X-ray or gamma ray systems or devices – Electronic circuit – For plural x-ray sources
Reexamination Certificate
1999-04-15
2001-05-15
Kim, Robert H. (Department: 2882)
X-ray or gamma ray systems or devices
Electronic circuit
For plural x-ray sources
C378S162000
Reexamination Certificate
active
06233309
ABSTRACT:
TECHNICAL DOMAIN
This invention relates to a system for recording information on a medium sensitive to X-rays. Applications of the invention are particularly in the medical fields of radiology and tomography, to add information such as data about the patient, information about conditions under which the radiology examination is carried out, or radiography instrument identification numbers, onto the radiographs of patients. The invention may also be used in other fields of application such as X-ray grating spectrography and fluorescence, for example to add data concerning the samples being treated to the records.
STATE OF PRIOR ART
Archiving and analysis of X-ray media, and particularly radiology films, is made very much easier if the film is accompanied by a certain number of data, for example such as the patient's name. These data may be entered on a label which can be glued onto the film, or may be written on the film directly by means of special inks developed with the film. Very simple data can also be recorded on the film using a code based on small perforations made in the film.
However, manipulating labels or film can be the source of human errors. Labels could be glued on a film to which they do not correspond, and text written on the film directly using special inks could become illegible if the film is overexposed.
Thus, techniques have been developed for recording information directly on the film, to avoid analysis or archiving errors. These techniques are described below.
Radiography films usually used for medical applications are films sensitive to visible light and are placed in an envelope of a luminescent material capable of converting X-radiation into visible radiation. This material can also make the film sensitive to X-rays in order to record radiographic images of patients.
To facilitate its manipulation, the film is placed inside an envelope opaque to visible light but transparent to X-rays.
There are several known techniques for adding patient identification information to the sensitive film.
According to a first technique, the film envelope is opened in safe light (in a dark room) and the film is placed under a device which will print on the undeveloped film and add information. Information is marked on the film by illuminating part of this film with visible light that passes through a label containing the information to be recorded.
One of the main difficulties when using this type of device is to avoid concealing the complementary part of the film on which the radiographic record has been or will be received.
Consequently, the film envelope may be a cassette containing a system of removable optical caches. These caches may be moved to expose a window so that only a portion of the film is illuminated, when transferring information.
According to a second technique, the information may be transferred onto the film by exposing it to a very fine light beam from a laser. This laser is moved parallel to the film surface to write characters or codes on the film. This operation is also carried out in a dark room, or by using a specially adapted opaque cassette.
According to one variant, the recording on the undeveloped film may also be made by applying an illuminated liquid crystal display (LCD) screen, or a vacuum fluorescent display (VFD) screen, to it.
In all these applications, it is observed that it is important to very carefully isolate the part of the film that will receive information from the part of the film that will receive the radiographic image. Light produced by information recording equipment and particularly ambient light can “pollute” or conceal all or part of the film.
According to a third technique, transfer elements in the form of letters and containing a material absorbing X-rays are used to write information on the film. Transfer elements are placed on the film envelope (opaque to visible light) and are subjected to X-radiation. This radiation may originate from the X-ray tube used for the radiography of the patient or another type of secondary X-ray tube.
In this case also, the transfer elements are used with a system of removable caches.
Document EP-A-0 238 464 also illustrates other processes using similar techniques for marking films sensitive to X-rays.
There are implementation difficulties with all the techniques mentioned above, related particularly to the need to optically isolate the part of the film on which the information will be received.
Parasite reflections of visible or infrared light could disturb the radiographic image on the film.
Furthermore, the processes described above are only suitable for simple reproduction of alphabetic or numeric characters, but cannot be used for the fine reproduction of various shades of gray. Therefore these processes are not suitable for transferring other information such as images or personalized icons onto the film.
DESCRIPTION OF THE INVENTION
The purpose of this invention is to propose a system for recording information on a sensitive medium that does not have the difficulties or limitations mentioned above.
One particular purpose of the invention is to propose such a system for recording information on a film without disturbing the radiographic image already recorded on the film, or that will be recorded later.
Another purpose is to be able to directly record data previously input to the computer, or stored on the computer, onto the film.
Another purpose of the invention is to record images or logos displayed in different shades of gray.
Finally, another purpose is to provide a device capable of guaranteeing good contrast of information marked on the film.
In order to achieve these purposes, the purpose of the invention is more precisely a system for recording information on a medium sensitive to X-rays, comprising a set of adjacent X-ray sources and selective source control means, to print a selected pattern on the said sensitive medium.
Sources are controlled concomitantly or sequentially to selectively provoke or not provoke emission of X-rays by each source. The intensity or the X-ray dose output by each source can also be varied to obtain different printing levels on the medium. These levels correspond to shades of gray in the case of a radiographic film.
According to a particular embodiment of the system, the system may comprise a single dimensional or a two-dimensional network of point X-ray sources.
A point source is a source that emits on a very small surface on an image, that can be treated like a point. A network of point sources can thus be used to reproduce a text or an image by placing points or image elements called pixels adjacent to each other.
For example, X-ray sources may be made in the form of microtip sources. These sources can form miniaturized inscription matrices with a large number of sources.
This type of matrix can be used to reproduce images with a good resolution and a large number of pixels.
More precisely, each X-ray source may comprise at least one source of electrons with microtips. Electron sources are associated with one or several anodes capable of emitting X-rays in response to electron impacts.
Each electron source may be associated with a particular anode. However, a set of sources may also share a common anode.
According to a first means of polarizing X-ray sources, the anode may be connected to a ground potential and control means may comprise switches associated with electron sources to selectively connect the microtips from the selected electron sources to a high negative voltage, and/or to power supplies designed to generate electron beams.
According to this polarization method, the switches are at a high voltage.
Control means may also comprise a control unit such as a computer to control the switches and/or power supplies.
The switches and/or power supplies may be connected to the computer through a galvanic isolation device in order to make it impossible for the computer to be at the same potential as the switches and/or power supplies.
According to another polarization option, the anode may be connected to a high positive voltage
Burns Doane , Swecker, Mathis LLP
Commissariat A l'Energie Atomique
Kiknadze Irakli
Kim Robert H.
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