Establishment of the DRL and warning dose value for CT examinations in our hospital and its application in chest CT dose optimization
10.3760/cma.j.issn.0254-5098.2020.07.010
- VernacularTitle:本院CT辐射剂量参考水平与警示值的建立及其在胸部CT剂量优化中的运用尝试
- Author:
Xinhong WANG
1
;
Wenhong DING
;
Mengxi XU
;
Weimin ZHANG
;
Minming ZHANG
Author Information
1. 浙江大学医学院附属第二医院放射科，杭州 310009
- From:
Chinese Journal of Radiological Medicine and Protection
2020;40(7):543-548
- CountryChina
- Language:Chinese
-
Abstract:
Objective:To optimize the scheme and process of chest CT scanning and control the dose level to the examined individuals by establishing the diagnostic reference level (DRL) and warning dose value from chest CT examinations in our hospital.Methods:The medical records for 205 511 examined individuals, who had undergone chest CT scans in the Second Affiliated Hospital of Zhejiang University Medical College from January 1, 2018 to December 31, 2019, were reviewed consecutively. For the two-year examination periods, these examined individuals were divided into two groups, one for 2018 totalling 90 507 and another for 2019 with a total of 115 004. The mean value of doses from chest CT scans in 2018 was set as the DRL for the hospital, with the 75th and 25th percentiles as the upper and lower limits of diagnostic reference range (DRR) and the 97.5th percentiles as the warning dose values. The doses above the upper limit of DRR were considered to be relatively-high whearas the ones exceeding the warning dose value to be over-high. Based on the analysis of the over high dose in 2018, the scanning scheme and inspection process of the chest CT scans were improved in 2019. The number of examinations were estimated for the 2018 period for chest plain CT scans, chest enhancement CT scans, lung cancer screening low-dose CT scans, and relatively-high and over-high dose CT scans, as well as the single scanning doses to the examined in the two groups. The number of examinations resulting in high dose to the examined due to different reasons before and after the improvement were studied. The various parameters on the examined in the two groups were compared statistically.Results:After the improvement, the average dose from chest plain CT scans decreased by 8.67 %, with the statistically significant difference as compared with before improvement ( t=55.71, P<0.05). The average dose from low-dose chest CT scans fell by 20.13% with statistically significant difference ( t=81.99, P<0.05). The fraction of the examinations with slightly-high doses arising from chest plain CT scans and low dose chest CT scans dropped by 3.66% and 17.15%, respectively. The fraction of the examinations with slightly-high dose from chest enhanced CT increased by 1.7%. The fraction of the examinations with over-high dose from chest plain CT scans, enhanced CT scans and low-dose CT scans decreased by 0.55%, 1.06% and 1.74%, respectively. After improvement, the optimized fraction of the examinations with over-high dose, dropped by 4.72%, 31.49% and 19.18% respectively. Conclusions:The establishment of the DRL and the warming dose value of for chest CT examinations in our hospital is helpful to find out the cause of high dose scanning, promote the optimization of dose, reduce the average dose to the examinedes, and avoid using excessive dose during scanning.
