T. Rokvic

Mammography with Synchrotron Radiation: First Clinical Experience with Phase-Detection Technique

PURPOSE To prospectively evaluate the diagnostic contribution of mammography with synchrotron radiation in patients with questionable or suspicious breast abnormalities identified at combined digital mammography (DM) and ultrasonography (US). MATERIALS AND METHODS The ethics committee approved this prospective study, and written informed consent was obtained from all patients. Mammography with synchrotron radiation was performed with a phase-detection technique at a synchrotron radiation laboratory. Forty-nine women who met at least one of the inclusion criteria (palpable mass, focal asymmetry, architectural distortion, or equivocal or suspicious mass at DM; none clarified at US) were enrolled. Forty-seven women (mean age, 57.8 years ± 8.8 [standard deviation]; age range, 43-78 years) completed the study protocol, which involved biopsy or follow-up for 1 year as the reference standard. Breast Imaging Reporting and Data System (BI-RADS) scores of 1-3 were considered to indicate a negative result, while scores 4-5 were considered to indicate a positive result. The visibility of breast abnormalities and the glandular parenchymal structure at DM and at mammography with synchrotron radiation was compared by using the Wilcoxon signed rank test. RESULTS In 29 of the 31 patients with a final diagnosis of benign entity, mammography with synchrotron radiation yielded BI-RADS scores of 1-3. In 13 of the remaining 16 patients with a final diagnosis of malignancy, mammography with synchrotron radiation yielded BI-RADS scores of 4-5. Therefore, a sensitivity of 81% (13 of 16 patients) and a specificity of 94% (29 of 31 patients) were achieved with use of the described BI-RADS dichotomization system. CONCLUSION These study results suggest that mammography with synchrotron radiation can be used to clarify cases of questionable or suspicious breast abnormalities identified at DM. SUPPLEMENTAL MATERIAL http://radiology.rsna.org/lookup/suppl/doi:10.1148/radiol.11100745/-/DC1.

Synchrotron Radiation Mammography: Clinical Experimentation

For several years a large variety of in‐vitro medical imaging studies were carried out at the SYRMEP (Synchrotron Radiation for Medical Physics) beamline of the synchrotron radiation facility ELETTRA (Trieste, Italy) utilizing phase sensitive imaging techniques. In particular low dose Phase Contrast (PhC) in planar imaging mode and computed tomography were utilized for full field mammography. The results obtained on in‐vitro samples at the SYRMEP beamline in PhC breast imaging were so encouraging that a clinical program on a limited number of patients selected by radiologists was launched to validate the improvements of synchrotron radiation in mammography. PhC mammography with conventional screen‐film systems is the first step within this project. A digital system is under development for future applications. During the last years the entire beamline has been deeply modified and a medical facility dedicated to in‐vivo mammography was constructed. The facility for PhC synchrotron radiation mammography is ...

A scanning system for intelligent imaging: I-ImaS

I-ImaS (Intelligent Imaging Sensors) is a European project aiming to produce adaptive x-ray imaging systems using Monolithic Active Pixel Sensors (MAPS) to create optimal diagnostic images. Initial systems concentrate on mammography and cephalography. The on-chip intelligence available to MAPS technology will allow real-time analysis of data during image acquisition, giving the capability to build a truly adaptive imaging system with the potential to create images with maximum diagnostic information within given dose constraints. In our system, the exposure in each image region is optimized and the beam intensity is a function not only of tissue thickness and attenuation, but also of local physical and statistical parameters found in the image itself. Using a linear array of detectors with on-chip intelligence, the system will perform an on-line analysis of the image during the scan and then will optimize the X-ray intensity in order to obtain the maximum diagnostic information from the region of interest while minimizing exposure of less important, or simply less dense, regions. This paper summarizes the testing of the sensors and their electronics carried out using synchrotron radiation, x-ray sources and optical measurements. The sensors are tiled to form a 1.5D linear array. These have been characterised and appropriate correction techniques formulated to take into account misalignments between individual sensors. Full testing of the mammography and cephalography I-ImaS prototypes is now underway and the system intelligence is constantly being upgraded through iterative testing in order to obtain the optimal algorithms and settings.

Design and Characterization of the I-ImaS Multi-Element X-Ray Detector System

I-ImaS (Intelligent Imaging Sensors) is a European project aiming to produce new, intelligent X-ray imaging systems using novel APS sensors to create optimal diagnostic images. Initial systems have been constructed for medical imaging; specifically mammography and dental encephalography. However, the I-ImaS system concept could be applied to all areas of X-ray imaging, including homeland security and industrial QA. The I-ImaS system intelligence is implemented by the use of APS technology and FPGAs, allowing real-time analysis of data during image acquisition. This gives the system the capability to perform as an on-the-fly adaptive imaging system, with the potential to create images with maximum diagnostic information within given dose constraints. The I-ImaS system uses a scanning linear array of scintillator-coupled 1.5-D CMOS Active Pixel Sensors to create a full 2-D X-ray image of an object. This paper describes the parameters considered when choosing the scintillator elements of the detectors. A study of the positioning of the sensors to form a linear detector is also considered, along with a discussion of the potential losses in image quality associated with creating a linear sensor by tiling many smaller sensors. Preliminary results show that the detectors have sufficient performance to be used successfully in the initial mammographic and encephalographic I-ImaS systems that are currently under construction.

Phase contrast mammography with synchrotron radiation: physical aspects of the clinical trial

Purpose: The first clinical facility for synchrotron radiation (SR) mammography is now operative at the SYRMEP beamline of ELETTRA, the SR facility in Trieste, Italy. The mammographic facility and the preliminary results of the clinical trial are presented in this contribution. Method and Materials: The distance between the SR source and the patient is about 30 m; the main features of the X-ray beam are: monochromaticity at ~0.2% bandwith in the energy range 8-35 keV, photon flux of about 108 ph/(mm2 s) and dimensions of 21 cm x 3.5 mm at the compressed breast. An innovative dosimetric system allows the on-line dose control during the examination. The images are acquired by scanning the patient, in prone position, in front of the stationary laminar beam; the average scanning time is about 10 s. The detector is a screen film system; it is at ~2 m from the breast in order to fulfil the so-called Phase Contrast (PhC) requirements. The breast thickness and glandularity defines the optimal beam energy for each examination. The patients are enrolled by radiologists, after routine examinations, on the basis of BI-RADS classification, according the research program approved by the local Ethical Committee. Results: This communication concerns the first 9 patients underwent the SR PhC mammography; the images match the quality obtained in previous in vitro studies. With reference to conventional mammography the diagnostic quality of the radiological images is better, without increasing the delivered dose to the patient.

Characterisation of the Components of a Prototype Scanning Intelligent Imaging System for Use in Digital Mammography: The I-ImaS System

The physical performance characteristics of a prototype scanning digital mammography (DM) system have been investigated. The I-ImaS system utilises CMOS MAPS technology promoting on-chip data processing; consequently statistical analysis is therefore achievable in real-time for the purpose of exposure modulation via a feedback mechanism during the image acquisition procedure. The imager employs a dual array of twenty CMOS APS sensing devices each individually coupled to a 100 mum thick thallium doped structured CsI scintillator. The X-ray performance of the sensors was characterised where the presampled modulation transfer function (MTF), normalised noise power spectrum (NNPS), and the detective quantum efficiency (DQE) was determined. The presampled MTF was measured utilising the slit technique and was found to be 0.1 at 6 lp/mm. The NNPS measured utilising a W/Al target/filter combination hardened with 38 mm PMMA was seen to decrease with increasing exposure as expected and the manifesting DQE was 0.30 at close to zero spatial frequency at an exposure of 1.75 mR. Preliminary image stitching of the individual steps acquired from the scanning system is presented. A conventionally acquired image that is without the implementation of beam modulation or off-line intelligence is compared and contrasted to an intelligently off-line processed image. Results indicate the implementation of real-time intelligence into the image acquisition phase of digital mammography is foreseeable.