Fred M. Behlen

HL7 Clinical Document Architecture, Release 2

Clinical Document Architecture, Release One (CDA R1), became an American National Standards Institute (ANSI)-approved HL7 Standard in November 2000, representing the first specification derived from the Health Level 7 (HL7) Reference Information Model (RIM). CDA, Release Two (CDA R2), became an ANSI-approved HL7 Standard in May 2005 and is the subject of this article, where the focus is primarily on how the standard has evolved since CDA R1, particularly in the area of semantic representation of clinical events. CDA is a document markup standard that specifies the structure and semantics of a clinical document (such as a discharge summary or progress note) for the purpose of exchange. A CDA document is a defined and complete information object that can include text, images, sounds, and other multimedia content. It can be transferred within a message and can exist independently, outside the transferring message. CDA documents are encoded in Extensible Markup Language (XML), and they derive their machine processable meaning from the RIM, coupled with terminology. The CDA R2 model is richly expressive, enabling the formal representation of clinical statements (such as observations, medication administrations, and adverse events) such that they can be interpreted and acted upon by a computer. On the other hand, CDA R2 offers a low bar for adoption, providing a mechanism for simply wrapping a non-XML document with the CDA header or for creating a document with a structured header and sections containing only narrative content. The intent is to facilitate widespread adoption, while providing a mechanism for incremental semantic interoperability.

Fluorescence spectroscopy of cold and warm naphthalene molecules: Some new vibrational assignments

The fluorescence excitation spectrum of naphthalene seeded in a supersonic free jet and the single vibronic level fluorescence spectrum of room temperature naphthalene vapor have been used to determine assignments for a number of combination and sequence transitions that were previously unassigned. Our data, when combined with data in the literature, require some changes in previous assignments. The spectroscopic literature on naphthalene and naphthalene‐d8 is reviewed and up‐to‐date tables of vibrational frequencies are presented.

Intersystem crossing in cold isolated molecules of naphthalene

We report the results of an extensive study of the rate of radiationless decay in very cold, isolated, naphthalene molecules. The experimental method employed, namely, pulsed narrow band laser excitation of a pulsed seeded supersonic free jet, avoids the complications imposed by the sequence congestion generated by the thermal excitation characteristic of ordinary vapor samples. Our analysis of the fluorescence decay includes a method for transforming room temperature quantum yield data to quantum yields characteristic of the molecules in the supersonic free jet. It is concluded that (a) the out of plane vibration 2(b2g) is very likely a promoting mode for intersystem crossing; (b) there is no need to invoke near resonant coupling of levels in the prepared singlet and final triplet manifolds to explain features of the radiationless decay; and (c) in general, the broad features of radiationless decay in naphthalene are very much like those of the corresponding decay in benzene, and can be similarly explained.

Dynamics of radiationless processes studied in pulsed supersonic free jets: Some naphthalene lifetimes

Abstract A pulsed supersonic free jet is used to prepare a low temperature sample of naphthalene vapor. Single vibronic level fluorescence lifetimes determined therein differ significantly from lifetimes previously obtained at room temperature.

“Permanent” records: Experience with data migration in radiology information system and picture archiving and communication system replacement

In the replacement of both a radiology information system (RIS) and a picture archiving and communication system (PACS) archive, data were migrated from the prior system to the new system. We report on the process, the time and resources required, and the fidelity of data transfer. We find that for two PACS archives, both organized according to the Digital Imaging and Communications in Medicine (DICOM) information model, data may be transferred with full fidelity, but the time required for transfer is significant. Transfer from off-line backup media was found to be faster than transfer from our robotic tape library. In contrast, the RIS replacement required extensive labor to translate prior data between dissimilar information models, and some data were inevitably lost in the translation. Standards for RIS information models are needed to promote the migration of data without loss of content.

A DICOM document-oriented approach to PACS infrastructure.

The need for long-term storage requires the future migration of image data from a PACS to its successor system. This paper considers the cost of such migration. It is proposed that storage of data as “documents” in DICOM Part 10 formats on industrystandard media could reduce the time and cost of data migration relative to on-line DICOM transfer. The relation to present efforts in developing document-oriented electronic patient records is discussed. DICOM Part 10 files are found to be a sufficient representation of image documents, but additional software tools will be needed to reach its full potential. There is a significant cost benefit of the document storage method, but it is one of many factors which must be balanced in the selection of a PACS.

User interface optimization in a radiography display console

Radiologist productivity has been a major factor limiting the acceptance of soft copy image displays. This situation is particularly acute in projection radiography. Three principal factors contribute to radiologist productivity: image quality, the user interface and system response time. These factors are not completely separable. In particular, it is difficult to optimize the user interface when system response times are a major limiting factor. A newly developed high speed multi-screen display system has enabled further refinement of the user interface into the subsecond regime. The present work focuses on optimizing control of zoom, roam and gray scale windowing. We describe the clinical optimization protocol and the user interface evolved therefrom. We also discuss the subjective impressions of the radiologists involved.© (1992) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

Long-term strategies for PACS archive design

A complete PACS must store images for decades. For reasons of either media life or drive obsolescence, no storage technology can practically retain data for much more than ten years. Procedures for migration of data to new media must be part of the system to provide the necessary storage life. In preparation for procurement of a PACS archive, clinical procedure volume and use patterns in the Department of Radiology were analyzed and projections of storage, network and retrieval requirements were developed. The analysis showed that an archive based on magnetic disk for short term storage and duplicate copies of high density magnetic tape for long term storage should meet the complete archiving needs of the Department. Advance notice of the need for retrievals from long term storage must be provided by the Radiology Information System for efficient functioning of the archive. The organization and data migration policies of the archive being procured are described.

Document-oriented approach for PACS and medical records

A model encompassing both PACS and medical records domains is described, wherein the entire patient record is represented by a collection of discrete information objects. These information objects can be stored DICOM Information Object Definitions (IODs) and the proposed HL7 Patient Record Architecture documents are found to fit this model. Relevant aspects of the both the proposed DICOM Structured Reporting and HL7 Document Patient Record Architecture standards are reviewed. The mapping of DICOM IODs to HL7 PRA documents is considered, and found to be one-to-one for all the use cases considered.

Multiresolution storage in a PACS archive

Many retrievals of images from a PACS archive do not require the full spatial resolution at which the images were originally acquired. Savings in retrieval times could be realized if images were retrieved at the lower resolution required for each display need. A PACS archive was constructed wherein images are stored and may be retrieved at lower than the originally-acquired resolution. Incoming images from the modality devices are minified by successive factors of two, down to 128 X 128. A DICOM extended private attribute was defined which enabled the reduced resolution images to be retrieved with a modified DICOM move requests. The reduced resolution images can be received by a standard DICOM workstation without the need for special workstation software. Multi-resolution storage requires approximately 30 percent more space. This additional media cost is deemed acceptable for this archive, in which data are stored on low cost magnetic tape.