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Conference Speaking Engagement: Dose Index Registry – Tips, Tricks, and Lessons Learned

I just returned from having presented at the Health Connect Partners 2017 Radiology & Imaging Conference.  My topic:  Using the DIR to Meet TJC’s Dose Incident Identification & Review Requirements.

During the presentation  I gave an overview of the DIR and shared what we’ve learned from having participated in it for four years, including specific areas we discovered for improvement.  Along the way I shared stories and anecdotes, and charts and graphs.    I also gave tips, tricks, and lessons learned attendees could take home and use themselves, including how to perform important quality checks on their DIR data – a critical step many overlook.

I also reviewed how and why we chose to use the process referred to as DoseID on this website to meet the Joint Commission’s requirements to establish expected dose ranges, test each exam against its expected range, and, identify any test that exceed its expected range (a dose incident), rather than buy an expensive third-party dose monitoring system.

(Hint, the words/phrases “very effective, low cost, and facility-specific” come to mind.)

I also went into some detail why XR-29 dose alerts/notification do not meet TJC’s dose monitoring requirements, including a review of the XR-25 Dose Check standard which forms the foundation of XR-29’s dose alerts and notifications.

(Hint:  While XR-29 alerts are pre-scan alerts, TJC requires facilities to check the total final dose as reported by the scanner at the conclusion of the exam against its expected range.  By definition, a pre-scan alert is not, does not, and cannot, represent the final actual dose,  which is one of the reasons why XR-29 dose alerts don’t meet TJC requirements.)

If your organization has an upcoming conference and you think its members would benefit from learning more about the Dose Index Registry, including tips, tricks, and lessons learned, please contact me by clicking here .

Need help getting more from your participation in the ACR’s Dose Index Registry® ?  Let Dose Registry Support Services tailor a program designed specifically to help your department succeed.  Contact Dose Registry Support Services to see how we can help.

Michael Bohl
Twitter:  @BohlM






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CTDIvol vs DLP – a simple explanation

What do they represent? CTDIvol is based on measurements obtained when scanning either a 16cm or 32 cm phantom.   Essentially, it represents scanner output.  DLP is derived from CTDIvol, but incorporates a scan length component.  Both function as reasonable proxies for absorbed dose but do not represent the actual patient dose.  In other words, if your CTDIvol and/or DLP is twice as high as it could be, then the doses you are imparting will be about twice as high as they could be.

Can CTDIvol and DLP results tell me two different things?     Yes.  CTDIvol represents the output when scanning a phantom, while DLP takes into account the scan length.  We’ve seen instances where CTIDvol is considered well within a “normal” range but DLP was unexpectedly high.  We found the scan settings were appropriate for the study, but the exam length  was longer than what others were using.

For example, a Chest CT could be started too high into the neck and end too far into the abdomen.  If this is the case CTDIvol (basic scanner settings) could be just fine, but because scans extended more than necessary above and/or below the requested area, the DLP could easily be too high.


The following information, obtained from, is a more technical discussion of CTDIvol and DLP for those interested.

The following is taken from an article posted on

CT Dose Index Volume (CTDIvol) The CTDIvol can be calculated as: CTDIvol = [(N x T)/I] x CTDIw where CTDIw = weighted or average CTDI given across the field of view N = number of simultaneous axial scans er x-ray source rotation T = thickness of one axial scan (mm) I = table increment per axial scan (mm)

In helical CT the ratio of the I to (N x T) is the pitch; therefore in helical mode:  CTDIvol = (1/pitch) x CTDIw

CTDIvol (or CTDI volume) represents the dose for a specific scan protocol which takes into account gaps and overlaps between the radiation dose profile from consecutive rotations of the x-ray source. Therefore CTDIw represents the average radiation dose over the x and y direction whereas CTDIvol represents the average radiation dose over the x, y and z directions.

Dose Length Product The dose length product (DLP) is the measure of ionizing radiation exposure during the entire acquisition of images.

Therefore, DLP (mGy-cm) = CTDIvol (mGy) x irradiated length (cm) (irradiated length is usually longer than imaged length in helical scanning)

CTDIw and CTDIvol are independent of scan length for determining the total energy absorbed whereas DLP is proportional to scan length.

Need help getting more from your participation in the ACR’s Dose Index Registry® ?  Let Dose Registry Support Services tailor a program designed specifically to help your department succeed.  Contact Dose Registry Support Services to see how we can help.

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End of Quarter: Time to Perform Your DIR Data Quality Checks

With the end of the quarter approaching the ACR’s NRDR sent a reminder to all participants to perform several quality checks so your report will be as accurate as possible.  These checks include making sure:

  1. The total volume of exams recorded in the DIR for your facility is reasonably close to the volume of studies you’ve performed;
  2. That any currently unmapped studies are mapped to an appropriate RPID; and,
  3. That your review your currently mapped studies to ensure they are assigned to the correct RPID.

I copied the NRDR’s email below in case you missed, or didn’t receive, it.   Please review and check your data.

Confirming Exam Name Mapping Accuracy

Checking your currently mapped study’s to ensure they are mapped correctly can be challenging and difficult.  For example,  the original facility we support began using the DIR in 2013 and currently has over 330 study names mapped to about 70 different RPIDs.  Suffice it to say some of the original studies were assigned incorrectly along the way.  The challenge they had was how to identify the incorrectly mapped studies? Looking at the list one at a time, and identifying studies that were incorrectly mapped, is tedious and time-consuming.

That is where Dose Registry Support Services was able to help – we developed a method of exporting and organizing all mapped studies in such a way that made it easy to grouped studies by RPID, which made it easier to identify mis-mapped studies.

Check back here soon.  Sometime in the next few days I plan to post step-by-step instructions describing the method we developed to easily identify incorrectly mapped studies.  We’ve used that approach for years and find it very useful.  I will likely post the announcement in a new blog post, but will put the instructions in an article on one of’s web pages.

As always, we are here to help.

Michael Bohl
Dose Registry Support Services

Need help getting more from your participation in the ACR’s Dose Index Registry® ?  Let Dose Registry Support Services tailor a program designed specifically to help your department succeed.  Contact Dose Registry Support Services to see how we can help.



Dear DIR Participant,

 We are preparing for the next aggregate report within the following week. Before we do so we would like for you to perform a Data Quality review of your own data. Please review the information below, follow the directions, and if you find errors in your data inform us right away. Failing to conduct a Data Quality review may result in a less accurate quarterly aggregate feedback report.


We highly encourage you to review your submitted data no less than every two months to monitor your data. We refer to this as a ‘data quality check.’ You may receive email notices from NRDR to remind you to perform a ‘data quality check’ but if you do not receive a notice, you are still held responsible to perform this critical step in preparation for your aggregate Feedback Report. To determine if we are receiving your data please log into the NRDR portal using your log-in credentials and password. After you have logged in, go to the DIR on the menu (left-hand side of the screen) and click to open the DIR Menu.

Comparing Volume of Exams Received vs. Volume of Exams Sent

  1. Under the DIR Report subheading, there are many reporting tools. To determine the last time your facility submitted exam data to the NRDR, use the ‘Summary of Data Submitted’ and ignore the date range fields, and click ‘Submit.’ The result of the search will display if we have received exam data from your facility recently.
  1. Clear the query to conduct a new one. Using ‘Summary of Data Submitted’ include one of the date ranges provided below to coordinate with the most recent reporting period. Make a note of the number of exams received during this reporting period.
    January 1 – March 31 (quarter Q1)
    January 1 – June 31 (semi-annual Q1Q2)
    July 1 – September 30 (quarterly Q3)
    October 1 – December 31 (semi-annual Q3Q4)

Compare the NRDR number of exams received to your volume of exams sent (your PACS may be able to help identify the number of exams sent).

  1. To know the volume of exams received per month, use the ‘Summary of Data Submitted’ and change the date range to capture one month at a time. Compare the NRDR monthly total of exams received against your monthly total number of exams submitted.

If the difference between the NRDR numbers and your total number of exams submitted is greater than 5% error, then please contact us at

Determine if Each CT Scanner is Sending Exam Data

  1. Under the DIR Report subheading, there are many report tools that can provide you with this data. An easy report tool to work with is ‘Dose Information by Exam.’ Click it to open the report page.
  2. Enter a date range of at least 3 months so that you can review what your CT scanners have been sending since the last aggregate report (which is issued quarterly). When the page populates go to the top of the screen and click ‘Export to Excel.’ Sort on the columns that contain information about your scanner, such as, Institution name, Scanner model and Scanner ID. In this manner, you can review the date that each of your scanners sent exam data to the NRDR. If any data is missing or if an entire CT scanner’s exam data is not appearing in the report, contact or call 703-390-9858 to troubleshoot data transmission.
  3. Also check the ‘Study Description’ column to affirm the names of your exams are being captured. If missing Study Descriptions for your exam names are greater than 5% error rate (per scanner) please use the email and phone number above to contact us.

Using the Standardize Dose Index Report Tool

The purpose of the Standardized DIR Report tool is to provide a user friendly reporting tool which can be searched by values not available in the other DIR reporting tools, a few of which have been mentioned above.

Map Exam Study Descriptions to a Radlex ID (RPID)

Exam names that have not been mapped to a RPID will not be included in the aggregate report. Please follow the instructions in the Exam Name Mapping User Guide to navigate through this task. If you have a Master-Child facility registration, you must perform your exam name mapping at the Master facility. Any mapping in the Child facility will be over written by the RPIDs selected in the Master facility every 24-hours. There are only a few Master-Child facility registrations that have ‘lifted’ restrictions, and are able to map at the Child facility. For the majority of Master-Child registrations, this is not the case. As a precaution, we suggest that you map at the Master facility level to avoid loosing your RPID mappings at a Child facility that may not have ‘lifted’ restrictions in place.

Please complete your quality data check and RPID exam name mapping within two weeks from the date of this email.

 Many best regards,

The NRDR Team

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Dose Reduction Case Study – Is Your CT Scanner Table Increasing Patient Dose?

During the 2017 Landauer Clinical Dose Optimization Symposium one of the session speakers, Douglas Pfeiffer, a medical physicist with Blackthorn Medical Physics, reported he had found the table-head rest extension connection mechanism increased CTDIvol and DLP when the body part being imaged was positioned over the connection mechanism.  Following the symposium, we worked with a facility for whom we provide Dose Index Registry Support and DoseID services to see if we could replicate Mr. Pfeiffer’s findings.  The results:  We found that scanning through the table-head rest extension connection mechanism increased doses by 28.5% to 31.7%.  In the following article, I describe how we performed the test, our findings, and changes we are making to reposition away from the connection mechanism when possible. 

Background:  This health system operates several scanners, two of which are Siemens Sensation 16 scanners.  The image below shows the head extension and the connection mechanism in the table end of one of the Sensation 16 scanners.  The black bar extending from the head rest inserts into the metal insert in the table end.  The facility uses this table configuration to perform CT Neck and CT Neck Angiograms, as well as to perform some extremity studies.   


Test Procedure:  We set the scanner to use the following scan parameters:  120kV; 217 Ref mAs; Auto-exposure set to On; 0.75 scan rotation time; with a 0.8 slice thickness.  We then imaged the 32cm phantom twice.  For the first scan we placed the 32cm phantom on the scanner table over table-head rest extension connection mechanism.  We positioned the phantom at isocenter and scanned through the visibly denser area in the table which represented the connection mechanism.  We noted the scan length.  We then repositioned the phantom so it was positioned on the table away from the table-head rest extension connection mechanism, again positioning the phantom at isocenter.  We rescanned the phantom using the exact same parameters and scan length. 

Results:  As the table below indicates, scanning the phantom when it was placed over the table-head rest extension connection mechanism increased CTDIvol by 28.5% and DLP by 31.7% when compared to scanning the phantom positioned on the table, but not over the connection mechanism.  Effective mAs (governed by auto-exposure) was 27.7% higher when the scan was performed through the table-head rest extension connection mechanism compared to scanning through the table top alone. 

Dose Diff Calcs

Discussion:  This confirms that some scanners’ head rest-table connection mechanism results in higher patient doses when the scanned anatomy is positioned over the connection mechanism than when the scan is performed through the table top and away from the connection mechanism.  We have not tested other system scanners so we can only report on what we found on the Siemens Sensation 16 scanner used to perform this test.  Also, depending upon the scan length, the overall dose increase during an actual study could be less than indicated here since our test scan was limited to the mechanism length while an actual scan may use a longer scanning range during which the scanner’s auto-exposure would compensate for the less dense areas above and below the mechanism. 

Summary:  We found that scanning through the table-headrest connection mechanism resulted in an increased CTDIvol and DLP 28.5% and 31.7%, respectively, compared to scanning through the table top itself (avoiding the connection mechanism altogether).  The facility is taking steps to change how they position patients relative to the head rest – table connection mechanism when possible to reduce patient dose.    


Need help getting more from your participation in the ACR’s Dose Index Registry® ?  Let Dose Registry Support Services tailor a program designed specifically to help your department succeed.  Contact Dose Registry Support Services to see how we can help.



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DoseID helps facilities identify duplicate and superfluous scanner protocols

One of the more interesting and unique benefits Dose Registry Support Services’ DoseID Program has for facilities is its ability to shed light on duplicate and superfluous protocols in use at their facilities.  DuplicatedProtocols

The table to the right shows how one facility had 7 different protocols being used on a single scanner during a recent 3 month period.  As you can see, all protocols are purportedly for a CT Abdomen/Pelvis without contrast exam, yet they are used with significantly varying frequency.  One is used by staff 714 (79%) of the 903 without contrast studies performed, yet 2 were used just under 40 times and 3 were used five or fewer times.  One has to question why these protocols exist and on what basis is staff choosing the infrequently used protocols.

This creates several issues, from hanging protocols in PACS to patient safety issues.  For example, when it is time to alter the protocol will whomever is updating the scanner parameters really change all 7 protocols?  This is important as facilities review their Dose reports and begin to make protocols changes to lower patient doses.

This is a widely recognized issue within the industry.  In its 2016-2017 development cycle Integrating the Healthcare Enterprise (IHE) is developing a new profile titled Enterprise Scanner Protocol Management to address this very issue.  Click here for more information on IHE’s initiative.

The good news is that because of the information contained in our reports, we are able to help them identify and eliminate duplicate and superfluous scanner protocols.

Need help getting more from your participation in the ACR’s Dose Index Registry® ?  Let Dose Registry Support Services tailor a program designed specifically to help your department succeed.  Contact Dose Registry Support Services to see how we can help.



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DRSS’s DoseID Service Now Includes Draft Policies For Client Use

DRSS is now providing clients with the following 8 draft policies it may adapt for use at their facilities:

  • [Facility Name] CT Dose Optimization Policy
  • [Facility Name] Quality Control and Maintenance Activities Policy
  • [Facility Name] Physicist Evaluation Policy
  • [Facility Name] Verification and Documentation of Medical Physicist Qualifications Policy
  • [Facility Name] Verification and Documentation of CT Technologists Qualifications Policy
  • [Facility Name] Process Prior to Conducting a Diagnostic Imaging Study
  • [Facility Name] Documentation of CT Radiation Dose Index Policy
  • [Facility Name] Policy for Reviewing and Analysis of the Dose Incidents Where the Dose Index Exceed its Expected Range