Sunday, December 12, 2010

Imaging and the PCAST (President's Council of Advisors on Science and Technology) Report

Summary: Is the national health care IT standards agenda going to ignore the lessons of the past and the progress made so far? If so, what impact will it have on imaging?

Long Version:

This morning I was sent a link to a report on Realizing the Full Potential of Health Information Technology to Improve Healthcare for Americans: The Path Forward released on December 8th, 2010 from the President's Council of Advisors on Science and Technology (PCAST). There is a video available of the press conference at which it was released, as well as some older video from July 16th, 2010 of a panel discussion about some of its content. The noble goals that the speakers in the videos espouse seems to be somewhat at odds with the actual content.

Already various healthcare IT bloggers involved in standards development and deployment have commented in some detail about the technical content of the report, including Keith Boone, John Halamka, and Joyce Sensmeier.

These bloggers all seem slightly dismayed that the report seems to dismiss, or at least not give adequate recognition to, many existing efforts that are well underway. In my own review I see that HL7 is barely acknowledged, CDA is attributed to the ONC rather than HL7, IHE gets a passing mention only, and there is no mention at all of XDS, XUA, XCA, BPPC or any of the many other IHE efforts to move information back and forth across communities.

Instead, amongst the other content of the report that seems pretty reasonable, there is the unsubstantiated assertion made that "document" or "record" oriented interchange is insufficient and that "tagged data elements" with accompanying meta data are necessary, and a new standard for that needs to be written.

If this were a broad non-technical review, I would have no issue with any of that, but it isn't. It is mostly a broad review, but dives into extreme detail about certain technical issues, including security and privacy and access control solutions, implying that somehow the narrowly focused technical solutions proposed are the only solutions applicable to the broad aims of the overall report. This I find distinctly surprising.

But back to imaging, and what prompted me to write this blog entry, given that the HIT professionals and their organizations are more than capable of speaking for themselves. A surprising aspect of the report is the mammogram use case, starting on page 41.

In this use case, a patient has had mammograms performed at multiple locations, and her current physician needs to retrieve them, given, and I am selectively quoting here, "enough identifying information about the patient to allow the data to be located", "privacy protection information—who may access the mammograms, either identified or de­identified, and for what purposes", and "the provenance of the data—the date, time, type of equipment used, personnel (physician, nurse, or technician), and so forth".

OK, sounds like your standard cross-community access to DICOM images use case, something that IHE RadTech is specifically addressing as a profile this year actually (XCA-I), which involves a relatively simple extension to the existing cross community access (XCA) profile used in the XDS world. Now, I don't mean to pretend that cross-community access control (e.g., via XUA) is easy, nor that reconciliation of patient identity across communities (PIX) is easy either. Merely to point out that the problems in this area are lack of deployment and shared infrastructure or the incentives to build such (as the PCAST report rightly emphasizes elsewhere), and NOT lack of standards. We already have standard mechanisms to provide images with the level of completeness and quality required for the specific use case, ranging from pre-windowed downsampled lossy compressed images for undemanding review applications, through to the full set of diagnostic quality images required for more sophisticated uses.

Since we already have standards to do exactly this, it is perhaps not the ideal use case for PCAST to pick. The idea that a mammogram image (or set of four standard view images, all 40 to 120 MB of them) can somehow be treated as a single "data element", like say, a single blood glucose value, flies in the face of decades of experience of an entire industry.

That said, if the example had been a "tagged data element" such as the BI-RADS category from the body of a series of mammography reports from different locations, the example would have been more plausible. Indeed, the notion of being able to query and retrieve that part of the content of what would traditionally be handled as entire documents is very attractive on the face of it, and undoubtedly a desirable goal, though one that does not require rejection of the traditional structured document oriented paradigm to achieve. Nor does the report address the key barrier to adoption of structured as opposed to unstructured content to facilitate data element extraction and query, which seems to be a combination of a lack of tools and incentives to author structured content in the first place.

Regardless, a new "tagged data element" approach is not a pre-requisite for progress, and we do not need to wait for new standards to be promulgated for this before realizing most, if not all of the benefits of connectivity and interoperability.

Nor frankly, do we need to be able to query across enterprises at a particularly granular level, say for which operator performed a study, or what kVP they used. The metadata envisioned by IHE is very narrowly focused for this reason, and the notion of exposing "all available meta data", whilst theoretically possible, has enormous performance implications. This is certainly not the biggest fish to fry in the short term.

The entire continuum from images through documents to "atomic" data elements share common barriers ... lack of any connection at all between enterprises and communities, lack of deployment of existing standard mechanisms for patient identity reconciliation, and lack of deployment of existing standard mechanisms for provisioning and controlling access.

Even on the access control front the report seems to ignore existing standards and infrastructure. After a basic tutorial on security principles, tied to the "tagged data element" concept, the mammography use case is revisited from this perspective, on page 51.

To paraphrase, an access control service authenticates the clinician, assures the patient has granted them access, and provides the locations of the encrypted mammography images, and supplies the necessary decryption keys. Then, and I quote, "in this and all scenarios, data and key are brought together only in the clinician’s computer, and only for the purposes of immediate display; decrypted data are not replicated or permanently stored locally".

Really ? It is hard to imagine how to enforce that. And how practical is it, given that you generally need a pretty clever viewer if not an entire mammography workstation or plugin to your PACS viewer to effectively utilize a mammogram ? Given that the standard of care currently seems to be to import outside studies into the PACS for use as priors and for distribution throughout the enterprise to allow them to be used with the (expensive and advanced) tools that expert physicians are used to using, the report's proposal seems unrealistic.

Though the mammography imaging use case almost reduces to the absurd the notion that this form of restricted access without local importation is workable, even in the case of a local doctor's EHR, I would imagine that they would want to record even a simple data element, such as the blood glucose, imported from outside systems, rather than be restricted to accessing them on demand only. Even to manifest the prior values in a graphical form or as a flow sheet, which would seem highly desirable for enhanced decision making, would be very challenging if "outside" data points could not be persisted locally, permanently. Indeed I dare say there might be a record keeping requirement to maintain such information.

Contrast the PCAST report's proposal with what is already well standardized; as described before with XDS-I used in conjunction with XCA and XUA and PIX mechanisms, the XDS-I Imaging Document Source would provide the DICOM images to the clinician once authorized, encrypted in transit but not otherwise, via the protocol and in the format requested by the recipient, and importable into a "real" mammography display system in the normal manner. All without having to have every DICOM-compatible viewer or display system be updated to support some mythical new "universal language" based on"tagged data elements" and without being prevented from importing the images for transient or persistent use as is necessary to provide quality care. See John Moehrke's blog for a primer on what security features IHE has to offer.

Anyway, without getting too strident about, at best I find some of the technical content of the PCAST report a disappointment. At worst, I see it as a distraction from the most important items of the national agenda, well espoused in other parts of the report, which include finding a way to provide the proper incentives to get connectivity adopted in a manner that improves the quality and efficiency of care, preferably in a manner that gives patients granular control over access to their information.

Also surprising is the choice of the mammography imaging use case as the poster child for PCAST, given that the ONC has essentially ignored imaging in its initial stages of "meaningful use" probably quite reasonably in terms of return on investment, but much to the chagrin of the various professional societies, judging by the ACR/ABR/SIIM/RSNA joint comments and MITA comments. When later stages of "meaningful use" get around to imaging, they will probably emphasize reporting, decision support and avoidance of unnecessary imaging (probably much more important goals), by which time, even in the absence of specific incentives, distributed cross-community image exchange via the "cloud" will probably be commonplace. One could certainly leave the RSNA show a week or so ago with the impression that this is a solved problem, and high time too.


Wednesday, November 24, 2010

RSNA 2010 RFID Update

By the way, RSNA is still using RFID tags, as described in a previous blog entry ... I checked my badge that arrived in the mail recently and indeed it contains such a tag.

Since last year I microwaved it for too long and it caught fire, and I wandered around the whole week with a black hole on my chest, this year I will use the knife or the chisel.

Just to confirm that indeed the vendors do have access to the tracking information, here is the link to the RFID Exhibitor Package Order Form, a press release from the provider, and the usual spiel in the RSNA materials about what the RFID tag will be used for and how to opt out.


Dose Matters at RSNA 2010

Summary: Look for vendors offering the NEMA X-25 Dose Check feature and DICOM Radiation Dose SR (RDSR) (IHE REM profile) output from their CT modalities, and products able to store and process RDSRs for dose monitoring, alerting and registry submission. Bring along a list of your installed base of CT, PACS and RIS model and version numbers, and ask your vendors when Dose Check and RDSR capability will be supported. Don't forget to ask your PACS, CD burning and importing, cloud/Internet storage and distribution, Modality Worklist (MWL), reporting system, ordering and decision support vendors about this too. Visit the RSNA dose demo at Booth 2852, Exhibit Hall A, South Building.

Long Version:

In my last blog entry, I discussed the need for tools for monitoring and controlling radiation dose from CT, and with RSNA's Annual Scientific Pilgrimage to Chicago coming up next week, I thought I would consider the progress in the last six months, and what attendees might want to focus on. Undoubtedly the CT vendors will be heavily focused on what new dose-reduction technology they can deliver in new products, but do not lose sight of the importance of evaluating the monitoring and management technology as well.

One notable event was the release in November of a public letter from the FDA to MITA (NEMA), the vendors' trade organization, summarizing their investigation of the brain perfusion incidents.

In October, NEMA released the X-25 Computed Tomography Dose Check standard, which you can download from here. This feature, which the vendors had already committed at the FDA Public Meeting to develop and implement, is intended to "notify and alert the operating personnel ... that prepare and set the scan parameters — prior to starting a scan — whether the estimated dose index is above the value defined and set by the ... institution ... to warrant notification to the operator". Clearly this requires two things, 1) the implementation of the feature in the scanner, and 2) suitable values to be configured by the institution. No doubt the vendors will promulgate default levels, and organizations like AAPM or ACR might provide them, or the local medical physicists may decide for themselves. Eventually the X-25 feature will get folded into the CT manufacturer's safety bible, IEC 60601-2-44.

The RSNA meeting will be an opportunity for you to ask the CT sales people and application specialists about the Dose Check feature, and particularly how and when they plan to retrofit the scanners you already have installed to support it and how much it will cost (if anything). A commitment to the FDA is one thing, but there is nothing like evidence of demand from the customers to motivate product managers to deliver.

X-25 distinguishes between "notifications" for "protocol elements" prior to scanning, and alerts for the "examination" that accumulate what has been done so far. There is also an alert prior to saving (not just attempting to perform) a protocol that exceeds limits, which specifically helps to address a concern that arose in the Cedars-Sinai perfusion incident. Proceeding despite a notification or alert requires the recording of who, what, when and why in an audit trail. DICOM is working on additional information to be included in the Radiation Dose Structured Report (RDSR) to record the X-25 parameters and audit trail information (see CP 1047). You might also want to ask the modality vendors at RSNA when they plan to implement CP 1047, which should be made final text at the Jan 2011 WG 6 meeting. If you are looking for dose monitoring systems that can process RDSRs, you might also want to ask them about when they plan to be able to provide you with a human-readable report of CP 1047 X-25 events.

On the subject of RDSR, one vendor, GE, has already provided a list of which models and versions of scanner support RDSR, and which earlier models produce dose screen secondary capture images; you can find the list here. Hopefully other vendors, perhaps at RSNA, will provide a similar list, and I will tabulate them on the Radiation Dose Informatics web site on the Software and Devices page. In lieu of information supplied by the vendors, I will also tabulate information based on what scanners and models that I encounter RDSR objects from, so feel free to submit samples to me if you encounter them.

When shopping for new CT scanners or upgrades next week, asking the vendors for RDSR support is something obvious that you should do, but even if you are not buying new equipment, it is reasonable to ask about upgrading your installed base. If I were you, I would bring along a complete list of all the equipment that I was responsible for including models and versions, and ask very specifically of the sales people, which of those on my list can be upgraded, and when, and which of those will never be upgraded. Not only will this serve to alert the product managers to your concern about this issue, but the answers will help you plan your own dose monitoring strategy. If you don't get the answer that you want to hear (all your scanners will soon support RDSR), then you are going to need to develop a strategy that perhaps involves a third-party solution that can either OCR the dose screens if the scanners produce them, or provides a means for operator data entry and transcription of the information displayed on the console.

As for "dose monitoring systems", or whatever the name the industry is going to converge on for monitoring and reporting CT scanner dose output, the upcoming RSNA is an opportunity to look around for vendors of those systems too. It remains to be seen whether this feature becomes routinely embedded in the PACS or the RIS, or whether for the time being or indefinitely, it will be the province of dedicated third-party systems (I will maintain a list of the latter at the Software and Devices page, which is, so far, depressingly short).

In the IHE REM profile, the modality can send RDSRs either to the Image Manager/Image Archive (IM/IA) (usually the PACS) or directly to a Dose Information Reporter (DIR), which might be the RIS or a third-party system, or such a system may query the PACS. The REM design assumes that since RDSRs are DICOM objects, the PACS is the logical actor to persist and distribute them.

However, RDSR output from the modality is not going to be of much immediate use to you if a) your PACS won't accept and store them, and b) you don't have something that will display their content and, more importantly, produce management reports of dose output, if not alerts and notifications when limits are exceeded. At the very worst, you can start storing these RDSRs in the PACS now, so that when you do settle on a dose management solution, you will be able to use your historical data, as both a benchmark for your local historical practice, as well as for individual patient dose management decisions (recognizing the limitations of using dose output as a surrogate for effective dose to the patient).

Accordingly, not only do you need to be asking your CT vendor for RDSR output, but you need to be asking your PACS vendor if they will accept, store and faithfully regurgitate RDSRs, even if they do not yet have plans to render and collate the contents.

This also includes recording RDSRs on CDs, since referring physicians want to know about dose too, as does the next facility in the chain that is going to import these CDs. So your third-party CD burning and import and viewer vendors are also candidates for interrogation next week about RDSR support. You also need to ask any Internet distribution and storage vendors offering "CD substitutes" in the "cloud" about this too.

Your RIS vendor doesn't escape either. Though they may not be planning on offering RDSR management, they will still be providing Modality Worklists (MWL) to the CT scanners. It turns out that it is really important to convey the age, sex, height and weight information, as well as anatomic and procedure codes, if downstream one is to make size-appropriate use of the dose output information (which after all is based on standard sized phantoms and needs adjustment for kids and for particularly small or large people). The CT scanner vendors are well aware of these issues, and hopefully can reliably copy the information from the worklist into the RDSR (another question to ask your scanner vendor if you want to get into that much detail with them).

Finally, when generating the radiology report, it is good practice if not required by regulation (such as in Germany or now California with SB 1237), to include information about the radiation dose, and a creative reporting system vendor could automatically copy information directly from the RDSR for the study into the report template being populated by the radiologist. Now is the time to get the reporting system vendors thinking about this, particularly since some of them already offer features for doing the same sort of thing from other types of structured report "input", notably for ultrasound and echocardiography. Even the ordering and decision support system vendors should not be immune to your questions, since they too can take advantage of patient-specific historical information acquired from RDSRs.

In conclusion, next week you have the opportunity to put penetrating questions about radiation dose to everyone you meet with a product that is involved in any part of the imaging chain, from ordering all the way through to reporting.

If you want to get a more detailed briefing, perhaps prior to visiting the vendors' booths, and see some of the components of the IHE REM profile in action, feel free to come and visit the RSNA Image Sharing and Radiation Dose Monitoring demonstration. A group of CT modality, PACS and dose reporting vendors, together with some academic groups, the ACR and myself will be participating. Strangely enough this will actually be held in the Technical Exhibits area, rather than in the Lakeside Learning Center, specifically Booth 2852, Exhibit Hall A, South Building. Email me if you can't find the demo or have any questions about it.


PS. By the way, while I am thinking of it, if you use lossy compression in your archive, make sure it is turned off for series that contain dose screens (or indeed any secondary captures containing text and graphics like perfusion curves), since not only will it make them look like crap but will also reduce the performance, if not entirely cripple, any OCR that you might later apply.

Monday, May 31, 2010

Dose Matters

Summary: Reducing the radiation exposure from diagnostic imaging is an increasing priority; standards exist for encoding dose information but are not yet widely adopted, though soon will be given regulatory pressure and industry commitments; few tools, commercial or open source, exist yet for monitoring and reporting radiation dose.

Long Version:

You would have to have been living on a desert island or under a rock to not be aware that there is a heightened sensitivity amongst the general populace and the regulatory authorities to the matter of radiation dose exposure from diagnostic imaging and the risk of cancer. Whether it be well publicized disasters like the Jacoby Roth or Cedars-Sinai incidents, or general concern related to dose from procedures like virtual colonoscopy, or articles evaluating the contribution of diagnostic imaging as a source of exposure, the need to deal with the matter is inescapable. This is true regardless of whether you are a "believer" in the linear no-threshold model, which says that no amount of radiation is safe, or not. The FDA is going to require that efforts be made to reduce the dose delivered by both CT and fluoroscopy, as discussed in their initiative white paper and reviewed at the recent public meeting, though they have been working on this for some time. Vendors are already delivering equipment incorporating dose saving technology. Attention is being drawn to the radiation dose caused by the ordering of repeat or low-yield procedures, as well as optimal strategies for pediatric imaging (image gently).

Yet so much remains in the hands of the user in terms of ordering as well as performance of the examination. If you cannot measure it, you cannot improve it (Lord Kelvin), so the question arises as to how one can track the amount of radiation being delivered, either to the population, or at a site, or to an individual, and hence benchmark one's own performance then make improvements to the process. Surprisingly, though devices have long been required to provide visual feedback to the operator at the console, it has proven remarkably difficult to get this information out of the scanners and into some sort of database or registry that can be searched or monitored.

DICOM has a number of ways that dose information can be encoded, but for the last few years has been focusing on the Radiation Dose Structured Report (SR), with the goal of having the modalities produce this directly. Many people expect that dose information would be in the image headers, but the image is the wrong place to encode this; images may be transmitted before the study is complete and hence not contain the cumulative information, and more than one image may be reconstructed from the same irradiation event, creating the risk that the dose may be counted more than once. Further, not all originally acquired images are necessarily retained (e.g., thin slices from CT), and a large volume of images is a poor means of communicating what is essentially a small amount of information. One upon a time, it was thought that the modality performed procedure step (MPPS) might be a suitable mechanism to communicate this information, but it was soon realized that there is no easy way to persist what is essentially a transient message, not to mention that MPPS is relatively poorly adopted.

To meet the users' immediate needs, some vendors have gone so far as to provide images that are saved screens containing the text of the delivered dose information. Both GE and Philips do this, and there is a large installed base of such scanners as well as archives full of such information. Though Philips had the foresight to also encode the same information in the header attributes of these images (albeit in a non-standard way), both as plain text and as individual elements, unfortunately GE did not, so many folks who want to perform a retrospective review of their dose information need to manually examine these images, or develop some optical character recognition (OCR) software.

For the time being, there is a relative paucity of tools available both to handle information from legacy devices, as well as to use more standard approaches, including that espoused in the IHE Radiation Exposure Monitoring (REM) profile, which is based on modalities producing DICOM Radiation Dose SR objects, and provides specific actors for consuming and reporting information, including transmission to registries, such as the ACR's Dose Index Registry. The good news is that there has been significant activity at recent IHE Connectathons with respect to implementing REM; you can review these yourself at the connectathon results page, where you can see which vendors have specific offerings in this field. MITA, the modality vendors' industry trade group, has made a strong commitment not only to dose reduction in general, and the CT Radiation Dose Check feature, but also to retrofitting at least the current platform in the installed base to produce DICOM SR objects .

At a recent teleconference of the newly convened Quality and Safety Subcommittee of the RSNA's Radiology Informatics Committee (RIC) , it was apparent that several academic groups have been working in this field, and the need to make available open source tools was highlighted, if for no other reason than to serve until the industry catches up and provides a robust infrastructure.

To this end I thought I would externalize some of my own primitive efforts, as extensions to my Pixelmed Java DICOM toolkit. Specifically, I put together a little application called DoseUtility, which brings together a number of components that I have been working on, including the construction and validation of Radiation Dose SR objects, as well as the ability to perform OCR on GE dose screen saved images. I have already used the validator to good effect during the last few connectathons, and the experience constructing and testing it has led to a number of proposed changes to the standard and the IHE profile.

Eventually I hope to extend this tool and its components to provide a complete infrastructure for dose management, at least from the DICOM and IHE side of the problem. Currently it focuses on CT, but it will be extended to fluoroscopy and projection X-ray soon, as well as injected dose from NM and PET, as those standards evolve.

I dare say that the various academic groups who have been working on the same types of problems may well have much more sophisticated tools, likely more easily integrated with their own PACS and RIS, perhaps taking advantage of proprietary APIs. As yet, I am unfamiliar with the specifics of most of them, but I will make a catalog of whatever becomes available.


Wednesday, April 28, 2010

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