X-ray or gamma ray systems or devices – Accessory – Alignment
Reexamination Certificate
2001-03-16
2002-08-27
Porta, David P. (Department: 2882)
X-ray or gamma ray systems or devices
Accessory
Alignment
C378S167000, C378S197000
Reexamination Certificate
active
06439769
ABSTRACT:
BACKGROUND OF INVENTION
The present invention generally relates to a system and method for controlling the position of a radiographic device. More particularly, the present invention relates to a system and method for automatically positioning an image receptor based on the position of a manually positioned diagnostic source assembly in an X-ray imaging device.
Radiographic imaging systems are used for a wide variety of applications in the medical field. One example of a radiographic imaging system used in medicine is an X-ray imaging system. X-ray imaging systems are typically used for diagnostic purposes in the medical field. Typical X-ray imaging systems operate by transmitting X-radiation or X-rays through a patient's body using a diagnostic source assembly (“DSA”). The DSA is typically a device that is capable of transmitting X-rays through the body of a patient. The position of the DSA is typically adjustable and the DSA is generally placed over the area of a patient's body that is being imaged. Once properly positioned, the X-rays transmitted through the patient's body by the DSA are more absorbed by dense structures in the body such as bones, and less absorbed by less dense structures such as tissue and organs. The X-rays passed through the patient's body are then typically received by an image receptor located beneath the patient. Typically, the image receptor is comprised of either an X-ray film or a digital solid state detector.
In order to achieve an X-ray image with sufficient information and contrast to provide a doctor with the diagnostic information needed, precise alignment of the DSA and the receptor often needs to be achieved. Typically, the DSA projects a beam of X-rays toward the image receptor surface and through body structure of the patient being imaged. The area of projected X-rays that is incident on the image receptor defines the active imaging area (AIA). Generally, the X-ray beam field or field of view (FOV), which is the intersection of the projected beam and the image receptor plane, must be coincident with, or lie within, the boundaries of the image receptor surface in order to avoid loss of image data. The FOV may be adjusted by rotating or tilting the DSA to vary the direction of the projected X-ray beam, and also by operating a collimator to vary the width and length dimensions of the X-ray beam. Further adjustments may also be made by linear translation of the DSA or the image receptor.
When the DSA is oriented so that the X-ray beam is directed in perpendicular or orthogonal relationship to the image receptor plane, the image receptor may be located directly below the DSA. However, X-ray technicians or operators may need to angulate the DSA with respect to the image receptor, that is, rotate or pivot the DSA so that the beam is not projected perpendicular to the image receptor. Angulation of the DSA may be desirable, for example, to ensure that the beam passes through a specific body structure of the patient, or to avoid imaging specific structures. As the DSA becomes increasingly angulated, the image receptor typically needs to be positioned at a location offset from the position of the DSA in order to receive the X-rays. Typically, the greater the degree of angulation the DSA is from perpendicular to the image receptor, the greater the offset between the image receptor and the DSA need to be. Therefore, in order to ensure the image receptor receives the X-rays from the DSA, the operator typically needs to precisely position the image receptor so that it is in the X-ray beam's FOV.
In the absence of optimal or appropriate alignment of the DSA and the image receptor, anatomical cutoff may occur during the imaging process. That is, the bodily structures intended to be imaged may not be completely imaged due to the incorrect offset between the DSA and the image receptor. Anatomical cutoff may necessitate that the imaging be repeated, which may increase procedure cycle time, raise examination costs, and expose the patient to higher levels of net radiation.
In typical prior art systems, efforts to attain the precise alignment of the DSA with the image receptor desired for successful imaging has been attempted by one of two methods. The first method typically used to align the DSA and image receptor is through direct alignment. That is, physically attaching the DSA to the image receptor in the desired alignment. The second method typically used to align the DSA and image receptor is through indirect alignment methods. That is, positioning the DSA and the image receptor individually when they are not attached together. Both methods are further described below.
In typical X-ray imaging systems that utilize direct alignment of the DSA and the image receptor, the DSA and the image receptor are physically attached to each other by a rigid structure. The DSA is typically attached in a perpendicular alignment to the image receptor so that the X-ray beam transmitted by the DSA will be transmitted directly into the flat plane of the receptor. In direct alignment systems, the DSA and the image receptor are typically not moveable or able to be repositioned by an operator or X-ray technician. Because of the rigidly fixed positioning of the DSA and the image receptor, X-ray imaging systems that utilize direct alignment may suffer from a number of drawbacks.
One drawback that may occur in direct aligned X-ray imaging systems is lack of flexibility in positioning of the system by the operator. That is, when the position of the system is fixed, the operator may have to adjust the patient's position in order to get an image. During imaging procedures it may be more difficult to adjust the patient to the X-ray system than it is to adjust the X-ray system to the patient. However, in a direct aligned system only limited adjustment of the system is possible. Therefore, if patients are required to hold difficult or uncomfortable positions in order to fit into the X-ray imaging system, bad images may be generated and frequent retakes may be required. Requiring frequent retakes may often be time consuming and may expose the patient to excess radiation. Additionally, with direct aligned X-ray imaging systems, retakes may be further complicated by patient access. That is, once a determination has been reached to retake an image, the patient may have exited the system or may have to be re-scheduled. Also, direct aligned X-ray imaging systems are less desirable because the systems are typically quite complex and costly.
In order to overcome some of the drawbacks related to the rigid inflexibility of direct aligned systems, some prior art X-ray systems have utilized indirect alignment methods. That is, the DSA and the image receptor are not physically attached to each other and may be individually positioned by an operator. Individually positioning the DSA and the image receptor may help give the operator more flexibility and may allow for better patient comfort than direct aligned systems. Typically positioning of the DSA and receptor in indirect aligned systems has been achieved by one of two methods. The first method typically used in indirect alignment systems involves manual positioning of both the DSA and the image receptor by an operator. The second method typically used in indirect alignment systems is motorized positioning of both the DSA and the image receptor.
In typical indirect alignment systems manually positioned, an operator physically positions the DSA and the image receptor by hand. Generally, at first, the DSA may be manually positioned by the operator in a position appropriate for the area of the patient's body being imaged. Next, the patient is typically positioned so that the area of the patient's body to be imaged is comfortably positioned with respect to the DSA. Finally, the image receptor may be manually positioned by the operator in the proper alignment with the DSA. The operator may use a visual light field projected by the DSA on to the patient or receptor to judge where the DSA should be positioned with
Boehm Manfred David
Ni Xianfeng
Polkus Vincent Stanley
Dellapenna Michael A.
GE Medical Systems Global Technology Company LLC
McAndrews Held & Malloy Ltd.
Porta David P.
Vogel Peter J.
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