Method and apparatus for adaptive exposure in x-ray systems
Inventors
Funk, Tobias • Burion, Steve Denis • Bechtel, Kate Leeann • Heanue, Joseph Anthony • Wilfley, Brian Patrick • LOWELL, AUGUSTUS PERCIVAL
Assignees
Publication Number
US-8848867-B2
Publication Date
2014-09-30
Expiration Date
2031-11-23
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Abstract
The present invention pertains to an apparatus and method for adaptive exposure in imaging systems. An x-ray source for producing x-ray radiation and an x-ray detector for measuring amount of x-ray radiation passing through the human patient and striking the detector can be used. A tomographic image of the human patient or a tomosynthetic image of the human patient can be generated. Region of interest filtering and equalization filtering can be utilized. Filtering can be accomplished with a mechanical shield or shutter or with electronic control of the x-ray source.
Core Innovation
The invention provides an x-ray imaging system and method for adaptive exposure that utilizes region of interest filtering and equalization filtering to optimize radiation exposure when imaging a human patient. The system uses an x-ray source to produce radiation, an x-ray detector to measure the amount of radiation passing through the patient, and a controller for selecting specific regions of interest within the patient to receive targeted x-ray exposure. Filtering devices, either mechanical (such as shields or shutters) or electronic (via control of the x-ray source), are used to reduce or terminate x-ray exposure to areas outside the region of interest, thereby optimizing patient and personnel dose.
The problem being solved is the risk of excessive exposure to x-ray radiation, which is associated with health risks such as increased probability of cellular damage and cancer, especially during lengthy or multi-frame imaging procedures. Current precautions, such as collimation and shielding, do not adequately tailor the amount of x-ray radiation to the specific patient or particular regions within the patient, resulting in potentially unnecessary exposure for both patients and medical staff. There is a need for imaging systems that can provide high-quality images rapidly while reducing the total radiation dose administered.
The disclosed system enables user or automatic selection of one or more regions of interest within the patient, with exposure parameters such as dwell time, beam current, or exposure quantity being adaptively controlled for these regions. Both real-time and offline implementations can be used. The approach can limit x-ray radiation to specific regions to no more than a required amount, terminate delivery to an area when a predetermined threshold is reached, and adjust exposures per projection or frame. Tomographic and tomosynthetic imaging are supported. Equalization filtration further refines image quality and minimizes dose by adjusting exposures based on local attenuation or signal to noise, using information either from immediate or previous scans.
Claims Coverage
There are two independent claims, each specifying a distinct inventive feature relating to adaptive x-ray exposure based on region of interest selection and limiting x-ray radiation delivered to the detector.
Region of interest-based adaptive x-ray exposure
An x-ray imaging system includes: - An x-ray source for producing x-ray radiation. - An x-ray detector measuring the amount of x-ray radiation passing through a human patient. - A controller for selecting a region of interest in the patient. - A filtering device, coupled to the controller and x-ray source, configured to reduce x-ray radiation to areas outside the selected region of interest. - The filtering device is an x-ray source controller for reducing the amount of x-ray radiation generated by the x-ray source.
Limiting x-ray radiation to detector using a filtering device
An x-ray imaging system includes: - An x-ray source for producing x-ray radiation. - An x-ray detector for measuring the x-ray radiation passing through a human patient and striking the detector. - A filtering device, coupled to the x-ray source, configured to limit the x-ray radiation reaching the detector to a specified amount or less. - The filtering device is an x-ray source controller for reducing the amount of x-ray radiation generated by the x-ray source.
In summary, the inventive features cover adaptive reduction and limitation of x-ray exposure based on selected regions of interest and limiting the total x-ray dose to the detector using a filtering device that electronically controls the x-ray source.
Stated Advantages
The system minimizes the x-ray dose delivered to the patient and reduces exposure to medical personnel.
High-quality images can be produced rapidly while maintaining lower radiation exposure.
Equalization filtration allows for compression of dynamic range and improved image quality by adapting exposure based on local attenuation.
Dose saving is achieved, with examples stating up to 82% primary photon dose reduction using region of interest approaches.
The ability to select regions of interest and adapt exposure reduces unnecessary dose to patient areas and to attending staff.
Documented Applications
Medical x-ray imaging of human patients where rapid, high-quality imaging is needed with reduced radiation exposure (including fluoroscopy and image-guided procedures).
Imaging procedures involving tomographic or tomosynthetic image generation for visualization of internal structures, organs, or surgical implements.
X-ray imaging for procedures that use contrast agents, such as cardiac interventions and blood vessel imaging.
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