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Objectives Quality assurance of breast imaging has a long history of using test objects to optimize and follow up imaging devices. In particular, the evaluation of new techniques benefits from suitable test objects. The applicability of a phantom consisting of spiculated masses to assess image quality and its dependence on dose in flat field digital mammography (FFDM) and digital breast tomosynthesis systems (DBT) is investigated. Methods Two spiculated masses in five different sizes each were created from a database of clinical tumour models. The masses were produced using 3D printing and embedded into a cuboid phantom. Image quality is determined by the number of spicules identified by human observers. Results The results suggest that the effect of dose on spicule detection is limited especially in cases with smaller objects and probably hidden by the inter-reader variability. Here, an average relative inter-reader variation of the counted number of 31% was found (maximum 83%). The mean relative intra-reader variability was found to be 17%. In DBT, sufficiently good results were obtained only for the largest masses. Conclusions It is possible to integrate spiculated masses into a cuboid phantom. It is easy to print and should allow a direct and prompt evaluation of the quality status of the device by counting visible spicules. Human readout presented the major uncertainty in this study, indicating that automated readout may improve the reproducibility and consistency of the results considerably. Advances in knowledge A cuboid phantom including clinical objects as spiculated lesion models for visual assessing the image quality in FFDM and DBT was developed and is introduced in this work. The evaluation of image quality works best with the two larger masses with 21 spicules. [ABSTRACT FROM AUTHOR]

Background: Projection imaging phantoms are often optimized for 2‐dimensional image characteristics in homogeneous backgrounds. Therefore, evaluation of image quality in tomosynthesis (DBT) lacks accepted and established phantoms. Purpose: We describe a 3D breast phantom with a structured, variable background. The phantom is an adaptable and advanced version of the L1 phantom by Cockmartin et al. Phantom design and its use for quality assurance measurements for DBT devices are described. Four phantoms were compared to assess the objectivity. Methods: The container size was increased to a diameter of 24 cm and a total height of 53.5 mm. Spiculated masses were replaced by five additional non‐spiculated masses for higher granularity in threshold diameter resolution. These patterns are adjustable to the imaging device. The masses were printed in one session with a base layer using two‐component 3D printing. New materials compared to the L1 phantom improved the attenuation difference between the lesion models and the background. Four phantoms were built and intra‐human observer, inter‐human observer and inter‐phantom variations were determined. The latter assess the reproducibility of the phantom production. Coefficients of variance (V) were calculated for all three variations. Results: The difference of the attenuation coefficients between the lesion models and the background was 0.20 cm−1 (with W/Al at 32 kV, equivalent to 19–20 keV effective energy) compared to 0.21 cm−1 for 50/50 glandular/adipose breast tissue and cancerous lesions. PMMA equivalent thickness of the phantom was 47.0 mm for the Siemens Mammomat Revelation. For the masses, the Vintra$V_{intra}$ for the intra‐observer variation was 0.248, the averaged inter‐observer variation, V¯inter$\overline{V}_{inter}$ was 0.383. Vphantom$V_{phantom}$ for phantom variance was 0.321. For the micro‐calcifications, Vintra$V_{intra}$ was 0.0429, V¯inter=$\overline{V}_{inter}=$ 0.0731 and Vphantom=$V_{phantom}=$ 0.0759. Conclusions: Position, orientation and shape of the masses are reproducible and attenuation differences appropriate. The phantom presented proved to be a candidate test object for quality control. [ABSTRACT FROM AUTHOR]

Computer-aided surgery (CAS), the intraoperative application of biomedical visualization techniques, appears to be one of the most promising fields of application for augmented reality (AR), the display of additional computer-generated graphics over a real-world scene. Typically a device such as a head-mounted display (HMD) is used for AR. However, considerable technical problems connected with AR have limited the intraoperative application of HMDs up to now. One of the difficulties in using HMDs is the requirement for a common optical focal plane for both the real-world scene and the computer-generated image, and acceptance of the HMD by the user in a surgical environment. In order to increase the clinical acceptance of AR, we have adapted the Varioscope (Life Optics, Vienna), a miniature, cost-effective head-mounted operating binocular, for AR. In this paper, we present the basic design of the modified HMD, and the method and results of an extensive laboratory study for photogrammetric calibration of the Varioscope's computer displays to a real-world scene. In a series of 16 calibrations with varying zoom factors and object distances, mean calibration error was found to be 1.24 [+ or -] 0.38 pixels or 0.12 [+ or -] 0.05 mm for a 640 x 480 display. Maximum error accounted for 3.33 [+ or -] 1.04 pixels or 0.33 [+ or -] 0.12 mm. The location of a position measurement probe of an optical tracking system was transformed to the display with an error of less than 1 mm in the real world in 56% of all cases. For the remaining cases, error was below 2 mm. We conclude that the accuracy achieved in our experiments is sufficient for a wide range of CAS applications. Index Terms--Augmented reality, binocular, head-mounted display, varioscope.

Development of complex software applications in image guided therapy (IGT) is often complicated by the fact that providing basic functionality for image processing and user interaction from a graphical user interfaces (GUI) requires considerable manpower for software development. We present a programming environment that combines the high-level image processing library AVW, in-house developed patient-to-image registration procedures, and an interface to position measurement hardware. A specific application can be developed by using Tcl/Tk, a simple platform-independent scripting language, for GUI development. This environment was applied to developing VISIT, a navigation system for computer-aided implant dentistry. VISIT is presented as a result of this paper. Parts of the development environment were made accessible to the public. Future work includes the implementation of video input for connecting ultrasound or fluoroscopy units. We conclude that our approach is well suited to accelerate the development of exploratory new applications of IGT. Index Terms--AVW, computer-aided surgery, oral implantology.