Characterisation of noise and sharpness of images from four digital breast tomosynthesis systems for simulation of images for virtual clinical trials.

In-depth evaluation of the noise and sharpness characteristics of FujiFilm Innovality, GE SenoClaire, Hologic Selenia Dimensions and Siemens Inspiration digital breast tomosynthesis (DBT) systems was performed with the intention of improving image simulation for virtual clinical trials. Noise power spectra (NPS) and modulation transfer function curves (MTF) were measured for planar modes and for the first and central projections for DBT modes. In DBT mode, the x-ray beam was blocked for the projections before the central projection in order to remove the influence of lag and ghosting from the previous images. A quadratic fit between the NPS and linearised pixel value gave the noise coefficients for planar and DBT imaging modes. The spatial frequencies corresponding to an MTF of 0.5 (MTF0.5) were calculated from the MTF measurements made on the breast support and at 40 mm above the breast support. This was done for the first and the central projections. The percentage of signal carried over from the first projection to subsequent images (lag) was measured using a slit. The noise associated with lag was also evaluated. The DBT modes typically had lower electronic noise coefficients but higher structural noise coefficients compared to the respective planar mode MTF0.5 measured 40 mm above the table was between 6% and 47% lower for continuous scanning systems compared to 1% lower for step and shoot systems. For wide angle DBT, the MTF0.5 of the first projection was 18% (FujiFilm) and 28% (Siemens) lower than for the central projection. Lag in the second projection was 2.2%, 0.3%, 0.8% for the FujiFilm, GE and Hologic systems respectively. In all cases, the noise associated with lag was negligible. Current modelling frameworks for virtual clinical trials of breast DBT systems need to be adapted to account for signals from lag and variations in the MTF at wide angles.

Optimization of propagation-based x-ray phase-contrast tomography for breast cancer imaging.

The aim of this study was to optimise the experimental protocol and data analysis for in-vivo breast cancer x-ray imaging. Results are presented of the experiment at the SYRMEP beamline of Elettra Synchrotron using the propagation-based phase-contrast mammographic tomography method, which incorporates not only absorption, but also x-ray phase information. In this study the images of breast tissue samples, of a size corresponding to a full human breast, with radiologically acceptable x-ray doses were obtained, and the degree of improvement of the image quality (from the diagnostic point of view) achievable using propagation-based phase-contrast image acquisition protocols with proper incorporation of x-ray phase retrieval into the reconstruction pipeline was investigated. Parameters such as the x-ray energy, sample-to-detector distance and data processing methods were tested, evaluated and optimized with respect to the estimated diagnostic value using a mastectomy sample with a malignant lesion. The results of quantitative evaluation of images were obtained by means of radiological assessment carried out by 13 experienced specialists. A comparative analysis was performed between the x-ray and the histological images of the specimen. The results of the analysis indicate that, within the investigated range of parameters, both the objective image quality characteristics and the subjective radiological scores of propagation-based phase-contrast images of breast tissues monotonically increase with the strength of phase contrast which in turn is directly proportional to the product of the radiation wavelength and the sample-to-detector distance. The outcomes of this study serve to define the practical imaging conditions and the CT reconstruction procedures appropriate for low-dose phase-contrast mammographic imaging of live patients at specially designed synchrotron beamlines.

[Comparison of a Radiation Dose During Standard Digital Radiography, Tomosynthesis, and Multislice Spiral Computed Tomography in an Experimental Study of Pediatric Anthropomorphic Phantom].

Objective: To compare a radiation dose obtained during standard digital radiography, tomosynthesis, and multislice spiral computed tomography (MSCT). Material and Methods: Life-size full body pediatric anthropomorphic mannequin phantom was examined with a Fujifilm FDR Ac Selerate 200 X-ray diagnostic apparatus and a Toshiba Aquilion Prime 64 computed scanner using the Piranha dosimetry equipment, as well as Gammex planar target, for comparison of the resolution of the apparatus. The effective radiation doses were calculated for different anatomical regions with the formulas specified in the methodical instructions, using the coefficients K and Kd. Results: The tables and graphs comparing the radiation dose when using different radiation diagnostic techniques were presented. The resolution of standard digital radiography versus that of tomosynthesis was analyzed. Fluctuations of the doses obtained were associated with the difference in the volume of irradiated tissue and in the presence of the doses in the irradiated volume of organs with high radiosensitivity. Optimal physical and technical parameters of photography were proposed, which could reduce a dose load on the patient, without significantly losing the quality of films. Conclusion: The effective doses of tomosynthesis were significantly higher than those of standard digital radiography (p < 0.05) while those of (MSCT) were above those of both X-ray and tomosynthesis, and the resolution of the latter was slightly lower.

X-ray tomography system to investigate granular materials during mechanical loading.

We integrate a small and portable medical x-ray device with mechanical testing equipment to enable in situ, non-invasive measurements of a granular material's response to mechanical loading. We employ an orthopedic C-arm as the x-ray source and detector to image samples mounted in the materials tester. We discuss the design of a custom rotation stage, which allows for sample rotation and tomographic reconstruction under applied compressive stress. We then discuss the calibration of the system for 3D computed tomography, as well as the subsequent image reconstruction process. Using this system to reconstruct packings of 3D-printed particles, we resolve packing features with 0.52 mm resolution in a (60 mm)(3) field of view. By analyzing the performance bounds of the system, we demonstrate that the reconstructions exhibit only moderate noise.

Characterization of a novel calibration method for mineral density determination of dentine by X-ray micro-tomography.

Laboratory micro-CT systems, although limited by beam hardening effect and instability of the source, have been utilized to measure mineral density in combination with specific image processing methods. However, few attempts have been made to accurately determine mineral density profiles in dentine due to the lack of suitable calibration standards. The aim of this study was to develop a calibration method to evaluate mineral density profiles in dentine including changes associated with dentinal caries. A series of K(2)HPO(4) solution phantoms in a concentration range between 0 and 0.9 g cm(-3)--coupled to a set of water infiltrated porous solid hydroxyapatite (HA) phantoms, with mineral densities ranging from 1.52 to 2.08 g cm(-3), was used in this investigation. First we evaluated the micrometer-scale homogeneity and noise in the HA phantoms using a commercial laboratory micro-CT system. Then an experimental validation was performed of the linearity over the entire density range of these two different calibration materials. The results show the HA phantoms extended the calibration curve obtained from K(2)HPO(4) solution phantoms to densities as high as 2.08 g cm(-3); the linearity remains stable at different energy levels. Finally, compared to the reference micro-CT calibration methods, the advantages of this new method are discussed. We conclude that this calibration method allows a more rational assessment of mineral density of dentine by micro-CT and has a promising potential for future studies.

[Determination of total filtration and half attenuation layer in X-ray diagnostic units by relative radiation output]. / Opredelenie summarnoi filtratsii i sloia polovinnogo oslableniia v rentgenodiagnosticheskikh apparatakh po otnositel'nomu radiatsionnomu vykhodu.

Described is a relatively simple technique applicable to estimating the independent and additional filtration of X-ray images by the relative radiation output with a voltage generation range of 50 to 120 kB. It is shown as possible to determine the half-attenuation first layer in its aluminum equivalent and without using any aluminum filters. The suggested technique can be used in turn-over and regular tests of medical X-ray units as well as in their exploitation.

Accuracy of detection and measurement of renal calculi: in vitro comparison of three-dimensional spiral CT, radiography, and nephrotomography.

PURPOSE: To compare accuracy of three-dimensional (3D) spiral computed tomography (CT) performed without administration of contrast material with that of radiography and linear nephrotomography in detection and measurement of renal calculi. MATERIALS AND METHODS: Fifty renal calculi within an abdominal phantom were imaged with 3D spiral CT, radiography, and linear nephrotomography. Spiral CT data were analyzed with workstation-based 3D imaging software, with a thresholding procedure based on the maximally attenuating voxel within each calculus during measurement. Measurement accuracy and detection rates were compared according to modality. Conventional and magnification-corrected measurements from radiography and linear nephrotomography were included. RESULTS: Spiral CT depicted calculi and allowed determination of the collective two-dimensional and 3D linear measurements statistically significantly more accurately than the other techniques; the mean linear measurement errors along individual axes did not exceed 3.6%. With 3D spiral CT, calculus volumes were determined with a mean error of -4.8%. CONCLUSION: 3D spiral CT enabled highly accurate determination of the volumes and all three linear dimensions of renal calculi. In addition, 3D spiral CT depicted calculi more sensitively than traditional techniques and provided new information and improved accuracy in the evaluation of nephrolithiasis.

Radiographic detectability of periodontal diseases. A comparison of perapical radiography with detailed zonography.

OBJECTIVE: To compare the diagnostic accuracy of conventional periapical radiography with detailed zonography using the Scanora system for the detection of periodontal disease. METHODS: We selected for comparison 311 periodontal sites in 165 patients. Five observers independently assessed the periapical radiographs and detailed zonograms for marginal widening of periodontal ligament space, crestal erosion, vertical bone loss, furcation involvement and calculus. RESULTS: ROC analysis revealed no significant differences between the two imaging techniques for either overall or lesion-specific interpretation of periodontal pathology. The sensitivity of periapical radiography was 79%, and of detailed zonography 91% (multiview) and 89% (stereoscopic). Specificities were 82%, 77% and 83%, respectively. CONCLUSION: Detailed zonography performs as well as periapical radiography in the detection of periodontal disease.

Trispiral tomography and magnetic resonance imaging of the wrist.

Tomography, which permits a far more accurate visualization of lesions than conventional radiographs, is conducted via several different methods, depending on the specific movement of the x-ray tube. Linear tomography is the simplest method but produces images that appear streaked. Zonotomography, which uses an elliptical or figure-8 movement of the x-ray tube, creates a uniform blurring of structures and a much clearer resolution of the plane of focus. Even sharper images are produced by multidirectional trispiral tomography, which is described as well as its application to specific anatomic areas of the wrist. The normal anatomy and a variety of problems of the wrist as visualized with magnetic resonance imaging are also described.

The role and limitations of computed tomographic scanning in the evaluation of cervical trauma.

We retrospectively reviewed the medical records, plain films, CT scans and complex-motion tomographic studies (TOMOS) of 216 consecutive patients with cervical injuries to determine the uses and limitations of CT in the evaluation of cervical trauma and the indications, if any, for the continued use of TOMOS in evaluating cervical trauma. There were 453 fractures and 104 subluxations or dislocations of the cervical spine in the 216 patients. Plain films detected 58% (262 of 453) of the fractures and 93% (97 of 104) of the subluxations and dislocations; and 94% (202 of 216) of the patients with abnormalities were identified. Computed tomographic scans detected 90% (406 of 453) of the fractures and 54% (56 of 104) of the subluxations and dislocations; 92% (198 of 216) of the patients with abnormalities were identified. Most of the abnormalities missed on the CT scans involved the dens, C-6, and C-7, and were oriented in the axial plane. Although CT scanning was better than plain films in detecting most types of cervical fractures, plain films were better than CT for detecting fractures of the vertebral body, dens, and spinous processes, and significantly better than CT in detecting subluxation and dislocation. When plain films and CT scans were combined they identified 98% (443 of 453) of the fractures and 99% (103 of 104) of the subluxations and dislocations; 100% (216 of 216) of the patients with abnormalities were identified. In the 20 patients who underwent both CT scanning and TOMOS, TOMOS detected more fractures, subluxations, and dislocations than CT scanning. Complex-motion tomographic studies detected atlanto-occipital dislocation and subluxation of the vertebral bodies and fractures of the spinous processes, lateral masses, articular processes, vertebral bodies, and dens better than CT scanning. Although the more routine use of CT scanning in evaluating cervical trauma should increase the detection of cervical abnormalities to near 100%, TOMOS remain the gold standard of diagnosis for atlanto-occipital dislocation, subluxation of the vertebral bodies, and fractures of the lateral masses, articular processes, vertebral bodies, and dens.

Is the volume retained after defecation a valuable parameter at defecography?

The intention of this study was to correlate the retained volume at the end of defecography to certain defecographic findings and to the sense of incomplete emptying. In 170 defecographic series, the retained barium was estimated planimetrically. No particular defecographic finding determined a higher or lower amount of remaining volume, and the sense of incomplete evacuation did not depend on the amount of retained volume. Thresholds of urge and perception on anorectal manometry did not differ between patients with and without the feeling of incomplete evacuation. A rectocele, isolated or combined with an internal prolapse, caused the retained volume to be in the lowermost part of the rectum, whereas, in the case of an isolated intussusception, the remaining volume was located in the middle or higher part of the rectum. It is concluded that defecographic findings do not in general explain incomplete emptying or the sense of incomplete emptying, but they may determine the localization of the retained volume.

Radiography of the auditory ossicles: a review.

Plain films capable of demonstrating the composite shadow of the ossicular chain included the 105 degrees base, the lateral oblique of Meyer or Owen, the anteroposterior transtemporal of Chausse and the anteroposterior transorbital of Guillen. The stapes and the incudostapedial joint can not be shown with plain films. The hypocycloidal anteroposterior or Guillen is the best of tomograms and may be supplemented by lateral, inclined lateral or basal examinations. The individual ossicles, including the stapes can be demonstrated as well as the incudostapedial joint. Axial and coronal cuts with high resolution computed tomography (HRCT) demonstrate with clarity all ossicular parts commonly involved in otologic pathology. Conventional tomography and HRCT are complementary in all other temporal bone structures but the latter proved superior in ossicular visualization.

Radiologic evaluation of urolithiasis.

Interobserver variations between three radiologists with different backgrounds (duration of practice, and departments) were studied in connection with the diagnosing of urolithiasis. Films from 152 consecutive patients (examined with conventional abdominal films, urography/tomography) were analyzed independently. With respect to the number of patients with or without calculi there was agreement between the three observers in 129 of the 152 cases, which was taken to represent very good agreement beyond chance. The total number of stones was interpreted as 832, 460 and 570 respectively, and the median stone size as 6, 9 and 11 mm2. There was a fair interobserver agreement rate regarding whether stones were localized to the renal parenchyma or calyces, and whether stenosis/stricture or hydronephrosis was present. Tomography appeared to reduce the interobserver variability significantly. Adequate bowel cleaning, oblique projections, and lack of clinical information apparently did not influence the agreement rate. It was concluded that such interobserver variations are factors of importance in the reliability of the radiologic evaluation of urolithiasis.

[Experimental dosimetric comparison between single tomography and multiple simultaneous tomography with Synchroplan in clinical practice]. / Confronto dosimetrico sperimentale tra tomografia singola e tomografia multipla simultanea con Synchroplan nella pratica clinica.

Reference is made to a dosimetric comparison between single tomography and simultaneous multiple tomography with Synchroplan in 10 patients subjected to nefroangiotomography. Data from several thermoluminescence dosimeters placed on different parts of the body were used in a careful statistical analysis that showed the absence of significant differences in absorbed dose in function of constitutional habitus. It was also found that the dose absorbed for 6 tomograms of the renal cavities in single tomography was about 4 times higher than with the Synchroplan (using a previously experimented set of high-sensitivity intensifying screens), which provides 6 tomograms in the same dynamic phase at different levels for the same exposure.

[Quality assurance in roentgen tomography. Initial report on a sectional phantom assembly for all parameters]. / Zur Qualitätssicherung in der Röntgentomographie. Erste Mitteilung über ein zusammensetzbares Schichtphantom für alle Parameter.

A tomographie phantom developed by a new principle is presented for quality assurance and testing of the installation as well as for postgraduate teaching and lectures. It is composed likely to a set for construction-games consisting of fitting cubes and parts. The phantom-cubes include some test objects not yet published. The concerning parameters and conditions of tomographic technique are thus able to be demonstrated separately, in a selected combination or all together by one exposure. All parameters are to be read off the tomogram without calculations or further operations. Some examples are selected out of the group of the parameter- and teaching-cubes.