Near monochromatic X-rays for digital slot-scan mammography: initial findings

Abstract

X-ray spectra are composed of a broad bremsspectrum and anode-characteristic emission lines. In mammography typically molybdenum (Mo), rhodium (Rh) or tungsten (W) anodes are used in combination with Mo, Rh or aluminium filters. Only the photons with energies between 17 and 22 keV of the resulting spectrum are suitable for the soft tissue imaging needed for mammography. The aim of this article is to present first results obtained with a monochromator module mounted at the exit of the X-ray tube of a conventional clinical mammography unit. The experimental setup consists of a Siemens Mammomat 300, an X-ray monochromator module and a linear array detector for image acquisition. The technique is similar to the slot-scan technique known from digital mammography. The experimental machine allows to obtain images both with polychromatic and monochromatic X-rays. Initial evaluation of the system was performed by examination of a contrast-detail phantom (CD-MAM-phantom, Nijmegen, The Netherlands). Images done with the new monochromatic technique were compared to images of the phantom done with polychromatic spectra, with film-screen mammography as well as with digital mammography. The new technique with monochromatic slot-scan mammography resulted in correct identification of 93% of the phantom. Digital slot-scan mammography with polychromatic beam resulted in correct identification of 87%, digital full-field mammography in 83% and conventional film-screen mammography in 70% of the phantom. The results suggest that monochromatization has a potential for improving image quality or decreasing dose in X-ray mammography.

Contrast-detail evaluation and dose assessment of eight digital chest radiography systems in clinical practice

“…Using a grid eliminates most of the scatter but also absorbs part of the primary radiation. When a slotscan method is used instead of a grid, more of the primary transmitted signal reaches the detector, with comparable low scatter fraction and an improved SNR quality [11,12]. For the slot-scan CCD system with CsI detector, better image quality has been shown as compared with conventional screen-film chest radiography [13,14].…”

Molecular imaging based on x-ray fluorescent high-Z tracers

“…Another distinguishing characteristic is the possibility to attach layers of HOPG to surfaces of almost arbitrary geometry. HOPG has been successfully applied, amongst others, as monochromator in prototypes of monochromatic slot scan mammography (Diekmann et al 2004) and its use in monochromatic enhanced radiation therapy has been investigated (Jost et al 2009).…”

Modeling, validation and application of a mathematical tissue-equivalent breast phantom for linear slot-scanning digital mammography

“…A narrow energy spectrum can provide better contrast and significant dose reduction (Burattini et al , 1995; Boone and Siebert, 1994; Lawaczeck et al, 2005). The initial evaluation of a prototype digital mammography unit operating with a nearly monochromatic x-ray beam showed that the use of monochromatic slot-scan mammography resulted in correct identification of 93% of calcifications within a contrast-detail phantom (Diekmann et al , 2004). Clinical installation of monochromatic x-ray sources for mammography would require high-power x-ray tubes and imaging with the slot-scanning technique (Lawaczeck et al, 2005).…”