CN109085637A - A method of beam position measurement is realized based on Radiochromic film - Google Patents
A method of beam position measurement is realized based on Radiochromic film Download PDFInfo
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- CN109085637A CN109085637A CN201810936181.7A CN201810936181A CN109085637A CN 109085637 A CN109085637 A CN 109085637A CN 201810936181 A CN201810936181 A CN 201810936181A CN 109085637 A CN109085637 A CN 109085637A
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- radiochromic
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01T—MEASUREMENT OF NUCLEAR OR X-RADIATION
- G01T1/00—Measuring X-radiation, gamma radiation, corpuscular radiation, or cosmic radiation
- G01T1/29—Measurement performed on radiation beams, e.g. position or section of the beam; Measurement of spatial distribution of radiation
- G01T1/2914—Measurement of spatial distribution of radiation
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Abstract
The invention discloses a kind of method for realizing beam position measurement based on Radiochromic film, this method is included the following steps: to be cut film to required size using film cropping tool, film is sticked on film fixed frame using vacuum rubber belt；Fixed frame, fixing groove, beam channel end face three are fixed using screw；It needs the calibration film to plan to demarcate before measuring, obtains film dosage-optical density response curve；Line bombardment verifying film changes colour when measurement, after scanner scanning, back-end processing software input demarcated curved line relation formula handles color change interval for dosage contour map, which can determine whether the relevant parameters information such as beam spot position.The principle of the invention is simple and reliable, and feasibility is high, and millimeter position resolution below may be implemented in strong operability, compared with traditional beam position sensor, solves the problems, such as not placing because accelerator hosting space is limited, to meet accelerator beam diagnostics requirement.
Description
Technical field
The present invention relates to beam current measurement technical fields, and in particular to one kind realizes that beam position is surveyed based on Radiochromic film
The method of amount.
Background technique
In recent years, accelerator is applied more and more extensive in fields such as medical treatment, industry, nuclear physics, especially in radiopharmaceutical
The fields such as pharmacy, oncotherapy start one research boom.Normal tissue can be reduced by destroying cancer cell for proton target practice
Damage needs clear accelerator line to draw parameter to accurately be treated to cancer cell tissue.How accurately and reliably
The relevant parameter of accelerator educt beaming flow is obtained, the extraction quality and efficiency for improving line are the problem of more concern at present.Face
The problem of should not placing biggish beam diagnostics device smaller to space in cyclotron, is unfolded a kind of using radiation film pair
The research that beam position and section measure.
Radiochromic film is one kind using organic material as substrate, the function film of dyestuff is coated on its surface, using spoke
The principle for penetrating autography technology changes colour.Currently, Radiochromic film is widely used in the agent of RADIATION PROCESSING or medical radiation
Measurement field.Dose response wider range of Radiochromic film has very high spatial resolving power, in certain dosage
Dose response having the same in range has tissue equivalent's property is good, can disposably obtain two-dimentional dosage to divide since it is very thin
Cloth, convenient for the advantages such as long-term preservation and analysis, be the parameters such as measurement charged particle absorbed dose, depth-dose distribution and energy compared with
One of good dosimeter.Therefore position needed for film being placed in measurement, can obtain line by discriminatory analysis film color change interval
Position and profile information, measuring principle is simple, and operation and disassembly are easy, and space occupied is small, meets measurement demand.
Summary of the invention
In order to overcome above-mentioned technical problem, the purpose of the present invention is to provide one kind to realize beam based on Radiochromic film
Flow the method for position measurement.
The purpose of the present invention can be achieved through the following technical solutions:
The present invention provides a kind of methods for realizing beam position measurement based on Radiochromic film, comprising the following steps:
1) before measuring, non-irradiated film is placed in water film body, with the proton beam radiation source of given energy to film
It is irradiated, the absolute absorption dosage of film color change interval is measured by ionisation chamber；
2) film after receiving irradiation is placed in scanner and is processed into grayscale image, which is imported at dosage
Its pixel value PV is extracted in reason software, netOD value is converted by pixel value PV, the absolute absorption agent of film is measured in conjunction with ionisation chamber
Amount, demarcates absolute absorption dosage-optical density response curve of film；
3) when measuring, different types of film will be placed to the beam spot position of measurement different zones, film passes through fixed group
Part is fixed, and is done front and back sides label with marking pen convenient for follow up scan, is subsequently placed into the fixing groove of passway, and carried out with screw
Positioning fastening；
4) after irradiating, film is taken out together together with fixation kit, color change interval is handled after removing film, with sweeping
Instrument scanned picture is retouched into grayscale image, the image file and calibrated absorbed dose-optical density are imported in dosage analysis software
Response curve relationship, to complete the absolute absorption dosage visualized operation of color change interval.
As a further solution of the present invention, so step 2) pixel value PV is converted into the mathematical formulae expression of netOD value
Are as follows:
Wherein: for the optical density of the film after exposure；
For unexposed film optical density；
For the pixel value of the film after exposure；
For the pixel value of unexposed film；
For the pixel value of the lighttight cardboard of one piece of black.
As a further solution of the present invention, the film that the step 3) uses is verifying film.
As a further solution of the present invention, the step 3) film is cut to required size using film cropping tool, should
Size matches with beam channel port sizes.
As a further solution of the present invention, the dosage of the step 3) receiving of each film in irradiation process is maximum
Value is different, need to control proton beam radiation duration according to film type.
As a further solution of the present invention, the step 3) fixation kit includes film fixed frame, film fixing groove；
Film fixing groove is fixed in beam channel port and by 2-4 M2 screw connection；Film fixing groove includes one for placing
The interior grooves of film framework, groove are semi-packing type；The film fixed frame and film fixing groove pass through a holding screw
Location fit；The film is attached on film framework by Kapton Tape, the one side edge and film fixed frame of film
Not closed side alignment.
Beneficial effects of the present invention:
The method for realizing beam position measurement based on Radiochromic film of the invention, principle is simple and reliable, and feasibility is high,
Strong operability may be implemented millimeter position resolution below and solve compared with traditional beam position sensor because of accelerator
The problem of hosting space is limited and can not place, to meet accelerator beam diagnostics requirement.
Detailed description of the invention
The present invention will be further described below with reference to the drawings.
Fig. 1 is the structural schematic diagram of fixation kit of the present invention.
Fig. 2 is the installation diagram of fixation kit of the present invention Yu film fixing groove.
Fig. 3 is film idealization dosage contour distribution map of the present invention.
Specific embodiment
Below in conjunction with the embodiment of the present invention, technical scheme in the embodiment of the invention is clearly and completely described,
Obviously, described embodiments are only a part of the embodiments of the present invention, instead of all the embodiments.Based in the present invention
Embodiment, all other embodiment obtained by those of ordinary skill in the art without making creative efforts, all
Belong to the scope of protection of the invention.
Theoretical basis based on the present invention, i.e. pixel value and the relationship of optical density (OD) value are provided by formula (2), specifically such as
Under: Radiochromic film does not need after the ionising radiation for absorbing doses physics or chemical method processing and is changed colour.It should
The photographic composition of sensitive layer is a kind of micromeritics of unsaturated hydrocarbons in film, and the unsaturated hydrocarbons as radiating color changing photographic composition is micro-
Polymerization can occur when by ionising radiation for crystal grain, generate a kind of condensate of dyestuff, therefore film changes colour.It absorbs
Dosage is bigger, develop the color it is deeper, i.e., measurement color change can obtain film by ionizing radiation dose, so by measurement film
" optical density " value (OD) absorbed dose of film can be surveyed.The mathematical formulae of optical density is expressed are as follows:
Wherein, I0For by the luminous intensity before film, I is the intensity of the light after film.
Radiochromic film is scanned using scanner, which uses triple channel mode, for difference
Film is handled using the optical channel of different colours, grayscale image is obtained after being scanned to the film after postdose, by rear
Processing software is held to extract pixel value therein, the pixel value and OD value that different light source scannings go out have certain relationship:
Wherein: ODexpFor the optical density of the film after exposure；
ODunexpFor unexposed film optical density；
PVexpFor the pixel value of the film after exposure；
PVunexpFor the pixel value of unexposed film；
PVbckgFor the pixel value of the lighttight cardboard of one piece of black；
The OD value for obtaining film by formula (2) is visualized using mapping software, is inhaled by calibrated film
Dosage-OD value polynomial curve is received, is demarcated in conjunction with film position, the distributed intelligence of available beam spot position.
Embodiment 1
A kind of method that beam position measurement is realized based on Radiochromic film is present embodiments provided, first consolidates film
Due on film framework, the frame fixing groove to match is placed in each beam channel port, the fixing groove by with film frame
Frame is cooperated, and film is installed to the passway of required measurement, and line is after the accelerating region of cyclotron is accelerated, warp
Extraction channel draws line, line during extraction through each passway when, line vertical incidence thin-film, film is shone
Change colour afterwards, judges beam position information by analyzing color change interval.It is required simultaneously according to accelerator internal operation, accelerator
Inside is in vacuum state.Wherein, the material of the components such as film fixed frame is preferably the low SUS316L material of magnetic conductivity,
The non-magnetic materials such as aluminium, copper can be used.
Embodiment 2
Present embodiments provide it is a kind of based on Radiochromic film realize beam position measurement method, before measurement, need by
Non-irradiated film is placed in water film body, is irradiated with the proton beam radiation source of given energy to film, is passed through ionisation chamber
Measure the absolute absorption dosage of film color change interval；Film after by photograph is placed in scanner and is processed into grayscale image, by this
Image file imports in dosage processing software and extracts its pixel value PV, is converted into netOD value by formula (2), surveys in conjunction with ionisation chamber
The absolute absorption dosage for obtaining film, demarcates absolute absorption dosage-optical density response curve of film；It should repeatedly measure much simultaneously
Item formula curve, so that the error of later period dosage contour distribution process is as small as possible.
When measurement, different types of film will be placed to the beam spot position of measurement different zones, film passes through fixation kit
It is fixed, front and back sides label is done convenient for follow up scan with marking pen, is subsequently placed into the fixing groove of passway, and determined with screw
Position fastening.Film is cut to required size with film cropping tool, which matches with beam channel port sizes.Wherein, exist
The dose maximum of the receiving of each film is different in irradiation process, need to control proton beam radiation duration according to film type.
As shown in Figure 1, fixation kit includes film fixed frame 1, film fixing groove 2；Film fixing groove 2 is fixed on line
In access port and pass through 2-4 M2 screw connection；Film fixing groove 2 includes one for placing the interior grooves of film framework,
Groove is semi-packing type；The film fixed frame 1 passes through a holding screw location fit with film fixing groove 2.Film 3 passes through
Kapton Tape is attached on film framework, and the one side edge of film 3 is aligned with the not closed side of film fixed frame 1.It surveys
Need to diagnose the position of beam spot when amount, and diagnostic position resolution ratio is within 0.5mm, thus to guarantee film into registration in frame,
And guarantee the positioning accuracy of frame and fixing groove.
After irradiation, film is taken out together together with fixation kit, color change interval is handled after removing film, with scanning
Instrument scanned picture imports the image file and calibrated dosage-OD value curve at grayscale image in dosage analysis software
Relationship, to complete the absolute absorption dosage visualized operation of color change interval.
As shown in Fig. 2, being provided with M1.6 threaded hole 11 on film fixed frame 1, the threaded hole is for the frame in line
Positioning and taking-up on 4 mouthfuls of channel, after the film fixed frame for being stained with film is pushed into fixing groove, with screw by frame with
Fixing groove connection, fixing groove is then to be fixed by M2 screw 12 with channel end surface.After line bombards film framework, for convenience
Disassembly, during taking film, places a blank sheet of paper for the bottom of the channel, prevents knockout screw from falling into host accidentally when removing
Bottom needs to be worn film framework to M1.6 threaded hole together with iron wire after screw has been torn open because space is smaller in accelerator host
It hauls out.
As shown in figure 3, being processed into grayscale image by scanner after the film after postdose is removed, handled by dosage soft
Part handles the image, inputs absolute absorption dosage-OD value response relation formula, forms dosage contour map.
In the present embodiment, the film of different location need to be taken multiple measurements by photograph, during concrete application, for proton weight
Ion beam current should be in vacuum environment internal irradiation, and local environment is directed to proton heavy ion without biggish humidity and higher temperature
Line should surrounding enviroment be without apparent mechanical oscillation and collision in vacuum environment internal irradiation, measurement process, indoor dust-free, without corruption
Corrosion gas etc., beam channel mouth position keep cleaning；The fixation thin film component material of selection need to be nonmagnetic, will not influence acceleration
Device internal magnetic field.
In the description of this specification, the description of reference term " one embodiment ", " example ", " specific example " etc. means
Particular features, structures, materials, or characteristics described in conjunction with this embodiment or example are contained at least one implementation of the invention
In example or example.In the present specification, schematic expression of the above terms may not refer to the same embodiment or example.
Moreover, particular features, structures, materials, or characteristics described can be in any one or more of the embodiments or examples to close
Suitable mode combines.
Above content is only to structure of the invention example and explanation, affiliated those skilled in the art couple
Described specific embodiment does various modifications or additions or is substituted in a similar manner, without departing from invention
Structure or beyond the scope defined by this claim, is within the scope of protection of the invention.
Claims (6)
1. a kind of method for realizing beam position measurement based on Radiochromic film, which comprises the following steps:
1) before measuring, non-irradiated film is placed in water film body, film is carried out with the proton beam radiation source of given energy
Irradiation, the absolute absorption dosage of film color change interval is measured by ionisation chamber；
2) film after receiving irradiation is placed in scanner and is processed into grayscale image, and it is soft which is imported dosage processing
Its pixel value PV is extracted in part, converts netOD value for pixel value PV, and the absolute absorption dosage of film is measured in conjunction with ionisation chamber,
Demarcate absolute absorption dosage-optical density response curve of film；
3) when measuring, different types of film will be placed to the beam spot position of measurement different zones, film is solid by fixation kit
It is fixed, front and back sides label is done convenient for follow up scan with marking pen, is subsequently placed into the fixing groove of passway, and positioned with screw
Fastening；
4) after irradiating, film is taken out together together with fixation kit, color change interval is handled after removing film, uses scanner
Scanned picture imports the image file and calibrated absorbed dose-optical density response at grayscale image in dosage analysis software
Curved line relation, to complete the absolute absorption dosage visualized operation of color change interval.
2. the method according to claim 1 for realizing beam position measurement based on Radiochromic film, which is characterized in that institute
The mathematical formulae expression of netOD value is converted into step 2) pixel value PV are as follows:
Wherein: ODexpFor the optical density of the film after exposure；
ODunexpFor unexposed film optical density；
PVexpFor the pixel value of the film after exposure；
PVunexpFor the pixel value of unexposed film；
PVbckgFor the pixel value of the lighttight cardboard of one piece of black.
3. the method according to claim 1 for realizing beam position measurement based on Radiochromic film, which is characterized in that institute
The film that step 3) uses is stated as verifying film.
4. the method according to claim 1 for realizing beam position measurement based on Radiochromic film, which is characterized in that institute
It states step 3) film and is cut to required size using film cropping tool, which matches with beam channel port sizes.
5. the method according to claim 1 for realizing beam position measurement based on Radiochromic film, which is characterized in that institute
The dose maximum for stating step 3) receiving of each film in irradiation process is different, need to control proton beam according to film type and shine
Penetrate duration.
6. the method according to claim 1 for realizing beam position measurement based on Radiochromic film, which is characterized in that institute
Stating step 3) fixation kit includes film fixed frame, film fixing groove；Film fixing groove is fixed in beam channel port simultaneously
It is connected by 2-4 M2 screw；Film fixing groove includes one for placing the interior grooves of film framework, and groove is half package
Formula；The film fixed frame and film fixing groove pass through a holding screw location fit；The film passes through polyimides glue
Band is attached on film framework, and the one side edge of film is aligned with the not closed side of film fixed frame.
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| Application Number | Priority Date | Filing Date | Title |
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| CN201810936181.7A CN109085637B (en) | 2018-08-16 | 2018-08-16 | Method for realizing beam position measurement based on radiochromic film |
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| Application Number | Priority Date | Filing Date | Title |
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| CN201810936181.7A CN109085637B (en) | 2018-08-16 | 2018-08-16 | Method for realizing beam position measurement based on radiochromic film |
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| CN109085637A true CN109085637A (en) | 2018-12-25 |
| CN109085637B CN109085637B (en) | 2020-12-15 |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN110398768A (en) * | 2019-07-15 | 2019-11-01 | 华中科技大学 | A Beam Spot Dynamic Monitoring Method and System Based on Pixel Ionization Chamber |
| CN111399029A (en) * | 2020-03-30 | 2020-07-10 | 合肥中科离子医学技术装备有限公司 | Continuous calibration method for curve motion |
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| US20070246657A1 (en) * | 2006-04-20 | 2007-10-25 | Isp Investments Inc. | Method for calibrating a radiation detection medium |
| CN104662443A (en) * | 2012-03-15 | 2015-05-27 | Isp投资公司 | Efficient method for radiochromic film dosimetry |
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2018
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Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US20070246657A1 (en) * | 2006-04-20 | 2007-10-25 | Isp Investments Inc. | Method for calibrating a radiation detection medium |
| CN104662443A (en) * | 2012-03-15 | 2015-05-27 | Isp投资公司 | Efficient method for radiochromic film dosimetry |
Non-Patent Citations (3)
| Title |
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| Y.HARA .ET AL: "Application of radiochromic film for quality assurance in the heavy-ion beam scanning irradiation system at HIMAC", 《NUCLEAR INSTRUMENTS AND METHODS IN PHYSICS RESEARCH SECTION B: BEAM INTERACTIONS WITH MATERIALS AND ATOMS》 * |
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN110398768A (en) * | 2019-07-15 | 2019-11-01 | 华中科技大学 | A Beam Spot Dynamic Monitoring Method and System Based on Pixel Ionization Chamber |
| CN111399029A (en) * | 2020-03-30 | 2020-07-10 | 合肥中科离子医学技术装备有限公司 | Continuous calibration method for curve motion |
| CN111399029B (en) * | 2020-03-30 | 2022-03-01 | 合肥中科离子医学技术装备有限公司 | Continuous calibration method for curve motion |
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