X-ray or gamma ray systems or devices – Specific application – Mammography
Reexamination Certificate
2002-08-06
2004-05-25
Church, Craig E. (Department: 2882)
X-ray or gamma ray systems or devices
Specific application
Mammography
C378S208000, C128S915000
Reexamination Certificate
active
06741673
ABSTRACT:
FIELD OF THE INVENTION
The present invention pertains in general to the x-ray mammography apparatus and method. It particularly relates to the detector device utilized with conventional and digital mammography x-ray devices in order to improve the accuracy of the reading and diagnosis.
BACKGROUND OF THE INVENTION
As the current medical profession battles to find a cure for breast cancer, x-ray mammography is widely utilized for the screening and diagnosis of breast cancer for millions of women throughout the world. With millions of women diagnosed with breast cancer, the ability to detect and diagnose the incidence of breast cancer as early as possible is absolutely essential. The mistakes or failures in detection end up barring the possibility of early treatment for breast cancer in the most effective manner, requiring expensive and significantly more dangerous surgical and other procedures and even causing death for some patients. In addition, the so-called “false positives” are very prevalent with current mammography devices and systems, which often translates into unnecessary costs (for biopsy tests, etc.) and patient trauma.
Mammography, which usually means the radiological examination of the human breast, is typically performed with x-ray or other film/screen techniques. The film screen x-ray mammography technique involves directing a beam of x-ray through the breast onto a phosphor screen, which converts each x-ray photon into a number of visible photons that expose a sheet of photosensitive film, which is located in a close proximity to the phosphor, thereby forming a latent image of the x-ray pattern. The photographic film is developed to transform the latent image into a visible analog representation of the x-ray pattern.
While still widely used throughout the word, the film-screen mammography technique is known to have some shortcomings and limitations. For example, one shortcoming of conventional x-ray mammography is that the range of contrast of the photosensitive film is limited and fails to display the entire range of contrast in the examined human breast. Because the gray-level of x-ray film has a sigmoidal response as a function of exposure, it causes some difficulties in differentiating the contrast at the extremes of the exposure range (in the most radiodense and radiolucent areas of the photo image), thereby complicating analysis and diagnosis of soft tissue masses in those areas.
A more precise approach to the diagnosis of breast cancer had been proposed with the advent of digital mammography techniques, where the phosphor and film detector is replaced with a digital image detector, which provides a much wider range of contrast than photosensitive film, and where the contrast response is linear over the entire contrast range. This allows the digital detector of the mammography device to differentiate among very subtle variations in attenuation of x-rays as they pass through the soft tissue of human breast.
As shown in
FIG. 1
, a typical mammography apparatus
1
that is commonly used today has an x-ray housing
2
that carries an x-ray arrangement
3
(or an x-ray tube), a subject table 4 and a compression mechanism
5
, with compression plate
8
. A detector cassette
6
, with photosensitive film can be inserted into subject table 4 in the horizontal direction. The housing
2
can be mounted on a rotary arm
7
that is rotatably attached to a movable stand (not shown), allowing the x-ray housing to rotate in order to be able to take x-ray measurements from the side. A more detailed description of a conventional x-ray apparatus is given in the U.S. Pat. No. 6,208,708 and U.S. Pat. No. 5,170,419, the disclosure of which is incorporated herein by reference.
It is also known in the art that a detector cassette itself may serve as a subject table, in which case the compression plate
8
presses the examination subject against the upper surface of the cassette holder when the x-ray beam
9
is emitted by the x-ray tube through the subject breast toward the detector cassette.
One significant shortcoming of the typical x-ray mammography devices that are currently utilized and known in the art, which is common to both the film screen x-ray devices and those that utilize digital detectors, is that the shape of the subject table 4 and the detector cassette
8
(or detector plate in digital mammography devices) is always rectangular. Because the human breast, rib cage below the breast and axillia areas are not linear, when the subject breast is compressed between the subject table and the compression plate and the x-ray beams transmitted, detected and imaged, certain portions
11
or
12
at the far corners of the junction of the breast
10
, as shown in
FIG. 2
are not properly detected and imaged, thereby creating a potential for misdiagnosis or requiring that the diagnostic mammography procedure be repeated, thus, subjecting the individual to additional x-ray exposure and increasing overall cost of mammography procedures in the aggregate. In many cases, the rectangular cassettes (or digital detectors) also fail to properly image the axilla area, and, therefore, fail to detect cancerous growth in that area, putting the patient's life at risk. If a cassette with a concave curved surface, formed by one arc with one radius, is utilized in a mammography cassette, the curved surface of such cassette would not be able to accommodate left and right curvature of human breast and curvature of the rib cage below the breast. Thus such cassette would not allow a complete x-ray reading and detection of all areas of the human breast under examination, particularly at all points of connection with the rib cage wall and the axilla area. Furthermore, one such curvature would not be capable of accommodating variations in shape of a rib cage and each breast in patient, as well as variations between individuals with substantially different physical characteristics. Thus, it is desirable to provide an x-ray mammography diagnostic apparatus and method that optimize the curvature of one or more sides of the subject table in such a way as to allow to take a more accurate reading of the left and right breast of an individual under examination, taking into account the different curvature of the breast and the rib cage on each side.
Therefore, there is a need for a simple and inexpensive solution to this problem that would allow a more accurate reading, detection and subsequent diagnosis of all areas of the human breast, particularly at all points of connection with the rib cage wall and in the axilla area.
It is further desirable to improve the accuracy of existing x-ray mammography devices and medical diagnoses based upon the images produced by such devices by providing a full and complete reading of all areas of the human breast and by avoiding significant technological modifications and replacement of thousands of existing x-ray mammography devices and the methods of their manufacturing.
It would be further desirable to improve the accuracy of existing x-ray mammography devices that use removable detector cassettes with photosensitive film, as well as those that utilize a stationary (and removable) digital detector plate as a subject table.
SUMMARY OF THE INVENTION
Accordingly, it is one object of the present invention to provide an x-ray mammography diagnostic apparatus that utilizes a subject table (which also operates as a detector in digital x-ray devices) with at least one side having a concave curved surface that accommodates curvature of the human breast and curvature of the rib cage below the breast to allow a complete x-ray reading and detection of all areas of the human breast under examination, particularly at all points of connection with the rib cage wall and in the axilla area.
It is another object of the present invention to provide an x-ray mammography diagnostic apparatus that utilizes a subject table with at least one side having a concave curved surface that accommodates curvature of the human breast and curvature of the rib cage below the breast and also accou
Kamenetsky Aleksey
Kamenetsky Mikhail
Pervak Marina
Pesok Aron
Vidgop Yelena
Chadbourne & Parke LLP
Church Craig E.
Yun Jurie
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