The Study Of Radiation Doses To Patients In Digital Radiography

PurposeThrough the measurement and investigation of patient’s radiation dose for the common12types of examination in digital radiography(DR), finding out the levels of radiation dose ofpatients, then providing basic data for the publishment of patient’s radiation dose referencelevels of DR in our province and further in our country.Methods1．Site investiagation The ESD of patients was estimated using the TLDs, and DAPwas measured by the dose-area product(DAP) meter. In site survey, the patient ’s basicinformation and projection conditions was recorded, including tube voltage(kV), mAs and soon. Measurements were made for12types of examination: skull PA, skull LAT, chest PA,chest LAT, abdomen AP, pelvis AP, cervix spine PA, cervix spine LAT, thoracic spine PA,thoracic spine LAT, lumber spine PA, and lumber spine LAT.2．Laboratory readings The TLDs were measured using RGD-3B type of thermaldosimeter. The ESD was equal to TLDs with bottom deducted multiplied by Scale factor.3．Estimate the effective dose(E) The E values were calculated from the DAP using theRefDose software based on Monte Carlo method.Results1．Levels of exposure parameters The exposure parameters, including kV and mAs,were significantly different between different radiologic projections(F=37.05、26.02，P<0.05).Both the kV and mAs had a wide variation in the same type of examination, in view of thecapabilities of post-processing, over-exposure and under-exposure could be transformed intoacceptable images. 2．Levels of radiation dose The ESD, DAP and E of patients were significantlydifferent between different radiologic projections(F=37.05、26.02， F=37.05、26.02，P<0.05).The dose for lumber spine in LAT direction was higher than others, while the ESDand DAP reached4.62mGy and2.26Gy·cm2in each radiography, respectively. The value ofE in abdomen radiography on AP direction was0.59mSv, higher than lumber spine LAT.3．Comparison with the conventional X-ray examinations The ESDs of DR in the chestPA, chest LAT, lumber spine PA, lumber spine LAT, abdomen AP, pelvis AP were lower thanthose of screen-film radiography(t=-5.44、-9.99、-15.87、-17.75、-8.50、-3.22，P<0.05).4．Comparison with developed areas The ESDs of the chest PA, chest LAT, spine PAand spine LAT reported in Shanghai were0.20mGy,0.72mGy,1.02mGy,1.63mGy in eachDR lower than those for this survey(t=6.00、3.08、8.43、4.45，P＜0.05).5．Comparison with the levels of foreign countries In addition to the abdomen AP, theESDs of the chest PA, chest LAT, lumber spine PA, lumber spine LAT, pelvis AP were higherthan those of similar foreign countries checks(t=16.02、9.16、6.25、6.54、2.53，P<0.05). Thelumber spine PA was the only one whose E was lower than that of estimated abroad(t=7.48、8.58、5.62、7.51、2.96，P<0.05).ConclusionsThe study found that levels of radiation dose for DR were lower than that of screen-filmradiography, but higher than that of developed areas in our country and foreign countrys.There were too much work need to be done in optimization of the radiological protection ofpatients undergoing DR, because of the wide variability in the exposure parameters andpatients radiation dose with acceptable images.Typical adult guide levels of radiation dose were preliminary recommended that theESDs of skull PA, skull LAT, chest PA, chest LAT, abdomen AP, pelvis AP, cervix spine PA,cervix spine LAT, thoracic spine PA, thoracic spine LAT, lumber spine PA, and lumber spineLAT in DR were1.05、0.55、0.36、0.76、2.02、0.68、0.63、1.95、3.23、3.16、4.98、1.39mGyin each check, respectively.