Frequently Asked Questions (FAQs)


Q: What is ALARA?
A: ALARA is an acronym for “as low as reasonably achievable” and means making every reasonable effort to reduce your exposure to ionizing radiation while considering what is practical and consistent with the purpose for which the radiation is being used. Examples include minimizing time spent near ionizing radiation, using tongs to increase distance, and using shielding when needed.

Q: What are commonly used isotopes at USC?
A: Beta emitters such as H-3, C-14, S-35, and P-32 are commonly used in labs across USC. Gamma emitters such as I-125 and F-18 are used on a routine basis in specific labs.


Q: What training is required to use radioactive materials?
A: You must complete Radiation Safety Training before beginning work.

Q: What training is required to use an X-ray producing device?
A: You must complete Radiation Safety Training with EH&S (except electron microscope users) and device-specific training with the owner of the machine. If you are using the X-ray irradiator, email to schedule the device-specific training.

Q: I am using an electron microscope. Do I need to attend Radiation Safety Training with EH&S?
A: No. Electron microscope (EM) users must review and sign the Electron Microscope Safety Guide Sheet. EM users must still complete device-specific training with the supervisor of the EM.

Q: Do I need to take Radiation Safety Training to use a laser?
A: No. Contact to complete Laser Safety Training.

Q: I completed Radiation Safety Training at my previous institution. Can I transfer it over?
A: No. The training at USC is tailored to follow all federal and state regulations, as well as USC-specific safety policies. Emergency procedures, ordering processes, and waste disposal may vary among institutions/facilities with radioactive materials licenses.


Q: What is a dosimeter?
A: A dosimeter is a small device that measures the amount of radiation that it is exposed to. The dosimeters used at USC come in three forms: a badge stuck on a wall in a lab, a clip-on badge worn on the shirt collar, and a ring worn on the finger.

Q: Do I need a dosimeter?
A: You are required to wear a dosimeter if you could receive a dose in excess of 500 millirem in one year. You will be issued a dosimeter if you:

  • Use radioactive material or a radiation producing machine in the Department of Radiation Oncology.
  • Handle radioactive material in the Departments of Nuclear Medicine and PET.
  • Regularly use an open-beam X-ray producing device.
  • Handle radionuclides that emit beta particles with energies greater than 1 MeV in quantities exceeding 5 mCi of activity.
  • Handle radionuclides that emit gamma rays in quantities exceeding 1 mCi of activity.
  • Declare your pregnancy.

If you own an X-ray producing device, the area around the device will be monitored using area dosimeters.

Q: Who do I contact if I lose my dosimeter?
A: If you lose your dosimeter or believe it is missing, contact your supervisor or Radiation Safety ( immediately. Do not continue radiation work until you receive a replacement badge. If you find your badge, please return it as soon as possible.

Q: Why is it important to turn in my dosimeter on time?
A: The purpose of the dosimeter is to monitor the amount of radiation that you receive. If the dosimeter results indicate a high reading, Radiation Safety will investigate the incident and take corrective action (e.g., have you stop radiation work, improve the process that caused the reading, identify faulty equipment). Turning in dosimeters late puts you and others in your lab at risk of exposure.

Q: What is a dose record (Form 5)?
A: A Form 5 report provides the final dose received by a participant in the dosimetry program during the monitoring period. The report is generated annually and distributed to lab supervisors.

Q: I do not need a dosimeter anymore. How do I cancel my dosimeter?
A: Use the Dosimeter Add/Delete Form to cancel your dosimeter. Dosimeters range from $3 to $20 each. If dosimeters are not cancelled in a timely manner, your lab may be charged for your unused dosimeters.


Q: How do I order radioactive material?
A: You must have a valid RAM permit for the isotope you want to order issued by Radiation Safety to place an order for radioactive material. All orders must be placed through eMarket. Visit the RAM Purchase page for more details.

Q: Can my order be delivered directly to my lab?
A: No. All packages are delivered to the Radiation Safety Office to be surveyed for damage and contamination. Once the package is processed, a member of the team will deliver it to your lab. A limited number of labs are allowed to receive certain orders directly due to the short life of the isotope. These scenarios are approved by the RSO on a case by case basis and come with additional requirements from the lab.

Q: My order was delivered directly to my lab. What do I do?
A: Do not open or handle the package and contact Radiation Safety immediately.


Q: How do I get rid of lead in my lab?
A: Many labs that use radioactive material will have lead in the form of shields or embedded into containers (pigs). Survey the object using an appropriate method and contact to schedule a pickup.

Q: Can I throw away or give away equipment that was used with radioactive materials?
A: The equipment must be decontaminated by the lab and surveyed by Radiation Safety prior to any equipment moves or disposals. Radiation Safety will post a clearance form on the equipment confirming that it is free of surface contamination.

Q: I have old radioactive waste in my lab, but I don’t know where it came from. How do I dispose of it?
A: If you find waste in your lab that you can’t link to any of your inventory in EHSA, contact Radiation Safety for guidance.


Q: Can radioactive material be transferred between labs on the USC campus?
A: Yes, however all transfers must be approved by Radiation Safety prior to the transfer. Visit the Transfer/Transport of Radioactive Materials page for more details.

Q: What do I do if my survey instrument is broken?
A: Do not perform a contamination survey with a broken instrument. Radiation Safety may be able to fix minor issues on portable survey instruments (not liquid scintillation counters or gamma counters). Labs are responsible for all costs associated with repairs. Contact Radiation Safety ( to assess the instrument or obtain a loaner while the instrument is being repaired.

Q: What do I do if my survey instrument needs to be calibrated?
A: Survey instruments used for contamination surveys must be calibrated annually. Radiation Safety calibrates all portable survey instruments, free of charge. If you find an instrument requiring calibration, email Radiation Safety ( to schedule a service. Liquid scintillation counters and gamma counters require professional service. Radiation Safety can assist you in finding a service provider.

Q: What do I do if my lab is closing or relocating?
A: Notify Radiation Safety as soon as possible with an estimated date of the close/relocation. A closeout inspection must be completed in order to confirm that the space is free of radioactive contamination.

Q: What should I do if I become pregnant while I am a radiation worker?
A: You have the right to voluntarily declare your pregnancy in writing to your supervisor and the Radiation Safety Officer. Consult the NRC REGULATORY GUIDE 8.13 INSTRUCTION CONCERNING PRENATAL RADIATION EXPOSURE. If you wish to declare, use the Declaration of Pregnancy Form. Once you declare, you will be issued a fetal dosimeter, and your annual dose limit will be limited to 500 mrem over the entire gestational period with little variation from month to month. You may confidentially consult with the Radiation Safety Officer if you have questions or concerns regarding prenatal radiation exposure.