Effect of leaded glasses and thyroid shielding on cone beam CT radiation dose in an adult female phantom

Abstract

Objectives:This study aims to demonstrate the effectiveness of leaded glasses in reducing the lens of eye dose and of lead thyroid collars in reducing the dose to the thyroid gland of an adult female from dental cone beam CT (CBCT). The effect of collimation on the radiation dose in head organs is also examined. Methods: Dose measurements were conducted by placing optically stimulated luminescent dosemeters in an anthropomorphic female phantom. Eye lens dose was measured by placing a dosemeter on the anterior surface of the phantom eye location. All exposures were performed on one commercially available dental CBCT machine, using selected collimation and exposure techniques. Each scan technique was performed without any lead shielding and then repeated with lead shielding in place. To calculate the percent reduction from lead shielding, the dose measured with lead shielding was divided by the dose measured without lead shielding. The percent reduction from collimation was calculated by comparing the dose measured with collimation to the dose measured without collimation. Results: The dose to the internal eye for one of the scans without leaded glasses or thyroid shield was 0.450 cGy and with glasses and thyroid shield was 0.116 cGy (a 74% reduction). The reduction to the lens of the eye was from 0.396 cGy to 0.153 cGy (a 61% reduction). Without glasses or thyroid shield, the thyroid dose was 0.158 cGy; and when both glasses and shield were used, the thyroid dose was reduced to 0.091 cGy (a 42% reduction). Conclusions: Collimation alone reduced the dose to the brain by up to 91%, with a similar reduction in other organs. Based on these data, leaded glasses, thyroid collars and collimation minimize the dose to organs outside the field of view.

Prevalence of Protective Shielding Utilization for Radiation Dose Reduction in Adult Patients Undergoing Body Scanning Using Computed Tomography

“…32 Some studies have indicated an increase in image noise in the area directly underlying the protective shield 31,33,34 ; in contrast, other studies indicate no significant effect on diagnostic image quality. 7,8,35 Radiation shields can be placed either over the area being studied and thus in the path of the radiation beam (i.e., ''in-plane'' shielding), or placed over areas outside of the …”

Are Bismuth Shields Useful in Dentomaxillofacial Radiology Practice for the Protection of Eyes and Thyroid Glands from Ionizing Radiation?

“…Although lead thyroid collars and lead glasses are proved to be effective in dose reduction, large lead glasses decrease image quality of the area between the maxillary sinus floor and the orbit, and thyroid shielding impairs the image quality in OPTG and CBCT scanning (7,14,20). Therefore, bismuth shielding may be considered as an alternative in shielding these areas.…”

Praktischer Strahlenschutz am Patienten in der radiologischen Diagnostik

“…Bei anderen Untersuchungen konnte gezeigt werden, dass durch Tragen einer Bleiglasbrille die Dosis der Augenlinse von 4,0 auf 1,5 mGy (61 %) gesenkt wurde, und durch Anlegen eines Schilddrüsenschutzes bei der DVT die Schilddrüsendosis von 1,6ö auf 0,9 mGy (42 %) sank [14,21].…”