X-ray or gamma ray systems or devices – Accessory – Alignment
Reexamination Certificate
2000-05-19
2002-04-30
Porta, David P. (Department: 2882)
X-ray or gamma ray systems or devices
Accessory
Alignment
C378S196000, C318S466000, C318S626000
Reexamination Certificate
active
06379042
ABSTRACT:
BACKGROUND OF THE INVENTION
The preferred embodiments of the present invention generally relates to improvements in a medical X-Ray imaging system, and more particularly relates to an improved positioning control for positioning an imaging X-Ray tube.
FIG. 1
illustrates an exemplary medical X-Ray imaging system
100
. The imaging system
100
includes a X-Ray tube
110
, a collimator
120
, a table detector
130
, an X-Ray table
140
, a patient
150
, and a clinical operator
160
. In operation, a patient
150
to be imaged is placed upon the X-Ray table
140
as shown. A clinical operator
160
, such as a radiologist or technologist, then positions the X-Ray tube
110
and collimator
120
at one of several pre-determined positions relative to the patient. Once the clinical operator has positioned the collimator
120
at the desired position, the X-ray tube
110
is energized and emits X-Rays. The X-Rays pass through the collimator
120
which directs the X-Rays through the patient to the table detector
130
. The energy of the X-Rays passing through the patient is attenuated by the anatomical features of the patient
150
. The table detector
130
detects the energy of the X-Rays and develops an image of the anatomical features of the patient
150
.
The X-Ray tube
110
and collimator
120
are typically fixed together to form an X-Ray assembly and are typically able to move in three dimensions relative to the X-Ray table
140
. That is, the collimator
120
may be moved upward or downward along the patient's
150
body, right to left across the patient's
150
body, and closer to or farther from the patient's
150
body in any of several fixed positions called detents. Each of the several fixed positions or detents may correspond to different X-Ray exposure and imaging parameters that have been predetermined in order to produce the clearest possible images of the patient
150
. For example, placing the collimator
120
farther from the patient may result in a different parameter for dynamic range of energy of the X-Rays received by the detector
130
.
Typically, imaging parameters are calibrated only for the several predetermined fixed positions, and not continually throughout the path of movement of the collimator
120
. That is, the imaging parameters are typically configured for only a single, specific position, and may change rapidly as the collimator is moved. Thus, precise positioning of the collimator
120
helps provide clearer, more clinically relevant images of the patient
150
.
Referring to
FIG. 1
, typically, an medical X-Ray imaging system may employ and configure detents to identify the several fixed imaging positions for radiographic examinations. As the collimator
120
is moved to one of several fixed imaging positions, a detent is engaged which holds the collimator
120
in the desired position while imaging takes place. Detents may be mechanical or electrical, however, detents employing electromagnetic locks and a position reference triggering device may preferably be employed because of, for example, better wear properties.
Positioning errors as small as a millimeter may significantly reduce the quality of the resulting image. For example, anatomical cutoff may occur due to misalignment or misregistration of the beam with respect to the detector. Improving positioning control of the X-Ray tube also aids in the repeatability of X-Ray images which may be of great importance in comparing X-Ray images taken at time intervals during a patient's treatment. Thus, a need exists for an improved X-Ray tube and collimator positioning system for a medical imaging system.
BRIEF SUMMARY OF THE INVENTION
The preferred embodiments of the present invention provide a system for reducing positioning errors of an X-Ray tube in an X-Ray imaging device. The system facilitates the accurate and repeatable positioning of the X-Ray tube at detents. A preferred embodiment of the present invention preferably includes a sensor unit generating positional or velocity signals indicative of the position or velocity of the X-Ray tube and a microprocessor receiving the positional signals and determining an overshoot correction. The overshoot correction is then used by the X-Ray system to control a locking system controlling the position of the X-Ray tube. The sensor unit may employ a potentiometer, a digital encoder, or preferably both in combination to determine the positional or velocity signals.
REFERENCES:
patent: 4188540 (1980-02-01), Reiniger
patent: 6025685 (2000-02-01), Paradayan
Hammel Mark Anthony
Polkus Vincent S.
Zhang John Jun
Dellapenna Michael A.
GE Medical Systems Global Technology Company LLC
McAndrews Held & Malloy Ltd.
Vogel Peter J.
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