Program Information
Advanced Methods for the Development of System-Specific and Size-Specific Radiographic Technique Charts Across the Radiology Enterprise
J Wells*, S Mann , E Samei , Duke University Medical Center, Durham, NC
Presentations
WE-AB-601-2 (Wednesday, August 2, 2017) 7:30 AM - 9:30 AM Room: 601
Purpose: The development of clinical technique charts is a non-trivial task, especially within a multi-vendor and multi-model radiography fleet. The introduction of novel imaging technologies can further complicate the standardization of acquisition parameters. Ultimately, quality technique charts should optimize or justify the use of prescribed patient exposure to achieve images of sufficient diagnostic quality, and radiation physics can be used to inform their development and use.
Methods: Monoenergetic wide-angle transmission Monte Carlo simulations were performed using ICRU four-component soft tissue at many combinations of energy (10-150 keV), material thickness (1.25- 50 cm), and field size (2.5-50 cm). These data were used to estimate primary and scatter transmission fractions for image-specific combinations of x-ray field size and soft tissue-equivalent anatomy thickness for simulated incident x-ray spectra. Unfiltered tungsten spectra obtained using TASMIP software [Med. Phys. 24, 1661‐1670 (1997)] were attenuated by enough added aluminum filtration to match system-specific beam quality measurements. Tube output characterization was used to calculate the system-specific mAs required to produce a clinical radiograph at the prescribed target detector exposure. The effect of incorporating an antiscatter grid was determined by a neural network algorithm. Finally, maximum mAs value limits were computed to satisfy diagnostic reference level (DRL) requirements.
Results: The proposed strategy for technique chart development produced results that were more reasonable than those obtained from previous work. In particular, by more rigorously accounting for the differential transport and attenuation of scatter versus primary radiation, techniques for bony extremities, pediatric patients, and large patients were closer to clinically appropriate values. The new technique chart is currently implemented across our institution.
Conclusion: The new method permits the easy generation of system-specific technique charts while also satisfying DRLs. Improved characterization of system geometry and ancillary equipment have further improved the results without imposing undue burden on the supporting physicist.
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