | 明峰医疗系统股份有限公司 | Alignment method of detector module |
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Address after: 100176 1st floor, building 8, 11 Kangding street, Beijing Economic and Technological Development Zone, Daxing District, Beijing Patentee after: Sinovision Technology (Beijing) Co.,Ltd. Address before: 100176 floor 1, Yuehong building, No.13, Yongchang North Road, Beijing Economic and Technological Development Zone, Daxing District, Beijing Patentee before: SAINUO WEISHENG TECHNOLOGY (BEIJING) Co.,Ltd. |
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