X-ray system simulation software tools for radiology and radiography education.

OBJECTIVES: To develop x-ray simulation software tools to support delivery of radiological science education for a range of learning environments and audiences including individual study, lectures, and tutorials. METHODS: Two software tools were developed; one simulated x-ray production for a simple two dimensional radiographic system geometry comprising an x-ray source, beam filter, test object and detector. The other simulated the acquisition and display of two dimensional radiographic images of complex three dimensional objects using a ray casting algorithm through three dimensional mesh objects. Both tools were intended to be simple to use, produce results accurate enough to be useful for educational purposes, and have an acceptable simulation time on modest computer hardware. The radiographic factors and acquisition geometry could be altered in both tools via their graphical user interfaces. A comparison of radiographic contrast measurements of the simulators to a real system was performed. RESULTS: The contrast output of the simulators had excellent agreement with measured results. The software simulators were deployed to 120 computers on campus. CONCLUSIONS: The software tools developed are easy-to-use, clearly demonstrate important x-ray physics and imaging principles, are accessible within a standard University setting and could be used to enhance the teaching of x-ray physics to undergraduate students. ADVANCES IN KNOWLEDGE: Current approaches to teaching x-ray physics in radiological science lack immediacy when linking theory with practice. This method of delivery allows students to engage with the subject in an experiential learning environment.

Comprehensive assessment of patient image quality and radiation dose in latest generation cardiac x-ray equipment for percutaneous coronary interventions.

This study aimed to determine whether a reduction in radiation dose was found for percutaneous coronary interventional (PCI) patients using a cardiac interventional x-ray system with state-of-the-art image enhancement and x-ray optimization, compared to the current generation x-ray system, and to determine the corresponding impact on clinical image quality. Patient procedure dose area product (DAP) and fluoroscopy duration of 131 PCI patient cases from each x-ray system were compared using a Wilcoxon test on median values. Significant reductions in patient dose ([Formula: see text]) were found for the new system with no significant change in fluoroscopy duration ([Formula: see text]); procedure DAP reduced by 64%, fluoroscopy DAP by 51%, and "cine" acquisition DAP by 76%. The image quality of 15 patient angiograms from each x-ray system (30 total) was scored by 75 clinical professionals on a continuous scale for the ability to determine the presence and severity of stenotic lesions; image quality scores were analyzed using a two-sample [Formula: see text]-test. Image quality was reduced by 9% ([Formula: see text]) for the new x-ray system. This demonstrates a substantial reduction in patient dose, from acquisition more than fluoroscopy imaging, with slightly reduced image quality, for the new x-ray system compared to the current generation system.

Impact of latest generation cardiac interventional X-ray equipment on patient image quality and radiation dose for trans-catheter aortic valve implantations.

OBJECTIVES: This study aimed to determine the impact on radiation dose and image quality of a new cardiac interventional X-ray system for trans-catheter aortic valve implantation (TAVI) patients compared to the previously-used cardiac X-ray system. METHODS: Patient dose and image data were retrospectively collected from a Philips AlluraClarity (new) and Siemens Axion Artis (reference) X-ray system. Patient dose area product (DAP) and fluoroscopy duration of 41 patient cases from each X-ray system were compared using a Wilcoxon test. Ten patient aortograms from each X-ray system were scored by 32 observers on a continuous scale to assess the clinical image quality at the given phase of the TAVI procedure. Scores were dichotomised by acceptability and analysed using a Chi-squared test. RESULTS: Significant reductions in patient dose (p << 0.001) were found for the new system with no significant change in fluoroscopy duration (p = 0.052); procedure DAP reduced by 55%, fluoroscopy DAP by 48% and "cine" acquisition DAP by 61%. There was no significant difference between image quality scores of the two X-ray systems (p = 0.06). CONCLUSIONS: The new cardiac X-ray system demonstrated a very significant reduction in patient dose with no loss of clinical image quality. Advances in Knowledge: The huge growth of TAVI may impact on the radiation exposure of cardiac patients and particularly on operators including anaesthetists; cumulative exposure of interventional cardiologists performing high volume TAVI over 30-40 years may be harmful. The Phillips Clarity upgrade including improved image enhancement and optimised X-ray settings significantly reduced radiation without reducing clinically acceptable image quality.

Does the use of additional X-ray beam filtration during cine acquisition reduce clinical image quality and effective dose in cardiac interventional imaging?

The impact of spectral filtration in digital ('cine') acquisition was investigated using a flat panel cardiac interventional X-ray imaging system. A 0.1-mm copper (Cu) and 1.0-mm aluminium (Al) filter added to the standard acquisition mode created the filtered mode for comparison. Image sequences of 35 patients were acquired, a double-blind subjective image quality assessment was completed and dose-area product (DAP) rates were calculated. Entrance surface dose (ESD) and effective dose (E) rates were determined for 20- and 30-cm phantoms. Phantom ESD fell by 28 and 41 % and E by 1 and 0.7 %, for the 20- and 30-cm phantoms, respectively, when using the filtration. Patient DAP rates fell by 43 % with no statistically significant difference in clinical image quality. Adding 0.1-mm Cu and 1.0-mm Al filtration in acquisition substantially reduces patient ESD and DAP, with no significant change in E or clinical image quality.

Do flat detector cardiac X-ray systems convey advantages over image-intensifier-based systems? Study comparing X-ray dose and image quality.

The recent introduction of "flat-panel detector" (FD)-based cardiac catheterisation laboratories should offer improvements in image quality and/or dose efficiency over X-ray systems of conventional design. We compared three X-ray systems, one image-intensifier (II)-based system (system A), and two FD-based designs (systems B and C), assessing their image quality and dose efficiency. Phantom measurements were performed to assess dose rates in fluoroscopy and cine acquisition. Phantom dose rates were broadly similar for all systems, with all systems classified as offering "low" dose rates in fluoroscopy on standard phantoms. Patient X-ray dose rate and subjective image quality was assessed for 90 patients. Dose area product (DAP) rates were similar for all systems, except system C, which had a lower DAP rate in fluoroscopy. In terms of subjective image quality, the order of preference was (best to worst): system C, system A, system B. This study indicates that the use of an FD detector does not infer an automatic improvement in image quality or dose efficiency over II based designs. Specification and configuration of all of the components in the X-ray system contribute to the dose levels used and image quality achieved.

X-ray dose reduction in fluoroscopically guided electrophysiology procedures.

This study assessed the efficacy of a new dose reduction regime in fluoroscopically guided electrophysiology (EP) procedures, which included diagnostic electrophysiological investigations, radiofrequency ablation, and biventricular pacing. A modified dose regime for fluoroscopy was implemented in one of our cardiac electrophysiology laboratories. The x-ray system was programmed with a hierarchy of three fluoroscopy doses, and therefore image quality and settings. The default (lowest) dose mode was not expected to be suitable for all patient sizes or for the entirety of all procedures. Staff raised the dose level in a stepped manner as and when required to optimize the imaging requirements of the procedure. Phantom studies indicated that the low dose mode provided adequate image quality for visualizing EP catheters, while significantly lowering patient skin dose. In 52 clinical cases, questionnaires were used to assess the subjective clinical image quality. The mean image quality score for the low dose setting was rated between "adequate" and "good." The fluoroscopy dose level was raised from the lowest level for 6% of the total fluoroscopy time. Procedural Dose Area Product (DAP) meter readings were analyzed for patients prior to (n = 85) and after (n = 150) the implementation of the low dose regime and showed an overall reduction in DAP rate of 74%. The hierarchical dose regime proved to be acceptable in routine clinical practice for EP procedures, leading to significant reductions in patient doses.