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Diagnostic imaging
Diagnostic Imaging

Current Studies in Diagnostic Imaging

Biological effects following in vitro and in vivo exposures to ionizing radiation


Dr. Karen Thomas, The Hospital for Sick Children
Dr. Diana Wilkinson, Defense Research and Development Canada (DRDC) Ottawa


This study will provide Health Canada and DRDC in Ottawa with the opportunity to identify new biomarkers of radiation exposure. 

A biomarker, short for biological marker, is a substance which is used to examine and measure physical changes. These biomarkers will provide information on unique stress responses brought on by radiation, resulting in a better understanding of long term radiation associated health risks. 

The knowledge gained will benefit medically exposed individuals, particularly paediatric patients since they are known to be at least ten times more sensitive to radiation induced damage than adults. This information may assist medical professionals in developing customized radiation therapy by minimizing doses to the most sensitive populations. Moreover, biomarkers may provide a means of identifying accidentally exposed individuals during a large scale radiological/nuclear accident when measurements of radiation exposure are unavailable.  


The study examines if any changes in white blood cells or in saliva cells can be detected after exposure to ionizing radiation at the level involved in CT and fluoroscopy examinations in the diagnostic imaging department. Blood and saliva samples will be taken from:

a)    20 radiologists, technicians and nurses working in fluoroscopy (before and after days work)
b)    20 patients undergoing CT examinations (before and after their CT scan)

The samples will be taken at SickKids, and then collected by the research team at DRDC - all further analysis will be performed in their labs.

Using patient and radiologist blood samples collected before and after the procedure, we will survey for direct and indirect radiation induced damage in different white blood cell populations. The window of time (<36 hours post CT scan) for patient sample collection will ideally ensure identification of the sample timing post exposure needed to determine best expression of the biomarkers. We will also evaluate the systemic response to these cellular fluxes by examining cytokine (growth factors) and all protein profiles in blood plasma and saliva before and after exposure.  

These strategies, in combination with the dicentric assay analysis, will be used to better assess individual radiation response.  Through the use of these proteomics technologies, we hope to improve detection of radiation induced effects and develop a better understanding of risks associated with low dose medical or accidental exposures.  This information will also provide a better understanding of diagnostic imaging and the associated risks to the individual patients and radiologists. 


Patients undergoing CT with contrast. 


Start Date: August 2005 
Current Status: Closed, under ongoing analysis

Contact Information

Dr. Karen Thomas, The Hospital for Sick Children
Phone: 416-813-8457
Fax: 416-813-7591
email: karen.thomas@sickkids.ca


The Hospital for Sick Children
Defense Research Development Canada