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CT Diagnostic Reference Levels – experience of the United States (Joint webinar with IOMP)

Video

Recorded broadcast →

Presenter: Kalpana Kanal
Date of broadcast: 16 April 2019, 4 pm CET (check your corresponding time)

Organized jointly with the International Organization for Medical Physics

About the webinar

The American College of Radiology (ACR) CT Dose Index Registry (DIR) has been used to recommend diagnostic reference levels (DRLs) and achievable doses (ADs) for the ten most common adult CT examinations in the US as a function of patient size. 

Ten most commonly performed adult CT examinations in the United States were analyzed from the DIR - head brain without contrast, cervical spine without contrast, neck with contrast, chest without contrast, chest with contrast, chest with pulmonary embolism protocol, chest abdomen pelvis with contrast, abdomen pelvis with contrast, abdomen pelvis without contrast, and abdomen pelvis nephrolithiasis protocol without contrast. For the head exams, lateral thickness dimension was used as an indicator of patient head size. For neck, c-spine, chest, abdomen and pelvis exams, effective diameter was used. Descriptive statistics were calculated for four facility characteristics (facility category, facility location, census region, and average volume of examinations per month) for all the exams included. Data from over 1.3 million examinations were used to determine median values (AD) as well as mean, 25th and 75th (DRL) percentiles of CTDIvol, DLP and SSDE. 

The abdomen pelvis exams made up the highest percentage (45%) of exams in the study. Over 46% of the facilities were from community hospitals and 13% from academic facilities. Over 48% were metropolitan followed by 39% suburban and 13% rural facilities. Over 50% of the facilities reported performing less than 500 exams per month. The median CTDIvol did not vary significantly but DLP increased with lateral thickness for head exams. For neck and c-spine, the median CTDIvol and the 75th percentile did not vary significantly but the median DLP did with effective diameter.  Similar trends were seen for the median CTDIvol and SSDE for chest, abdomen and chest-abdomen-pelvis exams. Our data agrees well with the data from other resources. 

The enormous volume of patient data, as well as the availability of automatically-determined patient size information, allows for the development of robust, size-specific ADs and DRLs. This work will enable facilities to compare their patient doses to size-specific national benchmarks and optimize their CT protocols resulting in lower dose at the appropriate image quality. 

Learning objectives

  1. To understand the definition of diagnostic reference levels and achievable doses 
  2. To get familiar with the diagnostic reference levels and achievable doses for ten most common adult exams in the USA
  3. How to use the diagnostic reference levels at your institution to implement change

About the presenter

Kalpana M. Kanal received her MS degree from UT Arlington, Arlington, TX, and her PhD in Radiological Sciences from the UT Health Science Center, San Antonio, TX. After completing the Medical Physics Residency Program at Mayo Clinic, she joined the Department of Radiology at University of Minnesota, in 1998. In 1999, Dr. Kanal was certified by the American Board of Radiology in Diagnostic Radiological Physics. She has been working in the Department of Radiology at the University of Washington since 2000 and is currently Professor and Director of the Diagnostic Physics Section. Dr. Kanal is also chair of the Radiation Safety Committee at University of Washington. Dr. Kanal is active professionally in the AAPM, ACR and ABR and recently became a medical physics trustee in ABR.  She has also served as the Chair of the ACR CT Dose Index Registry. She has published more than 50 papers in peer-reviewed journals and has made several scientific presentations throughout her career. She has also been recognized as a fellow by the AAPM, ACR and SCBTMR. 

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