Computed chest radiography for total body irradiation: image quality and clinical feasibility

OBJECTIVE

In myeloablative total body irradiation (TBI), lung shielding blocks are used to reduce the dose to the lungs and hence decrease the risk of radiation pneumonitis. Some centers are still using mega-Volt (MV) imaging with dedicated silver halide-based films during simulation and treatment for lung delineation and position verification. However, the availability of these films has recently become an issue. This study examines the clinical performance of a computed radiography (CR) solution in comparison to radiographic films and potential improvement of image quality by filtering and post-processing.

APPROACH

We compared BaFBrI-based CR plates to radiographic films. First, images of an aluminum block were analyzed to assess filter impact on scatter reduction. Secondly, a dedicated image quality phantom was used to assess signal linearity, signal-to-noise ratio (SNR), contrast and spatial resolution. Ultimately, a clinical performance study involving two impartial observers was conducted on an anthropomorphic chest phantom, employing visual grading analysis (VGA). Various filter materials and positions as well as post-processing were examined, and the workflow between CR and film was compared.

MAIN RESULTS

CR images exhibited high SNR and linearity but demonstrated lower spatial and contrast resolution when compared to film. However, filtering improved contrast resolution and SNR, while positioning filters inside the cassette additionally enhanced sharpness. Image processing improved VGA scores, while additional filtering also resulted in higher spine visibility scores. CR shortened TBI simulation by over 10 minutes for one patient, alongside a dose reduction by order of 0.1 Gy.

SIGNIFICANCE

This study highlights potential advantages of shifting from conventional radiographic film to CR for TBI. Overall, CR with the incorporation of processing and filtering proves to be suitable for TBI chest imaging. When compared to radiographic film, CR offers advantages such as reduced simulation time and dose delivery, re-usability of image plates and digital workflow integration.

Automated Segmentation and Diagnostic Measurement for the Evaluation of Cervical Spine Injuries Using X-Rays

Accurate assessment of cervical spine X-ray images through diagnostic metrics plays a crucial role in determining appropriate treatment strategies for cervical injuries and evaluating surgical outcomes. Such assessment can be facilitated through the use of automatic methods such as machine learning and computer vision algorithms. A total of 852 cervical X-rays obtained from Gachon Medical Center were used for multiclass segmentation of the craniofacial bones (hard palate, basion, opisthion) and cervical spine (C1-C7), incorporating architectures such as EfficientNetB4, DenseNet201, and InceptionResNetV2. Diagnostic metrics automatically measured using computer vision algorithms were compared with manually measured metrics through Pearson's correlation coefficient and paired t-tests. The three models demonstrated high average dice coefficient values for the cervical spine (C1, 0.93; C2, 0.96; C3, 0.96; C4, 0.96; C5, 0.96; C6, 0.96; C7, 0.95) and lower values for the craniofacial bones (hard palate, 0.69; basion, 0.81; opisthion, 0.71). Comparison of manually measured metrics and automatically measured metrics showed high Pearson's correlation coefficients in McGregor's line (r = 0.89), space available cord (r = 0.94), cervical sagittal vertical axis (r = 0.99), cervical lordosis (r = 0.88), lower correlations in basion-dens interval (r = 0.65), basion-axial interval (r = 0.72), and Powers ratio (r = 0.62). No metric showed adjusted significant differences at P < 0.05 between manual and automatic metric measuring methods. These findings demonstrate the potential of multiclass segmentation in automating the measurement of diagnostic metrics for cervical spine injuries and showcase the clinical potential for diagnosing cervical spine injuries and evaluating cervical surgical outcomes.

AAPM task group report 305: Guidance for standardization of vendor-neutral reject analysis in radiography

Reject rate analysis is considered an integral part of a diagnostic radiography quality control (QC) program. A rejected image is a patient radiograph that was not presented to a radiologist for diagnosis and that contributes unnecessary radiation dose to the patient. Reject rates that are either too high or too low may suggest systemic department shortcomings in QC mechanisms. Due to the lack of standardization, reject data often cannot be easily compared between radiography systems from different vendors. The purpose of this report is to provide guidance to help standardize data elements that are required for comprehensive reject analysis and to propose data reporting and workflows to enable an effective and comprehensive reject rate monitoring program. Essential data elements, a proposed schema for classifying reject reasons, and workflow implementation options are recommended in this task group report.

Patient's effective dose and performance assessment of computed radiography systems

Computed tomography is widely used for planar imaging. Previous studies showed that CR systems involve higher patient radiation doses compared to digital systems. Therefore, assessing the patient's dose and CR system performance is necessary to ensure that patients received minimal dose with the highest possible image quality. The study was performed at three medical diagnostic centers in Sudan: Medical Corps Hospital (MCH), Advance Diagnostic Center (ADC), and Advance Medical Center (AMC). The following tools were used in this study: Tape measure, Adhesive tape, 1.5 mm copper filtration (>10 × 10 cm), TO 20 threshold contrast test object, Resolution test object (e.g., Huttner 18), MI geometry test object or lead ruler, Contact mish, Piranha (semiconductor detector), Small lead or copper block (∼5 × 5 cm), and Steel ruler, to do a different type of tests (Dark Noise, Erasure cycle efficiency, Sensitivity Index calibration, Sensitivity Index consistency, Uniformity, Scaling errors, Blurring, Limiting spatial Resolution, Threshold, and Laser beam Function. Entrance surface air kerma (ESAK (mGy) was calculated from patient exposure parameters using DosCal software for three imaging modalities. A total of 199 patients were examined (112 chest X rays, 77 lumbar spine). The mean and standard deviation (sd) for patients ESAK (mGy) were 2.56 ± 0.1 mGy and 1.6 mGy for the Anteroposterior (AP) and lateral projections for the lumbar spine, respectively. The mean and sd for the patient's chest doses were 0.1 ± 0.01 for the chest X-ray procedures. The three medical diagnostic centers' CR system performance was evaluated and found that all of the three centers have good CR system functions. All the centers satisfy all the criteria of acceptable visual tests. CR's image quality and sensitivity were evaluated, and the CR image is good because it has good contrast and resolution. All the CR system available in the medical centers and upgraded from old X-ray systems to new systems, has been found to work well. The patient's doses were comparable for the chest X-ray procedures, while patients' doses from the lumbar spine showed variation up to 2 folds due to the variation in patients' weight and X-ray machine setting. Patients dose optimization is recommended to ensure the patients received a minimal dose while obtaining the diagnostic findings.

Ex vivo assessment of the buccal and oral bone by CBCT

PURPOSE

Identifying buccal and oral bone as an important supporting periodontal structure for teeth provides important information for treatment planning in periodontics and orthodontics. This study aims to add evidence to the knowledge of preciseness of cone beam computed tomography (CBCT) measurements of the vertical dimension of buccal and oral bone. The hypothesis is that CBCT is an accurate and reliable method to measure vertical vestibular and oral bone loss.

METHODS

The amount of vertical buccal and oral bone loss (bl) of 260 sites of 10 human cadavers was investigated clinically and radiographically by CBCT. Radiographic measurements were rated by two blinded raters. Measurements and the corresponding differences between clinical and radiological findings are described by medians and quartiles (Q1-Q3). For statistical analysis, Lin's concordance correlation coefficient (CCC) and Bland-Altman plots were calculated.

RESULTS

The CCC between the raters was 0.994 (95% confidence interval 0.992-0.995). The median bone loss (bl) distance from the cementoenamel junction (CEJ) to the bony defect (BD) was 3.5 mm (range 3-5 mm). The median bl measured in the CBCT was 3.8 mm (range 3.1-4.8 mm). The median difference of the 2 measurements for all sites included in the study (N = 260) was -0.2 mm (-0.7 to 0.3 mm).

CONCLUSIONS

CBCT seems to be an accurate and highly reliable method to detect and describe vertical buccal and oral bone loss. It could improve planning and prediction for successful combined periodontal and orthodontic therapies.

Characterization of the imaging settings in screening mammography using a tracking and reporting system: A multi-center and multi-vendor analysis

A tracking and reporting system was developed to monitor radiation dose in X-ray breast imaging. We used our tracking system to characterize and compare the mammographic practices of five breast imaging centers located in the United States and Brazil. Clinical data were acquired using eight mammography systems comprising three modalities: computed radiography (CR), full-field digital mammography (FFDM), and digital breast tomosynthesis (DBT). Our database consists of metadata extracted from 334,234 images. We analyzed distributions and correlations of compressed breast thickness (CBT), compression force, target-filter combinations, X-ray tube voltage, and average glandular dose (AGD). AGD reference curves were calculated based on AGD distributions as a function of CBT. These curves represent an AGD reference for a particular population and system. Differences in AGD and imaging settings were attributed to a combination of factors, such as improvements in technology, imaging protocol, and patient demographics. The tracking system allows the comparison of various imaging settings used in screening mammography, as well as the tracking of patient- and population-specific breast data collected from different populations.

Reject rate analysis in digital radiography: an Australian emergency imaging department case study

Introduction

Reject analysis in digital radiography (DR) helps guide the education and training of staff, influences department workflow, reduces patient dose and improves department efficiency. The purpose of this study was to investigate rejected radiographs at a major metropolitan emergency imaging department to help form a benchmark of reject rates for DR and to assess what radiographs are being rejected and why.

Methods

A retrospective longitudinal study was undertaken as an in‐depth clinical audit. The data were collected using automated reject analysis software from two digital x‐ray systems from June 2015 to April 2017. The overall reject rate, reasons for rejection as well as the reject rates for individual radiographers, examination types and projections were analysed.

Results

A total of 90,298 radiographic images were acquired and included in the analysis. The average reject rate was 9%, and the most frequent reasons for image rejection were positioning error (49%) and anatomy cut‐off (21%). The reject rate varied between radiographers as well as for individual examination types and projections.

Conclusions

The variation in radiographer reject rates and the high reject rate for some projections indicate that reject analysis is still necessary as a quality assurance tool for DR. A feedback system between radiologists and radiographers may reduce the high percentage of positioning errors by standardising the technical factors used to assess image quality. Future reject analysis should be conducted regularly incorporating an exposure indicator analysis as well as retrospective assessment of individual rejected images.

Ex vivo comparison of CBCT and digital periapical radiographs for the quantitative assessment of periodontal defects

OBJECTIVES

Accurate imaging is essential for effective treatment planning in periodontology. The aim of this ex vivo study was to investigate the accuracy of cone beam computed tomography (CBCT) and digital periapical radiographs (PA) in imaging periodontal defects. Hypotheses are: 1. That CBCT is a more accurate method than PA concerning vertical measurements of periodontal bone defects2. That CBCT itself is an accurate method to describe vertical periodontal bone loss MATERIAL AND METHODS: In this study, 117 periodontal defects from 10 human cadavers were investigated radiographically by CBCT and PA by one calibrated observer. Afterwards the vertical bone loss was measured with a periodontal probe by the same calibrated observer. Differences between radiographic and clinical measurements were calculated and analyzed. Bland-Altmann plots including 95% limits of agreement were calculated.

RESULTS

The 95% limits of agreement ranged from 3.29 to -3.27 mm between clinical measurements and measurements in PAs, and from 2.13 to -1.97 mm in CBCTs. The mean difference between clinical and radiographic measurements was 0.0009 mm for PA and 0.0835 mm for CBCT.

CONCLUSIONS

When comparing the clinical measurements, CBCT had a higher agreement and less deviations than PAs, and CBCT seems to be an accurate method to describe vertical periodontal bone loss.

CLINICAL RELEVANCE

Accurate description of defects is helpful for accurate treatment planning.

Retrospective evaluation of exposure indicators: a pilot study of exposure technique in digital radiography

INTRODUCTION

Digital radiography lacks visual clues of exposure techniques used to obtain radiographs, therefore manufacturers have included exposure indicators (EIs). EIs provides feedback about exposure techniques used and evaluating EIs will yield much needed information about exposure trends used in digital radiography.

METHODS

A retrospective explorative quantitative study was conducted at nine randomly selected imaging departments in Gauteng, South Africa. Data pertaining to EI was retrospectively collected using quota sampling and compared to manufacturer recommended (MR) standards.

RESULTS

A total of 1422 EIs were collected. 50% of these were within the MR standard. 27% of EI indicated overexposure and 23% indicated underexposure.

CONCLUSIONS

Greater evidence of overexposure was noted in the retrospective analysis of the EI. This pilot study shows the need for further investigation into exposure technique practices in digital radiography and the need for measures to halt the evidenced overexposure.

Chimera of digital radiography in spine surgery: False diagnosis of implant failure

BACKGROUND

Digital radiographs of the whole spine are made using marginally superimposed imaging plates exposed simultaneously to be combined by interpolation of the overlapping area. Post-processing artefacts in these radiographs leading to the misdiagnosis of implant breakage have not yet been described in the literature.

METHODS

An erroneous fusion of a digital spine x-ray after scoliosis surgery created an image showing two broken rods, whereas both rods proved complete continuity intraoperatively. Following an interdisciplinary error analysis, the chain of errors was systematically reconstructed. Using the digital imaging material of patients operatively treated the same way; the reproducibility of the error was analyzed. Erroneous image fusions were produced by slight displacement of existing, not yet combined x-ray images of these patients.

RESULTS

Under certain requirements, the false impression of implant breakage could be reproduced. Especially in the case of missing or malpositioned radiopaque markers, the hazard to overlook an erroneous image fusion is present. Within the post-processing step performed by qualified staff, control is indispensable and manual correction can be crucial.

CONCLUSIONS

This experimental study and causal analysis show the clinical relevance of post-processing artefacts in digital radiography. To prevent false diagnosis and maltreatment, the knowledge of possible sources of error is indispensable.

Simulation of a complete X-ray digital radiographic system for industrial applications

Simulating X-ray images is of great importance in industry and medicine. Using such simulation permits us to optimize parameters which affect image's quality without the limitations of an experimental procedure. This study revolves around a novel methodology to simulate a complete industrial X-ray digital radiographic system composed of an X-ray tube and a computed radiography (CR) image plate using Monte Carlo N Particle eXtended (MCNPX) code. In the process of our research, an industrial X-ray tube with maximum voltage of 300 kV and current of 5 mA was simulated. A 3-layer uniform plate including a polymer overcoat layer, a phosphor layer and a polycarbonate backing layer was also defined and simulated as the CR imaging plate. To model the image formation in the image plate, at first the absorbed dose was calculated in each pixel inside the phosphor layer of CR imaging plate using the mesh tally in MCNPX code and then was converted to gray value using a mathematical relationship determined in a separate procedure. To validate the simulation results, an experimental setup was designed and the images of two step wedges created out of aluminum and steel were captured by the experiments and compared with the simulations. The results show that the simulated images are in good agreement with the experimental ones demonstrating the ability of the proposed methodology for simulating an industrial X-ray imaging system.

Development of a tool to aid the radiologic technologist using augmented reality and computer vision

This technical innovation describes the development of a novel device to aid technologists in reducing exposure variation and repeat imaging in computed and digital radiography. The device consists of a color video and depth camera in combination with proprietary software and user interface. A monitor in the x-ray control room displays the position of the patient in real time with respect to automatic exposure control chambers and image receptor area. The thickness of the body part of interest is automatically displayed along with a motion indicator for the examined body part. The aim is to provide an automatic measurement of patient thickness to set the x-ray technique and to assist the technologist in detecting errors in positioning and motion before the patient is exposed. The device has the potential to reduce the incidence of repeat imaging by addressing problems technologists encounter daily during the acquisition of radiographs.

Combat radiology: Challenges and opportunities

Radiology services in a combat situation are essentially centred on assisting the battle field physicians/surgeons to save/salvage life and limb. Timely and accurate detection of type and mapping of extent of injury can aid in making imaging based triage which can be of immense help to the treating physicians/trauma surgeons. With the availability of rapid assessment (clinical as well as imaging based) and quick transport facility, the focus has gradually been shifting from merely limb-saving to life-saving strategies. Providing the right imaging modality at the right time for the right patient at the right place is the need of the hour and will dictate the success of combat casualty care. Although there are limitations in terms of terrain and hostility in a combat scenario, newer developments in the field of Radiodiagnosis and imaging can be optimally utilized for better casualty care services. Point of care Digital/Computed Radiography and basic Ultrasonography for trauma complemented by usage of multidetector computed tomography will go a long way in helping timely and accurate management of victims of blast and ballistic injury in a combat scenario. Following a rigid, easy to understand yet comprehensive protocol and radiology reporting system will be invaluable in the combat scenario despite various limitations.

RADIOGRAPHY IN THE FIELD: ASSESSING A LIGHTWEIGHT, HANDHELD, BATTERY-POWERED DENTISTRY UNIT FOR FIELD DIAGNOSTIC APPLICATIONS

Radiography units are not used commonly in wildlife medicine field settings, primarily because of their weight and requirement for a power supply. In this study, a portable, battery-powered, and lightweight radiography unit, originally developed for dentistry, was assessed for its potential field applications. Radiographs of various animal species (ranging in weight from 14 g to 1,000 kg) were imaged using varying source image distance (SID) and exposure time. The quality of these images was evaluated for their resolution, image noise, and motion blur. When required, image resolutions were further enhanced using computed radiography postprocessing. Other parameters evaluated were the freehand use of the device, its battery durability, the maximum obtainable image size, and multiple use of a single computed radiography cassette. Using an SID of 60 cm, radiographs delivered adequate image quality. The quality, however, was found deteriorated in images of larger animals (>50 kg) or thicker tissues (>15 cm). The use of a tripod proved unnecessary in most cases, and its exclusion greatly facilitated equipment handling. Under field conditions, the battery was depleted after a total running time of 1.6 hr or 36 radiographs. The maximum size of a radiographic image reached a diameter of 40 cm, and radiation shielding allowed the multiple use of a single computed radiography cassette. Taken together, the radiography unit evaluated in this study presented a balanced compromise between portability and radiograph quality for field use. However, the unit image resolution cannot replace those of the fixed standard radiography units commonly used in veterinary medicine.

Diagnostic Imaging of Dental Disease in Pet Rabbits and Rodents

Diagnostic imaging techniques are of paramount importance for dentistry and oral disorders of rabbits, rodents, and other exotic companion mammals. Aside from standard radiography, stomatoscopy is a complementary tool allowing a thorough and detailed inspection of the oral cavity. Computed tomography (CT) generates multiple 2-dimensional views and 3-dimensional reconstructions providing superior diagnostic accuracy also useful for prognosis and treatment of advanced dental disease and its related complications. MRI is a diagnostic imaging technique additional to CT used primarily to enhance soft tissues, including complex odontogenic abscesses.

An investigation into the accuracy of orbital X-rays, when using CR, in detecting ferromagnetic intraocular foreign bodies

PURPOSE

The aim of this study is to determine the accuracy of orbital X-rays, when using computed radiography (CR), in detecting ferromagnetic intra-ocular foreign bodies (IOFBs) prior to magnetic resonance imaging (MRI).

METHODS

A total of 64 orbital X-rays of an anthropomorphic head phantom were acquired using CR. For each image 1, 2, 3, or 4, large, medium, or small IOFBs were fixed to the anterior surface of the left or right orbit. Each of the acquired images with an IOFB was duplicated in order to increase the sample size. A further 16 normal images (no IOFB) were also included in the sample. Observers were invited to review the images and were permitted to manually magnify and window the images to detect any IOFBs present on each image.

RESULTS

10 observers (4 radiographers; 4 reporting radiographers; 2 consultant radiologists) independently reviewed the images. The mean (SD) sensitivity and specificity were 72.1% (7.3%) and 99.2% (0.8%) for all observers, respectively. According to size the sensitivity in detecting small, medium and large IOFB were 46%, 76% and 93%, respectively. According to location, the lower lateral quadrants had the lowest sensitivity (53%) whereas the upper medial had the greatest (88%).

CONCLUSION

Findings from this study using CR support previous conclusions that conventional X-rays fail to detect metallic IOFBs in all cases. Diagnostic performance is governed by IOFB size and location.

Spectrum optimization for computed radiography mammography systems

PURPOSE

Technical quality assurance is a key issue in breast screening protocols. While full-field digital mammography systems produce excellent image quality at low dose, it appears difficult with computed radiography (CR) systems to fulfill the requirements for image quality, and to keep the dose below the limits. However, powder plate CR systems are still widely used, e.g., they represent ∼30% of the devices in the Austrian breast cancer screening program. For these systems the selection of an optimal spectrum is a key issue.

METHODS

We investigated different anode/filter (A/F) combinations over the clinical range of tube voltages. The figure-of-merit (FOM) to be optimized was squared signal-difference-to-noise ratio divided by glandular dose. Measurements were performed on a Siemens Mammomat 3000 with a Fuji Profect reader (SiFu) and on a GE Senograph DMR with a Carestream reader (GECa).

RESULTS

For 50mm PMMA the maximum FOM was found with a Mo/Rh spectrum between 27kVp and 29kVp, while with 60mm Mo/Rh at 28kVp (GECa) and W/Rh 25kVp (SiFu) were superior. For 70mm PMMA the Rh/Rh spectrum had a peak at about 31kVp (GECa). FOM increases from 10% to >100% are demonstrated.

CONCLUSION

Optimization as proposed in this paper can either lead to dose reduction with comparable image quality or image quality improvement if necessary. For systems with limited A/F combinations the choice of tube voltage is of considerable importance. In this work, optimization of AEC parameters such as anode-filter combination and tube potential was demonstrated for mammographic CR systems.

Breast cancer detection rates using four different types of mammography detectors

OBJECTIVE

To compare the performance of different types of detectors in breast cancer detection.

METHODS

A mammography image set containing subtle malignant non-calcification lesions, biopsy-proven benign lesions, simulated malignant calcification clusters and normals was acquired using amorphous-selenium (a-Se) detectors. The images were adapted to simulate four types of detectors at the same radiation dose: digital radiography (DR) detectors with a-Se and caesium iodide (CsI) convertors, and computed radiography (CR) detectors with a powder phosphor (PIP) and a needle phosphor (NIP). Seven observers marked suspicious and benign lesions. Analysis was undertaken using jackknife alternative free-response receiver operating characteristics weighted figure of merit (FoM). The cancer detection fraction (CDF) was estimated for a representative image set from screening.

RESULTS

No significant differences in the FoMs between the DR detectors were measured. For calcification clusters and non-calcification lesions, both CR detectors' FoMs were significantly lower than for DR detectors. The calcification cluster's FoM for CR NIP was significantly better than for CR PIP. The estimated CDFs with CR PIP and CR NIP detectors were up to 15% and 22% lower, respectively, than for DR detectors.

CONCLUSION

Cancer detection is affected by detector type, and the use of CR in mammography should be reconsidered.

KEY POINTS

The type of mammography detector can affect the cancer detection rates. CR detectors performed worse than DR detectors in mammography. Needle phosphor CR performed better than powder phosphor CR. Calcification clusters detection is more sensitive to detector type than other cancers.

Effect of X-ray beam quality on determination of exposure index

We investigated the effect of X-ray beam qualities RQA3, 5, 7, and 9 on the exposure index (EI) as defined by International Electrotechnical Commission guideline 62494-1. Half-value layers (HVLs) of RQA5 X-rays passing through anti-scatter grids (grid ratios 6:1, 8:1, 10:1, and 12:1) were also evaluated because grids are frequently used in clinical situations. The maximum percent differences in the EIs for RQA3, 7, and 9 with respect to RQA5 were 35.0, 11.6, and 38.7 %, respectively. The range of HVLs for RQA5-7 beams was 7.10-9.10 mm of aluminum (mm Al). This was wider than the range of HVLs when grids were used (6.94-7.29 mm Al). The effect of variations in X-ray beam qualities in the RQA series on the EI was significantly greater than the effect of grids. This study indicated that, in clinical settings, the EI should be used carefully in X-ray examinations with different X-ray beam qualities.

Association between subjective evaluation and physical parameters for radiographic images optimization

PURPOSE

The purpose of this study was to develop a methodology to optimize computed radiographic techniques to image the skull, chest, and pelvis of a standard patient.

METHODS

Optimization was performed by varying exposure levels with different tube voltages to generate images of an anthropomorphic phantom. Image quality was evaluated using visual grading analysis and measuring objective parameters such as the effective detective quantum efficiency and the contrast-to-noise ratio. Objective and subjective evaluations were compared to obtain an optimized technique for each anatomic region.

RESULTS

Gold standard techniques provided a significant reduction in X-ray doses compared to the techniques used in our radiology service, without compromising diagnostic accuracy. They were chosen as follows 102 kVp/1.6 mAs for skull; 81 kVp/4.5 mAs for pelvis and 90 kVp/3.2 mAs for chest.

CONCLUSION

There is a range of acceptable techniques that produce adequate images for diagnosis in computed radiography systems. This aspect allows the optimization process to be focused on the patient dose without compromising diagnostic capabilities. This process should be performed through association of quantitative and qualitative parameters, such as effective detective quantum efficiency, contrast-to-noise ratio, and visual grading analysis.

Status and perspectives of detection by low-dose computed tomography or computed radiography in surgical patients with lung cancer, based on a five-year study

Background

A retrospective study involving 502 lung cancer patients who had received pulmonary resection from 2009–2013 was conducted in order to compare the clinical characteristics of patients whose diagnosis was detected by low‐dose computed tomography (LDCT) and computed radiography (CR).

Methods

Two groups were established, based on the method of detection: the LDCT group included 172 lung cancer patients; the CR group included 330 lung cancer patients. The evolution of proportions of patients in urban and rural regions was also analyzed, according to detection method.

Results

The percentage of patients with stage I was higher in the LDCT group than in the CR group (77.3%, 133/172 vs. 53.6%, 177/330). The incidence of postoperative complications within 30 days was significantly lower in the LDCT than in CR group (25.0% vs. 33.6%). The proportion of patients detected by LDCT or CR in urban regions was constantly higher than in rural regions (with an increase of 13.0% vs. 5.9%); the proportion of LDCT‐detected patients in urban regions was constantly higher than in rural regions (with an increase of 8.7% vs. 5.9%).

Conclusions

LDCT contributes to a higher proportion of early lung cancer diagnoses and a lower incidence of postoperative complications in surgical patients. The proportions of patients detected early and by LDCT have both increased steadily during the last five years. These two trends are more pronounced in urban compared with rural patients.

Evaluation of relative speed of latent images in relation to changes in fading time and storage temperature of imaging plates in computed radiography systems

This study aimed to evaluate the relative speed (RS) of latent images in relation to changes in the fading time and storage temperature of imaging plates (IPs) in computed radiography systems. The storage temperatures adopted were 20, 30, and 40°C, while the fading times employed were 0, 4, 8, 12, and 24 hours. The X-ray exposure factors were 50 kVp, 10 mAs, and a 150 cm distance from an IP to an X-ray source. In the processing of each image, the parameters used for multi-scale image contrast amplification were multiscale image contrast, noise reduction, edge enhancement, and latitude reduction, all assigned a value of 0. Image sensitivity was used to convert linear properties. The RS used for the characteristic curve was evaluated using a uniform aluminum 11-step wedge. Results show that the RS values of IPs with changing fading time were 17.8 ± 0.9 at 20°C, 13.9 ± 1.1 at 30°C, and 13.4 ± 0.9 at 40°C. On the basis of these findings, we conclude that IPs should be stored in the long term at temperatures as low as 20°C.

WE-E-211-01: Medical Physics in Federal and State Governments

In 2010, FDA's Center for Devices and Radiological Health (CDRH) launched an "Initiative to Reduce Unnecessary Radiation Exposure from Medical Imaging" and held a public meeting on "Device Improvements to Reduce Unnecessary Radiation Exposure from Medical Imaging" March 30- 31, 2010). In follow-up, FDA is pursuing efforts using its regulatory authority as it applies to imaging equipment and manufacturers and also partnering with professional organizations such as AAPM, industry and other governmental agencies to incorporate radiation protection principles into facility quality assurance, personnel credentialing, and training requirements.The current U.S. Federal guidance on medical x-rays was published in 1976 and addresses film imaging for radiographie and dental modalities. The Medical Workgroup of the Interagency Steering Committee on Radiation Standards (ISCORS) has modernized that document to address both diagnostic and interventional approaches, film and digital imaging, and the broad range of modalities that include radiography, computed tomography, interventional fluoroscopy, dentistry, bone densitometry, and veterinary practice. The current scope and status of the document will be presented.The Military Health System is committed to providing state-of- the-art care to its beneficiaries; both at home and abroad. Personnel constraints and the continuing wars oversees have created obstacles to this objective. In the past decade, tremendous advances have occurred in Electronic Health Records (EHR) and Teleradiology. Military Radiology seeks to leverage these advances as a means of surmounting many of the challenges it faces. In this talk, the current status of DoD teleradiology and EHR will be presented.

LEARNING OBJECTIVES

1. To provide a venue in which physicists working in the public sector can interface and discuss specific issues related to supporting the federal and state governments 2. To provide a venue for medical physicists to voice specific concerns with federal/state programs where medical physics should be involved in and/or more effective. 3. To educate audience on federal or state new or updated guidelines.

SU-E-I-102: Independent Implementation of AAPM TG-150 Draft Image Receptor Test Recommendations

PURPOSE

To determine whether a proposed suite of generic tests for digital radiography (DR) detectors could be reduced to practice.

METHODS

MATLAB software was developed to analyze images according to descriptions in a document drafted by the TG150 Detector Subgroup. Forprocessing images were acquired directly from the acquisition stations of three DR and one Computed Radiography system. Images included flat-field exposures at the manufacturer's calibration condition, twice the exposure, ½ the exposure, and a low exposure, plus three images of a lead bar pattern in different orientations, also at the calibration condition. The flat field images were analyzed to determine Detector Response; Gain Correction; Signal, Noise, and Signal-to-noise (SNR) Uniformity; SNR Magnitude; and Anomalous Detector Element (del) Identification. The program also allowed visual inspection for evaluation of collimation and non-uniformity. Bar pattern images were analyzed to evaluate spatial resolution by a variance method.

RESULTS

Acquisition revealed a number of pitfalls. Some manufacturers have multiple calibration points. For-processing images are not directly available from all systems, and PACS may modify them from their original state. The orientation of the flat field with respect to the anodecathode axis may not be defined by the manufacturer. Care must be taken to ensure collimation outside the edges of detectors, or the software must exclude collimator shadows. The matrix size of images differs among manufacturers, so the size of the region of interest (ROI) for analysis varies from the default size of 100×100 dels, as does the number of ROIs. The approach for dealing with edges and ROIs may affect the numerical results. The detector response function may also affect the interpretation of results.

CONCLUSIONS

The software successfully implements most of the detector tests recommended by TG150. Comparison of these results with those of the parallel effort will validate the draft test definition.

SU-D-BRCD-06: Measurement of Elekta Electron Energy Spectra Using a Small Magnetic Spectrometer

PURPOSE

To demonstrate how a small magnetic spectrometer can measure the energy spectra of seven electron beams on an Elekta Infinity tuned to match beams on a previously commissioned machine.

METHODS

Energyspectra were determined from measurements of intensity profiles on 6″-long computed radiographic (CR) strips after deflecting a narrow incident beam using a small (28 lbs.), permanent magnetic spectrometer. CR plateexposures (<1cGy) required special beam reduction techniques and bremsstrahlung shielding. Curves of CR intensity (corrected for non- linearity and background) versus position were transformed into energy spectra using the transformation from position (x) on the CR plate to energy (E) based on the Lorentz force law. The effective magnetic field and its effective edge, parameters in the transformation, were obtained by fitting a plot of most probable incident energy (determined from practical range) to the peak position.

RESULTS

The calibration curve (E vs. x) fit gave 0.423 Tesla for the effective magnetic field. Most resulting energy spectra were characterized by a single, asymmetric peak with peak position and FWHM increasing monotonically with beam energy. Only the 9-MeV spectrum was atypical, possibly indicating suboptimal beam tuning. These results compared well with energy spectra independently determined by adjusting each spectrum until the EGSnrc Monte Carlo calculated percent depth-dose curve agreed well with the corresponding measured curve.

CONCLUSIONS

Results indicate that this spectrometer and methodology could be useful for measuring energy spectra of clinical electron beams at isocenter. Future work will (1) remove the small effect of the detector response function (due to pinhole size and incident angular spread) from the energy spectra, (2) extract the energy spectra exiting the accelerator from current results, (3) use the spectrometer to compare energy spectra of matched beams among our clinical sites, and (4) modify the spectrometer to utilize radiochromic film.

Initial quality performance results using a phantom to simulate chest computed radiography

The aim of this study was to develop a homemade phantom for quantitative quality control in chest computed radiography (CR). The phantom was constructed from copper, aluminium, and polymenthylmethacrylate (PMMA) plates as well as Styrofoam materials. Depending on combinations, the literature suggests that these materials can simulate the attenuation and scattering characteristics of lung, heart, and mediastinum. The lung, heart, and mediastinum regions were simulated by 10 mm x 10 mm x 0.5 mm, 10 mm x 10 mm x 0.5 mm and 10 mm x 10 mm x 1 mm copper plates, respectively. A test object of 100 mm x 100 mm and 0.2 mm thick copper was positioned to each region for CNR measurements. The phantom was exposed to x-rays generated by different tube potentials that covered settings in clinical use: 110-120 kVp (HVL=4.26-4.66 mm Al) at a source image distance (SID) of 180 cm. An approach similar to the recommended method in digital mammography was applied to determine the CNR values of phantom images produced by a Kodak CR 850A system with post-processing turned off. Subjective contrast-detail studies were also carried out by using images of Leeds TOR CDR test object acquired under similar exposure conditions as during CNR measurements. For clinical kVp conditions relevant to chest radiography, the CNR was highest over 90-100 kVp range. The CNR data correlated with the results of contrast detail observations. The values of clinical tube potentials at which CNR is the highest are regarded to be optimal kVp settings. The simplicity in phantom construction can offer easy implementation of related quality control program.

Practical guidelines for radiographers to improve computed radiography image quality

Computed Radiography (CR) has become a major digital imaging modality in a modern radiological department. CR system changes workflow from the conventional way of using film/screen by employing photostimulable phosphor plate technology. This results in the changing perspectives of technical, artefacts and quality control issues in radiology departments. Guidelines for better image quality in digital medical enterprise include professional guidelines for users and the quality control programme specifically designed to serve the best quality of clinical images. Radiographers who understand technological shift of the CR from conventional method can employ optimization of CR images. Proper anatomic collimation and exposure techniques for each radiographic projection are crucial steps in producing quality digital images. Matching image processing with specific anatomy is also important factor that radiographers should realise. Successful shift from conventional to fully digitised radiology department requires skilful radiographers who utilise the technology and a successful quality control program from teamwork in the department.