A diagnostic medical physicist’s guide to the American College of Radiology Fluoroscopy Dose Index Registry

The University of Texas MD Anderson Cancer Center, Houston, TX, USA Cleveland Clinic, Cleveland, OH, USA American College of Radiology, Reston, VA, USA Emory University, Atlanta, GA, USA The University of Texas Southwestern Medical Center, Dallas, TX, USA Boston Children’s Hospital, Boston, MA, USA Memorial Sloan Kettering Cancer Center, New York, NY, USA Duke University Medical Center, Durham, NC, USA University of Washington, Seattle, WA, USA Montefiore Medical Center, New York, NY, USA


| INTRODUCTION
The American College of Radiology (ACR) computed tomography (CT) Dose Index Registry (DIR) has been extraordinarily successful, with dose indices collected for over 102 million CT examinations to date. 1,2 The CT DIR has provided an ongoing source of normative clinical data which has been the gold standard for national and international benchmarking. 3 The largest existing normative dataset for fluoroscopically guided procedures is the Radiation Doses in Interventional Radiology (RAD-IR) study, with a data collection period covering the mid-to late 1990's. [4][5][6] The RAD-IR study included 2142 clinical interventional flu- The purpose of this review is to provide guidance for sites wishing to participate in the Fluoroscopy DIR, and specifically to provide guidance for the diagnostic medical physicist who is assisting a healthcare organization in implementing the ACR Fluoroscopy DIR. The mechanics of participation will be discussed, as will common pitfalls in the process. This review is based largely on the experiences of the diagnostic medical physicists at the nine sites that participated in the pilot phase of the Fluoroscopy DIR. The pilot phase involved data collection for interventional radiology procedures from March 1, 2018 through December 31, 2019, and manual collection of data regarding fluoroscope configuration and use as well as the accuracy and stability of fluoroscope-reported dose indices. 9 Two checklists to aid in preparation for a site launch of the Fluoroscopy DIR have been provided at the end of this review. After reading this review, a site should be able to assemble a Fluoroscopy DIR team and launch the DIR while avoiding some of the major pitfalls that may otherwise be encountered along the way. We recommend that readers of this review also bookmark the NRDR TM Support Page for quick reference when needed.

| STEP 1. ASSEMBLE YOUR TE AM
A wide array of expertise is required to ensure a successful launch of the ACR Fluoroscopy DIR at your institution. Key team members and their roles are described briefly in this section.

2.A | NRDR TM user profiles
Healthcare organizations that have registered for the NRDR TM have a corporate account within the NRDR TM . One or more user profiles can be assigned to any user account associated with a corporate account. These profiles should be reviewed to determine which, if any, of the Fluoroscopy DIR team members should be assigned specific roles within the site corporate account. Among the NRDR TM user profiles, three specific administrative roles are defined, 10

2.A.3 | Registry administrator (RA)
The third administrative role, RAs are authorized by FAs to manage Facility User accounts. They control access to a specific registry, and may perform all functions of a Facility User.

2.A.4 | Service user
Service Users are authorized by CAAs to create and edit scanner mappings in the TRIAD ® Site Server configuration and to perform exam name mapping at the corporate account level. However, a Service User cannot view data or reports, and therefore some team members may need both the Service User and Facility User profiles assigned to their user account.

2.A.5 | Facility user
A Facility User can perform exam name mapping at the facility level and view reports.

2.B | Fluoroscopy DIR team roles
These are not official administrative roles or user profiles in the DIR, however, identifying the right personnel to play the following roles is key to a successful implementation of the Fluoroscopy DIR.

2.B.1 | Physician champion
The physician champion is the coordinator and director of the implementation process, and is essential to securing and maintaining institutional support for implementation of the ACR Fluoroscopy DIR.
Sites in states with requirements for fluoroscopy radiation protocol committees or similar committees may find their physician champion on one of these committees. At other sites, there may be a physician who is interested and engaged in quality improvement efforts who would make a great champion. One place to start looking is in your interventional radiology department, as interventional radiologists have much of the domain knowledge that will be required during later phases of the implementation process.

2.B.2 | Diagnostic medical physicist
The qualified diagnostic medical physicist is instrumental to a suc-

2.B.3 | Information technology (IT) specialist
Implementing the Fluoroscopy DIR requires interfacing with multiple hospital systems and servers, requiring the expertise of an IT specialist, particularly one who is familiar with imaging informatics.

2.B.4 | TRIAD ® site server administrator
The TRIAD ® Site Server Administrator is responsible for ongoing maintenance of the TRIAD ® Site Server. Both this role and the role of IT Specialist may be played by the same individual. Configuring fluoroscopes to create and transfer RDSR to another DICOM node may require service level access. This step is typically performed by the local service engineer under the guidance of the diagnostic medical physicist.

5.A | Direct connection to the TRIAD ® site server
The simplest configuration is to establish a direct DICOM connection between each fluoroscope and the local TRIAD ® Site Server, and then configure each fluoroscope to automatically create and transfer the RDSR to the Site Server after each procedure. Prior to configuring the fluoroscope, the local TRIAD Site Server must be installed and properly configured. Three pieces of information will be needed from the TRIAD ® Site Server administrator to configure each fluoroscope: 1. The host name and/or Internet Protocol (IP) address of the TRIAD ® Site Server.   configuration that the RDIM forward the RDSR without modification. The default behavior of some RDIM systems when exporting RDSR is to "rebuild" the RDSR using information parsed and stored from the original RDSR. In this scenario, fields may be missing, and the Device Observer Name (typically the Station Name) of the creating fluoroscope may be replaced with that of the RDIM, preventing the RDSR from being associated with the correct fluoroscope. Facilities electing this type of configuration are encouraged to contact their RDIM vendor early in the enrollment process to ensure proper configuration and avoid these potential pitfalls. The Station Name is part of the DICOM metadata (0008,1010), and while it is not a mandatory tag, most clinical imaging equipment populates this tag. The facility is responsible for ensuring that the Station Name has been configured using a unique identifier for all fluoroscopy systems that send RDSR to the DIR. RDSR from systems that are not mapped will be cached on the TRIAD ® Site Server for 14 days, after which they will be deleted. Facilities can filter out specific fluoroscopes from sending data to the registry by not configuring these systems in the TRIAD ® Site Server configuration console.

5.C |
It is recommended that the Station Name be the only configuration information entered for a fluoroscope, as all fluoroscope configuration information must match for RDSR to be processed by the TRIAD ® Site Server. 6 | STEP 5. DATA VALIDATION There are numerous failure modes that can interrupt data transfer between a facility and the DIR Central Server. Data validation is a quality assurance process that seeks to minimize interruptions in data transfer, minimize data bias, and maximize data fidelity. Regular data validation minimizes missing time periods, fluoroscopes, or procedure types in the data submitted from facilities to the DIR Central Server. Diagnostic medical physicists are experts in quality assurance and quality control, and can assist in designing appropriate quality assurance processes for data validation.

6.A | Initial data validation
Initial data validation focuses on ensuring that data are being received and processed at the ACR DIR Central Server from all fluoroscopes that a facility intends to connect to the Fluoroscopy DIR.
The facility should verify that the full anonymized RDSR, with the Station Name of the creating fluoroscope, is being received from each connected fluoroscope. The "Fluoro/DR Summary of Data Submitted," "Fluoro Dose Information By Exam," and "Fluoro Exam Detail" reports, which are available in the DIR Portal, can be used to perform initial data validation.      There are unique codes in the ACR Common lexicon that can be used to exclude specific facility clinical procedure names from future analysis. In the case of interventional fluoroscopy procedures, mapping a facility clinical procedure name to the code 9999998,'INV-FLUOR. Unwanted' will exclude that procedure from future analysis.

6.B | Periodic data validation
Facility clinical procedure name mapping will be very time intensive in the first few months after a site joins the Fluoroscopy DIR, and time requirements for mapping will decrease over time, although ongoing maintenance is required. Facility clinical procedure name mapping should be reviewed regularly, with more frequent reviews early on in the participation process.  individual Common procedure codes to "roll up" categories grouping similar procedures (e.g., all hepatic embolization). These reports will be very useful to diagnostic medical physicists in the performance of fluoroscopy dose audits 15,16 for the sites they support.
Currently, reports are provided on primary fluoroscopy dose indices, including reference air kerma (K a,r ), air kerma area product (P KA ), and fluoroscopy time; and for derived indices including: K a,r "rate" ¼ K a,r =fluroscopytime; Average x À ray field size in the plane of the reference point ¼ P KA =K a,r ; Percent of irradiation events using added filtration.
A suite of comparative benchmark reports similar to those available for the CT DIR will be provided to facilities as soon as a sufficient amount of fluoroscopic dose data from participating facilities becomes available.

| CLOSING THOUGHTS
A successful launch of the Fluoroscopy DIR is a collaborative effort requiring a team with members that possess the requisite expertise in interventional radiology, diagnostic medical physics, and clinical radiology informatics. Participation in the Fluoroscopy DIR is a key aspect of a quality assurance program in fluoroscopy, as it allows sites to compare their practice to regional and national benchmarks, which we hope will ultimately result in a reduction in variability in radiation usage for procedures performed using fluoroscopy and drive the adoption of best practices for fluoroscopically guided procedures. • Approved the final version to be published; and • Agreed to be accountable for all aspects of the work in ensuring that questions related to the accuracy or integrity of any part of the work are appropriately investigated and resolved.

ABBR EVIATIONS
ACR DIR central server, A server maintained by the ACR that receives data transmitted from individual TRIAD Site Servers, analyzes the data, and hosts the database of processed DIR data.
TRIAD ® Site Server, A physical or virtual server hosted by a participating site on which the TRIAD ® software is installed.
SCU, Service Class User, in DICOM this is the device that uses a DICOM service, for example, for the image storage service, sends images.
SCP, Service Class Provider, in DICOM this is the device that provides a DICOM service, for example, for the image storage service, receives images.
RDSR, Radiation Dose Structured Report, a DICOM object that contains detailed, structured information describing each irradiation event during an X-ray imaging procedure.
HL7, Health Level Seven, an international standards development organization that develops standards for interoperability between health information systems.
RDIM, Radiation Dose Index Monitoring system, a data system that receives, analyzes, and stores radiation dose information from medical imaging procedures. Facility clinical procedure name, The name assigned to a specific given clinical procedure by a site, for example, PERC NEPRHO PLC.
Facility clinical procedure names may differ at different facilities within the same corporate site, and will almost certainly vary among different corporate sites.
ACR Common procedure name, The standard procedure name used in the ACR Common lexicon, all sites map their unique facility clinical procedure names to standard ACR Common procedure names.
Device Observer Name, One of the Device Observer Identifying Attributes in the Observer Context of the Projection X-ray Radiation Dose Structured Report. Defaults to the Station Name from the General Equipment Module. This tag is not mandatory, but is populated by many fluoroscopes.
Digital Imaging and Communications in Medicine (DICOM), The international standard to transmit, store, retrieve, print, process, and display medical imaging information.
Picture Archiving and Communication System (PACS), A system consisting of hardware, software, and networking that allows the storage of medical images from multiple modalities and devices, viewing and manipulation of these images by users at multiple locations, and retrieval of images to other DICOM hosts.