In the developed JG method, paper pipes with negligible X-ray absorption were arranged in the room and individual detectors were attached at each point to obtain data. The pipes were placed at 50 cm intervals at a height of 50, 100, and 150 cm from the floor, according to the target room size.

The used dosimeter elements were optically stimulated luminescence (OSL) dosimeters, and the calibration constant of the measurement energy was calculated for each element and evaluated in air kerma.

The scattered radiation distribution of general imaging, angiography, fluoroscopy, CT imaging, and mammography was obtained in each specialized room. To determine the dose distribution resulting from the imaging techniques, a comparison of irradiation conditions and direction of the same equipment were compared. A 20 cm thick AAPM phantom was used to measure the scattered radiation. The radiation field and imaging distance conformed to what would be typically be used in a clinical situation. The irradiation cycle was repeated multiple times to obtain an adequate dose of scattered radiation, which was converted to the dose per test and evaluated.

1. The scattered radiation due to general imaging was evaluated for different irradiation sites. The imaging sites were the fronts of the chest and abdomen. The measurements were performed using a clinically relevant imaging distance and radiation field for an adult, with voltage and radiation intensity of 95 kV and 2 mAs, respectively, for thoracic imaging and 85 kV and 8 mAs, respectively, for abdominal imaging.

• In general, when working in the imaging room, abdominal imaging causes a larger spread of scattered radiation compared to that of thoracic imaging, owing to the differences in the voltage and dose on the abdomen (Fig.3).

2. The scattered radiation due to angiography was evaluated at different irradiation directions. The IVR reference point and LAO 45° were used and the irradiation conditions were the AEC function and standard fluoroscopy time with imaging cycles used in normal diagnostic catheter procedures. For fluoroscopy, the values were 113 kV (added filter: 1.5 mm Al + 0.6 mm Cu) and 10 min, and for imaging the values were 89 kV (added filter: 1.0 mm Al), 10 s and 5 exposures.

• The scattered radiation distribution caused by angiography differed according to imaging direction. The radiation dose 150 cm above the floor was very small when the radiation originated from below and the spread of the dose distribution differed (Fig.4).

3. The scattered radiation due to fluoroscopy was evaluated by studying the difference between the under-table and over-table methods. The irradiation conditions were as follows: AEC function and for both methods (under-table and over-table methods), fluoroscopy was 80 kV, 10 mA, 7.5 pulses, 10 min, and imaging was 85 kV, 200 mA, 0.02 s, 10 exposures.

• In fluoroscopy, a human body phantom was placed in unmeasurable sites when comparing the over-table and under-table methods, resulting in some data loss. However, in the over-table method, the dose was higher 150 cm from the floor in the location where the operator would likely be standing (Fig.5).

4. The scattered radiation from CT scanning was evaluated by studying the difference in tube voltages. CT was performed with 2 tube voltages, 80 kV and 150 kV+Sn0.6 mm filter. The irradiation conditions were as follows: 1 rotation/s, 550 mA, slice thickness of 64×0.6 mm (19.2 mm), beam pitch of 0.6, CTDIvol of 80 mGy, and DLP of 1288 mGy·cm.

• For CT scanning, more scattered radiation 50 cm from the floor was observed as a result of voltage changes, but the scattered radiation distribution also differed, with a wider spread at high voltage (150 kV+Sn0.6 mm) compared to that obtained at 80 kV. This difference was particularly pronounced near the device (Fig.6).

5. When evaluating scattered radiation from 3D mammography tests, a tomosynthesis device was used and the CC and R-MLO difference in HR mode was studied. The irradiation conditions were 31 kV, 56 mAs, W/Al, and the AGD was 2 mGy.

• For mammography, the different imaging positions resulted in different distributions, but the distribution from the CC position exhibited left-right symmetry whereas the distribution from the R-MLO position did not, showing more scattered radiation on the left side (Fig.7).

6. In addition, using fluoroscopy equipment, the difference between the installation of a protective instrument (lead equivalent of 0.25 mm) on the device was investigated. The difference was also measured when the irradiation field was changed from an incident surface of 40 cm x 40 cm to 20 cm x 20 cm.

• For fluoroscopy, the protection provided by the installed protective instruments decreased the amount of scattered radiation to a negligible level (Fig.8).
• In terms of radiation field differences, more scattered radiation occurred using a 40 cm x 40 cm radiation field, and scattered radiation affected all heights from the floor where the operator would likely stand. However, when using a 20 cm x 20 cm field, the quantity of scattered radiation was quite small (Fig.9).