CN103006252B - Measuring method and measuring device for point spread function of PET (positron emission tomography) system - Google Patents
Measuring method and measuring device for point spread function of PET (positron emission tomography) system Download PDFInfo
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- CN103006252B CN103006252B CN201210529331.5A CN201210529331A CN103006252B CN 103006252 B CN103006252 B CN 103006252B CN 201210529331 A CN201210529331 A CN 201210529331A CN 103006252 B CN103006252 B CN 103006252B
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Abstract
The invention provides a measuring method and a measuring device for a point spread function of a PET (positron emission tomography) system, and the measuring efficiency and precision can be improved. The measuring method comprises the following step: 11) dividing a scanning range of a detector into a plurality of measuring areas, and selecting a plurality of sampling points in one measuring area; 12) carrying out emission scanning on the sampling points one by one by a line source, and recording a polar coordinate of each sampling point; and 13) obtaining the polar coordinate of each sampling point in other measuring areas according to the polar coordinate of each sampling point in one measuring area, and calculating the point spread function. The measuring device comprises the line source, an angle ruler and a graduated scale, wherein the angle ruler and the graduated scale are respectively used for measuring polar angles and polar diameters of the sampling points; the graduated scale is provided with a datum line labeled with polar diameter scribed lines along a longitudinal direction; the line source is arranged in a vertical surface of the graduated scale, and is vertical to the datum line and can move along the datum line; and the graduated scale can rotate around a measuring center point of the angle ruler in a flat surface parallel to the angle ruler, and can be positioned at a preset angle.
Description
Technical field
The present invention relates to field of medical technology, particularly relate to a kind of measuring method of PET system point spread function.The invention still further relates to a kind of measuring device that adopts above-mentioned measuring method to measure.
Background technology
At present, PET(positron emission tomography, positron emission tomography) technology is widely used in field of medical technology.First PET imaging needs to inject radionuclide in human body, by the nucleic positron producing that decays, bury in oblivion generation Gamma photon pair with the negatron in human body, then utilize these photons to distribute to reconstructing the nuclide concentration of organ, thus the metabolism situation of reflection human body.
But, in the process of PET imaging, there is a phenomenon for diffusion, reduced largely resolution and the contrast of image, also can affect accuracy of quantitative analysis (for example standard uptake value).
The diffusion of so-called point refers to that a point diffuses into a distribution for a certain reason, and this distribution is called as PSF(point spread function, point spread function).Point diffusing phenomenon in PET imaging process are mainly caused by following factor:
1) meet right non-collimation.The momentum of positron before burying in oblivion is conventionally non-vanishing, cause Gamma photon after burying in oblivion between angle be not 180 degree, this phenomenon is main relevant with type and the medium of nucleic;
2) scattering of Gamma photon in detector and penetrating, causes photon to by labelling mistakenly, and this phenomenon is relevant with crystal type and incident angle, photon to vertical incidence in the situation that this kind of phenomenon can not occur;
3) approximate calculation in algorithm for reconstructing.Consider the feasibility of rebuilding, the acceptability of time and calculating, often need to be similar to ideal formula, for example, can adopt Fourier algorithm for reconstructing, and these approximate calculation are also factors that causes a diffusing phenomenon: PET iterative reconstruction algorithm is determined the distribution x of tracer in human body by true projection y and sytem matrix W, wherein x and y are column vectors, and three's component is all nonnegative value, use KL-divergence to measure the difference between true projection y and estimated projection Wx, just can obtain reconstruction model, then using EM(expectation maximization) algorithm obtains iterative formula, above-mentioned reconstruction model has only been considered ideal situation, situation about occurring without some diffusion, and in fact, any existing PET system all cannot be avoided a diffusing phenomenon, therefore the conclusion that adopts above-mentioned algorithm to draw does not obviously square with the fact.
In sum, first two factor depends on the uncontrollable factors such as type of nucleic and crystal, and approximate calculation in algorithm for reconstructing can be reduced by further measurement.
In prior art, the measure that solution process of reconstruction mid point extends influence mainly comprises measurement method, analytic method and Monte Carlo Analogue Method, and effect is better in actual applications with measurement method.
Please refer to Fig. 1 and Fig. 2, Fig. 1 is the method flow schematic diagram of a kind of PSF of carrying out matrix measurement in prior art; Fig. 2 is the structural representation of a kind of set-up mode of detector in prior art.
The method of using measurement method to obtain PSF matrix generally comprises:
S01: place a line source in frame;
S02: choose some sampled points and carry out emission scan in space, obtain the PSF of each sampled point;
S03: the PSF that obtains each point in space according to statistical property.
Theoretically, in above-mentioned steps S02, each location of pixels needs to carry out PSF measurement, but because most of detectors are regular polygon structure, as shown in Figure 2, during measurement, detector can be divided into a plurality of trianglees that equate with its limit number, then selected one of them triangle is measured zone and chooses sampled point in this region, be that sampled point only need to spread all over a measured zone, in other regions, the PSF of each pixel can obtain by image rotation.
Please further refer to Fig. 3, Fig. 3 is the structural representation of a kind of metering system of measuring system in prior art.
Existing measuring system adopts the motion up and down shown in Fig. 2 to realize the measurement of each pixel in sample area conventionally.Existing measuring device can comprise a crossfoot and a perpendicular chi, and both are connected by slide block, and then the motion up and down by slide block realizes the scanning of line source to each pixel in sample area, and then obtains and record the cartesian coordinate of these points.
But, above-mentioned existing metering system can not meet the measurement of point spread function in PET system preferably: experiment shows, existing metering system relatively expends time in, and it is mobile that the measurement of each point all needs two slide blocks to coordinate, and the amount of radiation that operator are subject to is larger; The PSF of sampled point need to be rotated, and then obtain PSF a little, and cartesian coordinate is not suitable for being rotated conversion, in practice, first the cartesian coordinate that adopts above-mentioned metering system to obtain needs to be converted into polar coordinate, and then by spin matrix, realizes PSF and rotate.
In above-mentioned PSF rotary course, need to carry out complicated Coordinate Conversion, but also likely have some approximate processing, this has not only reduced the efficiency of measuring, and has also affected to a certain extent certainty of measurement.
Therefore, how designing a kind of measuring method and measuring device thereof of PET system point spread function, to improve, measure efficiency and precision, reduce the amount of radiation that in measuring process, operator are subject to, is the current technical issues that need to address of those skilled in the art.
Summary of the invention
The measuring method and the measuring device thereof that the object of this invention is to provide a kind of PET system point spread function, can improve and measure efficiency and precision, reduces the amount of radiation that in measuring process, operator are subject to.
For solving the problems of the technologies described above, the invention provides a kind of measuring method of PET system point spread function, described measuring method comprises:
11) sweep limits of detector is divided into several measured zone, and in a measured zone, chooses some sampled points therein;
12) adopt line source to carry out one by one emission scan to described sampled point, measure simultaneously and record the polar coordinate of each sampled point;
13) according to the polar coordinate of each sampled point in a described measured zone, convert and draw the polar coordinate of each point in other measured zone, and calculate the point spread function of whole detector scanning scope.
The polar coordinate of each sampled point are directly measured and recorded to measuring method of the present invention, without the conversion of carrying out coordinate, simplified the measurements and calculations process of point spread function, can also avoid the impact of Coordinate Conversion program on certainty of measurement; Adopt polar coordinate to carry out record to sampled point, be convenient to realize PSF rotation, to rotate the polar coordinate that obtain sampled point in other measured zone, and then obtain system point spread function, it is higher that it measures efficiency.
Preferably, described step 12) is specially:
By line source along the sampled point of emission scan diverse location one by one of the same utmost point radial line in polar coordinate system, measure simultaneously and record utmost point footpath and the angle corresponding to this utmost point radial line of each sampled point, to obtain the polar coordinate of each sampled point on this utmost point radial line, after the measurement of all sampled points on completing this utmost point radial line, turn an angle and continue to measure the polar coordinate of each sampled point on another utmost point radial line, until complete the measurement of all sampled points in described measured zone.
When carrying out polar measurement, can first select the angle of a measurement, treated to carry out again the measurement of other angle sampled points after the measurement of each sampled point in this angle, this method can improve the efficiency of measurement, simplified measurement program, can also reduce the amount of radiation that survey crew is subject to.
The present invention also provides a kind of measuring device of PET system point spread function, comprise line source, described measuring device also comprise for measure sampled point polar angle bevel protractor and for measure sampling point pole footpath rule, described rule is longitudinally provided with along it datum line that mark has utmost point footpath groove, described line source is arranged in the vertical plane of described rule, described line source also can move along it perpendicular to described datum line, described rule can rotate by the measuring center point around described bevel protractor in the plane parallel with described bevel protractor, and is positioned at predetermined angular.
Measuring device of the present invention cooperatively interacts by bevel protractor and rule, during measurement, rule can be positioned at predetermined angular, this angle can measure by bevel protractor, then the datum line along rule moves line source to scan one by one each sampled point on this datum line, from rule, read the utmost point footpath of each sampled point, and then obtain the polar coordinate of sampled point; Then the measuring center axle around bevel protractor rotates rule, rule is navigated to another predetermined angular, record successively according to the method described above the polar coordinate of each sampled point, again the rotation of the polar coordinate by sampled point obtain within the scope of detector scanning polar coordinate a little, thereby obtain point spread function, it is simple in structure, easy operating; The present invention only just can realize the measurement of point spread function by bevel protractor and rule, has taken into full account the construction features of detector, has simplified the acquisition process of PSF, and it is higher that it measures efficiency, can reduce the amount of radiation that operator are subject to.
Preferably, described rule and described bevel protractor are articulated with the measuring center point of described bevel protractor, and described bevel protractor is circumferentially with a plurality of spacing holes along it, and described rule is provided with the connector being equipped with described spacing hole.
Rule is connected in the spacing hole of bevel protractor by connector, and can change the angle between rule and bevel protractor along with the change in location of selected spacing hole, and then realize the location of rule on certain predetermined angular, to realize the measurement of this angle up-sampling point, it is simple in structure, connects more reliable.
Preferably, described connector is spring-loaded plunger, and its connection and dismounting are more convenient, and location is more accurate.
Preferably, circumferentially uniform along described bevel protractor of a plurality of described spacing holes.
Preferably, described measuring device also comprises that described plate and described line source be arranged in parallel for accessing the plate in sick bed slot, thereby measuring device is installed and is positioned at a side of sick bed, and without special erection unit, is easy to carry and installs.
Preferably, described rule is longitudinally provided with leading screw along it, described line source is the flexible pipe that is perfused with radioactive indicator, described flexible pipe passes through cantilever support, the end of described cantilever is provided with the threaded portion coordinating with described leading screw, so that cantilever moving axially along described leading screw described in the rotating drive of described leading screw.
The movement of line source can be threaded connection realization, can be along rule leading screw is longitudinally set, then by the end of cantilever, realize being connected of line source and leading screw, when cantilever just can change the relative position of line source and rule during along leading screw axially-movable, line source scanning sample point one by one, operator just can measure by the reading of bevel protractor and rule the polar coordinate of each sampled point; The design of said structure is converted into the rectilinear motion of line source by rotatablely moving of leading screw, it is simple in structure, simple operation, and can realize the precise positioning of line source, to assist, improve the precision that sampled point is measured.
Preferably, described leading screw is also provided with for driving the runner of its rotation.For further strengthening the operability of measuring device, runner can also be set, the rotation by runner realizes the driving of leading screw and control.
Preferably, the both sides of described leading screw also have the guide rod of setting in parallel, and the end of described cantilever is also provided with the slide block being slidably connected with described guide rod.
In order further to improve, line source connects and the reliability of motion, can also guide rod be set in the both sides of leading screw, then the end of cantilever is connected to location with guide rod by slide block, and cantilever can be fixed by guide rod supplemental support, reduces the unstable factor of line source location; The end of cantilever is connected on guide rod by slide block, and can slide along guide rod, be that guide rod can also be as the tracks of line source, line source can be connected with leading screw, guide rod by cantilever, the mode of this multiple location can improve the reliability of connection, and multi-orbit motion mode can guarantee that line source accurately moves to the position at sampled point place reposefully, and then the order of accuarcy of assurance measurement result.
Accompanying drawing explanation
Fig. 1 is the method flow schematic diagram of a kind of PSF of carrying out matrix measurement in prior art;
Fig. 2 is the structural representation of a kind of set-up mode of detector in prior art;
Fig. 3 is the structural representation of a kind of metering system of measuring system in prior art;
Fig. 4 is the schematic flow sheet of measuring method provided by the present invention in a kind of specific embodiment;
Fig. 5 is measuring device provided by the present invention side structure schematic diagram in a kind of specific embodiment;
Fig. 6 is the structure schematic diagram of measuring device shown in Fig. 5;
Fig. 7 is the structural representation of a kind of set-up mode of plate provided by the present invention.
The specific embodiment
Core of the present invention is to provide a kind of measuring method of PET system point spread function, can improve certainty of measurement and efficiency, simplified measurement process.
Another core of the present invention is to provide a kind of measuring device that adopts said method to measure, and it is simple in structure, and simple operation can realize the polar coordinate measurement of sampled point, and its measurement structure is more accurate, is convenient to realize PSF rotation.
In order to make those skilled in the art person understand better the present invention program, below in conjunction with the drawings and specific embodiments, the present invention is described in further detail.
Please refer to Fig. 4, Fig. 4 is the schematic flow sheet of measuring method provided by the present invention in a kind of specific embodiment.
In a kind of specific embodiment, measuring method of the present invention comprises:
S11: the sweep limits of detector is divided into several measured zone equably, for example, when detector is regular hexagon, can will be divided into six measured zone, each measured zone is all with the Wei Qi summit, center of detector;
S12: a selected measured zone is measured, and chooses some sampled points in selected measured zone, and the factors such as the structure of detector, acceptable Measuring Time and acceptable picture quality are depended in the setting of sampled point;
S13: select a corresponding utmost point radial line of polar angle in selected measured zone;
S14: scan one by one the sampled point of diverse location on described utmost point radial line by line source, measure simultaneously and record the polar coordinate of each sampled point;
S15: judged whether the measurement of all sampled points on selected utmost point radial line, if so, performed step S16, if not, continued execution step S14;
S16: judged whether the measurement of all sampled points in selected measured zone, if so, performed step S17, if not, returned to execution step S13, until measure the polar coordinate of all sampled points in selected measured zone;
S17: obtain the polar coordinate of each point in other measured zone according to the polar coordinate rotation of the sampled point measuring, then calculate the point spread function of PET system.
Can expect, in above-mentioned steps S11, the division of measured zone can be adjusted accordingly according to the version of detector, and for example, measured zone can be divided into several symmetrical congruent structures that equate with its limit number.Because detector is generally regular polygon structure, and the tracer within the scope of detector scanning is uniformly distributed substantially, therefore can adopt the division of above-mentioned measured zone measures its part, and then be converted to the coordinate of each point in other parts, and then calculating the point spread function of whole PET system, concrete principle refers to prior art.
It should be noted that, step S13-S16 is only comparatively preferred a kind of embodiment in sampled point Polar Method, the present invention can also adopt other modes to realize the polar measurement of sampled point: for example, can also the sampled point in measured zone be scanned at random, then adjust the position of bevel protractor and dip stick, to draw respectively the polar coordinate of each sampled point.Obviously, first select an angle, then measure successively polar metering system of each sampled point in this angle, not only simplified measuring process, also be not easy to omit sampled point, therefore the method for employing above-mentioned steps S13-S16 is measured, more science is accurate.
Above-mentioned utmost point radial line refers to certain residing ray in utmost point footpath, and this ray be take polar coordinate initial point as launch point.
Please refer to Fig. 5 and Fig. 6, Fig. 5 is measuring device provided by the present invention side structure schematic diagram in a kind of specific embodiment; Fig. 6 is the structure schematic diagram of measuring device shown in Fig. 5.
The present invention also provides a kind of measuring device of PET system point spread function, and this measuring device can adopt above-mentioned measuring method to measure.
Measuring device of the present invention comprises bevel protractor 1, rule 2 and line source 3, and bevel protractor 1 is for measuring the polar angle of sampled point, and rule 2 is for measuring the utmost point footpath of sampled point; Rule 2 is longitudinally provided with datum line 21 along it, and datum line 21 is marked with utmost point footpath groove; Line source 3 arranges perpendicular to datum line 21, and in the vertical plane of line source 3 in rule 2, line source 3 can move along datum line 21; Rule 2 can rotate around the measuring center point of bevel protractor 1, and its rotational plane and the residing plane parallel of bevel protractor 1, rule 2 can optionally be located on predetermined angular, to measure the utmost point footpath of each sampled point in diverse location on the utmost point radial line that this predetermined angular is corresponding.The measuring center point of bevel protractor 1 is initial point corresponding to each angle on bevel protractor 1.
The angle that the residing measured zone of described sampled point covers forms an angular range, in order to measure all sampled point polar coordinate, rule 2 need to rotate and be positioned in any one angle in this angular range when measuring, or according to the distribution of sampled point, also can be positioned in several angles, therefore described predetermined angular is exactly arbitrarily angled value in this angular range or several selected angle values, therefore determining of predetermined angular is relevant with the selection of sampled point.
During use, measuring device of the present invention is arranged on to a side of sick bed, can first selectes an angle, then rule 2 is positioned to this angle, and by bevel protractor 1, reading the number of degrees of this angle, this angle value is exactly the polar angle of each sampled point on the datum line in rule 2; Along with line source 3 moves longitudinally at rule 2, each sampled point on datum line 21 is scanned one by one, now can measure the utmost point footpath of each sampled point, the scale value of the angle value of bevel protractor 1 and rule 2 has been indicated the polar coordinate of radioactive source jointly; After the diverse location of same angle has gathered, rule 2 is rotated to another angle, realize according to the method described above the polar coordinate of each sampled point in this another angle, so repeatedly measure, until draw the polar coordinate of all sampled points in a measured zone.
Certainly, first need to determine the position of sampled point before measuring, described in above-mentioned measuring method, the position of sampled point is determined after can considering according to combined factors such as the structure of detector, acceptable Measuring Time and acceptable picture qualities.
A kind of comparatively preferred embodiment in, bevel protractor 1 and rule 2 can be articulated with the measuring center point of bevel protractor 1, bevel protractor 1 can also circumferentially arrange a plurality of spacing holes 11 along it simultaneously, rule 2 can arrange connector 22, connector 22 can be realized and being located by connecting with spacing hole 11 adaptedly, to rule 2 is positioned in certain spacing hole 11, is positioned predetermined angular; Connector 22 can also be removed and being connected of certain spacing hole 11 in needs, then the measuring center point of bevel protractor 1 of take rotates rule 2 to another predetermined angular as center of rotation, spacing hole corresponding on another predetermined angular of connector 22 and this 11 is connected, to rule 2 is positioned to this another predetermined angular, and then realize the measurement of the sampled point in diverse location on this another predetermined angular.
Bevel protractor 1 adopts above-mentioned connection with rule 2, can realize by the swing of rule 2 reorientating of its angle position, thereby change the residing angle of rule 2, coordinate spacing hole 11 to position in all angles simultaneously, realize the alternative that rule 2 is located by connecting, and then complete the measurement of a plurality of sampled points in all angles.
When carrying out equipment installation, can use laser localized light comparing to position, to guarantee that the center of rotation of rule 2 overlaps with center, the visual field (being the center of detector rings), thereby guarantee that polar initial point overlaps with the summit of measured zone, the projection state that makes the angle that measures by above-mentioned bevel protractor 1 and rule 2 and utmost point footpath can reflect truly sampled point.Conventionally, the error of installation should be controlled at 1mm left and right.
Connector 22 can be spring-loaded plunger, and the torsion of spring-loaded plunger inner spring can guarantee the precision of location, in assurance and spacing hole 11 reliability of positioning, can also simplify installation and removal process, assisted Extraction high measurement efficiency; Connector 22 can also be screw, and spacing hole 11 now can be set to screwed hole, and both are threaded connection location.The version of connector 22 is various, can select in principle to realize the arbitrary structures that hole connects, but consider that the frequency of its installation and removal is higher, should be so that the principle of installation and removal for arranging.
It should be noted that, while adopting spring-loaded plunger as connector 22, rule 2 not only can be fixed on some predetermined angle (as mentioned above, these predetermined angles arrange according to the distribution of sampled point, and substantially can meet the demand of measurement), can also be fixed in other unscheduled angles, to meet the measurement demand of arbitrarily angled sampled point.Certainly, for coordinating, realize rule 2 locating at any angle, on bevel protractor 1, should spacing hole 11 be set at all angles value place, or along it, grooved rail be circumferentially set, be convenient to spring-loaded plunger and be connected and fixed.
The position of spacing hole 11 and number thereof should be carried out relative set according to the distribution situation of sampled point, and will meet the demand of each sampled point polar coordinate measurement.A plurality of spacing holes 11 can be evenly distributed in the circumferential of bevel protractor 1, make sampled point be distributed on all angles, and the sampled point measuring is like this more representative, and the point spread function calculating is thus also more accurate; Meanwhile, bevel protractor 1 the measurement that a plurality of spacing holes 11 can be realized point in all angles (even if not being sampled point) substantially is circumferentially set equably, thereby realize measurement demand at any angle, to expand the range of application of measuring device of the present invention.
Certainly, because sampling point distributions is in a measured zone, and there is an angular range in this measured zone, this angular range is exactly radian corresponding to described measured zone, therefore, to in theory, as long as spacing hole 11 can meet, rule 2 is positioned in the angular range of described measured zone.That is to say, spacing hole 11 also can be distributed in the part cambered surface of bevel protractor 1, and the angular range of this cambered surface should at least equate or be greater than the radian scope of described measured zone with the angular range of described measured zone; For realizing the measurement of sampled point in the present invention, and the nonessential all angles at bevel protractor 1 all will arrange spacing hole 11, and a plurality of spacing holes 11 also can be in the circumferential employing uneven distribution of spacing hole 11, it specifically arranges all and can adjust according to structure of detector etc.
Can expect, between rule 2 and bevel protractor 1, the alternative of angle can also realize by other version: for example, can between rule 2 and bevel protractor 1, dismountable intermediate member be set, this intermediate member can connect both or separation arbitrarily angled, to change the angle between rule 2 and bevel protractor 1, this class intermediate member can be the parts of the auxiliary positioning such as fastener or adhesion part; Or, the track sliding for rule 2 can be set on bevel protractor 1, on rule 2, slide fastener be set, described slide fastener is provided with fixture, rule 2 can swing arbitrarily along the circumferential of bevel protractor 1, and is located by the fixture on slide fastener in selected angle; Also can on rule 2, projection be set, then at bevel protractor 1 groove is circumferentially set, projection on rule 2 can engage with each groove in different angles mutually with separated, rule 2 now can be independent parts, itself and bevel protractor 1 can be separated from each other, but both can locate again accurately when measuring.
On this basis, rule 2 can also arrange leading screw 23, and leading screw 23 is along the longitudinal extension setting of rule 2, and line source 3 can be for being perfused with the flexible pipe of radioactive indicator, and this flexible pipe supports by cantilever 4, and perpendicular to the datum line 21 of rule 2; The end of cantilever 4 can arrange threaded portion 41 ordinatedly with leading screw 23, when leading screw 23 rotates, can drive cantilever 4 along the moving axially of leading screw 23, and then change line source 3 corresponding scale position on rule 2, realize one by one the scanning of the diverse location up-sampling point in same angle.
For realizing the support to flexible pipe, cantilever 4 can arrange special track, and this track is arranged in the vertical plane of rule 2, and extends setting perpendicular to the datum line 21 of rule 2, to guarantee that line source 3 can scan perpendicular to 21 pairs of sampled points of datum line.
Meanwhile, the end of leading screw 23 can also arrange runner 24, drives leading screw 23 constantly to rotate, to improve the convenience of operation by rotating wheel 24.Runner 24 can be for being connected with the handwheel of handle or by motor-driven Electric Motor Wheel etc., concrete version can be according to the present invention the application scenario of measuring device carry out relative set.
In addition, the both sides of leading screw 23 can also arrange guide rod 25, and guide rod 25 be arranged in parallel with leading screw 23; The end of cantilever 4 can also arrange slide block 42, and slide block 42 is equipped with guide rod 25, and can moving axially along guide rod 25.When being realized single-point and be connected by threaded portion 41 between cantilever 4 and leading screw 23, the stability of its connection and the precision of location are difficult to be guaranteed, and can adopt above-mentioned guide rod 25 and slide block 42 to carry out auxiliary positioning; Guide rod 25 and leading screw 23 are the track of cantilever 4 motions, rotational lead screw 23 is to drive cantilever 4 motions by threaded portion 41, cantilever 4 moving axially along leading screw 23, meanwhile, slide block 42 moves axially along guide rod 25, cantilever 4 is carried out to horizontal supplemental support, and the structure setting of this multi-track, branched support point can be guaranteed the precision of cantilever 4 motions, and can guarantee the reliability of location.
Theoretically, desirable line source 3 should be that diameter is zero and has the radioactive source of certain activity, and the form of line source 3 can adjust accordingly according to the structure of detector; Conventionally, while adopting the interior perfusion of flexible pipe radioactive indicator to form line source, the internal diameter of flexible pipe is less than 1mm, and wherein the radioactive indicator of perfusion can be the simulation line source of 0.1-0.5mCi.
Further can expect, the mode that line source 3 moves along rule 2 is not limited in above-mentioned lead screw transmission and connects.Can also adopt the parts such as driving-belt, travelling gear to replace the leading screw 23 in above-described embodiment, then the structure of cantilever 4 be improved accordingly; Or can be along datum line 21 directions of rule 2 a plurality of line sources 3 that gather, the setting corresponding to sampled point of a plurality of line sources 3; Also the slide rail of line source 3 can be set on rule 2, line source 3 can be along the longitudinal sliding motion of rule 2, to change at any time its position.
It will also be appreciated that, datum line 21 can be arranged on rule 2 centre position or using the dual-side of rule 2 along in one of them as its datum line 21 so that the mark of utmost point footpath groove, be beneficial to reading of numerical value in measuring process simultaneously; On the other hand, utmost point footpath groove can also be extended transversely to opposite side edge from a side of rule 2, even if sampled point can not measure the numerical value in its utmost point footpath on datum line 21 yet, further to improve measurement efficiency; Again, a plurality of datum marks can also be set on datum line 21, each datum mark substantially can be corresponding one by one with the sampled point in diverse location, datum line 21 now can be a virtual line, as long as the scale value that reads each datum mark just can access the utmost point footpath of each sampled point corresponding with it, can improve largely the efficiency of measurement; When but the structure that adopts datum mark is measured, in processing technique, be difficult to accomplish that sampled point mates with the accurate of datum mark, and in the situation that both can not overlap completely, take possibly to estimate the utmost point footpath numerical value that the method for reading records sampled point, thereby can affect to a certain extent the precision of measurement.
Please refer to Fig. 7, Fig. 7 is the structural representation of a kind of set-up mode of plate provided by the present invention.
Measuring device of the present invention can also arrange plate 5, and plate 5 is for inserting in the slot of sick bed, thus the integral body location of realizing measuring device.To guarantee that line source 3 is parallel with polar Z axis owing to measuring, therefore will guarantee that when installing line source 3 is horizontally disposed with, that is to say, the part in plate 5 insertion sick bed slots 6 will with line source 3 keeping parallelisms.During fabrication, carry out the control of the depth of parallelism to line source 3 and the insertion portion of plate 5, guarantee that both are parallel to each other, and then guarantee the precision of measurement result.Between line source 3 and plate 5, the error of the depth of parallelism should be controlled at 0.5 degree left and right.
As shown in Figure 7, plate 5 can comprise insertion section 51 and connecting portion 52, and setting is mated with the slot 6 of sick bed in insertion section 51, to realize and being located by connecting of sick bed; With further reference to Fig. 4 and Fig. 5, connecting portion 52 can be connected with bevel protractor 1, both can adopt integrated setting or adopt split setting, but can guarantee better the depth of parallelism of line source 3 and insertion section 51 while adopting integrated setting, avoid the dislocation causing because connecting.
Meanwhile, plate 5 also should have higher Rigidity and strength, avoids plate 5 to bend under the effect of shearing force, affects the levelness of line source 3.
Bevel protractor 1 and rule 2 all can adopt the materials such as steel plate to make, and are not only difficult for wearing and tearing, and can also guarantee to install and working strength.
Above the measuring method of PET system point spread function provided by the present invention and measuring device thereof are described in detail.Applied specific case herein principle of the present invention and embodiment are set forth, the explanation of above embodiment is just for helping to understand core concept of the present invention.It should be pointed out that for those skilled in the art, under the premise without departing from the principles of the invention, can also carry out some improvement and modification to the present invention, these improvement and modification also fall in the protection domain of the claims in the present invention.
Claims (10)
1. a measuring method for PET system point spread function, described measuring method comprises:
11) sweep limits of detector is divided into several measured zone, and in a measured zone, chooses some sampled points therein;
12) adopt line source to carry out one by one emission scan to described sampled point, measure simultaneously and record the polar coordinate of each sampled point, and when carrying out polar measurement, the angle of a first selected measurement, has treated that the polar measurement of other angle sampled points is carried out in the measurement of each sampled point in this angle afterwards again;
13) according to the polar coordinate of each sampled point in a described measured zone, convert and draw the polar coordinate of each point in other measured zone, and calculate the point spread function of whole detector scanning scope.
2. measuring method as claimed in claim 1, is characterized in that, described step 12) be specially:
By line source along the sampled point of emission scan diverse location one by one of the same utmost point radial line in polar coordinate system, measure simultaneously and record utmost point footpath and the angle corresponding to this utmost point radial line of each sampled point, to obtain the polar coordinate of each sampled point on this utmost point radial line, after the measurement of all sampled points on completing this utmost point radial line, turn an angle and continue to measure the polar coordinate of another each sampled point of utmost point radial line, until complete the measurement of all sampled points in described measured zone.
3. the measuring device of a PET system point spread function, comprise line source, it is characterized in that, described measuring device also comprise for measure sampled point polar angle bevel protractor and for measure sampling point pole footpath rule, described rule is longitudinally provided with along it datum line that mark has utmost point footpath groove, described line source is arranged in the vertical plane of described rule, described line source also can move along it perpendicular to described datum line, described rule can rotate by the measuring center point around described bevel protractor in the plane parallel with described bevel protractor, and is positioned at predetermined angular.
4. measuring device as claimed in claim 3, it is characterized in that, described rule and described bevel protractor are articulated with the measuring center point of described bevel protractor, and described bevel protractor is circumferentially with a plurality of spacing holes along it, and described rule is provided with the connector being equipped with described spacing hole.
5. measuring device as claimed in claim 4, is characterized in that, described connector is spring-loaded plunger.
6. measuring device as claimed in claim 4, is characterized in that, a plurality of described spacing holes are circumferentially uniform along described bevel protractor.
7. measuring device as claimed in claim 3, is characterized in that, described measuring device also comprises that described plate and described line source be arranged in parallel for accessing the plate in sick bed slot.
8. the measuring device as described in claim 3 to 7 any one, it is characterized in that, described rule is longitudinally provided with leading screw along it, described line source is the flexible pipe that is perfused with radioactive indicator, described flexible pipe passes through cantilever support, the end of described cantilever is provided with the threaded portion coordinating with described leading screw, so that cantilever moving axially along described leading screw described in the rotating drive of described leading screw.
9. measuring device as claimed in claim 8, is characterized in that, one of them end of described leading screw is also provided with for driving the runner of its rotation.
10. measuring device as claimed in claim 8, is characterized in that, the both sides of described leading screw also have the guide rod of setting in parallel, and the end of described cantilever is provided with the slide block being slidably connected with described guide rod.
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| CN106137237B (en) * | 2016-08-24 | 2019-11-12 | 东软医疗系统股份有限公司 | Mobile source application and its plane source, the bearing calibration of PET device, device |
| CN106618618A (en) * | 2016-11-21 | 2017-05-10 | 上海联影医疗科技有限公司 | Radioactive source control device and method for medical imaging equipment |
| EP3503810A4 (en) | 2016-09-30 | 2019-08-14 | Shenzhen United Imaging Healthcare Co., Ltd. | Method and system for calibrating an imaging system |
| CN106923854A (en) * | 2017-03-21 | 2017-07-07 | 泰山医学院 | A kind of comprehensive Quality Control body mould suitable for PET/CT |
| CN110751647B (en) * | 2019-10-29 | 2023-06-09 | 明峰医疗系统股份有限公司 | Point expansion estimation method for PET (positron emission tomography) system |
| CN113112558B (en) * | 2021-03-26 | 2024-03-15 | 江苏医药职业学院 | High-definition PET image reconstruction method |
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| JP2004188283A (en) * | 2002-12-10 | 2004-07-08 | Nagoya Oil Chem Co Ltd | Masking material for coating and method of recycling the same |
| DE10313038B4 (en) * | 2003-03-24 | 2005-02-17 | Klingelnberg Gmbh | Device for detecting the position of a probe element in a multi-coordinate measuring device |
| WO2007020543A1 (en) * | 2005-08-18 | 2007-02-22 | Koninklijke Philips Electronics, N.V. | Positron emission tomography time-of-flight list mode reconstruction with detector response function |
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| GB0712008D0 (en) * | 2007-06-21 | 2007-08-01 | Renishaw Plc | Apparatus and method of calibration |
| JP2011002306A (en) * | 2009-06-18 | 2011-01-06 | Shimadzu Corp | Iterative image reconstruction method for pet system |
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