Dual energy approach by spatially different x-ray spectra
Original Publication Date: 2002-Sep-01
Included in the Prior Art Database: 2003-Jul-23
Idea: Dr. Bernhard Sandkamp, Forchheim; Mathias Hoernig, Forchheim; Dr. Burkhard Groh, Forchheim; Dr. Volker Heer, Forchheim Conventional x-ray systems consist of x-ray source, collimators and the x-ray detector: The object of interest is interposed in the x-ray beam between source and detector. Dual energy is a well known technique to enhance the contrast of the object of interest. This is typically done by exposing two images with different x-ray spectra. Processing those images allows to enhance either bone or tissue contrast.
Dual energy approach by spatiallydifferent x-ray spectra
Idea: Dr. Bernhard Sandkamp, Forchheim;Mathias Hoernig, Forchheim;Dr. Burkhard Groh, Forchheim;Dr. Volker Heer, Forchheim
Conventional x-ray systems consist of x-ray source,collimators and� the� x-ray� detector:� The� object� ofinterest� is� interposed� in� the� x-ray beam betweensource and detector. Dual energy is a well knowntechnique to enhance the� contrast� of� the� object� ofinterest. This is� typically� done� by� exposing� twoimages with different x-ray spectra. Processing thoseimages� allows� to� enhance� either bone or tissuecontrast.
With the current technology it is necessary to exposetwo� images.� Therefore� a� certain� time� interval bet-ween the two exposures is unavoidable, resulting inpossible artefacts due to motion of the patient.
The� proposed� solution� consists� of� a� system usingspatially different x-ray spectra.
For instance in� a� pixelized� detector� without� anyobject in the x-ray beam the pixel P(i,j) is exposedwith the same beam quality BQa as the pixel P(i, j+1)and P(i, j+3) are exposed with the same beam qualityBQb etc. Therefore one can consider the single expo-sure as two different images, one exposed with beamquality BQa and� the� other� one� with� beam � qualityBQb. In this� example� the� odd� lines� represent� oneimage and the even lines the other one. The missingpixels in the� two� images� could� be� interpolated� toobtain two images having the same resolution and nospatial shift between them. Now, the images can beprocessed as two separate images exposed with twodifferent x-ray spectra and an ordinary dual energyapproach is possible.
A) A mask consisting of a support with a structure offiltering material (for instance copper) on the top isbrought in� direct� contact� with� the� detector.� Thisinfluences spatially the spectrum the detector "sees"(see example A).
B) A mask consisting of a single material but withlocally� different� thicknes...