The ALARA Principle

Posted by Clinical Product Specialist

Wed, May 20, 2015 @ 02:40 PM




ALARA = As Low As Reasonably Achievable


We are all aware that we are working with radioactive materials and will be exposed to some level of radiation. ALARA is the principle guiding us to keep our exposures to a minimum.

This principle assumes that there is no threshold for inducing “biological effects” and therefore any dose of radiation carries with it some risk. In other words, there is no level of “safe” radiation.

So HOW do we keep our exposure as low as reasonably achievable? We use the principles of Time, Distance and Shielding.

Many times during the day it is not the syringe, point source or CT that is exposing us to radiation but rather the patient. Below is a list along with some ideas and questions to think about as we move through our day:


  • Delivery of Radiopharmaceuticals - As previously stated, is the syringe being held with the plunger or needle ends facing the tech? Is the syringe staying in the dose carrier until we are ready to inject, or is the syringe being laid on the counter next to us? Are we taking advantage of remote injectors if they are available?

  • Transportation of patients - How close to the back of the wheelchair are we standing when transporting a patient?  How close to the patient are we standing when walking them either out of the department or into the scan room? 

  • Cleaning up spills (including patient blood or body fluids) - We need to consider how quickly we can clean spills or cover the contamination when necessary.

  • Holding / Lifting Patients - Here’s a practical one that happens every day in every department. We should be aware of how long we are standing or sitting directly next to a patient and where our radiation badge is during this time.

  • Standing next to the treadmill - And subsequently, standing next to a newly injected patient. Is there a way to reduce the time or especially distance during this period?

  • CT portion of SPECT/CT or PET/CT - In this new world of PET/CT and SPECT/CT, we need to be aware of the CT portion exposing us to xrays. Be sure to stand behind a leaded shield or leaded wall anytime the CT tube is active, even if it is only being used at a low mAs for attenuation correction purposes.

  • Filling phantoms - Wear ring badges when filling phantoms! Filling phantoms for QC or ACR work can be time intensive. Phantom mixing can be a source for high ring badge readings.To mix the phantom, consider placing absorbent paper on the floor and rolling the phantom back and forth with your foot.  

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