GB2280758A

GB2280758A - Method of identification in radiography and a cassette therefor

Info

Publication number: GB2280758A
Application number: GB9415608A
Authority: GB
Inventors: Rene Auguste Leon Guillet
Original assignee: Eastman Kodak Co
Current assignee: Eastman Kodak Co
Priority date: 1993-08-05
Filing date: 1994-08-02
Publication date: 1995-02-08
Anticipated expiration: 2014-08-02
Also published as: FR2708755B1; FR2708755A1; DE4427595A1; GB2280758B; GB9415608D0

Description

2280758 METHOD OF IDENTIFICATION IN RADIOGRAPHY AND A CASSETTE FOR IMPT

NTING THIS METHOD The present invention relates to a method and device for identifying radiographic plates'and particularly those used in mammography.

There are two types of system for marking radiographic plates, one using cassettes without a film window and the other using cassettes with a marking window covered with a retractable shutter.

When the cassettes have no window, the marking may be carried out either using complex devices involving irradiation with X-rays with appropriate layers (metallic screens or letters), which enable given information to be transferred automatically onto the radiographic film using local exposure, or in a dark room. In this latter method, the cassette containing the film to be identified is opened and the film is extracted and placed in a film marker. The film marker may be of any known type, for example the one sold under thename "Varay" or "Plastilix" by the companies Ondes et Rayons (Saint-Germain-en-Laye, FRANCE) and Plastilix (Hodent, FRANCE) respectively. The use of a marker enables the radiographic film to be exposed through a transparent mask bearing opaque information or vice versa.

Where the cassettes have a film window, the cassette is inserted into-an identification camera, for example the camera KODAK X-OMATIC Model 2 LR which moves the shutter in such a way as to leave the window clear and projects the identification information. This information can be printed, typed or handwritten on an appropriate medium, for example cardboard, paper or tracing paper. The film windows on the cassettes which are available on the market have relatively small dimensions, generally 75 mm x 15 mm.

once the radiographic film has been marked, the cassette is inserted, in daylight, into an automatic loading and unloading machine, generally referred to as a multiloader.

In mammography, the plates used have a format of approximately 18 cm x 24 cm, but the image of the breast does not cover the whole of the plate and leaves an unused area of about 3 cm in width over the entire length of the plate. Certain markers of the "Varay" or "Plastilix" type use the whole of this part of the plate to enter thereon the identification information not only for the patient but also for the medical practice, such as the address, telephone number and name of the doctor. With cassettes without a film window, this operation is carried out in a dark room.

When cassettes with windows are used, the dimensions of the latter are insufficient to enable all the desirable details to be-entered, and the name of the medical practice, its address and telephone number and the names of the doctor or doctors are not entered, at least not in a way which is clearly legible.

The aim of the invention is to enable easy marking to be obtained, on the whole length of the radiographic plate, of repetitive, non-modified information for cassettes with windows, which will enable the surface of the window of limited dimensions to be reserved for the identification of the patient.

US-A-3 631 243 describes another type of marking which can be used in radiography. The cassette has a slot which is impervious to light and which enables a semi-rigid strip of phosphorescent material to be inserted in contact with the photosensitive film. This strip is covered with a 4 mask bearing the information and has been activated just before being inserted into the cassette. US-A-5 189 689 describes the transfer of information relating to the orientation of the negative onto the photosensitive film. This technique, similar to the one indicated as being known in US-A-3 631 243 (column 1, lines 48 to 60) uses the light coming from the intensifier screens during exposure to X-rays to illuminate a mask which 10 modulates the beam with a view to transferring the information from the mask onto the photosensitive film. However, as indicated in the document US-A-3 621 243, the main difficulty with this technique lies in the fact that irradiation by X-rays 15 varies according to the anatomical object to be radiographed and frequently causes underexposure or over- exposure. In addition, no information is provided concerning the type of intensifier screen used and two different masks are needed, one on each 20 screen. In accordance with one aspect of the present invention, there is provided a method of applying a desired marking using X-ray energy.to a photosensitive film disposed inside a cassette for radiography, the 25 cassette comprising a first part for receiving the photosensitive film therein, a second part attached to the first part, and at least one intensifier screen for transforming incident X-ray energy into radiation for recording on the photosensitive film, the method 30 comprising the steps of:disposing a further intensifier screen in the cassette between the incident X-ray energy and the photosensitive film, the further screen facing a limited portion of the photosensitive film and having 35 an efficacy of transformation of incident X-ray energy which is notably greater than the efficacy of the at least one intensifier screen; masking the further intensifier screen to modulate the radiation emitted therefrom in acbordance with the desired marking; and applying X-ray energy to the cassette to effect the desired marking.

In accordance with a second aspect of the present invention, there is provided a cassette for mammography comprising:- a first portion which is oriented towards Xray apparatus during use; photosensitive film located in the first portion on which the mammogram is to be recorded; a second portion connected to the first portion; an intensifier screen located within the second portion, the intensifier screen being operable to transform incident X-ray energy into radiation for recording on the photosensitive film; a further intensifier screen disposed inside the first portion between the incident X-ray energy and the photosensitive film and covering only a limited part of the photosensitive film, the further intensifier screen having an efficacy of transformation of incident X-ray energy which is notably greater than the efficacy of the intensifier screen; and masking means for the further intensifier screen for modulating the radiation emitted therefrom in accordance with a desired marking, the masking means being positioned between the further intensifier screen and the photosensitive film.

Q' In accordance with a third aspect of the present invention, there is provided a cassette for radiography comprising:- first portion having an intensifiet screen therein; second portion connected to the first portion and having an intensifier screen therein; photosensitive film located between the intensifier screens of the first portion and the second portion, each intensifier screen being operable for transforming incident X-ray energy into radiation for recording on the photosensitive film; a further intensifier screen disposed inside the first portion between the incident X-ray energy and the photosensitive film and covering only a limited part of the photosensitive film, the further intensifier screen having an efficacy of transformation of incident X-ray energy which is notably greater than the efficacy of the intensifier screens; and masking means for the further intensifier screen for modulating the radiation emitted therefrom in accordance with a desired marking, the masking means being positioned between the further intensifier screen and the photosensitive film.

In accordance with a fourth aspect of the present invention, there is provided a marking device for radiography comprising:- support which is transparent to X-ray energy; high-efficiency intensifier screen attached to the support, the screen being operable for transforming incident X-ray energy into radiation for recording on photosensitive film to be used in radiography; masking means for the intensifier screen which modulates the radiation in accordance with a desired marking.

Various embodiments of the invention qill now be described by way of example only, with reference to the accompanying drawings in which:Figure 1 shows diagrammatically a cassette for mammography according to the present invention; Figure 2 shows another embodiment of a cassette according to the present invention intended to receive a radiographic film; Figure 3 shows a partial cross section along the line III-III in Figure 2; Figure 4 shows, in perspective, a marking device enabling the invention to be implemented.

In radiography as in mammography, the radiographic films used for recording are disposed in cassettes. In radiography the films have an emulsion surface on both sides of the support and the cassettes are provided with two intensifier screens situated on both sides of the photosensitive sheet or film. In mammography, in order to obtain a better definition, the photosensitive films have a single emulsion surface and a single intensifier screen fungtioning by "reflection" is used.

As shown in Figures 1 and 2, a cassette in accordance with the present invention consists of two parts 10 and 14, connected together by any appropriate means such as, for example, a hinge 12 or any other appropriate means. Part 10 comprises a flat wall portion 34 having a lateral wall portion 20 disposed at its periphery and which is perpendicular thereto. Similarly, part 14 has a flat wall portion 32 and a lateral wall portion 18. The lateral wall portions 18, 20 cooperate together so as to define, with their associated flat wall portions 32, 34, an enclosed space which is impervious to light. The two parts 10 and 14 are maintained in this closed position for use by means of catches 22.

One of the parts 10 is equipped with a pressure device 24 usually consisting of a layer of foam and a screen 26 (one part of which has been lifted up for better comprehension) enabling the X-ray flux received by the screen to be transformed into radiation of a different wavelength able to be recorded by the photosensitive film.

In mammography, the flat wall portion 32 of the cassette is directed towards the X-ray tube, as shown by arrow 1XI in Figures 1 and 2, and has a minimal thickness so that it is easy for the X-rays to pass through it. This enables the amount of X-rays irradiating the breast to be radiographed to be limited to the greatest possible extent.

According to the invention there is disposed in the part 14 of the cassette, which is directed towards the X-ray tube during use, another screen 30 made of high-efficiency phosphorescent material enabling-the excitation X-rays to be transformed into radiation, the energy of which is suited to. the photosensitive film inserted into the cassette. The other screen 30 has a reduced width compared with the width of the photosensitive film, its surface area corresponding to the region intended for marking.

In the cassette shown in Figure 1, screen 30 is covered with a mask 40 bearing information 36, 38 which is opaque to the light emitted by the intensifier screen 30 so as to modulate the flux coming from screen 26 in part 10.

The information carried by the mask 40 advantageously concerns general information such as the name of the medical practice, its address and telephone number and the names of the doctor or doctors working in the medical practice.

In addition, the mask 40 has an opaqde region 38 adapted so as to avoid exposure of the region corresponding to cassette marking window 100 and thus to permit subsequent recording, on an identification camera, of the name of the patient, her date of birth and the date of the examination.

In cassettes with a marking window 100 for identification by a camera of the type KODAK X-OMATIC Model 2 LR, the first intensifier screen 26 is cut out so as not to cover this region and the light flux coming from the intensifier screen 30 can be eliminated either by a mask 40 (Figure 1) or by a cutout 48 (Figure 2) in the other intensifier screen 30; the latter solution is made possible only by the absence of the first intensifier screen covering practically all the photosensitive surface.

According to the invention the choice of intensifier screen 30 is important. This is because the screen 30 must be situated, when the cassette is used, on the X-ray tube side so as to transform the maximum amount of energy of the X-rays in order to prevent the region on the first screen 26 which is situated opposite screen 30 from masking excessively the information provided by the unit consisting of the screen30 and mask 40.

In the preferred embodiment according to the invention for a cassette for mammography, the screen 26 covering almost the entire photosensitive film is a KODAK Min-R or Min-R Medium screen which enables very high definition to be obtained for mammography and the other intensifier screen 30 is a KODAK Lanex Fast Back screen. It is obvious that such a combination of screens enables maximum contrast to be obtained between the information from the mask 40 registered on the photosensitive film through the backing andthe parts of this film irradiated by the KODAK Min-R screen.

It is obvious that other combinations of screens produce a less heightened contrast but one which affords easy reading.

The KODAK Lanex Fast Back screen can be replaced, for example, by fast screens of similar or slightly lower sensitivity such as KODAK Lanex Regular, Agfa Orthoregular, Fuji Kyokko G12, GX1 or GH1, Konica KR, Dupont Quanta V, 3M Trimax 16 or Trimax 12 screens. In the same way, the KODAK Min-R or Min-R Medium screens can be replaced by other types of relatively slow screens such as for example Agfa MR Detail, Fuji HR Fine, 3M Trimax 2 or Dupont Ortho Micro. It is obvious that other combinations are possible.

Another embodiment that can be envisaged concerns cassettes with two screens which can be used in radiography as shown in Figure 2. It is obvious that this type of identification will introduce constraints in the use of the cassettes according to the invention; these cassettes must always present the same face to the X- ray tube. In order to do this, the part of the cassette directed towards the X-ray tube during use is provided with a two-part screen 30, 50 as shown in Figure 3.

Screen 50 serves to form the image in the usual way and screen 30 being notably more efficacious at transforming the X-ray excitation energy into light energy than the intensifier screen 26 disposed opposite and separated from it by the photosensitive -10 film. In addition the X-ray flux must be absorbed by screen 26 to a relatively significant extent.

In another embodiment shown diagrammatically in Figure 4, the invention is implemented by me&ns of a marking device 110 independent of the cassette. The device 110 consists essentially of a semi-rigid support 120 to which a screen 30 made of highefficiency phosphorescent material is fixed, enabling the excitation radiation to be transformed into light radiation, the energy of which is suited to the photosensitive film used.

The support 120 advantageously has the same dimensions as the photosensitive films used. In this case the screen 30 covers only part of this support and on the other part is disposed a shim 130 with the same thickness as the screen 30. The material forming the shim 130 must be transparent to the excitation Xrays. The material forming the support 120 must be not only transparent to the excitation X-rays but also to the light radiation coming from the screen 30.

Obviously the marking device 110 is equipped with the means 40 which is opaque to the light radiation emitted by the screen 30. This opaque means 40 can be carried by the support 120 or can be interposed between the support 120 and the screen 30. In the latter case the thickness of the shim 130 will make it possible to compensate not only for the thickness of the screen but also for the thickness of the opaque means 40.

In a preferred embodiment of the marking device the means which is opaque to light radiation i formed by a photographic emulsion deposited on the support, exposed and developed so as to provide an image opaque to the light radiation emitted by the intensifier screen 30.

When used, the marking device 110 is disposed in the part of the cassette which will be directed towards the x-ray tube so as to present its corresponding surface to the support 120 which'is in contact with the photosensitive sheet.

Claims

CLAIMS:

1. A method of applying a desired marking using X-ray energy to a photosensitive film disposed inside a cassette for radiography, the cassettthcomprising a first part for receiving the photosensitive film therein, a second part attached to the first part, and at least one intensifier screen for transforming incident X-ray energy into radiation for recording on the photosensitive film, the method comprising the steps of:- disposing a further intensifier screen in the cassette between the incident X-ray energy and the photosensitive film, the further screen facing a limited portion of the photosensitive film and having an efficacy of transformation of incident X-ray energy which is notably greater than the efficacy of the at least one intensifier screen; masking the further intensifier screen to modulate the radiation emitted therefrom in accordance with the desired marking; and applying X-ray energy to the cassette to effect the desired marking.

2. A method according to claim 1, wherein the applied X-ray energy has a level which activates the further intensifier screen without notably activating the at least one intensifier screen.

3. A cassette for mammography comprising:a first portion which is oriented towards Xray apparatus-during use; 30 photosensitive film located in the first portion on which the mammogram is to be recorded; a second portion connected to the first portion; an intensifier screen located within the second portion, the intensifier screen being operable to transform incident X-ray energy into radiation for recording on the photosensitive film; a further intensifier screen disposed inside the first portion between the incident X-ray efiergy and the photosensitive film and covering only a limited part of the photosensitive film, the further intensifier screen having an efficacy of transformation of incident X-ray energy which is notably greater than the efficacy of the intensifier screen; and masking means for the further intensifier screen for modulating the radiation emitted therefrom in accordance with a desired marking, the masking means being positioned between the further intensifier screen and the photosensitive film.

4. A cassette for radiography comprising:a first portion having an intensifier screen therein; a second portion connected to the first portion and having-an intensifier screen therein; photosensitive film located between the intensifier screens of the first portion and the second portion, each intensifier screen being operable for transforming incident X-ray energy into radiation for recording on the photosensitive film; a further intensifier screen disposed inside the first portion between the incident X-ray energy and the photosensitive film and covering only a limited part of the photosensitive film, the further intensifier screen having an efficacy of transformation of incident X-ray energy which is notably greater than the efficacy of the intensifier screens; and masking means for the further intensifier screen for modulating the radiation emitted therefrom 14- in accordance with a desired marking, the masking means being positioned between the further intensifier screen and the photosensitive film.

5. A cassette according to claim 3'or 4, wherein the further intensifier screen absorbs an appreciable part of the incident X-ray energy so that only moderate activation of the intensifier screen remote from the incident X-ray energy and covered by the further intensifier screen is obtained.

6. A cassette according to any one of claims 3 to 5, wherein the second portion of the cassette has a film. window provided therein with a shutter therefor, the shutter, when open, allowing identification of the photographic film by way of a further known marker.

7. A cassette according to any one of claims 3 to 6, wherein the further intensifier screen is a significantly faster screen than the intensifier screen.

8. comprising:- A marking device for radiography a support which is transparent to X-ray energy; a high-efficiency intensifier screen attached to the support, the screen being operable for transforming incident X-ray energy into radiation for recording on photosensitive film to be used in radiography; masking means for the intensifier screen which modulates the radiation in accordance with a desired marking.

9. A device according to claim 8, wherein the high-efficiency intensifier screen is a relatively fast screen.