How to Read a Radiation Dosimetry Report by Thomas Morgan
Radiation dose reports are a rich source of information about your current and past radiation exposure. Reports include information about the current monitoring period, accumulated quarterly exposure, year to date, and lifetime doses. Each individual is assigned a unique participant number when first issued a dosimeter, which is assigned based on the type of radiation expected to be encountered. For example, in the USE column, a “Pa” indicates a dosimeter sensitive to x-rays, as well as gamma rays, such as those from Cs-137, Tc-99m, F-18, or Tl-201 and betas, including P-32 or P-33. These dosimeters include a series of filters to assist in determining the penetrating power of the radiation. A “Ja” dosimeter is also sensitive to neutrons.
Radiation doses are reported as dose equivalent “DEEP,” “EYE,” and “SHALLOW.” DEEP is the dose expected at 1 cm depth in tissue. EYE applies to external exposure to the lens of the eye, which is at a depth of approximately 0.3 cm. SHALLOW represents the dose to top 0.07 mm of the skin.
Doses below certain minimum measurable quantities are recorded as “M.” The minimum reporting levels vary according to the dosimeter type and radiation quality:
- Photon (x or gamma ray): 1 mrem
- Beta: 10 mrem
- Neutron: 20 mrem (fast), 10 mrem (thermal)
- Fetal: 10 mrem
- Ring: 30 mrem
For reference, annual limits on exposure are as follows: whole body DEEP – 5,000 mrem; EYE – 15,000 mrem; SHALLOW – 50,000 mrem. Individuals who receive more than 2.5% of these doses (i.e. 125 mrem DEEP, 375 mrem EYE, or 1,275 mrem SHALLOW) in a calendar quarter are notified in writing by Radiation Safety. Please feel free to contact Radiation Safety should you have any questions about your dose report.
Columbia Hosts Emergency Preparedness Exercise by Kathleen Crowley
On March 25, 2011, EH&S was proud to host a second Symposium sponsored by the New York City Department of Health and Mental Hygiene (NYC DOHMH) Bureau of Environmental Emergency Response and Preparedness and the New York City Medical Reserve Corps (MRC) – “Operating a Community Reception Center: A Workshop for the NYC Radiological Reserve Corps.” Historically, emergencies are handled first at the local level. This workshop was held at the Russ Berrie Building and focused on development, deployment, and operation of task force to screen potentially contaminated victims of a nuclear or radiological incident in New York City. Senior DOHMH members attended and briefed participants from a wide variety of emergency response agencies – FDNY and NYPD, municipal and volunteer ambulance corps, and hospitals. Attendees had the opportunity to experience various stations in the reception center – screening, decontamination, dose assessment and registration.
This Symposium followed the one hosted in October 2010 at the Morningside campus, designed for Radiation Safety Officers and preparing for radiological emergencies. Recent events in Japan underscore the importance of preparedness, planning and exercising such plans.
|The Summer 2011 edition of SafetyMatters is the last for Paul Rubock, Chief Editor and Director of Biological Safety, who, after 11 years at EH&S and over 17 total with the University, has retired from Columbia. Please join us in wishing Paul the very best as we say “Thank You” and “Goodbye.” Best wishes, Paul!
Editorial Staff: Kathleen Crowley, Chris Pitoscia, Paul Rubock
Graphics, Design, Lay-out: Jean Lee
Do you have a suggestion for a future Safety Matters article? Do you have a comment on something you just read? Please share it with us at , firstname.lastname@example.org