Expressing DICOM SR constraints in XML

摘要

In using XML to encode DICOM Structured Reporting documents, it is desirable to mechanically enforce constraints expressed in natural language in the specification. XML Schema can be used to accomplish this partially but is not powerful enough to express all the constraints. We demonstrate how more complex constraints can be expressed in XML syntax using the Schematron language. The Digital Imaging and Communications in Medicine (DICOM) Structured Reporting (SR) standard [1], and the SR Documentation Model upon which it is based, improves the expressiveness, precision, and comparability of documentation about diagnostic images and waveforms. The DICOM SR Information Object Definition (IOD) supports the interchange of expressive compound reports in which the critical features shown by images and waveforms can be denoted unambiguously by the observer, indexed, and retrieved selectively by subsequent reviewers. Findings may be expressed by the observer as text, codes, and numeric measurements, or via location coordinates of specific regions of interest within images or waveforms, or references to comparison images, sound, waveforms, curves, and previous report information. The observational and historical findings recorded by the observer may include any evidence referenced as part of an interpretation procedure. Thus, DICOM SR supports not only the reporting of diagnostic observations, but can document fully the evidence that evoked the observations. This capability provides significant new opportunities for large-scale collection of structured data for clinical research, training, and outcomes assessment. This is a by-product of diagnostic image and waveform interpretation facilitating the pooling of structured data for multi-center clinical trials and evaluations. As is standard practice in DICOM, the SR specification is maintained in Microsoft Word format and published as a PDF file. This format is not amenable to machine processing and has the potential for misinterpretation, as is common in standards written in natural language.