Breast skin calcifications: localization with a stereotactic device

A novel flexure-based vertical nanopositioning stage with large travel range

This paper presents the design of a novel flexure-based vertical (or Z-axis) nanopositioning stage driven by a piezoelectric actuator (PZT), which is capable of executing large travel range. The proposed stage consists mainly of a hybrid displacement amplification mechanism (DAM), a motion guiding mechanism, and a decoupling mechanism. The hybrid DAM with amplification ratio of 12.1 is developed to transfer the transverse motion of the PZT actuator into the vertical motion. The motion guiding mechanism is introduced to avoid cross coupling at the output end. The decoupling mechanism can significantly reduce the cross coupling at the driving end to protect the PZT. The stiffness and dynamics of the proposed stage are improved by these mechanisms. Analytical modeling and finite element analysis (FEA) are then adopted to optimize dimensions of the stage. Finally, a prototype of the stage is fabricated and tested for verification. The results of static and dynamic tests show that the proposed stage is capable of vertical travel range of 214 μm with resolution of 8 nm, and the first two resonance frequencies are 205 Hz and 1206 Hz, respectively. Cross coupling tests under various lateral loads (0 g-1000 g) show that the maximum variances of the lateral and angular cross couplings are less than 0.78 μm and 95 μrad, respectively, indicating good decoupling capability. In addition, the low-profile structure of the stage is well suited to be used in limited vertical space.

Breast disease: the radiologist's expanding role

The role of the diagnostic radiologist in breast cancer has expanded during the eight-decade history of breast imaging. The radiologist's role now encompasses both breast cancer diagnosis and treatment. This article traces the expansion of the radiologist's role through the history of mammography. The current roles of the radiologist in breast cancer diagnosis are discussed, including screening mammography in the asymptomatic patient, problem-solving breast imaging, breast ultrasound, and galactography. The radiologist's roles in breast cancer treatment that are discussed include preoperative needle localization, percutaneous breast biopsy, and evaluation of the postoperative breast.