ence for benign lesions. In terms of complications, there was 1 pneumothorax in the radial EBUS group. Moderate bleeding was encountered in 2 cases in the AF group and 1 case in the radial EBUS group.

Finally, in 2021, Verhoeven and colleagues published a follow-up to their earlier study described above [59]. The goal of this investigation was to evaluate how radiation dosages and diagnostic accuracy changed over time as they gained more experience with cone-beam technology. The investigators changed how they administered radiation over the course of their experience. Initially, their imaging protocols sought to obtain the highest quality images possible. However, later realizing that lesser quality images could suffce depending on the indication, they eventually changed to an imaging protocol with three different radiation dosages: low dose when they needed only to know the relative positioning of tools and lesions; medium dose to evaluate when a ground glass nodule was accessed; high (original) dose to be able to visualize individual bronchi for navigation purposes. Regarding diagnostic accuracy, malignant and benign fndings on bronchoscopy were considered to be true if not negated by later fndings. Non-specifc benign results were considered true negatives if confrmed by subsequent biopsies (e.g., percutaneous or surgical) or clinical follow- ­up of at least six months. Patients were included from the beginning of the investigators’ CBCT-AF program. One hundred patients were included for the radiation analysis. Two hundred forty-eight lesions in 208 patients were included in the diagnostic accuracy analysis; median diameter was 13 mm. At the start of the program, the mean dose area product (DAP) was 47.5 Gy-cm2 (effective dose 14.3 mSv). Over time, as more experience was gained and the above-­ mentioned imaging protocols were instituted, procedural DAP decreased to 25.4 Gy-cm2 (5.8 mSv) by the end of the study period, largely attributable to a reduction in uoroscopic DAP. Diagnostic accuracy increased from 72% to 90% over the study period, despite the fact that lesion size did not change over time but fewer lesions had a bronchus sign.

Mobile CT Studies

Though not necessarily the focus of this chapter on conventional CBCT, the mobile CT technology that offers similar imaging with similar advantages is certainly worth citing. As alluded to above, these devices may, in fact, be more widely accessible to bronchoscopists than conventional CBCT.A few reports currently exist in the literature as to their application for peripheral lung nodules, but further research is already underway [60, 61].

Avasarala and colleagues were the frst to report the use of this technology in diagnostic bronchoscopy [62]. They employed the Cios-­ Spin (Siemens Healthineers, Malvern, PA), a mobile 2D/3D C-arm with a 30 cm2 imaging feld capable of 1952-pixel resolution, originally designed for orthopedic and spinal surgery. Eight patients underwent bronchoscopy. All cases used radial EBUS; two additionally used EMN. “Tool-­ in-­lesion” was confrmed in all cases. Interestingly, intraoperative atelectasis was noticed in the same lung as the target in 75% of cases and in the same segment (partially obscuring the lesion) in over one-third of cases. Diagnostic yield was not determined as patients were not followed longitudinally. Nevertheless, safety and feasibility were shown.

Subsequently, Sadoughi and colleagues reported a series of four patients evaluated with ultrathin bronchoscopy combined with radial EBUS and mobile CT [63].Interestingly, while none of the cases had a bronchus sign on preoperative CT, the radial probe was nevertheless found to be within the target in three of the cases and adjacent to it in the remaining case. This was confirmed by intraoperative CT in all cases. A diagnosis was obtained in all as well.

Finally, Chen and colleagues similarly reported a series of two patients [64].One patient had a peripheral nodule reached and diagnosed with the aid of mobile CT and, interestingly, another had a previously-diagnosed lung adenocarcinoma treated with microwave ablation after mobile CT confrmed that the ablation tool had reached the center of the lesion. CT imaging