Spot fluoroscopy: a novel innovative approach to reduce radiation dose in neurointerventional procedures

Abstract

Background Increased interest in radiation dose reduction in neurointerventional procedures has led to the development of a method called "spot fluoroscopy" (SF), which enables the operator to collimate a rectangular or square region of interest anywhere within the general field of view. This has potential advantages over conventional collimation, which is limited to symmetric collimation centered over the field of view. Purpose To evaluate the effect of SF on the radiation dose. Material and Methods Thirty-five patients with intracranial aneurysms were treated with endovascular coiling. SF was used in 16 patients and conventional fluoroscopy in 19. The following parameters were analyzed: the total fluoroscopic time, the total air kerma, the total fluoroscopic dose-area product, and the fluoroscopic dose-area product rate. Statistical differences were determined using the Welch's t-test. Results The use of SF led to a reduction of 50% of the total fluoroscopic dose-area product (CF = 106.21 Gycm², SD = 99.06 Gycm² versus SF = 51.80 Gycm², SD = 21.03 Gycm², p = 0.003884) and significant reduction of the total fluoroscopic dose-area product rate (CF = 1.42 Gycm²/min, SD = 0.57 Gycm²/s versus SF = 0.83 Gycm²/min, SD = 0.37 Gycm²/min, p = 0.00106). The use of SF did not lead to an increase in fluoroscopy time or an increase in total fluoroscopic cumulative air kerma, regardless of collimation. Conclusion The SF function is a new and promising tool for reduction of the radiation dose during neurointerventional procedures.

Keywords: X-ray; collimation; digital subtraction angiography (DSA); dose saving; fluoroscopy; neurointervention.

Fig. 1.

(a) White arrow indicates the upper left corner of the ROI. (b) The upper left corner is defined, and the arrow is being moved to the lower right corner. (c, d) ROI is now defined, and only this part of the FOV, outlined by the white-lined frame, will be exposed to irradiation; the LIH (upper left corner) will be superimposed over the collimated part of the FOV. “Spot” in each corner indicates that SF will be activated.

Fig. 2.

(a) Angiography of left internal carotid artery shows an aneurysm localized proximally on the M1 segment. (b) Conventional fluoroscopic road map used for creation of last image hold. (c) LIH in the left upper corner is no longer displayed – compare with Fig. 1, definition of the FOV. “Spot” in each corner indicates that SF is now activated – only the region inside the white-lined frame is exposed to radiation. Image shows positioning of balloon in front of the aneurysm. (d) Angiography of left internal carotid artery, last run, shows occluded aneurysm and minimal flow in the neck region of the aneurysm.

Fig. 3.

(a) A situation where rectangular ROI does not correspond to a conventional circular sensing area. (b) ROI and sensing area have the same, rectangular shape and completely correspond to each other. (c) Important technical parameters are displayed to the left of the fluoroscopic image. The size and position of the rectangular ROI exposed to irradiation can be changed at any moment during the intervention depending on the size, shape, and position of the targeted vascular structure.

Fig. 4.

SF leads to a significant reduction of the fluoroscopic dose area product (Gycm²), P = 0.03884.

Fig. 5.

SF leads to a significant reduction of total fluoroscopic dose area product per minute (Gycm²/min), P = 0.00106.

Fig. 6.

SF does not lead to increase of fluoroscopy time (min). Difference between the values of fluoroscopy times is not significant, P = 0.70782.

Fig. 7.

SF does not lead to an increase of total fluoroscopic air kerma (Gy). Difference between values of total fluoroscopic air kerma is not significant, P = 0.48906.