A K_α dual energy x‐ray source for coronary angiography

Abstract

The use of characteristic-line radiation from rare-earth targets bombarded by high-energy (up to 1 MeV) electron beams has been evaluated as an x-ray source for dual energy K-edge subtraction imaging of the human coronary arteries. Two characteristic-line x-ray sources, one using the split K alpha 1 and K alpha 2 lines of lanthanum excited by a high-energy electron beam and the other using the K alpha lines of barium and cerium, were studied. A Monte Carlo electron-photon simulation was used to calculate x-ray spectra and energy deposition profiles from targets of these elements bombarded by electrons in the energy range 140 keV to 1 MeV. A general dual-energy imaging model was developed that used these calculated source spectra to numerically investigate the dependence of the subtraction image signal-to-noise ratio on such factors as the ratio of K-line to x-ray continuum yield, continuum spectral shape, x-ray filtering, and detector response. A signal averaging technique for enhancing the signal-to-noise ratio was also evaluated. The results of these calculations were used to identify an optimum electron beam, target, filter, and detector configuration. A compact electron accelerator capable of providing the required electron beam parameters was designed. Calculations indicate that under ideal conditions the optimized system would be capable of imaging 2 mg/cm2 of iodine contrast agent in 20 g/cm2 of tissue with a signal-to-noise ratio of 5, a detector pixel size of 0.25 mm2, and a total image acquisition time of 10 ms. These parameters are consistent with those needed to image the human coronary arteries after an intravenous injection of iodine contrast agent. These capabilities, along with the relatively modest hardware requirements of this system, make it attractive as an x-ray source for dual energy transvenous coronary angiography.

Directional enhancement of characteristic relative to bremsstrahlung X-rays: Foil thickness optimization

“…Since bremsstrahlung from high-energy electrons is preferentially emitted in the forward direction, other authors have proposed enhancing the characteristic-tobremsstrahlung ratio by viewing the X-ray emission from optically thin (foil) targets in a direction antiparallel to that of the incoming electron beam (Manning et al, 1991;Sato et al, 2005;Harding et al, 2003;David et al, 2005). For convenience, the acronym FiRSt (Foil-induced radiation set-up), introduced by the last two sets of authors, will be used here for this concept.…”

Variable energy X-ray fluorescence source

“…Meijer and Unger [14] estimated x-ray production from a number of sources and targets for fluorescence analysis. Reference [15] describes a 1 MeV electron beam to excite La x rays to image human coronary arteries and refs. [16][17][18] studied the performance of an x-ray fluorescence emission from a 244 Cm source exciting target material for the Mars Pathfinder program.…”

Impact of rare earth element added filters on the X-ray beam spectra: A Monte Carlo approach

“…The application of rare-earth filters has been started since 1980s as added filter to reduce patient radiation dose [1,[3][4][5][6][7] and as a film/screen to improve image efficiency [4,[8][9][10][11][12][13][14][15]. Recently, with the increasing the radiation digital detectors' sensitivity, the use of rare elements has been reconsidered [18][19][20][21]. Recently, with the increasing the radiation digital detectors' sensitivity, the use of rare elements has been reconsidered [18][19][20][21].…”

“…As mentioned, Most of studies for rare-earth filters are reported between 80's and 90's [1,[3][4][5][6][7]20,21,25] . Regarding development of technology, the current study investigates the application of the rareelement based added filters for dental radiography purposes.…”