Detection of pulmonary edema in pigs: storage phosphor versus amorphous selenium-based flat-panel-detector radiography

The influence of liquid crystal display monitors on observer performance for the detection of interstitial lung markings on both storage phosphor and flat-panel-detector chest radiography

PURPOSE

To compare observer performance with a flat-panel liquid crystal display (LCD) monitor and with a high-resolution gray-scale cathode ray tube (CRT) monitor in the detection of interstitial lung markings using a silicon flat-panel-detector direct radiography (DR) and storage phosphor computed radiography (CR) in a clinical setting.

MATERIALS AND METHODS

We displayed 39 sets of posteroanterior chest radiographs from the patients who were suspected of interstitial lung disease. Each sets consisted of DR, CR and thin-section CT as the reference standard. Image identities were masked, randomly sorted, and displayed on both five mega pixel (2048x2560x8 bits) LCD and CRT monitors. Ten radiologists independently rated their confidence in detection for the presence of linear opacities in the four fields of the lungs; right upper, left upper, right lower, and left lower quadrant. Performance of a total 6240 (39 setsx2 detector systemsx2 monitor systemx4 fieldsx10 observers) observations was analyzed by multi-reader multi-case receiver operating characteristic (ROC) analysis. Differences between monitor systems in combinations of detector systems were compared using ANOVA and paired-samples t-test.

RESULTS

Area under curves (AUC) for the presence of linear opacities measured by ROC analysis was higher on the LCDs than CRTs without statistical significance (p=0.082). AUC was significantly higher on the DR systems than CR systems (p=0.006). AUC was significantly higher on the LCDs than CRTs for DR systems (p=0.039) but not different for CR systems (p=0.301).

CONCLUSION

In clinical conditions, performance of the LCD monitor appears to be better for detecting interstitial lung markings when interfaced with DR systems.

The usefulness of three-dimensional angiography with a flat panel detector of direct conversion type in a transcatheter arterial chemoembolization procedure for hepatocellular carcinoma: initial experience

The purpose of this study was to assess the usefulness of a three-dimensional (3D) angiography system using a flat panel detector of direct conversion type in treatments with subsegmental transcatheter arterial chemoembolization (TACE) for hepatocellular carcinomas (HCCs). Thirty-six consecutive patients who underwent hepatic angiography were prospectively examined. First, two radiologists evaluated the degree of visualization of the peripheral branches of the hepatic arteries on 3D digital subtraction angiography (DSA). Then the radiologists evaluated the visualization of tumor staining and feeding arteries in 25 patients (30 HCCs) who underwent subsegmental TACE. The two radiologists who performed the TACE assessed whether the additional information provided by 3D DSA was useful for treatments. In 34 (94.4%) of 36 patients, the subsegmental branches of the hepatic arteries were sufficiently visualized. The feeding arteries of HCCs were sufficiently visualized in 28 (93%) of 30 HCCs, whereas tumor stains were sufficiently visualized in 18 (60%). Maximum intensity projection images were significantly superior to volume recording images for visualization of the tumor staining and feeding arteries of HCCs. In 27 (90%) of 30 HCCs, 3D DSA provided additional useful information for subsegmental TACE. The high-quality 3D DSA with flat panel detector angiography system provided a precise vascular road map, which was useful for performing subsegmental TACE of HCCs.

Advances in Digital Radiography: Physical Principles and System Overview

During the past two decades, digital radiography has supplanted screen-film radiography in many radiology departments. Today, manufacturers provide a variety of digital imaging solutions based on various detector and readout technologies. Digital detectors allow implementation of a fully digital picture archiving and communication system, in which images are stored digitally and are available anytime. Image distribution in hospitals can now be achieved electronically by means of web-based technology with no risk of losing images. Other advantages of digital radiography include higher patient throughput, increased dose efficiency, and the greater dynamic range of digital detectors with possible reduction of radiation exposure to the patient. The future of radiography will be digital, and it behooves radiologists to be familiar with the technical principles, image quality criteria, and radiation exposure issues associated with the various digital radiography systems that are currently available.

Image quality and radiation dose on digital chest imaging: comparison of amorphous silicon and amorphous selenium flat-panel systems

OBJECTIVE

The aim of this study was to compare the image quality and radiation dose in chest imaging using an amorphous silicon flat-panel detector system and an amorphous selenium flat-panel detector system. In addition, the low-contrast performance of both systems with standard and low radiation doses was compared.

MATERIALS AND METHODS

In two groups of 100 patients each, digital chest radiographs were acquired with either an amorphous silicon or an amorphous selenium flat-panel system. The effective dose of the examination was measured using thermoluminescent dosimeters placed in an anthropomorphic Rando phantom. The image quality of the digital chest radiographs was assessed by five experienced radiologists using the European Guidelines on Quality Criteria for Diagnostic Radiographic Images. In addition, a contrast-detail phantom study was set up to assess the low-contrast performance of both systems at different radiation dose levels. Differences between the two groups were tested for significance using the two-tailed Mann-Whitney test.

RESULTS

The amorphous silicon flat-panel system allowed an important and significant reduction in effective dose in comparison with the amorphous selenium flat-panel system (p < 0.0001) for both the posteroanterior and lateral views. In addition, clinical image quality analysis showed that the dose reduction was not detrimental to image quality. Compared with the amorphous selenium flat-panel detector system, the amorphous silicon flat-panel detector system performed significantly better in the low-contrast phantom study, with phantom entrance dose values of up to 135 muGy.

CONCLUSION

Chest radiographs can be acquired with a significantly lower patient radiation dose using an amorphous silicon flat-panel system than using an amorphous selenium flat-panel system, thereby producing images that are equal or even superior in quality to those of the amorphous selenium flat-panel detector system.

Image quality and dose management in digital radiography: a new paradigm for optimisation

The advent of digital imaging in radiology, combined with the explosive growth of technology, has dramatically improved imaging techniques. This has led to the expansion of diagnostic capabilities, both in terms of the number of procedures and their scope. Throughout the world, film/screen radiography systems are being rapidly replaced with digital systems. Many progressive medical institutions have acquired, or are considering the purchase of computed radiography systems with storage phosphor plates or direct digital radiography systems with flat panel detectors. However, unknown to some users, these devices offer a new paradigm of opportunity and challenges. Images can be obtained at a lower dose owing to the higher detective quantum efficiency (DQE). These fundamental differences in comparison to conventional film/screens necessitate the development of new strategies for dose and quality optimizations. A set of referral criteria based upon three dose levels is proposed.

Digital radiography of the chest: detector techniques and performance parameters

Substantial advances in detector technology characterize digital chest radiography. This article compares the various systems from a radiologist's point of view. Computed radiography (CR) is a well-established system that is robust, has good reproducibility, and is relatively inexpensive. Image quality has been continuously improved in recent years while the physical size of the readout units has been reduced and the throughput increased. CR is the only digital system that can be used for bedside chest radiographs. Improved detector properties and dual reading have made it a dose-efficient system. Although now widely available, a 4K image matrix does not appear to offer a general diagnostic improvement for imaging the chest. New developments with respect to detector composition and readout process can be expected in the future. Direct radiography (DR) is the common name for different technologies that are characterized by a direct readout matrix that covers the whole exposure area. Conversion of x-ray intensity into electric signals can either be direct (selenium-based systems) or indirect (scintillator/photodiode systems). Advantages of DR systems are a high image quality and the potential for dose reduction. The role of selenium radiography (Thoravision) has decreased after the advent of DR systems although this dedicated chest unit offers high image quality at 400 speed acquisition dose. Especially in a PACS environment, CR and DR systems will increasingly substitute for conventional radiography with advantages for CR for bedside chest radiographs and for DR for high-end chest stands.