Study On Occupational Radiation Exposure Of PET/CT Technologists

Purpose: PET/CT has now become one of the most rapidly growing medical imagingmodalities which refers to a few radiation sources、a series of procedures and needs manyworkers. So the occupational radiation dose may be higher than other workers’ and notstable. As the utilization of PET/CT grows rapidly, occupational exposure attractsresearchers’ attention. We conduct a study in seven PET/CT facilities in ShandongProvince in order to identify the true dose level received by the staff through wearing TLDin chest, by neck or on fingers for whole body, thyroid or extremity dose respectively.Ultimately，we will compare the received dose between PET/CT staff and them in otherradiation department, find how much those technologists receive radiation exposure, aswell as the effects of the prevention measures. Those data and conclusion from this subjectwill provide basic data for radiation prevention consideration and contribute to improvingprotection program.Methods:（1） On-site inspection Before caring out the project, we chose7PET/CTfacilities located in different cities of Shandong province to know well the principles,stepsand attentions of PET/CT.（2） dose-measure The main instrument is TLD filled with powder or tablet （LiF, P,Mg）. The whole body dose value may be easily got by inspecting the TLD in the chest. Thetechnologists responsible of preparing and injecting radiopharmaceutical need wear ringdosimeters on one finger of every hand and TLDs on their collars when they areperforming. （3） Allocating TLDs Enough TLDs will be delivered to every PET/CT facility, thestaff will wear them as following the request above. Then all the TLDs must be assembledand inspected in The Radiation Medical Institute of SAMS.Chose one PET/CT facility to learn the exact dose of the technologists undertakingdistributing or injecting radiopharmaceutical for single patient.Chose another PET/CT facility to learn how much the lead garment can prevent theradioactive rays, more than50TLDs will be tied to the inside or outside surface of a pieceof lead garment, the difference may disclose the garment’ effect.（4） statistics （1）Assembling other radiation departments’ staff dose and compare themwith that of PET/CT staff by t test.（2） calculate the average hand and thyroid dose oftechnologists undertaking radiopharmaceutical.（3）Make clear how much the lead garmentreduce the whole body dose of technologists.（4）Find the exact radiation dose received bythe technologists during single patient inspection.（5） Main apparatus Thermoluminescence dosimeters and ring dosimeters aresupplied by Beijing Kangkeluo electronic Co, Send the prepared dosimeters to NationalInstitute of Metrology to carry on the scale. Calibration factors was Cf=7.51×10^-4mSv/Xiand6.19×10^-3mSv/Xi respectively, Xi was instrument measurement reading （deducted thebottom）.Results:（1）The average radiation dose of technologists in all seven PET/CT facilities forpreparing and administrating radiopharmaceuticals change in the range of0.13～0.73mSv/quarter, higher than that of the workers in other radiationdepartments（departments of radiology and CT）.（2） The PET/CT technologists’ thyroidsreceived the exposure of1.20～1.70mSv/year, as well as42～676mSv/year for extremitiesdose.（3）During one patient inspection, the technologists undertaking preparation andadministration receive the average total dose of6.58mSv/yr and5.83mSv respectively, andthyroid dose are6.39mSv/yr and5.64mSv/yr, as well as about90mSv/yr for hand dose.（4）A lead garment can reduce8%of radiation dose of technologists.Conclusions:（1） The layout, automatic systems, syringe shields and larger trolley- mounted shields play the most roles in radiation prevention in PET/CT facilities, and a leadgarment can reduce8%of radiation dose of technologists.（2）The total, thyroid and handdose of the technologists are0.42～2.92mSv,1.20～1.70mSv and42～676mSvrespectively, though the hand dose of some technologists exceed the dose limit.（3） Thetotal dose, thyroid dose and hand dose of the technologists received during one patientinspection are lower than6.58×10^-4mSv,6.39×10^-4mSv and100×10^-3mSv.