Radiographers’ perspectives’ on visual grading analysis as a scientific method to evaluate image quality

Introduction Radiographers routinely undertake many initiatives to balance image quality with radiation dose (optimisation). For optimisation studies to be successful image quality needs to be carefully evaluated. Purpose was to 1) discuss the strengths and limitations of a Visual Grading Analysis (VGA) method for image quality evaluation and 2) to outline the method from a radiographer's perspective. Methods A possible method for investigating and discussing the relationship between radiographic image quality parameters and the interpretation and perception of X-ray images is the VGA method. VGA has a number of advantages such as being low cost and a detailed image quality assessment, although it is limited to ensure the images convey the relevant clinical information and relate the task based radiography. Results Comparing the experience of using VGA and Receiver Operating Characteristic (ROC) it is obviously that less papers are published on VGA (Pubmed n=1.384) compared to ROC (Pubmed n=122.686). Hereby the scientific experience of the VGA method is limited compared to the use of ROC. VGA is, however, a much newer method and it is slowly gaining more and more attention. Conclusion The success of VGA requires a number of steps to be completed, such as defining the VGA criteria, choosing the VGA method (absolute or relative), including observers, finding the best image display platforms, training observers and selecting the best statistical method for the study purpose should be thoroughly considered. Implication for practice Detailed evaluation of image quality for optimisation studies related to technical definition of image quality

Simulation of Nodule-Like Pathology in Radiographs of the Lumbar Spine.

For the evaluation of the imaging properties of medical radiographic systems there are well-established standards for measuring techniques available, e.g. ISO 9236 for the measurement of the H/D curve. However, such measuring techniques require sophisticated equipment which is not available in a clinical environment. For a clinical routine of image evaluation, techniques like contrast-detail diagrams or the visual inspection of radiographs of grid pattern with varying contrast and spatial resolution are very common. The disadvantage of these techniques is that the corresponding results are very hard to be transferred to real patient images. Therefore, observer studies on the detection of certain pathology are commonly used to e.g. investigate the influence of different radiographic techniques on diagnostic image quality. As it is very difficult to find a sufficient number of patients with real pathologies for such studies, the pathologies are often simulated by fixing e.g. aluminium disks or other nodule-like objects to healthy volunteers when the radiograph is produced. This approach is relatively simple and rather successful in chest imaging. For lumbar spine images, however, the situation is different because nodule-like tumours cannot only consist of bony material which is increasing the X-ray absorption, but tumours can also destroy the bone material resulting in an increased transparency of the corresponding anatomical region. Such a behaviour is extremely hard to be simulated by fixing an external object to the patient. However, it can be easily simulated in a computer and applied to digital radiographic data. The current paper presents a computer model for the simulation of nodules in lumbar spine images. The model has been applied within a CEC founded research project, which was investigating the influence of MTF and noise power spectra on the diagnostic quality of radiographs of the lumbar spine

Digital radiography:optimization of image quality and dose using multi-frequency software

BACKGROUND: New developments in processing of digital radiographs (DR), including multi-frequency processing (MFP), allow optimization of image quality and radiation dose. This is particularly promising in children as they are believed to be more sensitive to ionizing radiation than adults. OBJECTIVE: To examine whether the use of MFP software reduces the radiation dose without compromising quality at DR of the femur in 5-year-old-equivalent anthropomorphic and technical phantoms. MATERIALS AND METHODS: A total of 110 images of an anthropomorphic phantom were imaged on a DR system (Canon DR with CXDI-50 C detector and MLT[S] software) and analyzed by three pediatric radiologists using Visual Grading Analysis. In addition, 3,500 images taken of a technical contrast-detail phantom (CDRAD 2.0) provide an objective image-quality assessment. RESULTS: Optimal image-quality was maintained at a dose reduction of 61% with MLT(S) optimized images. Even for images of diagnostic quality, MLT(S) provided a dose reduction of 88% as compared to the reference image. Software impact on image quality was found significant for dose (mAs), dynamic range dark region and frequency band. CONCLUSION: By optimizing image processing parameters, a significant dose reduction is possible without significant loss of image quality