RT Journal Article SR Electronic T1 A hand-held ultra-low dose intraoperative x-ray imager: Initial ex-vivo imaging study of human lung nodules without radiocontrast agent JF Journal of Nuclear Medicine JO J Nucl Med FD Society of Nuclear Medicine SP 315 OP 315 VO 60 IS supplement 1 A1 Haewook Park A1 Kook Nam Han A1 Byeong Hyeon Choi A1 Hyun Koo Kim A1 Jae Sung Lee YR 2019 UL http://jnm.snmjournals.org/content/60/supplement_1/315.abstract AB 315Objectives: Recently, we have investigated the novel concept of an intraoperative x-ray imager that can be useful for minimally invasive surgery. To verify this concept, we performed a large-animal imaging study using an agar-based lung nodule model and successfully acquired an impressive x-ray image contrast against normal lung tissue. In particular, our proposed device was able to yield an ultra-low radiation dose (i.e., 50~130 nGy) compared with the conventional C-arm fluoroscopy method (i.e., 5~70 mGy) during the operation. To further demonstrate the feasibility of contrast-agent-free x-ray imaging using our proposed device, in this work, we conducted an ex-vivo imaging study of human lung nodules with and without injecting a radiocontrast agent such as lipiodol. Here, we present the comparative results for x-ray images acquired using a conventional C-arm machine and the proposed device. Methods: Our proposed device consists of a carbon-nanotube-based miniature x-ray tube, which operates under a tube voltage of 40 kVp and a tube current of 2 mA, and an intraoral dental sensor suitable for low-dose x-ray imaging. The exposure time required to acquire a single x-ray snapshot image is 20 msec. Using this device, we performed an ex-vivo imaging study of solid lung nodule specimens resected from cancer patients. Unlike conventional C-arm-based in-situ nodule detection, which involves the preoperative injection of a radiocontrast agent, we identified the target lung nodule through palpation and localization using a 24-gauge needle under the guidance of a thoracic surgeon to demonstrate the feasibility of contrast-agent-free x-ray imaging. X-ray images were then acquired around the identified lesions using both C-arm and the proposed device to verify whether the target nodules can be clearly visualized with and without utilizing any radiocontrast agent. To further address the heat damage issues concerning our proposed device, we repeated the x-ray irradiation 12 times (once every 5 sec) to observe the temperature change after equilibrating our device with the ambient temperature. Results: Although the use of a radiocontrast agent yields a better x-ray image contrast for lung nodules in all patient cases, only the proposed device was able to visualize clinically-meaningful images that indicate the resection margins of solid lung nodules under contrast-agent-free conditions. Unlike conventional x-ray diagnostic equipment, such as computed tomography (CT) or C-arm fluoroscopy devices, no further enhancement was required for x-ray images from the proposed device because our device generates x-ray images at a very close distance without overlapping other organ structures to achieve high-resolution nodule detection. In the temperature measurement, we did not observe any temperature changes following repeated x-ray irradiation, demonstrating the robustness in terms of heat dissipation owing to the short exposure time. Conclusions: Based on the results, we can conclude that our proposed device exhibits a strong potential to replace the conventional C-arm-based in-situ nodule detection method, not only eliminating the use of a radiocontrast agent during x-ray imaging but also reducing the significant radiation doses to both medical staff and cancer patients. Moreover, we expect that our device would be beneficial in detecting tiny metastatic lesions that cannot be identified from preoperative CT-guided localization or finger palpation in surgical sites.