CN1023849C

CN1023849C - Radiation reduction filter for use in medical diagnostics

Info

Publication number: CN1023849C
Application number: CN 89101411
Authority: CN
Inventors: 肯尼思·E·迪蒙; 厄尔·J·麦卡瑟
Original assignee: Individual
Current assignee: Individual
Priority date: 1988-01-29
Filing date: 1989-01-28
Publication date: 1994-02-16
Anticipated expiration: 2004-01-28
Also published as: EP0356488A4; AU3056689A; DD294119A5; IN172608B; CA1250062A; DE8912419U1; EP0356488A1; ES2011731A6; CN1036285A; WO1989007322A1; JPH03503213A

Abstract

According to the present invention, an X-ray filter is provided which significantly reduces the low energy radiation normally absorbed by the object under examination without significantly affecting the desired high energy radiation. The filter is composed of one or more materials containing elements as main components, which are selected from aluminum and elements having atomic numbers between 26 and 50 to have an X-ray filtering characteristic such that the intensity of X-rays having an energy of 50Kev is reduced to about 8% to about 35% of its normal radiation level. As a result of the above-described configuration, the filter of the present invention filters out from the X-ray beam those energies that are normally absorbed by the examination object and that are not conducive to radiographic imaging of the examination object.

Description

Radiation reduction filter for use in medical diagnosis

The present invention relates to X-ray radiography and perspective, particularly about during medical treatment and dental diagnosis, limiting the filtrator of the x-ray radiation dosage that the patient is subjected to.

The X-ray produces owing to high-velocity electrons clash into a kind of target material in the X-ray tube, and this high-velocity electrons bump also penetrates the superficial layer of target material, by with the interaction or the bump of target atom, the energy of electronics is just given the electronics in the target material.

If during target, the energy of electronics is consumed by a series of bumps with the target atom outer-shell electron in bombardment, then energy is that form with heat or visible light is released.After a series of bump, also can from target, send electronics with the form of backscattered electron, these bumps cause the contribute energy of most of loss to generate heat in target, thereby have reduced the life-span of X-ray tube.

This electronics also can cause radiation bump, emits its portion of energy or is that whole energy are given photon sometimes.The photons that produced by these bumps have and are less than or equal to the energy that electronics is emitted.

If the energy of electronics is enough to the interior K layer bump with target atom, and launch out an electronics, so, when the electronics of this target atom that is excited on its skin enters the internal layer of this vacancy, will return its ground state and launch a photon from this layer.The energy of these transition depends on the atom of forming the target material, thereby the energy of the photon of emission is that this target atom is peculiar.This radiation is called the characteristic X-ray radiation in this technical field, and just can be produced by the X-ray tube when having only electron energy when the bombardment target to be higher than the required energy of bump target atom K electron.

The photon energy of forming the X-ray directly with and target molecule clash in the electronics energy of emitting relevant, as known, the relation between the wavelength of photon (λ) and its energy is by the Duana-Hunt formulate:

λ＝ 12.4/(KeV) A ⁰

So this process causes the X-ray of various wavelength, constitute so-called continuous X-alpha spectrum in this field.

The X-ray penetrates the energy that the ability of checking object depends on wavelength or X-ray photons, also depend on the composition of inspected object-be its chemical element, thickness and density are with regard to the wavelength or energy of X-ray, generally, penetration capacity is inversely proportional to wavelength or is directly proportional with energy.So short wavelength's's (high-energy) X-ray has than the stronger penetration capacity of long wavelength (low-yield) X-ray, general concerning forming the chemical element of checking object, Atom of Elements is higher, and the X-beam penetrates fewer.But when wavelength of limitting near these element absorption ends or energy, owing to the uncontinuity of X-radiation absorption degree on these aspects, these general rules are no longer set up.With regard to the thickness and density of checking object, generally, object is thick, and density is bigger, and it is also bigger to the receptivity of X-ray, can have only X-ray seldom to pass through this object.Penetration capacity is the combination of these factors, and these factors are relevant with the different compositions of the material that supplies X-radiography local diagnosis.So during medical diagnosis, X-ray equipment work Parameter selection is depended on checked object, its chemical composition, thickness and density.If need more detailed description, please refer to medico physics or radiologic text.

Usually the resolving power that is helpless to this method owing to low-energy X-ray is by checking that object absorbs and scattering, extremely making us wishing so removed more such X-rays from beam before X-beam contact inspected object.Some low-energy X-rays are usually by utilizing attenuator or filtrator to be removed from the X-beam like this.

Similar in appearance to checking the object role, the damping capacity of filtrator depends on chemical composition, density and the thickness of forming this filtrator material.Following equation has been represented these relations:

I＝I ₀e ^-μρX

Wherein I is by the intensity of the radiation of transmission, I ₀Be the intensity of incident radiation, e is the end of natural logarithm, and μ is a mass attenuation coefficient of forming this filtrator material chemical element, and ρ is the density of this filtrator material, and X is the thickness of implements matter after filtration.

In above-mentioned factor, except attenuation coefficient mu, the energy or the frequency-independent of all other factors and incident radiation.Attenuation coefficient changes with the energy of incident radiation is different, and relevant with filtrator material chemistry Atom of Elements.These coefficients are determined by experiment, and can for example find in the table by the such distribution of the UCRL50174 of people such as WHMcMaster work, and these tables can obtain at state-run technical information center (Springfield, Va., 22151).

For many years, be used for medical treatment and the most general X-ray filter device of dental diagnosis is to use the aluminium filtrator always.For example, United States Patent (USP) 2,225,940 disclose a V-arrangement sheet metal that is placed in the X-beam path.In addition, United States Patent (USP) 3,976,889 disclose at dentistry X-and utilize the aluminium filtrator of different-thickness to change the level of irradiation in the ray.The X-x-ray apparatus that nearly all merchant sells all has certain and about 1.0 to 1.5 millimeters intrinsic filtrations that aluminium is equal to.The device that is used for medical treatment and/or dental use has utilized additional aluminium to filter.

Utilizing filtrator outside the aluminium to come the intrafascicular low-yield X-ray of filtered x-ray is United States Patent (USP) 4,499,591 subject content is in this patent, adopt the ytterbium filtrator of 127 micron thickness to come the filtered x-ray bundle, made the energy that is lower than 20KeV in the beam be eliminated.Also have, " the Reduction of Patient Dose by Filtration in Pediatric Fluoroscopy and Fluorography " of Heinrick and Schuster. be Vol.19 (Ann.Radiol.(1976), the 57-66 page or leaf) in utilized 100 microns molybdenum filtrator to remove the radiation that is lower than 20KeV in the X-beam.

Koedooder and Venema(Phys.Med.Biol.(1986) Vol., the 585-600 page or leaf) computer program described, development is used for calculating and is used in possible filter material under a KPV (kilovolt peak value) (KVP) scope and the different imaging receiver.In their result, find that the reduction of dosage can reach height to 40%, still, under most of occasion, the load of X-ray tube is doubled, and causes the life-span of X-ray tube to reduce.

In X-ray crystallogram and diffraction investigation, having uniformly, the monochromatic x-rays bundle is useful.Adopt scope to produce these relatively evenly filtering materials of X-ray by restriction X-beam wavelength always.So at United States Patent (USP) 1,624, in 443, find to utilize have than the target of X-ray tube slightly the filtrator of low atomic weight can produce the X-beam of the comparison homogeneous that is suitable for X-ray crystallogram.This patent discloses in a most preferred embodiment utilizes a zirconium filtrator under the molybdenum target situation.Utilization has also shown the X-beam that can cause a comparison homogeneous with the filtrator of the same material of target.United States Patent (USP) 3,515,074 discloses and utilizes molybdenum as target and filtrator, and in taking pictures especially for mammal, there, having found to be taken pictures in using mammal by the energy level of the K α line of molybdenum target emission is very desirable to differentiating tumour.

Therefore, when coming into contacts with, owing to unnecessary radiation dose injurious effects exist danger with diagnosis X-ray.So effective X-ray filter of needs reduces such dosage and it will be suitable for existing X-ray equipment.

According to the present invention, provide an X-ray filter, it has significantly reduced does not have significantly influence by checking the low-energy radiation that object absorbs to required energy-rich radiation usually.This filtrator is made up of one or more materials, as its Main Ingredients and Appearance, contain the element of selecting the group that the element between 26 to 50 is formed from aluminium and atomic number, this filtrator is chosen to has such X-ray filtering feature, makes the intensity of the X-ray of 50KeV energy be reduced to 8% to 35% of common radiation level.

In one aspect of the invention, filtrator is embedded in the plastic layer that approaches, and this plastic layer provides protection to filtrator when transporting, also can absorb the secondary radiation that some are sent by filtrator when the contacted filter of X-beam.

In another aspect of the present invention, this filtrator is made up of the metal forming that an independent element material constitutes, and this element material is selected from the group of being made up of niobium, copper, silver, tin, iron, nickel, zinc, zirconium, aluminium or molybdenum.

In another aspect of the present invention, this filtrator is about 75 microns niobium metal paper tinsel or one deck niobium metal paper tinsel by maximum ga(u)ge and filtration paper tinsel that some are other is formed.

Because top structure, the filtrator of the present invention energy that elimination is absorbed by the inspection object usually from the X-beam, and not influence of radiography imaging to checking object.This is to realize under the load that does not have what (if any) increase X-ray tube, under other situation, increases its load and can reduce its useful life.According to following detailed description, will be understood that these and other some feature of the present invention to optimum implementation of the present invention.

Accompanying drawing has been represented optimum implementation more of the present invention, wherein.

Fig. 1 is the skeleton view by a filtrator of the present invention's formation;

Fig. 2 is the cut-open view of Fig. 1 filtrator;

Fig. 3 is the front elevation that filtrator of the present invention is placed on an X-X-ray diagnosis X equipment under the appropriate location;

Fig. 4 is the X-ray wave spectrum of Fig. 3 exemplary apparatus, shown after filtering and unfiltered spectrum; And

Fig. 5 is the X-ray wave spectrum of Fig. 3 equipment, shown utilize under second embodiment filtrator of the present invention unfiltered and filter after spectrum.

Fig. 1 and 2 has represented the optimum implementation of the filtrator of the present invention that a total usefulness 10 is represented, is made up of the metal forming that a monomer material that preferably is selected from niobium, copper, silver, tin, iron, nickel, zinc, zirconium or the molybdenum constitutes.Particularly suitable structure is the thick niobium to 75 microns of thickness, and 40 to 60 microns better, and the thickness of niobium metal paper tinsel the best is 50 microns.This metal forming is embedded in the chromo board 14, and the thickness that top color is used as this filter material of mark and it maybe will be employed the means of occasion.One deck plastic jacket layer covers and parcel filtrator 12 and cardboard strip of paper used for sealing 14, plays a part the filtrator protective cover.In addition, cardboard 14 and plastic jacket layer 16 also play some secondary radiations that absorb by metal forming 12 emissions when the X-ray contacts with this metal forming, have have also reduced or eliminated contacting of metal forming and air simultaneously, thereby have reduced oxidation.One is used for filtrator is fixed to the side that device on the X-x-ray apparatus is connected in filtrator 10, is a double sticky tape 18 among the figure.The method that filtrator is added on the X-x-ray apparatus will be discussed below.

Fig. 2 is the sectional view of Fig. 1 filtrator 10, has clearly illustrated that metal forming 12, the relation between cardboard strip of paper used for sealing 14 and the plastic jacket layer material 16.

Fig. 3 represents the X-ray generation equipment of a typical lead base structure, and this equipment comprises an X-ray tube with negative electrode 22 and rotary anode 24.The filament (not shown) is housed in the negative electrode, around negative electrode, produces electron cloud during by current flow heats.When the high voltage that comes from a generator (also not drawing) is added between negative electrode 22 and the anode, the form that electronics in the cathode electronics cloud is accelerated into electron beam flies to the anode of being made up of the metal material that is fit to do target 24, under the most common situation, target is made of tungsten.When electron beam bump target material, target material absorbs the energy of electron beam and illustrated as the front, causes the generation of X-ray.

Because the structure of anode 24, X ray is focused to a great extent and is launched out from these X-ray equipment 20 through ports 26.Mouthfuls 26 are made up of the glass of inherent filtration effect and about 0.5 millimeter aluminium flake equivalent or the window that plastics are made usually.In typical application, be focused by using a collimating apparatus 38 from the X-beam of pipe emission, the purposes of collimating apparatus 38 is the X-beam to be directed to only cover the needed areal extent of examination object, and this realizes by the openings 34 of regulating

aperture

32 and 36 setting collimating apparatuss.

The X-ray equipment also has intrinsic or the additional filtering effect, its usually with aluminium equivalent of 2.5 to 3.5 millimeters, removing very low-energy X ray from beam, these low-yield rays just are absorbed in initial several millimeters of inspected object usually.These extremely low-energy X ray are determined not have at all to the resolution of radiography and are helped, and only help to have increased the exposure dose of checking object.In case X ray is by inspected object 42, they are by a radiation detector, and for example one becomes image multiplier to detect or directly to the film 40 of a radiation imageable.

Filtrator 10 is added in this equipment, can find out it is between the mouth 26 and collimating apparatus 38 of pipe 30 on scheming.With double sticky tape 18 by or be attached to it on the mouth 26 of pipe 30 or be attached on the additional aluminium filtrator filtrator is installed on this equipment.In addition, in the application that can not do like this, promptly in some dental applications, it can be fixed on the opening of collimating apparatus.

Fig. 4 has shown the wave spectrum by the X ray of the X-ray equipment emission of Fig. 3 usually.This equipment is made target with tungsten and is had filtration with 3.5 millimeters aluminium equivalent, is operated under the accelerating potential of 80KVP, produces one and has minimum wavelength and be about 0.15 ⁰The about 0.21A of the difference of A and tungsten ⁰And 0.18A ⁰Feature K α and the continuous spectrum of K β radiation.Solid line has been represented the wave spectrum of the normal X beam radiation of this equipment emission before filtering with 50 microns niobium filtrator.Long dotted line is the attenuation characteristic of 50 microns niobium filtrators.Atomic number is that 41 niobium is at about 0.65A ⁰There is K absorption edge limit at the place and at about 4.58A ⁰There is a L at the place ₁Absorption edge limit (not drawing among the figure).Short dash line is represented the wave spectrum by X-ray beam behind this niobium filtrator.From about 0.25A ⁰To 0.65A ⁰These X ray wavelength before the K absorption edge limit at place have tangible reduction, just at 0.65A ⁰K absorption edge limit before the place, the normal radiation of having only about 3% incident is not by this filter absorbed.After this, in fact normal X-ray beam radiation is attenuated to that all radiation all are absorbed.

The requirement of diagnostic techniques is depended in the selection of filter material, because different technology can require different X ray wave spectrums.The most of medical or tooth that is operated in 55KeV to 110KeV crest voltage for X-ray equipment is with diagnostic techniques, and any its principal ingredient is that the material of the element of atomic number between 26 to 50 all is suitable for the X-ray beam of decaying.Atomic number approximately has K absorption edge limit at 26 to 50 element between 7KeV and the 30KeV, thereby can not present tangible K end limit phenomenon in these KVP scopes, so play non-particular filter usually.The selection of filter material is also depended on whether to obtain to be suitable for filtration device structure form, the particularly material of suitable thickness metal in foil form.

Because the characteristic of these materials, these elements of particularly can metal in foil form obtaining, required filtrator is thinner, normally in 200 microns or the littler order of magnitude, change, produce the X ray filtrator thickness of material with 30 to 120 micron number magnitudes preferably, the thickness that the material of best formation X ray filtrator has 30 to 70 micron number magnitudes.This is set forth in following table, has listed metallic foils filter modulator material and the preferred thickness recommended in the table.

Atom sequence number element thickness range optimum thickness

26 Fe 50-250 125

27 Co 50-225 125

28 Ni 50-200 100

29 Cu 50-180 120

30 Zn 60-205 125

38 Sr 100-305 205

39 Y 55-165 100

40 Zr 35-105 70

41 Nb 25-75 50

42 Mo 20-60 40

43 Tc 15-50 35

44 Ru 15-45 30

46 Pd 15-40 30

47 Ag 15-45 30

48 Cd 20-50 35

49 In 20-60 40

50 Sn 20-55 35

Atomic number between 26 to 50, can not can be by a kind of material formation of they and other alloy be utilized with those elements that metal in foil form obtains.To forming alloy useful especially is aluminium.The filtrator that constitutes by the present invention is suitable for existing X-ray apparatus easily, can reduce patient's radiation and can not increase expense significantly.This filtrator also has the attendant advantages that reduces from the next incident scattered radiation of x-ray source, thereby has reduced the radiation level to the equipment operator that may be shone.

If wishing to remove from X-ray beam energy is that important area is (generally from 0.15A near the radiation of the K absorption edge limit of niobium to diagnosing ⁰To about 0.4A ⁰) decay do not bring tangible increase, then can adopt combination filter.Combination filter contains one or more by the material of forming more than a kind of element, and these elements are selected the element 26 to 50 from aluminium and atomic number.Combination filter can be formed by each metal foil layer formation or by these materials being formed alloys and becoming independent paper tinsel layer.The wave spectrum of desirable X ray is depended in the selection of the element of material and composition material, and wave spectrum depends on concrete application.

As shown in Figure 5, adopted by 25 microns niobiums and 50 microns combination filters that selenium is formed.The substance of curve is identical with Fig. 4, and solid line is unfiltered spectrum, and long dotted line is the decay pattern of this combination filter, and short dash line is the spectrum after filtering.As can being clear that among the figure, adopted the K absorption edge limit that makes up with niobium to be about 0.98A ⁰Selenium, combination filter has been removed from X-ray beam substantially than 0.6A ⁰All X ray of long wavelength more.

So, in example shown in Figure 5, when application is to wish with wavelength less than about 0.4A ⁰X-ray beam the time, the combination of this niobium and selenium is particularly useful.If wish a harder beam, promptly wavelength is lower than 0.3A ⁰Or 0.2A ⁰Beam, should select so to remove than this filter material of long wavelength's X ray more.For example, K absorption edge limit is at about 0.42A ⁰Tin or K absorption edge limit at about 0.44A ⁰Indium or K absorption edge limit at 0.48A ⁰About silver can be useful.Similar other material of above-mentioned or attenuation characteristic can be limit at about 0.6A with one or more K absorption edges ⁰To 1.0A ⁰Material from technetium to germanium in the material of scope, for example periodic table is used in combination.

As previously mentioned, the optimum thickness of chosen material depends on density and attenuation coefficient.Usually, the total thickness of filtrator should select to such an extent that to make this thickness be about 0.15 to about 0.45 scope with the multiply each other product that obtains of density under the 50KeV and attenuation coefficient, is preferably in about 0.25 to 0.35.In combination filter, this sum of products of each independent element is in the above in this scope.For the situation of the combination filter of being made up of two independent elements, each independent element preferably should be about 0.075 to about 0.225 scope, especially with better about 0.125 to about 0.175.

In following example, further specify the application of filtrator of the present invention:

Example 1

A niobium filtrator of 50 microns that covers in the plastics is placed in the front of the collimating apparatus of being made up of one 3 phase 6 pulse units, has the total filtration with 3.5 millimeters aluminium equivalences.The dosage that enters is measured with a Victoreen irradiation instrument.There are being and do not having to have taken under the niobium filtrator a series of radiation photos of analysing and observe, in order on the radiation photo, to obtain same light intensity, radiation to the radiation photo after filtering slightly increases by 8 to 10%, because the pettiness of this radiation increases, the dosage decrease is revised.

Table 1 records enters dosage

The KV scope does not have to test and tested % dosage

(KVP) the filter filter reduces

40 .9 milliroentgen/.22 milliroentgen/72%

The mAs mAs

50 2.0 .55 72%

60 3.4 1.21 64%

70 5.0 2.1 58%

80 6.7 3.1 54%

Table 1 be presented at and do not have to obtain under the niobium filtrator enter to have significantly between the dosage measurement value and reduce.Reducing under lower KVP of this dosage is the most remarkable.

Example 2

This experiment is to have under 150KVP and the automatic ray beam restriction device of the inherent filtration effect of 1.5 millimeters aluminium equivalences carries out with a general three-phase electricity generator and one.That radiation detector is used is Red Check Plus, model 06-526.The additional filtration and 2.0 millimeters aluminium equivalent makes the aluminium equivalent of total filtration and 3.5 millimeters.Because most of X-ray examinations carry out under 75 to 100KVP, so generator uses under following setting value: mA-200; Time-.35 second; KVP-80.

Under following condition, carried out the experiment of half numerical value bed thickness and the radiation dose that obtains compared:

A) operate as normal-between source and detector, have only 3.5 millimeters aluminium or equivalent.

B) and a) just the same, additional one 100 microns ytterbium just at the place, source of this scope.

C) and a) just the same, just added 50 microns niobium at the place, source of this scope.

D) and a) just the same, additional 25 microns niobium just at the place, source of this scope.

The additional overtreatment mR % dosage of ruuning situation reduces

Filter effect (comparing) with A

A) normal operation

0 262

1mm 210

2mm 176

3mm 148

4mm 124

5mm 107

Half numerical value bed thickness=3.7mmAl.

B) to the additional 100 microns ytterbiums of A

0 149 44

1mm 128 39

2mm 112 37

3mm 95 36

4mm 83 33

Half numerical value bed thickness=4.85mmAl.

C) to the additional 50 microns niobiums of A

0 138 48

1mm 118 44

2mm 99 44

3mm 83 44

4mm 72 42

5mm 64 40

Half numerical value bed thickness=4.35mmAl.

D) to the additional 25 microns niobiums of A

0 175 34

1mm 148 30

2mm 125 29

3mm 107 28

4mm 91 27

5mm 79 26

Half numerical value bed thickness=4.25mmAl.

Example 3

With 5cm, 10cm, the water model that 15cm and 20cm are dark is tested.The optical density (O.D) of a classification wedge to provide one can measure is provided in the water.Adopt Siemens Tridoros Optimatic 800 generators to test with 0.6 focal spot size.Test is finished with the digital dosimeter of Keithly35055 under 115cmFFD.Half the numerical value bed thickness of HVL(that under 80KV, records before the test) be 3.8mmAl.Survey outside collimating apparatus 3.8mmAl is added one 50 microns niobium filtrator, its result is as table (seeing the literary composition back).

Example 4

Under the condition that following table shows, clap and got a series of backbone and belly radiation photograph.The dosage measurement value obtains (table is seen the literary composition back) with a Capintec radiation estimator.

Give experienced dept. of radiology expert judgments with the film of obtaining under the niobium filtrator, conclude that the film when not filtering has better sharpness.

Example 5

Test under 70KVP and 10mA with WEBER dental X-ray device having under 50 microns niobium filtrators.Discovery is in order to obtain on an equal basis in illumination and film quality having under the niobium filtrator, and exposure time will be increased to 1.5 to 2 times when having only the aluminium filtrator.When having only the operate as normal of aluminium filtrator, exposure time normally 0.2 to 0.3 second, when having used the niobium filtrator, they are 0.3 to 0.5 second.The dosage reduction is indicated in the following table:

Filtrator exposure time dosage MR % dosage reduces

Al 0.2 116 69%

Nb 0.2 36

Al 0.2 116 50.9%

Nb 0.3 57

Al 0.2 116 37.9%

Nb 0.4 72

Al 0.3 171 66.7%

Nb 0.3 57

Al 0.3 171 57.9%

Nb 0.4 72

Al 0.3 171 50.3%

Nb 0.5 85

Al 0.3 171 30.4%

Nb 0.6 102

So under common operative scenario, 50 microns niobium filtrator causes that patient's irradiation dose descends 30 to 50%.

Though, describe various specific embodiments of the present invention here in detail,, under the situation that does not break away from main idea of the present invention or claims scope, one of skill in the art can make various modification to it.

Example 3 tables

The additional filter radiation tube voltage dosage % dosage of model reduces

5cm 10 mAs 63KV 28.4mR

5cm 0.05mmNb 10mAs 63KV 10.2mR 64%

5cm 0.05mmNb 12mAs 63KV 16mR 44%

5cm 4mmAl 10mAs 63KV 10.2mR 64%

10cm 20mAs 77KV 94mR

10cm 0.05mmNb 20mAs 77KV 50mR 47%

10cm 0.05mmNb 25mAs 77KV 73mR 22%

10cm 3mmAl 20mAs 77KV 51mR 46%

15cm 32mAs 96KV 283mR

15cm 0.05mmNb 32mAs 96KV 170mR 40%

15cm 0.05mmNb 40mAs 96KV 215mR 24%

15cm 3mmAl 50mAs 96KV 172mR 39%

20cm 50mAs 117KV 715mR

20cm 0.05mmNb 50mAs 117KV 453mR 37%

20cm 0.05mmNb 64mAs 117KV 569mR 20%

20cm 3mmAl 50mAs 117KV 460mR 36%

Example 4 tables

The not filtering dosage filtration post dose % dosage minimizing of project FFD KVP mA time

Crest bone 40 70 100 .1 31 7 78

Spinal column bone 40 90 300 .2 556 264 54

Full spine 72 90 300 .2 110 50 55

Belly 72 90 100 .2 110 50 55

Claims

1, a kind of X-ray apparatus that is used for medical science or dental diagnosis comprises an x-ray source, and it can be worked under the crest voltage between 55KeV and the about 110KeV, in order to to stand from the irradiation of the X-ray beam of this x-ray source checked object research,

This radiographic source comprises an X ray generation device, and it has: a hole is passed through for X ray speed,

One focalizer in order to the X-ray beam from the X ray generation device is focused on and a filtrator, positively is being fixed to directly over the hole on the said X ray generation device,

The invention is characterized in:

Said filtrator has the flexible configuration of a light weight, comprise a key component element as filter material, this key component element is chosen from aluminium and atomic weight are 26 to 50 element, and a filter material supports, and comprises a seal casinghousing around said filter material.

2, X-ray apparatus as claimed in claim 1, it is characterized in that: said filtrator comprises fixed mechanism, in order to said filtrator directly is fixed to said hole directly over said X ray generation device on, described fixed mechanism comprises the double-back tape between described filtrator and described X ray generation device.

3, a kind of filtrator that is used for the X-ray apparatus that existing medical science or dental diagnosis use, this X-ray apparatus comprises-x-ray source, it can be worked to the crest voltage of about 110KeV at about 55KeV, in order to be checked object research from the irradiation of this radiogenic X-ray beam to standing, an X-ray beam focalizer that invests this x-ray source

Said filtrator is characterised in that:

Has a flexible configuration, supporting institute by a filter material and a flexible filter modulator material constitutes, said filter material comprises a kind of key component element of being chosen in the element set between 26 and 50 by aluminium and atomic weight, and said flexible filter modulator material supports and to comprise said filter material is enclosed in a flexible housing wherein.

4, filtrator as claimed in claim 3, it is characterized in that said filter material supports and comprises a transparent plastic housing, said filter material is enclosed in this housing, and the recognition device of plastic casing inside, in order to discern the characteristic of the filter material that is adopted in the said filtrator.

5, filtrator as claimed in claim 3 is characterized in that, said filtrator comprises a stationary installation, in order to said filtrator directly is fixed on the said x-ray source.

6, filtrator as claimed in claim 5 is characterized in that, said stationary installation comprises the double-back tape in the outside of the described plastic casing that is arranged at described filter material support.