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

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

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

State-of-the-art setups for K-edge imaging

Spectral imaging is an emerging area of X-ray imaging that includes all the techniques which exploit the energy-dependent absorption properties of the matter to either provide quantitative information about the scanned object or to discriminate different materials. Though the potentials of spectral imaging are well known for over many years, the interest on spectral techniques is rapidly increasing only in recent years due to the development and widespread of dedicated acquisition systems able to acquire simultaneous (or nearly simultaneous) X-ray images at different energies. In this context, the development of energy resolving X-ray photon counting detectors (XPCDs) and the increasing availability of synchrotron radiation can provide interesting solutions for spectral imaging applications such as e.g. the K-edge technique. This thesis presents the implementation and the optimization of two state-of-the art acquisition systems suitable for spectral imaging applications with particular interest on the K-edge technique. The first system is an acquisition setup for spectral Computed Tomography (CT) made by coupling a polychromatic source with an energy resolving XPCD implementing two energy thresholds. The work carried out with this setup concerned the thorough characterization of an innovative XPCD featuring a sharp energy resolution, the design of a dedicated image processing procedure to achieve high quality CT images and the development of an automated procedure to produce accurate 3D maps of a K-edge element within a sample. Moreover, to allow further optimization studies, a simulator able to reproduce X-ray images with energy resolving XPCDs has been modeled, developed and validated. The last part of this thesis presents the development and the implementation of an acquisition setup for spectral imaging at synchrotron sources based on bent-Laue crystal optics. The results achieved with a prototype setup optimized for energies around 20 keV are presented, the future developments of the technique are discussed

Characterization of a system for breast-CT with synchrotron radiation

Early detection of breast cancer greatly increases the chances for successful treatments reducing mortality by at least 20% [1]. To date, although mammography is the main tool for detecting breast cancer, it poses several limitations to the detectability of tumors due to the superimposition of breast glandular structures [2]. Various studies have shown that breast-computed tomography (CT) increases the sen-sitivity of breast cancer detectability eliminating superimposition [3]. Moreover, it has been demonstrated that breast-CT improves contrast resolution compared to mammog-raphy, leading to a better identification and classification of breast tissues at the cost of an increased dose [4] [5]. In the past, the main disadvantages of breast-CT (using whole-body CT scanners) were low spatial resolution and high dose to the patient compared to mammography [6]. Recently, the increased interest in breast-CT among radiologists led to the implementation of dedicated breast-CT scanners able to meet the needs for high spatial and contrast res-olution. In particular, a dedicated breast-CT imaging system with synchrotron radiation at the SYRMEP (Synchrotron Radiation for Medical Physics) beamline of Elettra (Tri-este) was developed through the SYRMA-3D (SYnchrotron Radiation Mammography-3D) project. SYRMA-3D uses ‘Pixirad-8’, a direct detection photon counting device with CdTe sensor and pixel size of 60 m, which potentially provides improved performances in terms of noise, efficiency and spatial resolution. The quality of CT images depends mainly on the source, the detector and the recon-struction software. This work focuses on the characterization of the detection system and on the opti-mization of the CT reconstructions using the objective metrics for the evaluation of the spatial resolution and the noise. The detector imaging properties have been assessed from planar images. In frequency domain (FD), the noise has been evaluated by means of the Normalized Noise Power Spec-trum (NNPS). The spatial resolution has been measured with an innovative technique, which allows analysis at single pixel level. The presampling Edge Spread Function (pESF) and the presampling Line Spread Function (pLSF) have been employed as metrics in the spatial domain (SD), while the presampling Modulation Transfer Function (pMTF) has been used in FD. This analysis has shown how the imaging properties of this system can be influenced by physical limitations1, specific pixel geometry and resampling process. The choice of the algorithm and of the parameters of reconstruction for CT-images, such as the voxel size, are not univocal. For this system, the optimal algorithm for CT reconstructions has been investigated between the Filtered Back Projection (FBP) with different filters, the Simultaneous Algebraic Reconstruction Technique (SART) and the Simultaneous Iterative Reconstruction Technique (SIRT). CT images have been recon-structed, using two voxel sizes (V60 = 603 m3 and V120 = 1203 m3), with ASTRA toolbox (All Scales Tomographic Reconstruction Antwerp), an open source software char-acterized by its modularity and customization [7]. For CT reconstructions, noise and spatial resolution have been assessed through the NNPS (measured on a homogeneous phantom [8]) and the Point Spread Function (PSF), the LSF and the MTF (measured with the thin wire method [9], [10]). Finally, the measurements of the NNPS and the MTF have been used to calculate the Noise Equivalent number of Quanta (NEQ). This quantity summarizes the informations about the spatial resolution and the noise and can be used to directly compare the overall quality of the images. In particular, NEQ has been used to directly compare the CT reconstructions performed in different conditions. This analysis allowed to characterize the performances of the reconstruction algorithms. This provides a guide for choosing the best algorithm and voxel size to be used, in order to achieve optimal performances in terms of spatial resolution and noise. References [1] World Health Organization regional office for Europe website: http://www.euro.who.int [2] O’Connell, Avice M. and Karellas, Andrew and Vedantham, Srinivasan, The Potential Role of Dedicated 3D Breast CT as a Diagnostic Tool: Review and Early Clinical Examples, The Breast Journal, vol.20, nr.6, 2014. [3] Boone JM, Kwan AL, Yang K, et al. Computed tomography for imaging the breast. J Mammary Gland Biol Neoplasia. 2006;11:103-111. [4] Boone JM, Nelson TR, Lindfors KK, et al. 2001, Dedicated breast CT: radiation dose and image quality evaluation. Radiology 221:657-667. [5] Nelson TR, Cervina LI, Boone JM. Classification of breast computed tomography data. Med Phys. 2008;35:1078-1086. [6] Glick S. Breast CT. Annu Rev Biomed Eng. 2007;9:501-526. [7] W. Van Aarle, W.J.Palenstijin, J. De Beenhouwer, T. Atlantzis, S. Bals, K. J. Baten-burg and J. Sijbers, Fast and Flexible X-ray Tomography Using the ASTRA toolbox, Optics Express, 24(22), 25129-25147, 2016. [8] S. N. Friedman, G. S. K. Fung, J. H. Siewerdsen, and B. M. W. Tsui. "A simple approach to measure computed tomography (CT) modulation transfer function (MTF) and noise-power spectrum (NPS) using the American College of Radiology (ACR) accreditation phantom" Med. Phys. 40, 051907-1 - 051907-9 (2013). [9] JT Bushberg, JA Seibert, EM Leidholdt Jr. and JM Boone, The Essential Physics of Medical Imaging, 2nd ed., Philadelphia: Lippincott Williams & Wilkins, 2002. [10] X Tang, S Narayanan, J Hsieh, JD Pack, SM Mcolash, P Sainath, RA Nilsen and B Taha, Enhancement of in-plane spatial resolution in volumetric Computed Tomog-raphy with focal spot wobbling – Overcoming the constraint on number of projection views per gantry rotation, J. X-ray Sci. Technol., v.18, pp. 251-65, 2010

[OA158] Noise equivalent number of quanta (NEQ): A tool for choosing the optimal reconstruction algorithm in computed tomography (CT)

Purpose Evaluate optimal reconstruction algorithm and voxel size for a breast CT system using NEQ