Comparison of the x-ray attenuation properties of breast calcifications, aluminium, hydroxyapatite and calcium oxalate

Abstract

Aluminium is often used as a substitute material for calcifications in phantom measurements in mammography. Additionally, calcium oxalate, hydroxyapatite and aluminium are used in simulation studies. This assumes that these materials have similar attenuation properties to calcification, and this assumption is examined in this work. Sliced mastectomy samples containing calcification were imaged at ×5 magnification using a digital specimen cabinet. Images of the individual calcifications were extracted, and the diameter and contrast of each calculated. The thicknesses of aluminium required to achieve the same contrast as each calcification when imaged under the same conditions were calculated using measurements of the contrast of aluminium foils. As hydroxyapatite and calcium oxalate are also used to simulate calcifications, the equivalent aluminium thicknesses of these materials were also calculated using tabulated attenuation coefficients. On average the equivalent aluminium thickness was 0.85 times the calcification diameter. For calcium oxalate and hydroxyapatite, the equivalent aluminium thicknesses were 1.01 and 2.19 times the thickness of these materials respectively. Aluminium and calcium oxalate are suitable substitute materials for calcifications. Hydroxyapatite is much more attenuating than the calcifications and aluminium. Using solid hydroxyapatite as a substitute for calcification of the same size would lead to excessive contrast in the mammographic image.

Investigating the feasibility of classifying breast microcalcifications using photon-counting spectral mammography: A simulation study

“…Small calcifications of varying sizes were embedded into the breast phantom. The calcifications sizes were randomly selected from a uniform probability density ranging from 200 μ m to 600 μ m with weight density of 2.1 g/mm 3 to represent the attenuation properties of real breast calcifications . A tungsten anode x‐ray tube was modeled, operating at 45 kV with 2 mm of added aluminum filtration as shown in Fig.…”

Toward image quality assessment in mammography using model observers: Detection of a calcification‐like object

“…The disks were inserted at the center of the ROI by replacing the pixel values within the area of the disk with values calculated using the original pixel values, the contrast and the system transfer properties of the Amulet Innovality. This procedure is similar to the procedure described by Warren et al 25 although, for practical reasons, we did not correct for scatter. In total, 64 experiments were generated: four background types with four fixed contrast settings at four different image quality levels.…”

Classification of breast microcalcifications using dual-energy mammography

“…The calcifications sizes were randomly selected from a uniform probability density ranging from 200 to 900 μm 20 with weight density of 2.1 g∕mm 3 to approximate attenuation properties of real breast calcifications. 21 X-ray spectra were generated for a tungsten target by using the IPEM report 78 22 and data from Ref. 23.…”