ABSTRACT
Objectives: The study aimed to analyze different ways to control air quality during/after aerosol-generating procedures (AGPs) in a small skills lab with restricted natural air ventilation in preclinical dental training (worst-case scenario for aerogen infection control). Different phases were investigated (AGP1: intraoral high-volume evacuation (HVE); AGP2: HVE plus an extraoral mobile scavenger (EOS)) and afterward (non-AGP1: air conditioning system (AC), non-AGP2: AC plus opened door). Methods: Continuous data collection was performed for PM1, PM2.5, and PM10 (µg/m3), CO2 concentration (ppm), temperature (K), and humidity (h-1) during two summer days (AGP: n = 30; non-AGP: n = 30). While simulating our teaching routine, no base level for air parameters was defined. Therefore, the change in each parameter (Δ = [post]-[pre] per hour) was calculated. Results: We found significant differences in ΔPM2.5 and ΔPM1 values (median (25/75th percentiles)) comparing AGP2 versus AGP1 (ΔPM2.5: 1.6(0/4.9)/-3.5(-10.0/-1.1), p=0.003; ΔPM1: 1.6(0.6/2.2)/-2.2(-9.3/-0.5), p=0.001). Between both non-AGPs, there were no significant differences in all the parameters that were measured. ΔCO2 increased in all AGP phases (AGP1/AGP2: 979.0(625.7/1126.9)/549.9(4.0/788.8)), while during non-AGP phases, values decreased (non-AGP1/non-AGP2: -447.3(-1122.3/641.2)/-896.6(-1307.3/-510.8)). ∆Temperature findings were similar (AGP1/AGP2: 12.5(7.8/17.0)/9.3(1.8/15.3) versus non-AGP1/non-AGP2: -13.1(-18.7/0)/-14.7(-16.8/-6.8); p ≤ 0.003)), while for ∆humidity, no significant difference (p > 0.05) was found. Conclusions: Within the limitations of the study, the combination of HVE and EOS was similarly effective in controlling aerosol emissions of particles between one and ten micrometers in skill labs during AGPs versus that during non-AGPs. After AGPs, air exchange with the AC should be complemented by open doors for better air quality if natural ventilation through open windows is restricted.
ABSTRACT
OBJECTIVE/AIM: To identify small particle concentrations (eight categories: ≤0.1 µm × ≤5.0 µm) induced by aerosol-generating procedures (AGPs; high-speed tooth preparation, ultrasonic scaling; air polishing) under high-flow suction with a 16-mm intraoral cannula with and without an additional mobile extraoral scavenger (EOS) device during student training. MATERIALS AND METHODS: Twenty tests were performed (16.94 m2 room without ventilation with constant temperature (26.7 (1.1) °C and humidity (56.53 (4.20)%)). Data were collected 2 min before, 2 min during, and 6 min after AGPs. The EOS device and the air sampler for particle counting were placed 0.35 m from the open mouth of a manikin head. The particle number concentration (PN, counts/m3) was measured to calculate ΔPN (ΔPN = [post-PN] - [pre-PN]). RESULTS: Mean ΔPN (SD) ranged between -8.65E+06 (2.86E+07) counts/m3 for 0.15 µm and 6.41E+04 (2.77E+05) counts/m3 for 1.0 µm particles. No significant differences were found among the AGP groups (p > 0.05) or between the AGP and control groups (p > 0.05). With an EOS device, lower ΔPN was detected for smaller particles by high-speed tooth preparation (0.1-0.3 µm; p < 0.001). DISCUSSION: A greater reduction in the number of smaller particles generated by the EOS device was found for high-speed tooth preparation. Low ΔPN by all AGPs demonstrated the efficacy of high-flow suction. CONCLUSIONS: The additional use of an EOS device should be carefully considered when performing treatments, such as high-speed tooth preparation, that generate particularly small particles when more people are present and all other protective options have been exhausted.
ABSTRACT
PURPOSE: To evaluate the radiation exposure for operating personnel associated with rotational flat-panel angiography and C-arm cone beam CT. MATERIALS AND METHODS: Using a dedicated angiography-suite, 2D and 3D examinations of the liver were performed on a phantom to generate scattered radiation. Exposure was measured with a dosimeter at predefined heights (eye, thyroid, breast, gonads and knee) at the physician's location. Analysis included 3D procedures with a field of view (FOV) of 24 cm × 18 cm (8s/rotation, 20s/rotation and 5s/2 rotations), and 47 cm×18 cm (16s/2 rotations) and standard 2D angiography (10s, FOV 24 cm×18 cm). RESULTS: Measurements showed the highest radiation dose at the eye and thyroid level. In comparison to 2D-DSA (3.9 µSv eye-exposure), the 3D procedures caused an increased radiation exposure both in standard FOV (8s/rotation: 28.0 µSv, 20s/rotation: 79.3 µSv, 5s/2 rotations: 32.5 µSv) and large FOV (37.6 µSv). Proportional distributions were measured for the residual heights. With the use of lead glass, irradiation of the eye lens was reduced to 0.2 µSv (2D DSA) and 10.6 µSv (3D technique with 20s/rotation). CONCLUSION: Rotational flat-panel angiography and C-arm cone beam applications significantly increase radiation exposure to the attending operator in comparison to 2D angiography. Our study indicates that the physician should wear protective devices and leave the examination room when performing 3D examinations.
