Radioprotection 60-3 | Page 23

R. A. C. Guassu et al.: Radioprotection 2025, 60( 3), 221 – 233 223

Table 1. Protocol details for each examination, categorized into areas of intervention: coronary, cerebral, and peripheral. Procedure

Base kV

Frames per second

Pulse width( Williams)

Focus

Dose / frame( mGy / fr)

Projections( C-arm Positions)

Variations in the position of operators during procedures were considered in the data analysis, with the range of movement within predetermined margins. The time spent by operators A and B during procedures also varied but was minimal due to the standardization of procedures in our institution.

The study spanned seven months of dosimetric measurements. During this period, dosimeter readings were conducted monthly to ensure accuracy and continuity of the data collected. These regular measurements allowed for a detailed analysis of the accumulated dose over time. Additionally, the number and category of procedures conducted were recorded each month. For all analyzed procedures, the following parameters were collected at the workstation of each fluoroscopic equipment: exposure time, Air kerma, and P KA.

2.4 Total equivalent dose per procedure type

Fig. 1. Flowchart for all dosimetry assessment and correlations.

These devices were provided by Sapra Landauer, ensuring the accuracy and reliability of the collected radiation exposure data.

The operators were categorized into two groups, A and B, and evaluated in six different interventional radiology procedures. Operator A consisted of an experienced physician leading the procedure, maintaining an average distance of 0.5 m from the patient. Conversely, Operator B, composed of various assistants across different procedures, maintained an average distance of 1 m from the patient. It is noteworthy that, due to the nature of being a teaching hospital, we sought to maintain a standard height for Operator B, which was accurately recorded, as depicted in Figure 2.

For each professional, a set of six dosimeters was used in the same manner as presented in a previous study( Miller et al., 2010b): one at eye level( positioned centered in the mask); one near the thyroid; one at the chest; one at the abdomen; one on the wrist( closer to the X-ray tube), and one on the ankle( closer to the X-ray tube).

All procedures were conducted using radiological protection equipment, including lead aprons, thyroid shields, and lead glasses. Additionally, suspended screens on the ceiling and floor protections were implemented to ensure safety during operations.

An equivalent dose rate( EDR r) was calculated for each monitored region( r) from the total accumulated equivalent dose( AED r) recorded by the dosimeters during monthly measuring cycles( Eq.( 1)). This equation takes into consideration the Total time( Tt)( Bacchim Neto et al., 2017) of exposure, defined as the total time of fluoroscopy in each cycle.

EDR r ¼ AED r

T t

To obtain the Equivalent Dose( ED r, P) related to different procedures, the EDR r was multiplied by the Fluoroscopy Time( T f) of each procedure in the cycle, according to Eq.( 2).

ED r ¼ EDR r T f ð2Þ

ð1Þ

With these data, equivalent dose profiles were estimated for all procedure types and evaluated regions.

2.5 Effective dose estimation through dosimetry

An effective dose( E D) was calculated for each examination using the ED r, T of the six monitored regions. Conversion factors( CF T) of equivalent dose from the six outer regions to 26 internal organs and tissues were used. These CF T s were obtained in previous studies conducted by our research group( Bacchim Neto et al., 2017) and are presented in Table 2. The effective dose was obtained for each procedure using equation( 3). The same experimental conditions employed by Bacchim et al.( 2017). were used in this study.