Medical X-ray Research Articles

Petrophysical Properties of Opalinus Clay Drill Cores Determined from Med-XCT Images

The determination of petrophysical properties such as density, porosity and mineralogical composition of the rock are key objectives in cored sections of drilling campaigns. In view of the large amount of sample material that accumulates during a drilling campaign, a seamless determination of the properties along the cores is not feasible if only direct methods are used. Therefore, fast, non-destructive and affordable methods have been developed. Three-dimensional images of Opalinus Clay drill cores were acquired by using a medical X-ray computed tomographic scanner (med-XCT). The CT numbers of the images were density calibrated, which allowed to determine bulk density variations along drill cores. Then, a relationship between rock composition and bulk density was built in form of linear regression models to predict the porosity or the contents of major components from density calibrated image data. This relationship was established on the basis of rock samples, of which mineralogical compositions and porosities were measured in the laboratory. It turned out that the bulk density of Opalinus Clay is systematically related to porosity and the contents of clay minerals, quartz and calcite. With increasing density, porosity and clay minerals content decrease. This is because the pores and clay minerals together form the porous clay matrix and are thus structurally connected. The density of the porous clay matrix is comparatively low, and its content therefore controls the bulk density of Opalinus Clay. With a decrease in the content of the porous clay matrix, the calcite and quartz contents both increase, which is associated with an increase in bulk density. No systematic behavior was found for the accessories. Thus, their influence on bulk density is considered to be small. Med-XCT in combination with reference samples allows the determination of the rock composition and porosity along drill cores. In the case of Opalinus Clay, a larger number of reference samples (> ~50) are required to predict the properties with confidence.

Optical CT scanning for experimental demonstration of medical x-ray CT and SPECT

Learning the concept of computerised tomography (CT) and single photon emission tomography (SPECT) by biomedical engineering and medical physics students is hampered by limited access to clinical scanners. The use of ionising radiation and radioactive sources in x-ray CT and SPECT further complicates the design of a teaching laboratory session. We here propose an inexpensive and safe educational demonstration tool for CT and SPECT whereby a visible light source serves as source and a charge-coupled device camera serves as detector. The equivalent of a SPECT radionuclide in optical CT scanning is a chemiluminescent material which can be obtained relatively inexpensive in the form of party glow sticks. The proposed teaching tool comprises several learning outcomes such as hands-on construction of the scanner, the acquisition of images and image reconstruction. Also, different imaging artefacts can be simulated and investigated.

Comprehensive dosimetry for seven exposure sources at the earliest US uranium processing facility

Mallinckrodt Chemical Works (MCW) was the earliest uranium processing facility in the United States, beginning in 1942. The 2,514 workers included in the epidemiologic study were exposed to external gamma radiation, medical x-rays, internal radiation from intakes of pitchblende ore and its extracted radionuclides (mainly uranium isotopes and radium-226), and ambient levels of radon and its progeny [1].

Image Quality Assessment of the Digital Radiography Units in Tabriz, Iran: A Phantom Study.

Creating a high-quality image with the low patient dose is one of the most important goals in medical X-ray imaging. In this study, the image quality parameters of the digital radiographic units in Tabriz city were considered and compared with the international protocols. The image quality parameters were measured at 11 high workload digital radiography (DR) imaging centers in Tabriz city, and the results were compared to DINN 6868/58 standards. All centers equipped with the direct DR units passed the spatial resolution, low contrast detectability, contrast dynamic range, and noise tests, while the computed radiography (CR) units only could pass the two last tests. The highest spatial resolution was observed 3.2 lp/mm in the DR unit while the lowest one was 1.8 lp/mm in the CR unit. The highest noise was measured to be 0.03 OD that was observed in the DR unit. The most difference between the nominal and measured peak kilovoltage and mAs was 3.1% and 6.8%, respectively. The entrance surface air kerma in all units was obtained <0.63 mGy. The measured half-value layer range was between 2.4 and 3.54 mmAl. The physical parameters of image quality such as spatial resolution, contrast, and noise are robustness quantitative parameters for the assessment of the image quality performance of the units. Therefore, measurement and control of these parameters using two-dimensional phantoms are very critical.

Research of Establishing of Standard Radiation Qualities and Radiation Conditions for Use in the Determination and Characteristics of Medical Diagnostic X-ray Equipment

The standard of YY/T 0481-2004 Medical diagnostic X-ray equipment-Radiation conditions for use in the determination and characteristics has been revised and replaced in 2012. This paper first introduces the key technical problems to be solved in establishing standard radiation quality and radiation conditions by comparing the main changes of the two versions standards, including the expression of radiation quality and radiation conditions, the measurement of X-ray tube voltage, and the measuring of the practical peak voltage. Then it introduces a procedure for establishing standard radiation quality and radiation conditions.

An analysis of medical X-ray examination frequency in ten hospitals in Tianjin, China

Objective: To investigate the usage frequency of radiological diagnosis devices in ten hospitals in Tianjin, China, and to provide a basis for the survey of medical radiation frequency in Tianjin. Methods: Ten hospitals from the ten districts in Tianjin were enrolled as subjects by a convenient sampling method. A survey was conducted to assess the general information and radiological diagnosis device information and usage frequency in those hospitals in 2016. The radiological examination frequency in Tianjin was estimated. Results: A total of 610 458 patients received radiological examinations in the sampled hospitals in 2016. In those patients, 371 882 received X-ray examinations for imaging and 238 576 for computed tomography (CT) ; there were slightly more female patients than male patients, suggesting a relatively equal gender distribution; patients older than 40 years accounted for 65.53%, which was the highest among all the age groups. Different types of radiological diagnosis devices were mostly used in tertiary and secondary hospitals. In Tianjin, the estimated frequency of X-ray examination for imaging and CT scanning was 451 and 188 per thousand people, respectively, in 2016. Conclusion: The frequency of radiological diagnosis is relatively high in the ten hospitals in Tianjin. The investigation of medical radiation in Tianjin needs to be improved.

X-ray image global enhancement algorithm in medical image classification

The current global enhancement algorithm for medical X-ray image has problems of poor de-noising and enhancement effect and low reduction of the enhanced medical X-ray image. To address the problems, a global enhancement algorithm for X-ray image in medical image classification is proposed in this paper. The medical X-ray image is gray scaled, which provides the basis for the further processing of the image. The noise in medical X-ray image is removed by using multi-wavelet transform to improve the enhancement effect of the method. With the curve-let domain the medical X-ray image is enhanced, the reduction degree of medical X-ray image is improved and the global enhancement of the medical X-ray image is completed. Experimental results show that the de-noising effect of the proposed method is effective, the enhanced medical X ray image is better, and the reduction degree of medical X-ray image is high.

The recalcitrant invention of X-ray images

ABSTRACTThis article extends new materialist theorizing on the constructive role played by the physical stuff of the world. Specifically, it draws on Kenneth Burke’s writings on recalcitrance to theorize the materialities of rhetorical invention. It takes X-rays as a case study in recalcitrance-driven invention, focusing on two particular applications, traditional medical X-rays, a pervasive category of contemporary technical communication, and backscatter X-ray airport security scans, a controversial and short-lived one. Its analysis shows how recalcitrance (1) is harnessed as means of technical invention and (2) is key to invention’s bidirectionality, by which our material interventions, in turn, work upon us.

PENGUKURAN LAJU PAPARAN RADIASI PADA RUANG PEMERIKSAAN MSCT 64 SLICE

Background:Radiation exposure rate measurements have been done on the MSCT 64 Slices examination room radiology section Dr. Moewardi Surakarta Hospital due to lack of repeat measurement after replacement of examination door. This study aims to determine the rate of radiation exposure and radiation safety in the examination room for workers and public refers to the NCRP report no. 147 about stuctural shielding design for medical x-ray imaging facilities.&#x0D; Methods: This type of research is quantitative research with survey approach. This research was conducted in March 2018. Data collection was done by observation, documentation, and measure the radiation exposure in measurement points some places, which are controlled and uncontrolled areas. Data analysis was done descriptively by comparing data with NCRP report no.147.&#x0D; Results:The measurement results of the rate of radiation exposure, point A and B shows the leakage of radiation exposure. While the point of C, D, E no leakage of radiation.&#x0D; Conclusions: The value of background radiation exposure in the MSCT 64 Slices examination room radiology section Dr. Moewardi Surakarta Hospital exceeds the dose rate base on the height of the location according to UNSCEAR. Leakage of radiation exposure occuring at point A is woorkes door and point B front door MSCT 64 Slices examination room not safe for workes and public because it exceeds the limit of radiation exposure rate value which allowed

Image Reconstruction Quality and Parameters in Tomosynthesis

The effect of tomosynthesis reconstruction parameters on the quality of medical X-ray images is considered.

New flatness‐based control of a high‐voltage generator for medical X‐ray applications

This study presents a new flatness-based control scheme for the quantum series–parallel LCC-type resonant converter with output voltage doubler for high-voltage pulse applications, like medical X-ray imaging. Based on a previously derived continuous time model of the system, a flat output of the system model is shown. Moreover, an optimised trajectory planning algorithm with limited resonant current and the controller design are addressed. Details on the experimental set-up and the real-time controller implementation on an FPGA are given. Measurement results show the accuracy of the presented control method.

Simulation study on X-ray phase contrast imaging with dual-phase gratings.

Two phase gratings in an X-ray grating interferometers can solve several technical challenges for clinical use of X-ray phase contrast. In this work, we adapt and evaluate this setup design to clinical X-ray sources and detectors in a simulation study. For a given set of gratings, we optimize the remaining parameter space of a dual-phase grating setup using a numerical wave front simulation. The simulation results are validated with experimentally obtained visibility measurements on a setup with a microfocus tube and a clinical X-ray detector. We then confirm by simulation that the Lau condition for the [Formula: see text] grating also holds for two phase gratings. Furthermore, we use a [Formula: see text] grating with a fixed period to search for periods of matching phase grating configurations. Simulated and experimental visibilities agree very well. We show that the Lau condition for a dual-phase grating setup requires the interference patterns of the first phase grating to constructively overlay at the second phase grating. Furthermore, a total of three setup variants for given [Formula: see text] periods were designed with the simulation, resulting in visibilities between 4.5 and 9.1%. Dual-phase gratings can be used and optimized for a medical X-ray source and detector. The obtained visibilities are somewhat lower than for other Talbot-Lau interferometers and are a tradeoff between setup length and spatial resolution (or additional phase stepping, respectively). However, these disadvantage appears minor compared to the overall better photon statistics, and the fact that dual-phase grating setups can be expected to scale to higher X-ray energies.

IMPROVEMENT OF RADIATION SAFETY STANDARDS. PART 1. APPROPRIATENNES OF THE LIMITAION OF THE MEDICAL EXPOSURE OF HEALTHY INDIVIDUALS

Dose limits are commonly not applied for the radiation protection from medical exposure in the international practice; the principles of justification and optimization are used instead. However, the Russian Norms of the Radiation Safety NRB 99/2009 provide for the limitation (non-exceedance) of the doses for the healthy individuals undergoing X-ray examinations related to the employment-related, legal or screening purposes by 1 mSv per year. The aim of the study was to assess the feasibility of limiting the doses for the healthy individuals undergoing diagnostic medical X-ray examinations in the context of the revision of the Norms of the Radiation Safety. The study included the analysis of the existing Russian legislative documents regulating the medical exposure related to the employment-related, legal and screening purposes; evaluation of the imaging modalities commonly used for these purposes and conservative estimation of the effective doses per employment-related medical examination or a periodic health assessment. The results of the study indicate that a limit of 1 mSv per year is systematically exceeded for the healthy individuals undergoing X-ray examinations related to the employment-related, legal or screening purposes. Implementation of the modern screening methods (low-dose computer tomography, breast tomosynthesis) would lead to the significant increase of the effective dose per periodic health assessment up to 3-8 mSv per year. Hence, it is proposed to use the principle of the optimization with the establishment of the diagnostic reference levels for the screening X-ray examinations for the radiation protection of healthy individuals from medical exposure.

Image Reconstruction Parameters in Dual Energy Radiography

The effect of reconstruction parameters used in dual energy radiography on the quality of medical X-ray imaging is considered.

P142] Interpretation of radiation risks from low dose diagnostic scans

Purpose Scientists disagree on how to interpret risks from low dose radiation exposures. In particular, publications which rely on the Linear No Threshold (LNT) model for estimating of the number of future cancers that may be caused by medical x-rays have led to considerable debate. Some scientific bodies have described such estimates as “highly speculative”. There has also been criticism of a commonly used dose metric, Effective Dose (ED), which it is argued, should be used for “radiation protection purposes” only. Methods This paper offers a partial defence of estimates of cancer risk in a population after exposure to low dose x-rays. We argue that (i) ED is too readily dismissed as a tool for estimating risks in a population, and (ii) that the context for the unmeasurable risk from low dose x-rays is not always given sufficient attention. Results On the first point we argue that criticisms cataloguing the averaging assumptions underpinning the estimation of ED can only be used to calculate an error bar; the conclusion that ED cannot be used in risk estimates because of this error bar does not follow. Secondly, we criticize the use of the term “highly speculative” for risk from exposures below 50 mSv. It is easy to suppose that if science cannot detect a risk, then that risk must be negligible: however, this ignores the fact that because cancer is a common disease, x-rays would have to cause large numbers of cancers before the risk could be detected. In this context, unmeasurable risk cannot be equated to inconsequential risk. Conclusions Confusion about radiation risks has the potential to disrupt the optimum use of medical imaging technology. This paper argues against views which give insufficient weight to low dose radiation risk [1] , [2] .

2018 ACC/HRS/NASCI/SCAI/SCCT Expert Consensus Document on Optimal Use of Ionizing Radiation in Cardiovascular Imaging: Best Practices for Safety and Effectiveness.

2018 ACC/HRS/NASCI/SCAI/SCCT Expert Consensus Document on Optimal Use of Ionizing Radiation in Cardiovascular Imaging: Best Practices for Safety and Effectiveness.

X-ray image denoising with fast non-local means (FNLM) approach using acceleration function in CdTe semiconductor photon counting detector (PCD): Monte Carlo simulation study

The noise reduction algorithms have been widely used in the field of medical X-ray imaging system using semiconductor photon counting detector (PCD). Among these algorithms, fast non-local means (FNLM) method is based on use of the encoded information and considering the local region in the image. The aim of this study was to design FNLM noise reduction algorithm using acceleration function with Euclidean distance, which is feasible to cope with practical problems, and to confirm its application feasibility in CdTe PCD. We simulated X-ray imaging system with PCD using Monte Carlo simulation tool (Geant4 Application for Tomographic Emission (GATE)) version 6 and applied conventional and proposed noise reduction algorithms in acquired water phantom image. We conclude that the results of the image performances associated with noise characteristics demonstrated the superiority of the proposed FNLM noise reduction algorithm in CdTe PCD imaging system.

Improved total-variation noise-reduction technique with gradient method using iteration counter and its application in medical diagnostic chest and abdominal X-ray imaging

The development of novel noise-reduction algorithms is one of the main research areas in the field of medical diagnostic X-ray imaging. The purpose of this study is to develop an improved total-variation (TV) noise-reduction technique using a gradient method that employs an iteration counter, and confirm its feasibility for applications in chest and abdominal X-ray imaging systems. We evaluated image qualities using contrast–to–noise ratio (CNR) and relative standard deviation (RSD) calculations with the proposed and conventional noise-reduction algorithms for both chest and abdominal X-ray images. The results of the quantitative CNR and RSD evaluations demonstrated the superiority of the proposed TV noise-reduction technique over other algorithms; in particular, the comparison between the conventional and proposed TV techniques revealed that the proposed method has improved noise-reduction characteristics in all cases. In conclusion, the results demonstrated that the improved TV noise-reduction technique with the gradient method using the iteration counter can be used to acquire images with a better quality than those of conventional algorithms. This can lead to lowering of the radiation dose in chest and abdominal X-ray imaging systems.

High Bandwidth Non-Resonant High Voltage Generator for X-Ray Systems

High-voltage supplies for medical X-ray systems require up to 150 kV DC at up to 100 kW to supply the tube. The challenge for the power supply however is not only to deal with the high voltage and high power demand, but also to provide short voltage rise- and fall times in the range of 100μs. A coupled interleaved circuit variant of a single active bridge concept, the coupled interleaved single active bridge converter, is demonstrated in this work providing very fast output voltage control due to its non-resonant structure. The conduction modes of the circuit are analysed in detail and compared to the uncoupled interleaved single active bridge approach, demonstrating the advantages of low inverter RMS current, zero voltage switching (or at least zero current switching) over the full operating range with constant switching frequency. Analytic expressions for the output current-duty cycle relationship are provided. Experiments on a 60 kW (low voltage equivalent) prototype show that rise times as low as five switching cycles are possible, allowing to reach the target of 100μs rise time using a switching frequency of only 50 kHz.

Dose-response relationships between internally-deposited uranium and select health outcomes in gaseous diffusion plant workers, 1948-2011.

To examine dose-response relationships between internal uranium exposures and select outcomes among a cohort of uranium enrichment workers. Cox regression was conducted to examine associations between selected health outcomes and cumulative internal uranium with consideration for external ionizing radiation, work-related medical X-rays and contaminant radionuclides technetium (99 Tc) and plutonium (239 Pu) as potential confounders. Elevated and monotonically increasing mortality risks were observed for kidney cancer, chronic renal diseases, and multiple myeloma, and the association with internal uranium absorbed organ dose was statistically significant for multiple myeloma. Adjustment for potential confounders had minimal impact on the risk estimates. Kidney cancer, chronic renal disease, and multiple myeloma mortality risks were elevated with increasing internal uranium absorbed organ dose. The findings add to evidence of an association between internal exposure to uranium and cancer. Future investigation includes a study of cancer incidence in this cohort.