title: On a dark-field signal generated by micrometer-sized calcifications in phase-contrast mammography.
abstract: We show that a distribution of micrometer-sized calcifications in the human breast which are not visible in clinical x-ray mammography at diagnostic dose levels can produce a significant dark-field signal in a grating-based x-ray phase-contrast imaging setup with a tungsten anode x-ray tube operated at 40 kVp. A breast specimen with invasive ductal carcinoma was investigated immediately after surgery by Talbot-Lau x-ray interferometry with a design energy of 25 keV. The sample contained two tumors which were visible in ultrasound and contrast-agent enhanced MRI but invisible in clinical x-ray mammography, in specimen radiography and in the attenuation images obtained with the Talbot-Lau interferometer. One of the tumors produced significant dark-field contrast with an exposure of 0.85 mGy air-kerma. Staining of histological slices revealed sparsely distributed grains of calcium phosphate with sizes varying between 1 and 40 μm in the region of this tumor. By combining the histological investigations with an x-ray wave-field simulation we demonstrate that a corresponding distribution of grains of calcium phosphate in the form of hydroxylapatite has the ability to produce a dark-field signal which would-to a substantial degree-explain the measured dark-field image. Thus we have found the appearance of new information (compared to attenuation and differential phase images) in the dark-field image. The second tumor in the same sample did not contain a significant fraction of these very fine calcification grains and was invisible in the dark-field image. We conclude that some tumors which are invisible in x-ray absorption mammography might be detected in the x-ray dark-field image at tolerable dose levels.
authors.affiliation: Erlangen Centre for Astroparticle Physics (ECAP), Friedrich-Alexander-Universität Erlangen-Nürnberg, Erwin-Rommel-Str 1, D-91058 Erlangen, Germany. Thilo.Michel@physik.uni-erlangen.de
authors.forename: Thilo
authors.initials: T
authors.lastname: Michel
authors.forename: Jens
authors.initials: J
authors.lastname: Rieger
authors.forename: Gisela
authors.initials: G
authors.lastname: Anton
authors.forename: Florian
authors.initials: F
authors.lastname: Bayer
authors.forename: Matthias W
authors.initials: MW
authors.lastname: Beckmann
authors.forename: Jürgen
authors.initials: J
authors.lastname: Durst
authors.forename: Peter A
authors.initials: PA
authors.lastname: Fasching
authors.forename: Wilhelm
authors.initials: W
authors.lastname: Haas
authors.forename: Arndt
authors.initials: A
authors.lastname: Hartmann
authors.forename: Georg
authors.initials: G
authors.lastname: Pelzer
authors.forename: Marcus
authors.initials: M
authors.lastname: Radicke
authors.forename: Claudia
authors.initials: C
authors.lastname: Rauh
authors.forename: André
authors.initials: A
authors.lastname: Ritter
authors.forename: Peter
authors.initials: P
authors.lastname: Sievers
authors.forename: Rüdiger
authors.initials: R
authors.lastname: Schulz-Wendtland
authors.forename: Michael
authors.initials: M
authors.lastname: Uder
authors.forename: David L
authors.initials: DL
authors.lastname: Wachter
authors.forename: Thomas
authors.initials: T
authors.lastname: Weber
authors.forename: Evelyn
authors.initials: E
authors.lastname: Wenkel
authors.forename: Andrea
authors.initials: A
authors.lastname: Zang
mesh_terms: D001943:Breast Neoplasms / Q000000981:diagnostic imaging* / Q000378:metabolism / Q000473:pathology*; D002114:Calcinosis / Q000000981:diagnostic imaging / Q000473:pathology*; D002130:Calcium Phosphates / Q000378:metabolism; D003624:Darkness; D005260:Female; D006801:Humans; D007368:Interferometry; D008327:Mammography / Q000379:methods*; D008875:Middle Aged
chemical_list: D002130:Calcium Phosphates; C020243:calcium phosphate