Objective To investigate the radon activity concentrations in subways of Nanning City and assess the average annual effective doses for subway staff and passengers due to radon exposure. Methods Sixty-three stations across the subway lines 2, 3, and 5 were selected as study sites. Radon activity concentrations were measured using the scintillation counting method with scintillation vials. Results The radon activity concentrations in subway lines 2, 3, and 5 were 7.9-24.4, 12.0-26.2, and 12.6-18.2 Bq/m³, respectively. The average radon activity concentrations for these three lines were (17.4 ± 4.6), (19.1 ± 4.1), and (14.6 ± 1.7) Bq/m³, respectively. Statistical analysis using SPSS 26.0 software revealed a significant difference in radon activity concentrations among these stations (P<0.01). Considering the data in previous research, the average radon activity concentration across all stations in the subway lines of Nanning City was determined to be 17.4 Bq/m³. The estimated average annual effective dose due to radon exposure was 0.131 mSv for subway staff and 0.033 mSv for passengers. Conclusion The radon activity concentrations in the subway lines of Nanning City were significantly lower than the national standard limit (400 Bq/m³). The annual effective doses from radon exposure for both subway staff and passengers were below the limits specified in the Basic Standards for Protection Against Ionizing Radiation and for the Safety of Radiation Sources (GB18871—2002). The health impact of radon and its progeny on subway staff and passengers in the subway lines of Nanning City was extremely low and can be considered negligible.

Objective:To discuss the problems existing in the implementation of the Chinese health industry standard WS 523-2019 by testing SPECT device.Methods:Under the WS 523-2019 standards, a total of 10 SPECT devices were tested with regard to their SPECT reconstructed spatial resolution (SRSR), system planar sensitivity (SPS), system spatial resolution (SSR), whole body system spatial resolution (WSSR), intrinsic uniformity (IU), intrinsic count rate performance (ICR), intrinsic spatial resolution (ISR) and intrinsic spatial linearity(ISL).Result:Under the requirements of WS 523-2019 standards for qualified limits, there are 3 devices with ISL unqualified and the rest of the performances qualified. The new standards basically can meet the clinical requirements and reflected the overall performance of SPECT.Conclusions:The distance between the radiation source and the surface of the detector has great influence on the spatial resolution.In the measurement of ISL, there must be a lead grid separately in the x and y directions. The lead grids with the parallel slits shall be positioned on the detector with the center slit centered on the detector. It is suggested to add rotation center in the new standards.

Objective To understand the level of quality control in medical linear accelerator in Guangxi, and to provide technical support for the health administrative department to make related standards. Methods To select medical linear accelerators in Guangxi by random sampling method. Results A total of 118 accelerators were checked in 2017—2019, the initial inspection pass rates of medical linear accelerators were 56.8% and re-inspect pass rate were 96.6%. Conclusion The quality control level of the radiology institutions needs to be improved. The health administrative department should strengthen routine management，it is necessary to implement quality control in medical linear accelerator.