This work compares estimates of the radiation dose in mammography obtained using three different fibroglandular tissue distributions. Ninety volumetric images of patient breasts were acquired with a dedicated breast CT system and the voxels automatically classified as containing skin, adipose, or glandular tissue. The classified images underwent simulated mechanical compression to mimic the mammographic cranio-caudal acquisition. The voxels containing fibroglandular and adipose tissue were then distributed in the breast phantoms following three different methods: patient-based (i.e., maintaining the original distribution), homogeneous (i.e., each voxel is a homogeneous mixture of adipose and glandular tissue) and newly-proposed continuous (i.e., the glandular tissue is distributed according to a general model, derived from the patient breast CT data). All breast phantoms were used in Monte Carlo simulations to estimate the radiation dose. The results show that the doses estimated using the continuous fibroglandular tissue distribution agree within 3% of the doses estimated using the heterogeneous patient-based distribution, and that it leads to a dose reduction of 27% compared to the homogeneous distribution.
Aim: In recent years Phase Contrast Tomography (PCT) has been rapidly progressing towards clinical translation as an advanced imaging technology for breast cancer diagnosis. Recent optimization of PCT with mastectomy samples has refined imaging protocols and biomedical-engineering prowess is now required to formalize patient table and breast immobilisation requirements. PCT imaging requires women to lie in prone position similar to conventional breast CT, however the imaging couch rotates above the beam allowing exposure of the breast beneath. Motion artefact through involuntary movement of the breast through the rotation cycle has the potential to reduce diagnostic quality of the results. Methods: This paper details the biomedical engineering cycle of breast holder development alongside medical physics considerations. Breast immobilisation via a plastic or silicone supporting material which is sufficiently transparent for X-rays in the targeted energy range is explained, including the two step process of considering single cup versus double cup solutions and how mild-suction to the breast can be implemented in order to maximum breast tissue visualization and assist with dose uniformity. Results: Considering patient comfort, breast positioning and implications upon attenuation and phase shift, a number of models were developed in Australia and Italy. Early prototypes are described here with some preliminary imaging. Considerable work is taking place over the next three months as models undergo imaging with mastectomy samples at the Imaging and Medical Beamline at the Australian Synchrotron and the ELETTRA Synchrotron Italy. Consumer representatives will be rating the immobilisation device for comfort prior to the start of clinical trials in 2020.
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