Using AI to Solve the cmbX Mapping Challenge in the ACR Dose Index Registry

The ACR’s recent introduction of the “cmbX” designation in the Dose Index Registry (DIR) is a meaningful step forward. By separating combination studies, the DIR now allows for more accurate mapping to combination RPIDs—or, when necessary, assignment to RPID88 to remove them from the “unmapped” category. But as many facilities are now discovering, this improvement… Read More

Streamlining cmbX Mapping in the ACR Dose Index Registry

Background On February 17, 2026 the American College of Radiology (ACR) announced an important enhancement to the Dose Index Registry (DIR): the introduction of a “combination study” designation, identified by the cmbX prefix in Study Descriptions. This change represents a meaningful improvement in how the DIR handles multi-part or combined CT exams. The Challenge While… Read More

Important DIR Update – Combination Exam Mapping Changes

To my Dose Registry Clients and Friends, The DIR recently announced changes in how the NRDR maps combination CT studies.  In my opinion, this is one of the most significant and welcome changes to the DIR in years.  See the link immediately below.  https://nrdrsupport.acr.org/support/solutions/articles/11000135515-dir-improves-the-accuracy-of-combination-exams-for-ct The article explains changes to how the DIR records and processes… Read More

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… Read More

Expanding Your Use of the DIR to Include Fluoroscopy, Nuclear Medicine, and Digital Radiography Doses

Here is an interesting article on the ACR’s Dose Index Registry (DIR). It is titled “Physicist Spotlight: Meet the Chair of the ACR Dose Index Registry Committee.” I encourage you to pay specific attention to the article’s discussion of the DIR’s ability to accept and compare doses, not only from CT scanners, but now also… Read More

New Scanner Dose Review – A Unique DoseID Service

Generally speaking, today’s scanners are much more dose efficient than the ones they are replacing. When a site installs a new scanner I like to provide them with an overview of just how their doses changed so they can share their success within the institution. One of my clients installed a new scanner a few… Read More