Diagnostic Reference Levels in Medical Imaging

Draft document: Diagnostic Reference Levels in Medical Imaging
Submitted by Loose, Reinhard, European Society of Radiology - ESR
Commenting on behalf of the organisation

ESR suggests changes in chapter 2.5 as follows (marked red):

2.5. Data collection methods

96) There are various options for data collection. If database facilities for automated
recording are limited, paper forms tailored to the examination may be used. These are time
consuming for the operator to complete, and the validity of the results depends on the
accuracy of data entry and subsequent data transfer. This method was used for many years in
the UK, other European countries, and the U.S. (FDA 1984).

97) The advent of Hospital Information Systems (HIS) and Radiology Information
Systems (RIS) has allowed review of patient examination data to be performed
retrospectively. RIS data collection has the advantage that far greater numbers of patients can
be included, but results may be for multiple views such as PA and LAT projections in radiography. The results also rely on the accuracy and consistency of data entry, particularly with regard to the proper identification of the procedure and the correct units for the dosimetric quantities, and may not include patient weight. Because much larger numbers of patients can be included in data collected via a RIS, these problems can be overcome, to some extent, through the exclusion of outliers.

97a) Bitmap images are another widely used option to store dosimetric data as graphic images in the PACS and attach them to a study. For further analysis or processing these images have to be converted by OCR programs into digital characters. Depending on the resolution and quality of bitmap dose images, OCR conversion may produce many errors.In addition the content of information is much lower than with DICOM Dose SR Objects.

98) Modality Performed Procedure Step (MPPS) services can send x-ray procedure,
patient and image information from Digital Imaging and Communications in Medicine
(DICOM) headers to the HIS/RIS server upon completion of the examination (Ten et al., 2015; Vano et al., 2008; Vano et al., 2013). It is not recommended to use MPPS for new installations as MPPS has been withdrawn by the DICOM committee.

98b) Collation of data in Radiation Dose Structured Reports (RDSRs) can allow access to procedure data in a structured digital format and can be used to notify clinical staff and medical physicists when dosimetric quantities exceed pre-set levels. This allows for convenient and systematic follow-up of patients at risk of developing tissue reactions such as skin injuries (Fernandez-Soto et al., 2015).

99) Another option that will become more widely available in the future is the use of data
from Picture Archiving and Communication Systems (PACS). Exposure data recorded in the
RDSR, MPPS or the DICOM header can be transmitted to the PACS. Currently, data access is not straightforward, but patient dose management systems are now available which facilitate the establishment of databases as repositories of dosimetric data in the future (Cook et al., 2011; Sodickson et al., 2012; Ikuta et al., 2012; Charnock et al., 2013; Vano et al., 2013). Alternatively, dosimetric data can be transmitted to a separate, stand-alone data archive intended to aid in radiation protection quality assurance and quality improvement.
The use of dose parameters from each DICOM image of CT examinations allows to follow the changing CTDIvol by dose modulation along the z-axis of a patient, which is not possible with RDSR alone. RDSR reports only an averaged CTDIvol of an entire series. On the other side, if dose of fluoroscopic imaging or interventions is only extracted from acquired DICOM images, the contribution of fluoroscopy is missing which for some procedures may exceed the dose of acquired image series significantly.

100) As programmes for collection and analysis of dosimetric data become more
established, the numbers of examinations and numbers of patients included in surveys can be
expanded. This allows to build large dose registers with reliable data. For example, the UK now has a system whereby dosimetric data collected by medical physicists in hospitals throughout the UK are sent to Public Health England for collation and analysis. The UK survey performed in 2010 collected data for 165,000 Ka,e measurements for radiographs, 185,000 P KA measurements for radiographs and 221,000 P KA measurements for fluoroscopy (Hart et al., 2012). Similarly, the American College of Radiology’s Dose Index Registry has used automated methods to collect data on more than 5 million CT examinations (Bhargavan-Chatfield et al., 2013, Spelic et al., 2009). Furthermore dose management systems will be helpful to fulfill legal requirements like dose reporting to authorities for clinical audits or following the EU BSS directive to identify unintended overexposures. Integrating the Healthcare Enterprise (IHE) has established a well accepted standard worklow to ensure interoperability among modalities, PACS, dose report systems and even national archives.   Regardless of the data source used, the validity of the dosimetric indicators must be verified by calibration.