Experimental Study of Dose and Radiogenic Risk Reductions During Brain CT Angiography

The objective of this investigation was to assess and quantify the dose reduction to the thyroid gland and eye lens in pediatric brain Computed tomography angiography (CTA) examinations. This evaluation was conducted before and after implementing thyroid and eye lens shielding and deactivating the tube current modulation (ATCM) techniques. Additionally, the study aimed to evaluate the radiogenic risk associated with these protocols. An experimental inquiry was carried out employing the CIRS ATOM phantom in conjunction with a multi-slice 16 CT scanner. Dosimetry was executed utilizing optically stimulated luminescence dosimeters (OSL) chips. The investigation encompassed the application of circumferential thyroid and eye lens shielding, facilitating a comparative examination against unshielded conditions and the deactivation of ATCM techniques. The introduction of protective materials yielded a substantial 77.51% reduction in lens dose, concurrently lowering the risk of radiation-induced cancer development in the lenses by 77.5%. This transitioned the rate from 3 procedures per 1000 to 6.78 procedures per 10000 Conversely, deactivating the ATCM techniques led to significant dose increases in the thyroid, eye lens, and entrance dose by 50%, 24.3%, and 50.26%, respectively. Notably, the deactivation of ATCM resulted in a 24.3% rise in radiogenic risks to the lens, shifting the rate from 3 per 1000 procedures to 3.74 per 1000 procedures. Similarly, the radiogenic risk to the thyroid gland experienced a 47% escalation, progressing from 23 to 34 procedures per 100000.