Computed Radiography Technology Research Articles

Is digital mammography reducing radiation doses to women?

This study aims to investigate the impact of national quality programs in mammography and technological advances in digital mammography units on the radiation doses delivered to women in Brazil. Radiation dose assessments in mammography units were conducted through a mail-based dosimetric system. For each unit of facilities that applied to one of the two national quality programs, a postal dosimetric system is dispatched, comprising an optically stimulated luminescent dosimeter (OSL) attached to the surface of a 4.0 cm thick polymethyl methacrylate (PMMA) phantom, simulating a compressed breast with 4.5 cm thickness. Testing instructions to expose the dosimetric phantom for assessing the mean glandular dose (MGD) are provided. Between 2012 and 2023, the programs evaluated the MGD in 1,687 mammography units of computed radiography (CR) and direct digital radiography (DR) technologies from 1,399 facilities located in all Brazilian regions. A total of 1,660 (70.5%) evaluations were carried out on CR technology mammography units and 696 (29.5%) on DR units, totaling 2,356 MGD evaluations. The overall average MGD was 1.60 ± 0.80 mGy, with 1.68 ± 0.83 mGy for CR technology and 1.42 ± 0.68 mGy for DR technology. A comparison of average MGD between the periods 2012 - 2018 and from 2019 onwards shows a dose reduction of 8.6% for CR systems and of 26.0% for DR systems (p = 0.000). As CR systems use analog mammography units, which did not undergo technological advances between the two periods, the reduction in doses observed is due to the actions of national quality certification programs and by using image plates for dual-sided reading or needle-based image plates. The reduction observed in DR systems is due to both national quality programs and technological advances in mammography units, especially the use of radiation beams generated by X-ray tubes with tungsten targets.

REPEAT RADIOGRAPHY ANALYSIS AND CORRECTIVE MEASURES IN A PRIVATE MEDICAL COLLEGE AND TEACHING HOSPITAL

Aims and objectives: The primary goal of this study is to identify the body parts that undergorepeated radiographic examinations the most frequently and the prevalent causes of these examinations. Materials and Methods: A prospective study was carried out in the Department of Radio-Diagnosis and Imaging to investigate the reasons behind repeated radiography in a private university hospital in India. A total of 6832 samples were evaluated between November 1, 2021, and April 30, 2022. Discussion: Repetition of a patients radiographic projection can be caused by several circumstances. The common factors found in this study are collimation error, wrong centering, patient motion and incorrect positioning, appearance of artifacts owing to insufficient patient preparation at times and patient non-cooperation like patient motion. Repeat radiographs using the computed radiography technology are influenced by a plethora of circumstances. These variables include technical parameters chosen,the patients Body Mass Index (BMI)and the patients level of preparation. Conclusion: Repeat radiography plays an important role as a key indicator in evaluating the quality of the service provided by the medical imaging department and gives us an insight on whether the dose rates are within the given guidelines or not.

SU‐E‐T‐497: Initial Characterization of a Novel 2D Computed Radiography (CR) Dosimeter for SBRT

PurposeFor 2D, sub‐mm resolution dose measurements Gafchromic™ film is currently a standard in radiotherapy; mainly because of its energy independence and water equivalence. However, EBT film is disposable. Therefore, the dosimetric and uniformity characteristics needs to be estimated from a second, possibly different, (calibration) film. Moreover, EBT has a post‐irradiation coloration and a non‐linear dose dependence with saturation, which limits the applicable time interval and dose range. CR technology forms an interesting alternative for EBT. Dose dependent CRplates have a sub‐mm resolution, and additionally a linear dose dependence over decades of dose. But, CR has an inherent signal fading and energy dependence. Here, for the first time, a radiotherapy 2D CR prototype was characterized for an extended dose range (up to 35Gy), signal fading, and basic energy dependence.MethodsThe prototype was irradiated with a standard 10×10cm 6MV photon beam, and scanned with a commercial CR 15‐X(R) scanner. The time between the start of irradiation and scanning (T_Scan) was monitored. The linearity of the dose response was evaluated between 0 and 35Gy using a fixed T_Scan of 4min, if possible (i.e. ≤10Gy). Next, the signal fading was characterized for a T_Scan‐range of 4 to 20min. The energy dependence was assessed by a comparison of out‐of‐field measurements of CR, EBT, and TLD.ResultsThe radiotherapy CR prototype has a linear response over the complete SBRT dose range (0– 35Gy). The prototype had a small (5%), but linear signal fading over the time interval of interest (4–20min). Out‐of‐field, the prototype has a 8% over response due to an increased amount of low energy photons. The impact of the over response on intensity modulated radiotherapy remains to be evaluated.ConclusionCR technology is promising for SBRT dose measurements up to 35Gy. It is a reusable linear alternative for film dosimetry.

Teleradiology quality assurance -- lessons learnt.

Quality assurance in radiography is an important process in identifying weaknesses in radiographic practice. Understanding where improvements can be made helps to keep the focus on those aspects of radiologywhere intervention can improve image quality. Quality assurance of radiographic images is also feasible for teleradiology platforms, andwithinMedecins Sans Frontieres (MSF) all radiographic images sent for teleradiology are evaluated for quality (Fig. 1). Analysis of the image quality has proved useful in guiding the planning and prioritisation of radiology services withinMSF. The lessons learnt may also useful for other users of radiography in resource-limited settings. Comparing computed radiography images with those of film and chemistry, it is clear that computed radiography images are consistently of significantly higher quality [1]. This observation suggests that wherever possible, transitioning to computed radiography imaging can improve image quality compared to film and chemistry. This is partly because computed radiography technology can compensate for variables such as exposure and film processing. MSF sites that demonstrate better quality with computed radiography imaging have also had radiographer training as a part of the computed radiography installation. Good radiographic technique is a fundamental factor in improving image quality, and radiographer training, whether with computed radiography imaging or film and chemistry, results in better image quality. Wherever possible within MSF, radiographer training is prioritised and then regular visits are planned for continuation of training. A point of discussion at MSF is whether to continue utilisation of referral radiology facilities where the image quality has proved to be consistently poor. If MSF is not in a position to upgrade equipment or provide an investment in radiographer training, it should be considered whether it might be detrimental to patient outcomes to consult images that are very poor in diagnostic quality. Further, MSF has learnt a few other lessons along the way. The teleradiology platform itself must be user-friendly and not require complex processes that require too much time or too many steps. If it’s not straightforward, clinicians might find other avenues to ask for advice. Conversely, feedback to volunteer radiologists is very important in maintaining their interest and in respecting their time and investment in the outcome of the patient. Practically, this has been a difficult point for MSF to promote among field clinicians because their high workload, remote conditions and competing priorities leave less time for follow-up with consultants than clinicians would otherwise like. Last, we have found that radiologists’ reports should attempt to help with a differential diagnosis as much as possible beyond just reporting radiologic findings in order to provide the most benefit to clinicians.

Technical and clinical breast cancer screening performance indicators for computed radiography versus direct digital radiography

To compare technical and clinical screening performance parameters between computed radiography (CR) and direct digital radiography (DR) systems. The number of women screened with CR was 73,008 and with DR 116,945. Technical and patient dose survey data of 25 CR and 37 DR systems were available. Technical performance was expressed by threshold thickness values at the mean glandular dose (MGD) level of routine practice. Clinical indicators included recall rate (RR), cancer detection rate (CDR), percentage of ductal carcinoma in situ (DCIS), percentage of cancers with T-scores smaller than 1 cm and positive predictive value (PPV). Contrast threshold values for the 0.1-mm gold disk were 1.44 μm (SD 0.13 μm) for CR and 1.20 μm (SD 0.13 μm for DR). MGD was 2.16 mGy (SD 0.36 mGy) and 1.35 mGy (SD 0.32 mGy) for CR and DR respectively. We obtained for CR, respectively DR, the following results: RR in the first round of 5.48 % versus 5.61 %; RR in subsequent rounds of 2.52 % versus 2.65 %; CDR of 0.52 % versus 0.53 %; DCIS of 0.08 % versus 0.11 %; a rate of cancers with T-scores smaller than 1 cm of 0.11 % versus 0.11 %; PPV of 18.45 % versus 18.64 %; none of them was significantly different. Our screening indicators are reassuring for the use of CR and DR, with CR operating at 60 % higher MGD. • Breast cancer screening can employ both computed (CR) and direct digital radiography (DR). • Screening performance parameters for CR and DR technology are not significantly different. • Screening parameters are in accordance with European Guidelines. • Radiation doses employed for CR are generally 60 % greater than for DR.

Dosisreduktion und adäquate Bildqualität in der digitalen Radiographie: ein Widerspruch?

Dose reduction and adequate image quality in digital radiography - a contradiction? Digital radiography has already replaced traditional screen-film systems. Substantial improvements in both dose efficiency and spatial resolution demonstrate the rapid developments in digital radiography. Needle-detector systems have shown up to a 50% dose reduction compared to traditional screen-film systems. There is also a dose reduction capability of up to 50% comparing direct radiography (DR) systems to computed radiography (CR) systems for chest X-rays. However, despite the most recent achievements of CR technology, the dose efficiency of DR systems (caesium iodide flat-panel detector) is unparalleled. The progress in detector technology has contributed to dose reduction and improved image quality, while saving time and providing a higher examination rate. The use of dose indicators and longitudinal dose control are important to avoid substantial accidental dose increase. The dose applied to patients should fall markedly below the defined diagnostic reference levels within the European Union. Regular quality control, as well as continuous education and training of medical and technical personnel, contribute to ensure that the ALARA (as low as reasonably achievable) principle is consistently followed.

Feasibility of Dose Reduction Using Needle-Structured Image Plates Versus Powder-Structured Plates for Computed Radiography of the Knee

A newly developed computed radiography (CR) detector that uses a storage phosphor plate made of needle-shaped crystals provides improved dose efficiency. The aim of our study was to compare the image quality of standard-dose CR and dose-reduced CR achieved using needle technology for knee imaging in a clinical setting. We compared standard CR images obtained using a powder-structured image plate (PIP) (ADC Compact Plus) with images obtained using the new needle-structured image plate (NIP) (DX-S). In 30 consecutive patients with knee pain willing to participate in this study, anteroposterior knee radiographs were acquired with both systems at a standard dose. In addition, NIP images were obtained with approximately 75% and 50% of the standard dose (corresponding incident doses: 300, 235, and 154 μGy, respectively). Images were evaluated in a blinded, side-by-side comparison. Six radiologists determined whether there was an appreciable difference in image quality at five anatomic landmarks in regions with high and low differences of attenuation. They also assessed the delineation of selected abnormalities and ranked them using a 10-point scale. The rating scores were tested for statistical differences using an analysis of variance with repeated measures. The mean overall rating scores for the evaluation of anatomic landmarks were 6.97 for NIP images obtained at full dose, 6.48 for NIP images obtained at about 75% dose, 5.47 for NIP images obtained at half dose, and 6.01 for PIP images. There was a significant difference in favor of the CR system with an NIP at the same dose level (p < 0.05). The NIP images obtained at a dose of about 75% were also ranked significantly better than the PIP images with regard to the depiction of both anatomic landmarks and abnormalities. The readers ranked half-dose NIP images inferior to the PIP images with regard to abnormalities and anatomic landmarks in areas with high attenuation, whereas in areas with low attenuation, the image quality was regarded as equivalent to the standard technique. NIP technology allows a dose reduction of approximately 25% compared with PIP while still providing higher image quality. Even at the half-dose level, there was no relevant loss of image quality with regard to the delineation of anatomic landmarks in areas with low attenuation in anteroposterior knee images. The higher dose efficiency of the needle-detector CR technology compared with conventional CR can be used either for dose reduction or for improved image quality.

Optimizing digital radiography of children

Pediatric projection imaging differs from imaging of the adult patient. Children are smaller, more radiosensitive, and less compliant than their adult counterparts. Their characteristics affect the way projection imaging is practiced and how dose is optimized. Computed radiography (CR) and digital radiography (DR) have been embraced by pediatric practitioners in order to reduce dose and improve image quality. Unfortunately, dose optimization with CR and DR has been hampered by a lack of definition of appropriate exposure levels, a lack of standardization in exposure factor feedback, and a lack of understanding of the fundamentals of CR and DR technology. The potential for over-exposure exists with both CR and DR. Both the Society for Pediatric Radiology and the American Association of Physicists in Medicine recognize the promise and shortcomings of CR and DR technology and have taken steps to join with manufacturers in improving the practice of CR and DR imaging. Although the risks inherent in pediatric projection imaging with CR and DR are low, efforts to reduce dose are worthwhile, so long as diagnostic quality is maintained. Long-standing recommendations for limiting radiation dose in pediatric projection imaging are still applicable to CR and DR.

Digital mammography performed with computed radiography technology

Introduced by Fuji Photo Film Japan in the early 1980s, computed radiography (CR) technology has developed considerably since then to become the mature widely installed technology it is today (about 7500 systems worldwide). Various mammographic examinations require high performance results to which CR complies on demand or following some procedures such as geometrical magnification carried out during the examination. The basic CR principles and digital image processing as well as technical improvements are detailed in this study, which also includes a synthesis of the articles on CR mammographic applications referenced in the bibliography, focusing on strong points, limits and current methods of surpassing these limits. New CR technology development perspectives in mammography and computed assisted diagnosis (CAD) algorithms will allow wider use of this method in the near future.

Digital radiography and conventional imaging of the chest: a comparison of observer performance.

The purpose of this study was to compare observer performance in interpreting high-quality, digitally acquired computed radiographs of the chest displayed on either laser-printed radiographs or a workstation with observer performance in interpreting conventional chest radiographs. We performed a receiver-operating-characteristic study in which the presence or absence of five abnormalities was determined by nine experienced radiologists on 310 posteroanterior radiographs of the chest displayed in three forms: conventional radiographs, laser-printed films of digital radiographs, and digital radiographs on a high-resolution workstation. The results of our study suggest that observer performance with laser-printed films of digital radiographs obtained with high-resolution (4K x 5K), high-contrast sensitivity (12 bits) and appropriate exposure is comparable to observer performance with conventional radiographs. Observer performance with digital radiographs displayed on the workstation was found to be significantly lower for abnormalities that contained high-frequency and low-contrast information (e.g., interstitial disease and pneumothorax). Computed radiography technology can produce image quality that is adequate for interpreting posteroanterior radiographs of the chest. Observer performance is not as good when radiographs displayed on workstations are used to diagnose specific abnormalities.

Signal, noise and SNR transfer properties of computed radiography

An investigation of the signal, noise and signal-to-noise transfer properties of a Fuji 7000 series computed radiography (CR) system using third-generation storage plate technology has been undertaken. The results show a significant improvement in signal-to-noise performance of the system compared to an earlier generation of CR technology. Results of the CR evaluation compare favourably to those obtained from a selection of rare-earth screen-film systems evaluated under identical exposure conditions. These results were further substantiated by results from threshold contrast-detail detectability tests.