Radiation Exposure Monitoring

Radiation Exposure Monitoring (REM) facilitates the collection and distribution of information about estimated patient radiation exposure resulting from imaging procedures.

Summary

The REM Profile requires imaging modalities to export radiation exposure details in a standard format. Radiation reporting systems can either query for these "dose objects" periodically from an archive, or receive them directly from the modalities.

The radiation reporting system is expected to perform relevant dose QA analysis and produce related reports. The nature of such analysis and format of the reports is not considered a topic for standardization and is not covered in the profile.

The profile also describes how radiation reporting systems can submit dose reports to centralized registries such as might be run by professional societies or national accreditation groups.

By profiling automated methods, the profile allows dose information to be collected and evaluated without imposing a significant administrative burden on staff otherwise occupied with caring for patients.

Benefits

In the vast majority of medical procedures involving radiation, the potential benefit to the patients’ health from the information gained far outweighs the small potential risk from being exposed to radiation, but the trade-off should not be overlooked. The technological mechanisms provided by this profile can facilitate a conscious evaluation of that trade-off.

Estimating radiation dose delivered to patients for medical purposes can facilitate a number of important activities:

For facilities exposing patients to radiation, monitoring such exposures can help ensure their policies, procedures and protocols are adequate and being followed appropriately.
For imaging physicians, monitoring such exposures can assist them in determining how changes in techniques and protocols impact radiation dose as well as image quality. This will enable them to maintain patient doses As Low As Reasonably Achievable (ALARA).
For patients’ physicians, overall data provided from monitoring such exposures can help them determine (in consultation with the imaging physician) if the benefit from the diagnostic information provided by an individual examination (or additional examinations) outweigh any small risk that may be associated with the imaging exam.
For medical physicists, having such post-procedure information available for individual patients may help them make essential patient-specific dose estimates for pregnant patients or patients exhibiting skin erythema as a result of long fluoroscopy examinations.
For professional societies and regulatory agencies, a collection of exposure data can be useful when setting or reviewing radiation dose related guidelines. Many such groups have expressed a desire to establish standards of practice or dose reference levels based on a quantitative understanding of current practice, however they have found it prohibitively difficult to collect such data.
For physicists and physicians, this kind of data can be vital to answering some of the fundamental scientific questions that remain and developing a more detailed understanding of the health impacts of radiation exposure and how it should be measured and managed.

Details

The REM Profile is based on the work done by DICOM supported by IEC to define DICOM SR templates appropriate for radiation dose monitoring of CT and projection X-Ray procedures. These dose objects are created, stored, queried, retrieved, de-identified, and may be processed and displayed just like other DICOM objects such as digital measurements or images. As such, many sites may choose to archive these objects in the study on the PACS together with the images.

The use of DICOM SR objects overcomes weaknesses of MPPS or Image headers as dose monitoring methods. The SR templates provide far more complete details in a persistent format. MPPS were designed for workflow and are not stored. If images are deleted or not sent to PACS there are similar gaps in the dose record and both MPPS and Image headers lack important dose details.

Dose details are recorded for each irradiation event, which is defined as one continuous occurrence of irradiation being applied to a patient. A single pulsed fluoro X-Ray acquisition, or a single (multi-slice) helical CT scan are examples of single events. A CT scanogram and the accompanying helical scan are two separate events, as are two different presses of the fluoro pedal, or simultaneous irradiation from two X-ray tubes.

Typically, one dose object is created at the end of each procedure step performed on the modality. That dose object collects together all the irradiation events from the procedure step and adds summary dose index values for the procedure step as a whole. Dose management systems may choose to re-organize the data at a higher or lower level of granularity.

The Profile addresses dose reporting for imaging procedures including CT, angiography, fluoroscopy, mammography, CR, DR, and plain X-ray. It does not currently address procedures such as nuclear medicine (PET or SPECT), radiotherapy, or implanted seeds.

The exact details recorded in the dose objects may be found in TID 10001 through TID 10014 in DICOM PS 3.16 (see Radiation_Exposure_Monitoring#Specification).

Some of the key details include:

All modalities
- kVP, mA, collimation, filters, etc.
- Patient/Order/Study details
CT
- DLP, CTDIvol, Effective Dose (optional)
Projection X-Ray
- DAP, Dose@RP, Imaging geometry, Fluoro Dose, Fluoro Time
Mammography
- AGD, Entrance Exposure@RP, Compression, Half Value Layer

In addition to supporting Profile quality assurance (QA) of the technical process (was the dose appropriate for the procedure performed) at the local facility, the profile also supports population analysis performed by national registries. Compliant Dose Info Reporter actors are capable of de-identifying and submitting dose reports to a national dose register over Secure FTP, making it relatively simple for groups such as ACR to collect and process dose data from across the country once they have recruited participating sites.

While this profile has been strongly supported by medical physicist and radiologist groups, it is important to understand the technical and practical limitations of such dose monitoring and the reasons why the monitored values may not accurately provide the actual radiation dose administered to the patient:

The values provided by this tool are not “measurements” of dose, but only calculated estimates.
For computed tomography, “CTDI” is a dose estimate to a standard plastic phantom. Plastic is not human tissue. Therefore, the dose should not be represented as the dose received by the patient.
For planar or projection imaging, the recorded values may be exposure, skin dose or some other value that may not be patient’s body or organ dose.
It is inappropriate and inaccurate to add up dose estimates received by different parts of the body into a single cumulative value.

Despite such limitations, interest in monitoring radiation dose estimates is clearly expressed in such documents as the European directive Euratom 97/43 and the American College of Radiology Dose Whitepaper.

Note that the Profile focuses on conveying the details of individual irradiation events. A proper radiation exposure management program at an imaging facility would involve a medical physicist and define such things as local policies, local reporting requirements, annual reviews, etc. Although this Profile is intended to facilitate such activities, it does not define such policies, reports or processing, or in itself constitute a radiation exposure management program.

Systems Affected

Modalities may create and transmit dose objects.
PACS systems may store and manage dose objects.
RIS, PACS or standalone Reporting Workstations may retrieve, process and analyze dose objects.
Workstations may retrieve, display and possibly supplement dose objects.
National or regional repositories may receive dose objects submitted by reporting systems at participating sites.

Actors & Transactions:

Specification

Profile Status: Final Text

Documents:

Current Radiology Technical Framework (includes REM as of Revision 11)

Radiation Exposure Monitoring Supplement 2010-11-16 (Obsolete Trial Implementation Draft as Revised to include CPs 195,196,197,198,199,203,204)

Radiation Exposure Monitoring Supplement 2008-07-03 (Obsolete Trial Implementation Draft prior to CPs)

CP-RAD-195 Internationalize Series Description requirement in Dose Report in RAD-62 (Final Text)
CP-RAD-196 REM De-identification in RAD-63 (Final Text)
CP-RAD-197 Replace Register with Registry in REM (Final Text)
CP-RAD-198 Remove inappropriate weakening of DICOMDIR in Submit Dose Transaction in REM (Final Text)
CP-RAD-199 Patient Longitudinal Record Use Case in REM (Final Text)
CP-RAD-203 Require Irradiation Event UID in Images (Final Text)
CP-RAD-204 REM Patient Characteristics (Final Text)

Underlying Standards:

DICOM

DICOM PS 3.16 2011 contains Radiation Dose SR Templates
CPs (that may be relevant, were recently or are not already included in 2011 and are in varying states of completion) ...

DICOM CP 1024 Support IEC 62494 Exposure Index of Digital X-ray Imaging System (Final Text)
DICOM CP 1047 Dose Check support in DICOM CT Radiation Dose Report (Final Text)
DICOM CP 1063 Clean up radiation dose reports (Final Text)
DICOM CP 1065 Device information in radiation dose reports (Final Text)
DICOM CP 1068 Scan location in CT dose reports (Final Text)
DICOM CP 1069 Inconsistent capitalization of X-Ray code meaning in radiation dose reports (Final Text)
DICOM CP 1070 Additional sources of information in radiation dose reports (Final Text)
DICOM CP 1076 Bad person participant relationship in TID 1020 in Dose SR (Final Text)
DICOM CP 1077 Add CR report type to Dose SR and relax content conditions (Final Text)
DICOM CP 1107 No human readable label for irradiation events in CT Dose SR (Final Text)
DICOM CP 1114 Correct UCUM multiplication (requires period in DLP units; i.e., mGy.cm rather than mGycm) (Final Text)
DICOM CP 1115 Add Dose Reference Point codes for CR/DR
DICOM CP 1123 Add attributes and codes for dose reports generated during QA scans (Final Text)
DICOM CP 1127 Add fields for Organ Dose to Dose SR
DICOM CP 1151 Correct Condition for "Number of Pulses" in TID 10003 (Final Text)
DICOM CP 1168 Device observer code meaning incorrectly capitalized (Final Text)
DICOM CP 1170 Add AAPM 204 Size-Specific Dose Estimates to CT RDSR (Final Text)
DICOM CP 1173 Clarify basis for Total Fluoro Time and Total Acquisition Time in XA Dose Report (Final Text)
DICOM CP 1194 Clarify dose for breast X-Ray (Final Text)
DICOM CP 1196 Add phantom-specific Total DLP Values to allow for Head and Body in same RDSR scope of accumulation
DICOM CP 1201 Correct Calibration Factor CI Definition (TID 10002) (Final Text)
DICOM CP 1219 Clarify Completion Flag for Dose SR (Final Text)
DICOM CP 1223 Additional Items for Dose SR (by IEC PT 61910-1) (Final Text)
DICOM CP 1232 Add iterative reconstruction to CT RDSR (Final Text)
DICOM CP 1233 Add Patient Size (Height) to Modality Worklist (Final Text)
DICOM CP 1254 Correct Definition of Irradiation Duration (Final Text)
DICOM CP 1317 Refactor Accumulated Projection X-Ray Dose Templates
DICOM CP 1318 RDSR From MPPS Without Exposure Dose Sequence for Projection Radiography

Registry submission network protocol

Secure FTP (TLS)

NEMA CT Dose Check

NEMA XR 25-2010

Radiation Exposure Monitoring

Contents

Summary

Benefits

Details

Systems Affected

Specification

See Also

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