A Comparative dose and image quality assessment of a portable, multi-modality extremity imaging system for austere...

Rapid technological innovation in diagnostic imaging requires timely, evidence-based safety and quality assessment to ensure optimal patient care. This study evaluates a novel multi-modality extremity imaging system (OXOS MC2) designed for deployment in remote and austere environments.

To systematically evaluate the radiation safety and image quality characteristics of the MC2 system in its three imaging modalities (radiography, fluoroscopy, and Dynamic Digital Radiography [DDR]), and to compare them with two conventional, single-modality reference systems: a portable radiographic unit and a mobile C-arm fluoroscopic unit.

Radiation dose and image quality were assessed for four extremity regions (hand, shoulder, ankle, knee). Patient dose metrics (Entrance Air Kerma [EAK] and Entrance Air Kerma Rate [EAKR]) were estimated using clinical techniques and measured primary radiation output. Operator dose (effective dose equivalent, H_E) was estimated using a "virtual badge" method based on measured scatter map, leakage rate, and clinical setups provided by practicing orthopedic surgeons. Spatial resolution was quantified by the Modulation Transfer Function (MTF) using the slant-edge method. Contrast performance was analyzed using a Gammex contrast-detail phantom. The image receptor input dose (IRID) and input dose rate (IDRIR) were also measured. Dose comparisons were summarized descriptively due to the small sample size. Image quality comparisons were performed using generalized linear models with Bonferroni correction for multiple comparisons (statistical significance set at p < 0.0019 for each individual test).

The MC2 system demonstrated substantially lower patient EAK compared to the radiographic reference system (14%-59% of the reference). Although EAKR varied relative to the reference fluoroscopic system (15%-245% of the reference) due to differences in setup, the MC2's maximum AKR (3.53 mGy/min) remained well below the regulatory limit (44 mGy/min), indicating a negligible risk of radiation-induced skin injury for the patient. The IRID and IDRIR exhibited trends similar to the EAK and EAKR. Operator doses for the MC2 were consistently lower than those of both reference systems, with the H_E at 9%-45% of the radiographic reference and 2%-80% of the fluoroscopic reference. Patient and operator doses of DDR were comparable to those of fluoroscopy. The MC2 system showed consistent image quality across all three imaging modalities. Its spatial resolution (1.8-1.9 lp/mm) was comparable to the fluoroscopic reference system (1.8-1.9 lp/mm, p = 0.92) but significantly lower than the radiographic reference system (2.1-2.2 lp/mm, p < 0.001). Despite delivering a lower dose to the detector, the MC2 demonstrated no significant difference in low-contrast performance (all p ≥0.11). Handheld operation showed no significant impact on image quality.

The OXOS MC2 is a safe and versatile imaging system capable of meeting various extremity imaging needs in remote and austere environments. With substantially reduced radiation dose and improved portability, it provides a robust alternative to conventional portable radiographic systems. While the MC2 system exhibits compromises in spatial resolution and beam hardness, its unique multi-modality capabilities enable the field deployment of previously inaccessible fluoroscopic and DDR imaging, thereby greatly enhancing patient access to advanced imaging techniques in resource-limited settings.