Optimization of the energy for Breast monochromatic absorption X-ray Computed Tomography

The limits of mammography have led to an increasing interest on possible alternatives such as the breast Computed Tomography (bCT). The common goal of all X-ray imaging techniques is to achieve the optimal contrast resolution, measured through the Contrast to Noise Ratio (CNR), while minimizing the radiological risks, quantified by the dose. Both dose and CNR depend on the energy and the intensity of the X-rays employed for the specific imaging technique. Some attempts to determine an optimal energy for bCT have suggested the range 22keV\u201334keV, some others instead suggested the range 50keV\u201360keV depending on the parameters considered in the study. Recent experimental works, based on the use of monochromatic radiation and breast specimens, show that energies around 32keV give better image quality respect to setups based on higher energies. In this paper we report a systematic study aiming at defining the range of energies that maximizes the CNR at fixed dose in bCT. The study evaluates several compositions and diameters of the breast and includes various reconstruction algorithms as well as different dose levels. The results show that a good compromise between CNR and dose is obtained using energies around 28keV

Speckle-based imaging (SBI) applications with spectral photon counting detectors at the newly established OPTIMATO (OPTimal IMAging and TOmography) laboratory

Speckle-based imaging (SBI) is an advanced X-ray imaging technique that measures phase and dark-field signals, in addition to absorption signals. SBI uses random wavefront modulators to generate speckles and requires two images: one with a speckle pattern alone, and one with both the sample and speckles. SBI reconstruction algorithms retrieve three signals (transmission, refraction, and dark-field) by comparing the two images. In SBI, speckle visibility plays a crucial role in the retrieval of the three signals. When translating the technique from synchrotron sources to compact laboratory setups, the reduced coherence of the source and limitations in the available resolution yield lower speckle visibility, hampering the retrieval of phase and dark-field signals. In this context, direct-detection CdTe X-ray photon-counting detectors (XPCDs) provide an attractive solution, as they allow for a high detection efficiency and optimal spatial resolution enhancing speckle visibility. In this work, we present the newly established OPTIMATO (OPTimal IMAging and TOmography) laboratory for X-ray imaging hosted at the Elettra synchrotron (Trieste, Italy). The setup for SBI with resolutions up to 15 μm including an XPCD and a charge-integrating flat-panel detector (FPD) has been used to acquire SBI data. The main limiting factors when moving SBI applications from synchrotron facilities to compact laboratory setups are summarized. The advantages of XPCDs over FPDs are discussed by comparing the SBI images obtained using both detectors. The potential of the spectral decomposition approach via multi-threshold acquisitions using XPCDs is briefly introduced. The results shown in this work represent the first step toward the realization of a multimodal and multiresolution X-ray facility

High-speed processing of X-ray wavefront marking data with the Unified Modulated Pattern Analysis (UMPA) model

Wavefront-marking X-ray imaging techniques use e.g., sandpaper or a grating to generate intensity fluctuations, and analyze their distortion by the sample in order to retrieve attenuation, phase-contrast, and dark-field information. Phase contrast yields an improved visibility of soft-tissue specimens, while dark-field reveals small-angle scatter from sub-resolution structures. Both have found many biomedical and engineering applications. The previously developed Unified Modulated Pattern Analysis (UMPA) model extracts these modalities from wavefront-marking data. We here present a new UMPA implementation, capable of rapidly processing large datasets and featuring capabilities to greatly extend the field of view. We also discuss possible artifacts and additional new features.Comment: 18 pages, 7 figures, submitted to Optics Expres

Hodgkin's disease presenting below the diaphragm. The experience of the Gruppo Italiano Studio Linfomi (GISL)

Background and Objective. Infradiaphragmatic Hodgkin\ub4s disease is rare, making up 5-12% of cases in clinical stages I and II; consequently, several questions concerning prognosis and treatment strategy remain to be answered. The aim of this study was to analyze the clinical and prognostic characteristics and outcome of his condition. Methods. A series of 282 patients with CS I-II Hodgkin\ub4s disease (HD) was investigated. In 31 patients the disease was confined below the diaphragm (BDHD), and in the remaining above the diaphragm (ADHD). The presenting features and outcomes were compared in the two groups. Results. The BDHD group was older (p < 0.0002), had a higher frequency of males (p < 0.08) and a different histological subtype group distribution (p < 0.0001). Stage II BDHD patients had a worse overall survival rate (OS) than stage II ADHD patients (68.8% vs 86.6% at 8 years, p < 0.01) if age is not considered; patients with more than 40 years of age, in fact, had the same survival rates as those with ADHD. BDHD patients with intra-abdominal disease alone had worse prognostic factors and OS (p = 0.12) than patients with inguinal-femoral nodes. Interpretation and Conclusions. Although BDHD patients present distinct features, they have the same OS and relapse-free survival rate as age-adjusted ADHD patients. According to our experience patients with stage I peripheral BDHD respond well to radiotherapy-based regimens. Those with stage II and or intra-abdominal disease are more challenging; chemotherapy or a combined therapy seem to be more suitable approaches for these patients

High-speed analysis of speckle-based imaging data with unified modulated pattern analysis (UMPA)

When a partially coherent X-ray source illuminates an object with an irregular surface, a near-field speckle pattern may appear at some distance downstream. Speckle-based X-ray, a relatively novel imaging technique, exploits this effect to extract information about attenuation, refraction, and small-angle scatter induced by a sample. Over the last ten years, different acquisition and image processing techniques have been developed to extract this information from the image data. One of these techniques, Unified Modulated Pattern Analysis (UMPA), uses a speckle-tracking approach, implemented by the least-squares minimization of a cost function that simultaneously models all three image modalities. We here present a new implementation of UMPA. By shifting from Python to C++ and Cython, execution speed was increased by a factor of about 125. Furthermore, a new acquisition modality, “sample-stepping”, was introduced. Finally, we discuss the origin and mitigation of two types of image artifacts that may arise during image processing with UMPA

Helical sample-stepping for faster speckle-based multi-modal tomography with the Unified Modulated Pattern Analysis (UMPA) model

Speckle-based imaging (SBI) is a multi-modal X-ray imaging technique that gives access to absorption, phase-contrast, and dark-field signals from a single dataset. However, it is often difficult to disentangle the different signals from a single measurement. Having complementary data obtained by repeating the scan under slightly varied conditions (multiframe approach) can significantly enhance the accuracy of signal extraction and, consequently, improve the overall quality of the final reconstruction. In order to retrieve the different channels, SBI relies on a reference pattern, generated by the addition of a wavefront marker in the beam (i.e., a sandpaper or gratings). Here, we show how a continuous helical acquisition can extend the field of view (FOV) and speed up the acquisition while maintaining a multiframe approach for the signal retrieval of a test object

Far-field spectral characterization of conical emission and filamentation in Kerr media

By use of an imaging spectrometer we map the far-field ($\theta-\lambda$) spectra of 200 fs optical pulses that have undergone beam collapse and filamentation in a Kerr medium. By studying the evolution of the spectra with increasing input power and using a model based on stationary linear asymptotic wave modes, we are able to trace a consistent model of optical beam collapse high-lighting the interplay between conical emission, multiple pulse splitting and other effects such as spatial chirp.Comment: 8 pages, 9 figure

WHATSAPP MESSENGER AS A REAL-TIME TOOL FOR A LONG-DISTANCE ACTIVITY OF A MULTIDISCIPLINARY

Introduction: Communication between doctors is traditionally conducted by written clinical charts. Mobile health is becoming an integral part of modern medical systems, improving accessibility and quality of medical care. Recent papers suggest that an increasing number of doctors are using in their clinical practice mobile tools to communicate clinical informations (1, 2). The aim of our study was to verify the adoption of WhatsApp Messenger in everyday clinical practice to obtain a real-time multidisciplinary collaboration among medical centers located in different areas of the city. Materials and Methods: In January 2016 a WhatsApp Messenger group was created among 25 specialists: 9 urologists, 9 oncologists, 3 urology residents, 3 radiotherapists and 1 general practitioner. A general coordinator and a group coordinator for each specialty was monthly appointed. The participants were invited to interact within the group clinical cases of genitourinary tumors of particular complexity requiring a multidisciplinary approach. All the chats were registered. A preliminary analysis of the activity of the group was planned after the first 10 entered patients. An evaluation questionnaire was sent after 6 months to evaluate the level of appreciation. The questionnaire was composed of a first section investigating the appreciation among the members of the group and a second section analyzing the impact in their everyday clinical practice of whatsapp multidisciplinary consultation. Results: In 10 (91%) out of 11 patients the WhatsApp consultation was completed, one case was not of oncological interest. An average of 8 (range=2-13) specialists joined the chat for each patient. An average of 17.6 (range: 4-43) interventions for each clinical case was recorded. On the average, 27%, 54% and 19% of the interventions for each clinical case were provided by oncologists, urologists and radiotherapists respectively. In 9 (81.8%) cases a final agreement on the patient's management was reached. At the evaluation questionnaire in a scale 1-10, the average rating score of appreciation was 7.8 (range=4-10). Relevant suggestions to improve the Whatsapp Messenger consultation were obtained and will be considered for future application the ameliorate the tool. Discussion: WhatsApp is a useful alternative and powerful complementary communication tool because of its capability to rapidly transfer large amount of clinical and radiological data. In our experience this new approach for multidisciplinary consultations improved collaboration among different specialist in different areas of the city through an easier and more informal change of opinions. In difficult and complex cases a rapid multidisciplinary approach allowed to offer the patient a personalized and tailored therapy management. GSTU Foundation. 1Sidhoum N, Dast S, Abdulshakoor A, Assaf N, Herlin C and Sinna R: WhatsApp: Improvement tool for surgical team communication. J Plast Reconstr Aesthet Surg 69: 1562-1563, 2016. 2 Gould G and Nilforooshan R: WhatsApp Doc? BMJ Innov 2(3): 109-110, 201

Phase-contrast breast CT: the effect of propagation distance

X-ray phase imaging has the potential to dramatically improve soft tissue contrast sensitivity, which is a crucial requirement in many diagnostic applications such as breast imaging. In this context, a program devoted to perform in-vivo phase-contrast synchrotron radiation breast computed tomography is ongoing at the Elettra facility (Trieste, Italy). The used phase-contrast technique is the propagation-based configuration, which requires a spatially coherent source and a sufficient object-to-detector distance. In this work the effect of this distance on image quality is quantitatively investigated scanning a large breast surgical specimen at 3 object-to-detector distances (1.6, 3, 9 m) and comparing the images both before and after applying the phase-retrieval procedure. The sample is imaged at 30 keV with a 60 \ub5m pixel pitch CdTe single-photon-counting detector, positioned at a fixed distance of 31.6~m from the source. The detector fluence is kept constant for all acquisitions. The study shows that, at the largest distance, a 20-fold SNR increase can be obtained by applying the phase-retrieval procedure. Moreover, it is shown that, for phase-retrieved images, changing the object-to-detector distance does not affect spatial resolution while boosting SNR (4-fold increase going from the shortest to the largest distance). The experimental results are supported by a theoretical model proposed by other authors, whose salient results are presented in this paper