ABSTRACT
Objective:To analyze and compare the X-ray procedures and radiation dose composition of ophthalmic inpatients, and to explore the changes of the X-ray examination mode in recent years and the effect of optimization in imaging technology on the radiation dose level of the patients.Methods:The simple random sampling method was used to retrospectively select the imaging data of the ophthalmic inpatients in the Second Affiliated Hospital of Zhejiang University School of Medicine from July 1st to November 31st in 2019 and from July 1st to November 31st in 2020. A total of 516 cases were selected according to the imaging time, including 258 cases in 2019 and 258 cases in 2020. Based on our previous research and the related documents of low-dose CT screening, a series of optimizations on CT scanning parameters and process were carried out in 2020, including the frequency of DR and CT scanning, the number of examinations per capita, the composition ratio of CT and DR, and X-ray dose per capita.Results:In 2020, the average effective doses of chest CT and orbital CT for ophthalmic inpatients were (2.587±1.586) mSv and (0.877±0.733) mSv, significantly lower than those in 2019 ( F=0.52, 0.72, P<0.05), and decreased by 34.82% and 37.13%, respectively. There was no significant difference in the average effective dose of chest DR and head CT between 2020 and 2019 ( F=6.01, 1.81, P>0.05). The number of X-ray examination per capita increased by 0.15 times, and the effective dose increased by 1.44 times (1.589 mSv). Chest DR was the main type of X-ray examination, accounting for 68.79% of all examinations in 2019, while chest CT was the main type, accounting for 71.05% in 2020. The composition of chest CT in 2020 increased by 63.17% compared with 2019, and the compositions of chest DR, orbital CT and cranial CT were decreased by 53.88%, 5.79% and 2.89%, respectively. Conclusions:With dose optimization measures, the single CT dose of ophthalmic inpatients in 2020 was lower than that in 2019. Chest CT increased significantly in frequency, and became main X-ray examination instead of chest DR which made the effective dose of ophthalmic inpatients increasing significantly.
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.