(Radiation Safety FAQs: Please call the RSO if you have any questions; we welcome any opportunity to discuss any of your safety concerns!)

We welcome submission of questions for inclusion in this FAQ section! 
(Send any comments, questions, or suggestions to the Radiation Safety Office.)

Your Permit Holder distributes or posts monitoring data every two months.  If you can't find your results, call the RSO at extension 2-3005 (617-632-3005), or just come to our office during normal business hours (Longwood Galleria, 'mezzanine level', 8 AM - 4 PM).

The "M" in your dosimetry report or summary stands for "MINIMAL".   It means that your (external) radiation dose during the period being reported is too low to accurately quantify; effectively, this can be translated as less than 1 millirem.   

(Your dose was ≤ 1 mrem 'net' occupational exposure for the period the badge was worn or used.)

Occupational exposure limits established by DPH (and the USNRC) are considered conservative and "health protective".  At the Dana-Farber Cancer Institute, we have implemented even lower administrative objectives, equivalent to one-tenth (10%) of the annual occupational exposure limits.  If your results indicate exposures approaching or exceeding these levels, you will be contacted by the Radiation Safety Office to:

If your badge was not returned on time, it is also likely that the exposure from X-ray irradiation received in transit was reported as an occupational exposure.  This apparent personal dose (not 'real') can exceed 100 mRem.

Contact the Radiation Safety Office (ext. 2-3005) to review or discuss your data during normal business hours. 

DPH regulations establish monitoring requirements; people in positions or assignments that may cause them to exceed one-tenth (10%) of the applicable limits are badged monthly.

Other people (most Research applications or uses) do not need the increased frequency to detect conditions that could lead to radiation exposures above our limits; in this case, users are issued badges every 2 months. 

For technical details, contact the RSO, but for the purposes of this FAQ section, and practical application in radiation protection at DFCI, treat them all the same.

In practical application, these units are fairly large so we tend to use one one-thousandth (1/1,000) of these units: "milliRad" or just "mR", "milliRem" or "mRem", etc. 

DDE = Deep Dose Equivalent
LDE = Lens (of the eye) Dose Equivalent
SDE = Shallow Dose Equivalent

Different parts of your body vary in their radiosensitivity (susceptibility to damage).   Since the type and energy of the incident radiation affect the penetration depth within your body, we are concerned with both the amount and location of ionizing energy deposited in your body.  The term "dose equivalent" means that it has already been corrected for the type and energy of the radiation exposure.  DDE is a measure of the amount of ionizing radiation dose received by tissues at a depth of 1,000 mg/cm² or more.  Similarly, LDE is measured at 300 mg/cm², and SDE at 7 mg/cm². 

At low doses, we tend to think of DDE as the dose to your (blood forming) organs, and SDE as the dose to your skin. 
 

Even though your dosimeter badge cannot respond to tritium emissions (very weak betas), at DFCI we also use the 'whole body' dosimeter badge as a visual cue in our challenge system, a significant part of our program to prevent unauthorized access to radioactive materials.  If you see anyone working with, or trying to gain access to radioactive materials without a DFCI badge and dosimeter, you are required to either 'challenge' the individual(s) to ascertain whether they are authorized to be there, or immediately call Security (2-3131) and pass on that responsibility to them.

If you are an authorized and trained user of the irradiator(s), but you are not allowed access, call the Radiation Safety Office. 

If you have not previously used the irradiator, call Radiation Safety (extension 2-3005) for information on how to get access authorization.
 

All radioactive materials are purchased or provided by the Permit Holder.  Quantities and isotopes must be authorized under his/her Permit.  There is an electronic ordering system for a limited number of isotopes in various aliquots and chemical forms; this is the easiest way to procure isotope 'stock solutions'. 

Links to common suppliers or vendors are also listed on the "Links" page of  this website.

Refer to the topic labeled "Purchasing, Shipping & Receiving" for more information.

Actually, no one has ever asked this question, but I wish they would.

So, let me answer anyway: there are more than 600 people in > 300 labs being monitored by the Radiation Safety Office.

Over the course of each month, we are required to survey/audit each location where radioactive materials are stored or used.  There just isn't enough working time in a month to allow us more than a few minutes in each lab area (do the math!).  

DFCI relies on YOU to monitor and protect yourself and your work area, but you can always call us for assistance. 

The General Stores Catalog lists many of the supplies commonly used supporting routine safety needs.  Other supplies may be purchased from external vendors; the "links" page gives some names of selected vendors frequently used by DFCI.

The Radiation Safety Office does not stock these materials for the Permit Holders; if your needs are urgent, please call the RSO, and we will try to find a temporary supply.  

The schedule for waste pickup is clearly published - if your waste was not properly packaged and labeled by the time and day specified, we could not remove it. 

We have no way of knowing how much and which isotopes are present in the waste containers unless you provide that information (on the waste tag).  This material remains on DFCI's license inventory, even after you are done with it.  The waste tags are legal records needed to document the Institute's compliance with license possession limits!

(>95% of the time, this is the reason waste was not removed!  The pickup schedule can be found in the Radiation Safety Handbook, and at the Radioactive Waste Disposal web page.)

There is no "set" answer, but if the question occurs to you in the course of an incident, it makes sense to call us (Radiation Safety at ext. 2-3005).  Certainly, if a spill involves more than 100 microCuries (uCi, or µCi) of radioactive material, or more than 100 ml of a radioactive solution, you should call the RSO to notify us of the incident and discuss response or follow-up actions.

For your own protection, get us involved early; if the spill turns out to be minor or trivial, at least we will be able to confirm and document remedial activities and residual status of the facility or area involved. 

That depends on what you are using the instrument to look for; if you're looking for low levels of activity, or weak (low energy) emissions, you must remove the cap, or any other material covering the detector before use.
Taking the cap off the detector is almost always a good idea; the only time the cap or cover should be used is when you are working with energetic emissions, and need to prevent contamination of the detector itself.
If you are looking (monitoring or surveying) for iodine-125, you should be using a sodium iodide detector (also called a 'scintillation detector'), and the cap should be off.  If you are looking for sulfur-35 or carbon-14, the cap must be off (not covering) the G-M detector. 

DFCI's General Stores maintains an inventory of the 'D'-cell batteries used in most of the portable survey instruments used in DFCI. 
The Radiation Safety Office replaces your batteries at the time of calibration, if they are found 'dead', weak, or marginal.  

Make sure the instrument is clean, then bring to to the Radiation Safety Office; we will attempt minor repairs to the instrument, and recalibrate it (free of charge).  If we are unable to repair the instrument, it remains the Permit Holder's responsibility to provide an equivalent replacement (if necessary). 

Click here to return to the Radiation Safety home page.

(ver. 03Nov08: EBA)