Image Quality In Digital Radiography Research Articles

Image quality in partially erased DenOptix® storage phosphor plates

This study aimed at investigating the effect of the partial erasing of DenOptix system storage phosphor plates on the image quality of digital radiographs. Standardized digital radiographs were acquired of a phantom mandible, using size 2 intraoral DenOptix storage phosphor plates (n = 10). Subsequently, the active areas of the plates were placed in a viewing box with a constant light intensity of 1,700 lux for 130 seconds to achieve complete erasing (control plate), as well as for 0, 5, 10, 15, 20, 25, 34, 66, and 98 seconds, to compose the experimental group of partially erased plates. The same exposure settings were repeated using the control and experimental plates, which were scanned at a resolution of 300 dpi. Five radiologists independently examined the pairs of digital radiographs obtained with the control and partially erased plates, in random order, and indicated the best image for oral diagnosis. Cochran-Mantel-Haenszels chi-square test, at a significance level of 5%, was used to compare the percentages of superior quality images in each combination of control and partially erased plates, subjectively assessed. No significant differences were found between radiographic images acquired with control and partially erased plates, except for the combination of 0 second (30%) versus 130 seconds (70%), p = 0.0047. It can be concluded that, under adequate light intensity conditions, erasing intraoral DenOptix storage phosphor plates may require time intervals of as little as 5 seconds.

Dose reduction in digital chest radiography and perceived image quality

The aim of the study was to investigate whether radiologists can rank the image quality of digital radiographs with different doses; a preliminary study investigated whether reduced dose images provide sufficient diagnostic quality. Raw data of 40 chest radiographs (posteroanterior (PA) and lateral) obtained with a full-field slot-scan charge-coupled device system in 20 patients with chest pathology were used. Noise was added to simulate reduced dose levels to 50%, 25% and 12%. Four observers ranked the quality of the corresponding images and judged the diagnostic quality. Linear regression analysis was performed. Differences were found in image quality at the different dose levels for both PA (p</=0.0001) and lateral images (p<0.002). The quality was graded sufficient in 159/160 100% dose-level observations and in 159/160 50% dose-level observations. At lower doses, substantially fewer images were graded as having sufficient quality: for PA images, 69/80 for the 25% dose and 63/80 for the 12% dose; for lateral images, 74/80 for the 25% dose and 63/80 for the 12% dose images. In conclusion, observers recognized the reduced quality of lower dose radiographs, although 50% dose imaging was regarded as equal to the 100% dose in having sufficient quality to answer clinical questions. Preliminary findings suggest that a 50% dose reduction seems feasible in a variety of chest pathologies, whereas further dose reduction reduces the diagnostic quality.

WE-E-330D-04: High-Performance Dual-Energy Imaging with a Flat-Panel Detector: Answering the Challenge of Dual-KVp Flood-Field Correction

Purpose: Flood‐Field correction is a critical step in achieving high image quality in digital radiography (DR) and dual‐energy (DE) imaging. The optimal Dark‐Flood correction scheme suggests collection of Flood‐Fields at the same technique as the Projection data. In practical applications calibration data are often collected at the start of the day, and Flood‐Fields not collected for all techniques. The problem of proper Flood‐Field correction is compounded in DE imaging where two projections at different energies need to be considered. The purpose of this study is to quantitatively examine the effects of various Flood‐Field correction schemes on DE imaging performance. Method and Materials: In DE imaging two Projections are collected: a low‐energy image (e.g., 60–90 kVp) and a high‐energy image (e.g., 120–150 kVp). Five Flood‐Field correction schemes were considered: optimal correction (Flood‐Field at the same kVp as the Projection) and four sub‐optimal cases (variations wherein the Flood‐Field kVp is different from that of the Projection). Imaging performance was evaluated in terms of the uniformity, noise‐power spectrum (NPS), and detective quantum efficiency (DQE) in Projection and DE image data. Phantom images were used to assess the contrast‐to‐noise ratio and perceived image quality of DE images processed under each correction scheme. Results: The results reveal a systematic degradation in the performance of the corrections as energy separation between the Projections and the Flood‐Field increases. Sub‐optimal correction schemes degraded imaging performance significantly: image uniformity degraded by a factor of 5–10; soft‐tissue contrast degraded by ∼13%; low‐frequency NPS was significantly increased; and DQE was degraded by >10% at low‐ and mid‐frequencies. Conclusion: The choice of Flood‐Field correction scheme has significant impact on DE imaging performance. This study provides valuable guidance in the implementation of a high‐performance calibration scheme for DE imaging. Deployment in a pre‐clinical DE chest imaging system at our institution is underway.

The Effect of Dose Reduction on Image Quality in Digital Radiography Using a Flat-panel Detector: Experimental Study in Rabbits

Purpose: To evaluate the effect of dose reduction on image quality in digital radiography using a flat-panel detector. Materials and Methods: Digital radiographs of 30 rabbits were obtained at two different dose levels (33.23 Gy for the standard dose group and 20.09 Gy for the reduced dose group). The amorphous selenium-based flatpanel detector system had a panel size of 78.5 inches, a matrix of 12801536 (pixels?), and a pixel pitch of 138 m. Four observers evaluated the soft-copy images on a high-resolution video monitor (256020488 bits) in random order. The observers rated the visibility of 13 different anatomic structures on a 5-point scale, viz. the retrocardiac lung, subdiaphragmatic lung, heart border, diaphragmatic border, proximal airway, unobscured lung, liver border, kidney border, bowel gas, flank stripe, ribs, and vertebrae in the mediastinal and abdominal regions. Statistical significance was determined using Wilcoxon’s signed rank test. Results: There was no statistically significant difference in the visibility of the anatomic structures on digital radiography between the standard and reduced dose groups. Conclusion: Digital radiography using an amorphous selenium-based flat-panel detector can preserve the image quality, even though the does is reduced to 40% of the standard level.

5506504 Method and apparatus for conducting a spatially resolving magnetic resonance examination of a test subject

The anode heel effect can be used to optimize image quality and/or patient dose in digital radiography (DR). In film-screen radiography, the effect can equalize optical density in regions of varying attenuation. Clinical experience suggests that the implementation of DR has led to less awareness of anode orientation. Post-processing is assumed to compensate, but may also alter image impression and potentially obscure image details. Published evidence was examined for the influence of the anode heel effect on image quality in DR.A systematic literature search was carried out using PubMed, Embase, and Web of Science databases. Title and abstracts were screened blinded by three authors, according to in-/exclusion criteria, followed by full-text analysis for final inclusion. Studies where technical and/or visual image quality were reported, was included. All studies were analyzed and assigned quality scores, according to relevant questions. The authors devised a scoring system based on reported information pertaining to reproducibility, interpretation, and generalizability of the methods and conclusions.Five studies were included of heterogeneous design, each with methodological shortcomings. Only a few anatomical areas were covered. Very few patients were examined, and in no studies were images evaluated by radiologists or reporting radiographers. Relevant information such as post-processing, image quality criteria and analysis was insufficient in most studies, making reproduction difficult. Results were contradictory, especially concerning technical vs visual image quality.Limited published evidence was found quantifying the influence of the anode heel effect on image quality using DR technology. More methodologically, robust studies are needed. The published evidence neither proves nor disproves the impact of the heel effect on image quality in DR.Based on a systematic review, no firm recommendations for anode orientation relating to image quality in DR can be provided.