X-ray or gamma ray systems or devices – Electronic circuit – With switching means
Reexamination Certificate
2002-03-04
2004-09-21
Glick, Edward J. (Department: 2882)
X-ray or gamma ray systems or devices
Electronic circuit
With switching means
C378S095000
Reexamination Certificate
active
06795526
ABSTRACT:
BACKGROUND OF INVENTION
The present invention relates generally to x-ray imaging systems and more particularly, to exposure management in an x-ray imaging system.
Traditionally, in x-ray imaging systems, exposure management is handled by an automatic exposure control subsystem. These subsystems typically utilize a small number of predefined, fixed sensor areas that terminate the exposure when a predefined limit has been reached. The sensors areas are x-ray sensitive and usually include an ion chamber. The automatic exposure control subsystem requires dedicated hardware and calibration that is costly and difficult to maintain.
A further disadvantage of these subsystems with fixed sensors is that minimal, if any, adjustments can be made for various patient sizes, anatomical views/orientations, pathologies, or system geometries. Consequently, an optimal exposure level is not always reached, especially in cases where patient characteristics are atypical. The patient must be positioned such that the anatomy of interest is superimposed on the ion-chamber location. This is sometimes difficult and can lead to variable exposures from patient to patient and from exposure to exposure. While some portions of the image may be properly exposed, other portions are improperly exposed with some regions underexposed and other regions overexposed.
Improperly exposed images require a retake of the x-ray, which results in increased radiation dose to a patient, increased patient discomfort, increased cost to the hospital, and decreased hospital productivity.
SUMMARY OF INVENTION
It is therefore one object of the invention to predict the appropriate exposure technique parameters for an x-ray image. It is another object of the present invention to predict optimal exposure technique parameters for an x-ray image. It is still a further object of the present invention to use a low-dose preshot image and virtual ion chambers to select and control the diagnostic exposure to be imaged in a subsequent shot.
In one aspect of the invention, an automatic exposure control mechanism is provided that uses a low-dose preshot image and virtual ion chambers to select and control the diagnostic exposure to be imaged in a second shot directed to an identified region of interest. The virtual ion chambers can be configured for various patient sizes, anatomical views/orientations, pathologies, and system geometries.
According to the present invention, a virtual ion chamber or soft sensor area is defined by an overlay having divisions therein whereby all, or part, of the overlay can be selected to define a region of interest in a digital x-ray image. The region of interest may be defined by any configuration, or combination, of shapes and sizes within a given x-ray image. In one embodiment of the present invention, the region of interest is defined using a matrix of N×M simple geometric shapes.
Other objects and advantages of the present invention will become apparent upon the following detailed description and appended claims, and upon reference to the accompanying drawings.
REFERENCES:
patent: 5164583 (1992-11-01), Aichinger et al.
patent: 5574764 (1996-11-01), Granfors et al.
patent: 6047042 (2000-04-01), Khutoryansky et al.
patent: 6118892 (2000-09-01), Williams
patent: 6233473 (2001-05-01), Shepherd et al.
patent: 6325537 (2001-12-01), Watanabe
patent: 6459765 (2002-10-01), Ganin et al.
Kump Kenneth S.
Nicolas Francois S.
Unger Christopher D.
Walker Matthew J.
GE Medical Systems Global Technology Co. LLC
Glick Edward J.
Song Hoon
Vogel Peter J.
LandOfFree
Automatic exposure control for a digital image acquisition... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Automatic exposure control for a digital image acquisition..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Automatic exposure control for a digital image acquisition... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3219700