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Tissue-mimicking material (TMM) is a fundamental element and important to replace actual tissue. One TMM application creates real mimicking models or phantoms to assess the performance of mammographic imaging modalities through quality assurance and control procedures. The TMM must have tissue equivalence properties to reflect the actual tissue. This tissue equivalence assessment depends on the attenuation value of the material. Therefore, this study aimed to evaluate the linear attenuation coefficient and image quality of 3D Printed materials using mammography computed radiography. This study used polyvinyl alcohol (PVA) filament with a percentage variation of 85-100% which was used to make breast phantoms with a 3D Printer. The phantom was box-shaped with an area of 10×10 cm² with a thickness of 1 cm and featured cylindrical, fiber, and speckled lesions. The phantom was exposed to an energy range of 23 – 35 kV, 40 mA, gantry angle of 0°, filter using Mo/Mo, and without compression. The results showed that the linear attenuation coefficient decreased with increasing energy with values of 3.232 – 0.586 cm−1 for 100% PVA, 0.986 – 0.024 cm−1 for 95% PVA, and 0.682 – 0.019 cm−1 for 85% PVA. Meanwhile, the results of image quality analysis from the signal difference-to-noise ratio parameters of cylindrical, fiber, and speckles lesions can be clearly distinguished from the background for all voltages, except on 23 kVp. In the end, 3D Printed PVA filament phantoms provide promising potential as mammographic phantoms from attenuation coefficient and image quality. [ABSTRACT FROM AUTHOR]

The Imaging Plate (IP) is the main component in the computed radiography system that functions to capture and store latent X-ray images. Imaging Plates are very sensitive to radiation and should be cleaned in less than a week of regular use to remove background radiation and scattering. The Imaging Plate will capture the energy from the X-rays and then store it in phosphor material which will be converted into digital data by a laser scanner in the image reader. After the Imaging Plate has gone through the scanners, the image will be displayed on a computer monitor, while the Imaging Plate is entered into the erasing data section to be cleaned so that it can be reused for other samples. The CR reader, which has an erasing mode, allows cleaning of the resulting image on the Imaging Plate. The remaining image on the IP (Ghost Image) can interfere with the interpretation of radiographic images and cause inaccurate interpretation results. Therefore, additional erasing is needed in addition to using a CR scanner. Erasing uses four removal methods with Reader Scanner High Definition (HD) CR 35 NDT, exposed under Visible light LED Lamp, exposed under direct sunlight in the clear sky from 12.00 am to 12.30 pm, and exposed under the UV LEDs Lamp. Of the four methods, it can be compared which one is the cleanest. It can be concluded that erasing using the method of exposing under the UV LEDs lamp after 360 hours for IP 35x43 cm and 48 hours for 10x24 cm gets the best results for removing Ghost Image. [ABSTRACT FROM AUTHOR]

The objective was to analyze image quality, average glandular dose (AGD) and overall performance of analog and digital mammography systems operating in Mexico between 2000 and 2016, by applying quality control tests to 17 screen film (SF), 23 computed radiography (CR) and 13 digital radiography (DR) systems. The following were evaluated: overall equipment performance, X-ray source, automatic exposure control (AEC), image receptor, image quality, AGD and display. For SF, the results were acceptable, although mechanical and image quality problems were found. For CR, the malfunctioning of the AEC and the poor image quality were severe. For DR, the results were acceptable, except for the performance of the AEC. Some systems produced artifacts and noise beyond acceptance criteria. The average AGD were 1.4 mGy for SF, 2.2 mGy for CR, and 1.4 mGy for DR. CR showed the most problems, and the most severe. From the analysis carried out, the need to implement maintenance and quality control programs to ensure the quality of mammographic images is identified, as well as update national regulations and monitor their compliance. [ABSTRACT FROM AUTHOR]

In 2021, Indonesia established the Indonesian Diagnostic Reference Level (IDRL) for CT-scan and general radiography modalities. Therefore, IDRL can be used to improve the optimization of medical exposure. This study evaluated the optimization of medical exposure from each region in Indonesia by comparing the regional dose profile with the IDRL value for CT-scan and general radiography modalities. Data collection for regional dose profile analysis was conducted through a survey using the Patient Dose Data Information System (Si-INTAN) application from January to December 2021. Survey participants came from representative hospitals of each region that reported patient dose data in CTDIvol, DLP, and ESAK for each type of examination on CT-scan and general radiography modalities for adult patients. Five regions are analyzed from this study, namely Java, Sumatra, Kalimantan, Sulawesi, and Bali Nusa Tenggara. From the results of the analysis for CT-scan and general radiography modalities, it was found that several types of examination have regional dose profile values that exceed the IDRL value. Therefore, it is necessary to improve the optimization for each modality through evaluation of examination procedures, quality of human resources, and evaluation of the technology used. In addition, several types of examination have regional dose profiles that are lower than the IDRL. Therefore, it is necessary to ensure that the low regional dose profile does not reduce the quality of the resulting diagnostic image. [ABSTRACT FROM AUTHOR]

Covid-19 infection originated from a mutated virus that affects the human lung immediately as per the clinical study of infected reports. The fatal viral infection affects personal lives, health, and the economy. Covid-19 caused a huge death rate in shorter time due to the virus spread in the air media but still, no country has an proficient approach to control it. Rapid COVID-19 identification in suspected patients is essential for the present critical situation for prompt quarantine options and to proceed with effective remedial action. The most effective imaging procedures for identifying lung-related diseases are chest x-ray radiography and Chest Computed Tomography. Hence a faster and more accurate review of the COVID screening process from the huge Population through CT scans is effectively done through Deep and machine learning approaches. A poster-Anterior chest image was used to identify the covid-19 persons to differentiate them from healthy persons. Here the SVM based model is used to categorize the COVID-19 Patient for the rapid screening process to control the present situation. [ABSTRACT FROM AUTHOR]

Since 2010 diagnostic reference levels have been implemented in Russian regulatory documents on radiation protection; numerical values of diagnostic reference levels have been established for radiography, computed tomography and diagnostic nuclear medicine. However the concept of optimization based on diagnostic reference levels was seldom used in practice. This study is focused on the evaluation of ten years of existence of diagnostic reference levels system in the Russian Federation, identifying main problems and weak spots. Additionally, differences in international and Russian approaches to diagnostic reference levels system were evaluated. The results of the study indicate that successful application of optimization principle requires more defined division of responsibilities between radiation protection authorities and healthcare authorities. [ABSTRACT FROM AUTHOR]

X-rays are electromagnetic waves that have a short wavelength of about 1 Ǻ (10-8 cm), so they can be used to diagnose human diseases. Apart from being beneficial, X-rays also have a negative impact on human health. Currently, film-based conventional radiography (RK) systems have begun to be replaced with digital radiography (RD) systems. One example of a modified radiography from a conventional radiography system to a digital radiography system is the radiography system located at the UNNES Medical Physics Laboratory. However, the X-ray plane has one important parameter that must be controlled, namely the quality of the X-ray beam. The quality of the X-ray beam can be measured using the half value layer (HVL), that is, the thickness of the material needed to reduce the intensity of the X-ray by half its initial value. The type of material used in this study is used lead plate with various thicknesses. The results showed that the intensity value could be reduced by increasing the thickness of the lead plate. The decrease in the intensity value shows that there is a difference in the gray level of each step on the lead stepwedge. The HVL of lead obtained was 1.96 cm; 2.13 cm; 2.59 cm; 2.72 cm; 3.17 cm; and 3.44 cm at voltages of 40 kV, 50 kV, 60 kV, 70 kV, 80 kV, and 90 kV, respectively. Based on the amount of voltage used and the HVL value obtained, the HVL value obtained is proportional to the magnitude of the X-ray voltage. The greater the X-ray voltage used, the greater the HVL value obtained. [ABSTRACT FROM AUTHOR]

Image stitching is a promising method for developing longer digital x-ray radiographs without sacrificing image resolution. This paper presents our effort on developing the image stitching method based on the SIFT (Scale Invariant Feature Transform) algorithm and the template matching method. Digital radiographic images generally have different contrast and brightness values that need to be adjusted in the image stitching procedure. In this paper, research was carried out related to the effect of differences in contrast values on image stitching results. The reference image, which is a thorax image, is cut into two parts and one of its part is changed the contrast values, to then be merged and stitched into one single complete image. The process of stitching images that has been carried out uses the Scale Invariant Feature Transform (SIFT) method and key point matching. The results of the stitched image are then analyzed using digital image correlation (DIC) values. The results of digital correlation coefficient value obtained from the DIC analysis is close to 1 for all variations in contrast. This shows that the image stitching result is similar and almost identical to the reference image. Therefore, with the method used, it can be obtained a longer image stitching result even though it has differences in contrast. [ABSTRACT FROM AUTHOR]

General Radiography is a type of x-ray modality that is used widely for diagnostic purposes in Indonesia. There are three types of imaging systems in General Radiography technology in its development, namely Film, Computed Radiography (CR), and Digital Radiography (DR). In this research, an analysis was made related to comparing the three imaging systems for the Chest PA procedure in Indonesia. Comparing the radiation doses of each technology with the Diagnostic Reference Level in Indonesia (IDRL) has been done. Data collection was carried out using the Si-INTAN application from January 1st, 2019, to December 31st, 2019. The analysis was carried out statistically through a t-test to obtain conclusions about each technology's different radiation doses. Comparisons with IDRL are based on the value of Q3 (75 percentiles) radiation doses distribution for each technology. The research results showed that CR technology gave the highest dose for the Chest PA examination, which was 0.27 mGy, while DR gave the lowest dose, which was 0.11 mGy. Comparison with IDRL showed that there were doses that exceed IDRL for CR technology, whereas Film and DR technology has no dose data that exceed IDRL. This condition was influenced by an extensive dynamic range on the CR modality that allows overexposure. [ABSTRACT FROM AUTHOR]

: In this study, we used the method of color contrasting in computed radiography images post-processing. This method is based on the color vision quantum hypothesis and ensures the psychological compatibility between the colored radiography image and the original one. The study was conducted using the example of X-ray computed images of the brain of patients with acute cerebrovascular accident as well as computed radiography images of the chest organs of patients with coronavirus pneumonia. As a result, the diagnostic information was visually optimized after color post- processing of X-ray images. The study showed a qualitative increase in the efficiency of diagnosis of some acute diseases due to the use of our proprietary color contrasting method in the post-processing of X-ray computed images. [ABSTRACT FROM AUTHOR]

This study implements a selective mean filter (SMF) and determines its effectiveness on computed radiography (CR) images. A phantom of the Kualitas Citra Imajing (KUCING) was used. The effectiveness of the SMF was compared to the adaptive mean filter (AMF). The assessment of image quality was based on several parameters, such as the peak signal to noise ratio (PSNR), mean squared error (MSE), structural similarity index (SSIM), contrast consistency (CV), contrast linearity (CL), and modulation transfer function (MTF). The results show that the PSNR value generated by the SMF is higher than with the AMF. The MSE value generated by the SMF algorithm is lower than AMF. The SSIM values showed that SMF algorithm produces a better image similarity between the original image and the filtered image compared to the AMF algorithm. In consistency and linearity, the AMF leads to significant changes from the original image, while the SMF image is closer to the original image. The 10% MTF generated by the SMF is the same as the original image, while AMF produces a significant decrease in the 10% MTF. The SMF took 17.9 ± 0.7 seconds for denoising one CR image, while AMF took 519 ± 5 seconds. SMF decreases image noise without a significant effect on the spatial resolution of the image. SMF filtering is superior to AMF filtering in terms of spatial resolution and a shorter computational time. [ABSTRACT FROM AUTHOR]

This review consists on the progress of flat-panel detectors for digital radiography based on amorphous materials; flat panel detectors remain the essential element for radiography improvement. The X-ray converter and the readout pixel array consists the most important components of flat-panel detectors where their parameters and developments will be described. This review also presents the innovative development perceptions of new detectors. In addition, we will define the cascaded linear systems method because it is a very influential tool for improving the design and assessment of X-ray imaging detector systems. [ABSTRACT FROM AUTHOR]

Plain radiography still remains a modality of choice for the imaging of the newborn and prematurely newborn in the intensive care units. The common use of mobile X-ray units for the imaging of that categories of pediatric patients is associated with several difficulties, with the major issue being the poor ergonomics of the X-ray units and lack of dedicated pediatric protocols for the patients with abnormally low body mass. The aim of the current study was to compare the patient doses between the typical digital mobile X-ray unit and the prospective portable X-ray unit. The data on the anthropometric characteristics of prematurely born patients was collected on the base of the perinatal center of the Almazov North-West National Medical Research Centre. A model of patient exposure was developed using PCXMC 2.0 software. The results of the patient dose assessment indicated that the use of prospective portable X-ray unit will allow reducing patient doses up to an order of magnitude – to 9-14 µSv per one babygram. Effective doses and dose-area product per babygram estimated in this study were significantly higher compared with the available data. Estimated radiation risks per one babygram for both surveyed X-ray units belonged to "negligible" or "very low" categories [ABSTRACT FROM AUTHOR]

The encoding phase in full-search fractal image compression (FIC) is time-intensive as a sequential search must be performed through a massive domain pool to find the best-matched domain for each block of ranges. In this paper, a peer adjacent with the sum of absolute difference (SAD) mapping has been suggested to enhance the FIC speed while retaining the reconstructed image quality. The SAD similarity measure applied in searching the most matching domain between domain pool for a range before transformation in order to shorten the mapping process. Therefore, instead of performing a complete search in the next level, one requires to only search a close neighbourhood of the region computed from the previous search. The efficiency of the proposed method is evaluated using standard test image, SMPTE test pattern and standard computed radiography digital images from JSRT database, from which the peak signal-to-noise ratio (PSNR), compression time and compression ratio are calculated. The experimental results validate the effectiveness of the proposed method. [ABSTRACT FROM AUTHOR]

X-ray multi-energy adaptive security radiography and computed tomography inspection techniques have superior performance compared to conventional dual-energy methods where two image slices are acquired by alternating energies. This new technique allows improving the quality of radiographic and CT images, expanding the range of areal densities of the interrogated objects over which effective discrimination of materials by atomic number is possible, eliminating artifacts in the image of boundaries of different densities, and reducing the time of inspection and the required dose. For this new inspection technology, RadiaBeam Technologies is developing several new types of x-ray sources that are based on linear electron accelerators. To provide an adaptive mode of operation of inspection systems, such accelerators use fast feedback from the detector array. Depending on the application, the range of the electron energy can vary from 180 keV up to 9 MeV. In this paper, we discuss the requirements for such linear accelerators, some details about their designs, and present the results of high-power and beam testing of the S- and X- band accelerators. [ABSTRACT FROM AUTHOR]

Historians and librarians are interested in watermarks and mould surface patterns in historic papers, because they represent the “fingerprints” of antique papers. However, these features are usually covered or hidden by printing, writing or other media. Different techniques have been developed to extract the watermarks in the paper while avoiding interference from media on the paper. Beta radiography provides good results, but this method cannot be widely used because of radiation safety regulations and the long exposure times required due to weak isotope sources employed. In this work, two promising methods are compared which can be used to extract digital high-resolution images for paper watermarks and these are electron radiography and low energy X-ray radiography. For electron radiography a “sandwich” of a lead sheet, the paper object, and a film in a dark cassette, is formed and it is exposed at higher X-ray potentials (> 300 kV). The photoelectrons escaping from the lead sheet penetrate the paper and expose the film. After development, the film captures the watermark and mould surface pattern images for the paper being investigated. These images are then digitized using an X-ray film digitizer. The film employed could potentially be replaced by a special type of imaging plate with a very thin protection layer to directly generate digital images using computed radiography (CR). For the second method, a low energy X-ray source is used with the specimen paper placed on a digital detector array (DDA). This method directly generates a low energy digital radiography (DR) image. Both methods provide high quality images without interference from the printing media, and provide the potential to generate a “fingerprint” database for historical papers. There were nevertheless found to be differences in the images obtained using the two methods. The second method, using a low energy X-ray source, has the potential to be integrated in a portable device with a small footprint incorporating user safety requirements. Differences obtained using the two methods are shown and discussed. [ABSTRACT FROM AUTHOR]

Computed Radiography (CR) based on photostimulable imaging plates (IP) is a potential replacement technique for traditional silver film radiography. For the inspections of components with high wall thicknesses requiring higher energy sources, however, imaging plate performance suffers from a spectral response which is low for the higher energies and high in the energy range where scattered radiation is typically observed. For these applications, care must be taken to apply appropriate filtering. Simulation tools are expected to be helpful in determining optimal operating conditions. We present a computer model which combines deterministic and Monte Carlo methods to simulate the imaging chain, focusing in particular on the scanner model. [ABSTRACT FROM AUTHOR]

Perona Malik Anisotropic Diffusion (PMAD) is a very useful and efficient denoising technique if the parameters are properly selected. Overestimating the parameters may cause oversmoothed and underestimating it may leave unfiltered noise. This makes the selection of parameters a crucial process. In this paper the PMAD model is solved using a finite difference scheme The discretized model is evaluated using different diffusion coefficient of exponential and quadratic on defective radiographic images in terms of quality and efficiency. In the application of the PMAD model on image data, a set of defective radiographic images of welding is used as input data. Peak Signal to Noise Ratio (PSNR), Structural Similarity Measure (SSIM) and temporal time are used to evaluate the performance of the model. The implementation of the experiment has been carried out using MATLAB R2009a. In terms of quality, results show that the Quadratic Diffusion Coefficient Function (QDCF) provides better results compared with the Exponential Diffusion Coefficient Function (EDCF). In conclusion, the denoising effect using PMAD model based on finite difference scheme shows able to improve image quality by removing noise in the defective radiographic image. [ABSTRACT FROM AUTHOR]

In image processing, it is important to remove noise without affecting the image structure as well as preserving all the edges. Perona Malik Anisotropic Diffusion (PMAD) is a PDE-based model which is suitable for image denoising and edge detection problems. In this paper, the Peaceman Rachford scheme is applied on PMAD to remove unwanted noise as the scheme is efficient and unconditionally stable. The capability of the scheme to remove noise is evaluated on several digital radiography weld defect images computed using MATLAB R2009a. Experimental results obtained show that the Peaceman Rachford scheme improves the image quality substantially well based on the Peak Signal to Noise Ratio (PSNR). The Peaceman Rachford scheme used in solving the PMAD model successfully removes unwanted noise in digital radiographic image. [ABSTRACT FROM AUTHOR]

Computed radiography (CR) using phosphor imaging plate detectors is taking an increasing place in Radiography Testing. CR uses similar equipment as conventional radiography except that the classical X-ray film is replaced by a numerical detector, called image plate (IP), which is made of a photostimulable layer and which is read by a scanning device through photostimulated luminescence. Such digital radiography has already demonstrated important benefits in terms of exposure time, decrease of source energies and thus reduction of radioprotection area besides being a solution without effluents. This paper presents a model for the simulation of radiography with image plate detectors in CIVA together with examples of validation of the model. The study consists in a cross comparison between experimental and simulation results obtained on a step wedge with a classical X-ray tube. Results are proposed in particular with wire Image quality Indicator (IQI) and duplex IQI. [ABSTRACT FROM AUTHOR]

Segmentation is the most critical task and widely used to obtain useful information in image processing. In this study, Level set based on Chan Vese method is explored and applied to define weld defect on digital radiographic image and its accuracy is evaluated to measure its performance. A set of images with region of interest (ROI) that contain defect are used as input image. The ROI image is pre-processed to improve their quality for better detection. Then, the image is segmented using level set method that is implemented using MATLAB R2009a. The accuracy of the method is evaluated using Receiver Operating Characteristic (ROC). Experimental results show that the method generated an area underneath the ROC of 0.7 in the set of images and the operational point reached corresponds to 0.6 of sensitivity and 0.8 of specificity. The application of segmentation technique such as Chan-Vese level set able to assist radiographer in detecting the defect on digital radiographic image accurately. [ABSTRACT FROM AUTHOR]

Radiography is one of the most common and widely used non-destructive testing (NDT) technique in inspecting weld discontinuity in welded joints. Conventionally, radiography inspector is requires to do the inspection analysis manually on weld discontinuity based on visual characteristics such as location, shape, length and density. The results can be very subjective, time consuming and inconsistent. Hence, semi-automated inspection using digital image processing and segmentation technique can be applied for weld discontinuity detection. The goal of this work is to detect the weld discontinuity on digital radiographic image using Foreground Marker Controlled Watershed. It is usually implemented in image processing because it always generates closed contour for each region in the image. In this paper, image enhancement on radiographic image is aim to remove image noise and improve image contrast. Then, marker controlled watershed with foreground markers is applied on the image to detect the discontinuity. The accuracy of the technique is evaluated using Receiver Operating Characteristic (ROC) curve. The accuracy of the technique has been compared with the ground truth and the result shows that the accuracy is 67% and area under the curve is 0.7134. The application of image processing technique in detecting weld discontinuity is able to assist radiographer to improve the inconsistent results in evaluating the radiographic image. [ABSTRACT FROM AUTHOR]

Similar to the success story of digital photography a major upheaval has been observed in digital industrial radiology. Digital Detector Arrays enable the increase of contrast sensitivity up to a factor of 10 in comparison to film radiography. Computed radiography with phosphor imaging plates substitutes film applications. The increased sensitivity of digital detectors enables the efficient usage for dimensional measurements and functionality tests substituting manual maintenance. The measurement of wall thickness and corrosion status is state of the art in petrochemical industry. X-ray back scatter techniques have been applied in safety and security relevant applications with single sided access of source and detector. Computed tomography (CT) applications cover the range from m to nm scale. The scope of CT applications changes from flaw detection to dimensional measurement in industry. Mobile computed tomography is applied for in-service radiographic crack detection and sizing in welded pipes in nuclear power industry and aerospace applications. CT has been applied for evaluation of hot cracking susceptibility of modern weld alloys. In combination with modified varestraint transvarestraint tests (MVT) the cumulative crack length as function of stress and depth was determined. This enables the quantitative characterization of the weldability properties of different materials. [ABSTRACT FROM AUTHOR]

A recently developed algorithm for positioning of small defects within metal bodies using digital radiography has been experimentally validated. The algorithm has been validated in the high contrast to noise limit. A calibration method has also been developed and validated. The average error in defect interspacings are found to be approximately 0.03mm with a maximum at 0.2 mm, this is at the same order as the errors predicted by simulations. The relative error in interspacings are all less than 2% which is comparable to simulated ideal case at 0.25%. [ABSTRACT FROM AUTHOR]

Users of EN 14784-2 (general principles for computed radiography with phosphor imaging plates) reported about difficulties to achieve testing class B in weld testing with imaging plates. One of the reasons is the insufficient consideration of the inherent detector unsharpness (ui) in the minimum requirements. Digital detectors have a higher inherent unsharpness compared to film, which can even exceed the geometrical unsharpness (ug) of the typical contact technique. In EN 444 and ISO 5579 (general principles for film radiography) ui is neglected for the calculation of the minimum source-to-object distance (SOD), because it is small compared to the geometric unsharpness (ug). Considering ui for digital detectors results in a new equation for SOD (see ISO/FDIS 17636-2). Therefore, the increase in total image unsharpness requires the compensation by a larger SOD to reduce ug. This contribution discusses the need for change of the SOD for different setups (detectors, focal spots, etc.) and explains the difference in image quality, achieved on basis of the extended equation of ISO/FDIS 17636-2. Furthermore, the detection of image quality indicators depends on the achieved Contrast-to-Noise ratio (CNR) and total image unsharpness. Both of them are essential parameters, which influence the contrast sensitivity. Additionally, new compensation principles (e.g. compensation of missing spatial resolution by enhanced contrast sensitivity) allow to widen the application range of digital detectors for radiographic weld testing. [ABSTRACT FROM AUTHOR]

Despite the recent acquisition of significant quantities of computed radiography CR equipment for mammography, Mexican regulations do not specify the performance requirements for digital systems such as those of CR type. The design of a quality control program QCP specific for CR mammography systems was thus considered relevant. International protocols were taken as reference to define tests, procedures and acceptance criteria. The designed QCP was applied in three CR mammography facilities. Important deficiencies in spatial resolution, noise, image receptor homogeneity, artifacts and breast thickness compensation were detected. [ABSTRACT FROM AUTHOR]

The presently active standards on Computed Radiography (CR) need a major revision. It was observed by many users that the image quality for class B of EN 14784-2 is not achievable under the same exposure conditions as used for film exposure. A mathematical model was developed and tested, which allows the calculation of the image quality, proven by image quality indicators (IQI), depending on the fixed pattern noise and the efficiency of the used imaging plate (IP) scanner system. All tested IP scanner systems provide a fixed correlation between the measured signal/noise ratio (SNR) and the grey values in the digital images. The maximum achievable SNRmax depends on the fixed pattern noise of the plate (high dose limit). Depending on the exposure dose an optimum visibility of IQIs can be predicted by calculation and measured considering the attenuation coefficient for calculation of the contrast/noise ratio (CNR). The diameter of the just visible wire is proportional to 1/sqrt(CNR). The optimum tube voltage for best visibility of IQIs and maximum CNR depend on the exposure dose. The optimum tube voltage for best visibility is achieved only at exposures with high dose. A dose dependant optimal tube voltage was not observed for film radiography. [ABSTRACT FROM AUTHOR]

Restoration of digital mammograms, as a pre-processing tool, using deconvolution procedures, is analysed. It implies, knowing Modulation Transfer Function (MTF) of the mammography device and the estimation of the mammogram's noise. Wiener filter is used, as the most objective in mammograms restoration by deconvolution. Using MATLAB program the deconvolution procedures are conducted in two ways with different level of approximation. The first method approximates the noise/signal power ratio by a constant and the second method uses autocorrelation functions of the noise and signals. Abilities and limitations of the methods are analysed and checked by using the raw images of the bar-pattern due to better visualisation of the obtained results. The raw images are obtained at a Computed Radiography (CR) mammography device in Clinical Centre in Podgorica. It is found that quality of the restored image highly depends of knowledge of type and magnitude of noise. In the both methods spatial resolution of the restored images are improved, but much better in a case where autocorrelation functions of the noise and signal are used. This procedure is proposed as an objective pre-processing tool to put back imperfectness of mammography devices. [ABSTRACT FROM AUTHOR]

The application of Digital Radiography in the Nondestructive Evaluation (NDE) of space vehicle components is a recent development in India. A Real-time DR system based on amorphous silicon Flat Panel Detector has been developed for the NDE of solid rocket motors at Rocket Propellant Plant of VSSC in a few years back. The technique has been successfully established for the nondestructive evaluation of solid rocket motors. The DR images recorded for a few solid rocket specimens are presented in the paper. The Real-time DR system is capable of generating sufficient digital X-ray image data with object rotation for the CT image reconstruction. In this paper the indigenous development of CT imaging based on the Realtime DR system for solid rocket motor is presented. Studies are also carried out to generate 3D-CT image from a set of adjacent CT images of the rocket motor. The capability of revealing the spatial location and characterisation of defect is demonstrated by the CT and 3D-CT images generated. [ABSTRACT FROM AUTHOR]

The present paper synthesizes the results obtained in the evaluation of a 64 microstrips crystalline silicon detector coupled to RX64 ASIC, designed for high-energy physics experiments, as a useful X-ray detector in advanced medical radiography, specifically in digital mammography. Research includes the acquisition of two-dimensional radiography of a mammography phantom using the scanning method, and the comparison of experimental profile with mathematically simulated one. The paper also shows the experimental images of three biological samples taken from breast biopsies, where it is possible to identify the presence of possible pathological tissues. [ABSTRACT FROM AUTHOR]

A x-ray detection system based on Silicon strip detectors and low noise multichannel readout system was developed in the framework of the collaboration project. The study of the feasibility of this detector system for medical applications was done. Our system has characteristics that match the requirements of a digital image system. [ABSTRACT FROM AUTHOR]

Aim of this paper is to give a general idea of the characteristic of a system for medical digital imaging based on a GaAs pixel detector bump-bonded to a VLSI electronic chip. After a discussion on the characteristics of the GaAs detector, and its detection and charge collection efficiency properties, it follows a description of the high-density channel VLSI chip named Photon Counting Chip (PCC). Then, a description of the apparatus used to characterize the detector and to perform electrical measurements is made. Finally are discussed irradiation tests and the laboratory setup used at the laboratory course of the ICFA 99 school. [ABSTRACT FROM AUTHOR]

Noise in medical images is recognized as an important factor that determines the image quality. Image noise is characterized by noise power spectrum (NPS). We compared two methods of NPS determination namely the methods of Wagner and Dobbins on Lanex Regular TMG screen-film system and Hologic Lorad Selenia full field digital mammography system, with the aim of choosing the better method to use. The methods differ in terms of various parametric choices and algorithm implementations. These parameters include the low pass filtering, low frequency filtering, windowing, smoothing, aperture correction, overlapping of region of interest (ROI), length of fast Fourier transform, ROI size, method of ROI normalization, and slice selection of the NPS. Overall, the two methods agreed to the practical value of noise power spectrum between 10-3-10-6 mm2 over spatial frequency range 0-10 mm-1. [ABSTRACT FROM AUTHOR]

During the earliest tests of a free-air ionization chamber a poor response to the X-rays emitted by several sources was observed. Then, the Monte Carlo simulation of X-rays transport in matter was employed in order to evaluate chamber behavior as X-rays detector. The photons energy deposition dependence with depth and its integral value in all active volume were calculated. The obtained results reveal that the designed device geometry is feasible to be optimized. [ABSTRACT FROM AUTHOR]