High-Resolution Laser Surface Scanning for Patient Registration in Cranial Computer-Assisted Surgery

OBJECTIVE

Markerless patient registration is a new procedure that may reduce logistical efforts and possibly also the radiation load on the patients prior to a computer-assisted intervention. Congruent surfaces, such as bone surfaces or skin surfaces, represented in a data set and in the surgical site, can be overlapped using surface-matching. Previous studies describing this kind of markerless registration, however, show inaccuracies of up to 10 mm during computer-assisted navigation. Furthermore, these systems use less than 1000 surface points of the soft tissue surface in order to establish a correlation between the patient and the data set. Previous papers did not answer the question whether it is this scanning resolution that induces these inaccuracies in registration or rather intraoperative skin deformations.

STUDY DESIGN

In the present study therefore a new navigation system (SSN++) was used which is able to register up to 180,000 surface points of the surgical site. SSN++ is an infrared navigation system enlarged by a Minolta VI 900 3D volume digitizer. Three different kinds of laser scan-resolution were used for data correlation. An additional congruence analysis was performed in order to assess the geometry of the matched skin surfaces. 22 patients suffering from different cranial diseases (tumors, bony malformations, foreign bodies) were prepared for a computer-assisted intervention. Intraoral titanium-markers, rigidly fixed on the patients by a maxillary splint, were placed as targets while the CT data sets were made. These targets were - after markerless laser scan registration of the patients - supposed to serve for validating the new high-resolution navigation system SSN++.

RESULTS

The accuracy of markerless laser scan registration depends on the intraoperative laser scan's resolution. A high accuracy of the data correlation can be achieved if the number of the laser scan cloud points is about the same as the number of voxels of the corresponding surface on the CT data set. A reduction of the laser scan cloud points to less than 10 % compared to the number of voxels of the CT surface, however, leads to a significant loss of accuracy after markerless patient registration.

CONCLUSION

The markerless laser scan registration of the surgical site may achieve the same accuracy as a patient registration made by rigidly fixed titanium screws (mean accuracy: 1.2 mm) as long as a high-resolution laser scan is being used.

Zero-Check: A Zero-Knowledge Protocol for Reconciling Patient Identities Across Institutions

Context.—Large, multi-institutional studies often involve merging data records that have been de-identified to protect patient privacy. Unless patient identities can be reconciled across institutions, individuals with records held in different institutions will be falsely “counted” as multiple persons when databases are merged.

Objective.—The purpose of this article is to describe a protocol that can reconcile individuals with records in multiple institutions.

Design.—Institution A and Institution B each create a random character string and send it to the other institution. Each institution receives the random string from the other institution and sums it with their own random string, producing a random string common to both institutions (RandA+B). Each institution takes a unique patient identifier and sums it with RandA+B. The product is a random character string that is identical across institutions when the patient is identical in both institutions. A comparison protocol can be implemented as a zero-knowledge transaction, ensuring that neither institution obtains any knowledge of its own patient or of the patient compared at another institution.

Results.—The protocol can be executed at high computational speed. No encryption algorithm or 1-way hash algorithm is employed, and there is no need to protect the protocol from discovery.

Conclusion.—A zero-knowledge protocol for reconciling patients across institutions is described. This protocol is one of many computational tools that permit pathologists to safely share clinical and research data.

[Development of an automated patient-recognition method for digital chest radiographs using edge-enhanced images]

It is important that all images in a picture archiving and communication system (PACS) environment should be stored in the correct location, e.g., in the proper patient's folder. However, if patient information, such as identification number or patient name, has been entered incorrectly, the image may be stored in the wrong place. We are developing an automated patient recognition method for chest radiographs based on a template-matching technique to prevent such filing errors. To further improve the performance of our method, we investigated the usefulness of a new automated patient-recognition method based on a template-matching technique by using edge-enhanced and smoothed images. We found that the relationship between the correlation values obtained with and without the edge-enhancement technique tended to provide different criteria for identifying correct or incorrect patients. When we combined the two methods to distinguish the images by a rule-based method, 67.1% of wrongly identified patients in our database could be identified as wrongly identified, without any false warnings for correctly identified patients. We consider that this automated method for patient recognition based on edge-enhanced images would be useful in preventing "wrong" images from being stored in a PACS environment.

Electronic health record on cards

The paper is dedicated to the brief evaluation of smart card technology in terms of implementing EHR. Basic standards and recommendation are mentioned, so as currently running European activities. It has to be stressed, that despite the health care (and social insurance) is controlled throughout EU on national basis, strong international harmonisation and interoperability is being perceived. EFMI WG Cards contribution in this sense is drafted as closing remark to the paper.

Sensors keep patients flowing smoothly at surgery center

The typical outpatient surgery facility is a hard place to find anything. Staff members make hundreds of phone calls each day to determine where patients are, keep updated on surgeries, and track down specialized equipment. Each time a call is dialed, a colleague on the other end must stop what he or she is doing to answer. The phones in the new 60,000-square-foot surgical suite at Providence St. Vincent Medical Center don't get nearly as heavy a workout because the facility's automatic tracking system displays the location of each patient in real time.

Barcode technology: its role in increasing the safety of blood transfusion

BACKGROUND

Incorrect blood component transfusion is the most frequent serious incident associated with transfusion. Errors responsible for these incidents frequently involve patient misidentification.

STUDY DESIGN AND METHODS

This study evaluated a barcode patient identification system involving hand-held computers for blood sample collection for compatibility testing and the administration of blood. Audit of practice was carried out before and after its introduction.

RESULTS

The baseline audit revealed poor practice, particularly in patient identification. Significant improvements were found in the procedure for the administration of blood following the introduction of barcode patient identification, including an improvement from 11.8 to 100 percent in the correct verbal identification of patients (p </= 0.001). Similar significant improvements were found in matching verbally stated identification details with details on patient identification wristbands, in correct patient identification before the collection of blood samples, and in the proportion of correctly labeled samples. Staff found the barcode identification system easy to operate and preferred it to standard procedures.

CONCLUSIONS

A barcode patient identification system was found to simplify the clinical transfusion process and improve practice. These results provide support for further work on the development of such systems for transfusion and for other hospital procedures requiring patient identification.

Audit of transfusion procedures in 660 hospitals. A College of American Pathologists Q-Probes study of patient identification and vital sign monitoring frequencies in 16494 transfusions

CONTEXT

Hemolytic transfusion reactions are often the result of failure to follow established identification and monitoring procedures.

OBJECTIVE

To measure the frequencies with which health care workers completed specific transfusion procedures required for laboratory and blood bank accreditation.

DESIGN

In 2 separate studies, participants in the College of American Pathologists Q-Probes laboratory quality improvement program audited nonemergent red blood cell transfusions prospectively and completed questionnaires profiling their institutions' transfusion policies.

SETTING AND PARTICIPANTS

A total of 660 institutions, predominantly in the United States, at which transfusion medicine services are provided.

MAIN OUTCOMES MEASURES

The percentages of transfusions for which participants completed 4 specific components of patient and blood unit identifications, and for which participants monitored vital signs at 3 specific intervals during transfusions.

RESULTS

In the first study, all components of patient identification procedures were performed in 62.3%, and all required patient vital sign monitoring was performed in 81.6% of 12 448 transfusions audited. The median frequencies with which institutions participating in the first study performed all patient identification and monitoring procedures were 69.0% and 90.2%, respectively. In the second study, all components of patient identification were performed in 25.4% and all patient vital sign monitoring was performed in 88.3% of 4046 transfusions audited. The median frequencies with which institutions participating in the second study performed all patient identification and monitoring procedures were 10.0% and 95.0%, respectively. Individual practices and/or institutional policies associated with greater frequencies of patient identification and/or vital sign monitoring included transporting units of blood directly to patient bedsides, having no more than 1 individual handle blood units in route, checking unit labels against physicians' orders, having patients wear identification tags (wristbands), reading identification information aloud when 2 or more transfusionists participated, using written checklists to guide the administration of blood, instructing health care personnel in transfusion practices, and routinely auditing the administration of transfusions.

CONCLUSIONS

In many hospitals, the functions of identification and vital sign monitoring of patients receiving blood transfusions do not meet laboratory and blood bank accreditation standards. Differences in hospital transfusion policies influence how well health care workers comply with standard practices. We would expect that efforts designed to perfect transfusion policies might also improve performance in those hospitals in which practice compliance is substandard.

Health systems' accountability for patient safety

Patient safety experts, including the Institute of Medicine Committee on Quality of Health Care in America, have emphasized the need to focus on systems failure as the source of most error in health care. This requires an emphasis on prevention and on health systems' accountability for error. This article discusses traditional and evolving approaches to systems' accountability for error. While there are some significant recent developments, such as the JCAHO new Patient Safety Goals, many issues remain about how to determine and enforce systems' accountability for error. These include identifying what systems will be held accountable for and how accountability will be enforced. While reporting of errors is one route toward accountability, many questions remain regarding the most effective approach toward error reporting. Research on and evaluation of reporting systems and other approaches toward systems' accountability will be important in moving forward in this area.

Health cards as a part of French health telematics

The concept of the healthcare smart card is being discussed by more and more countries all over the world since the late eighties. After a long period of pilots, health cards are now an important part of the French health telematics. How did this happen? This paper highlights the prerequisite for a large implementation.

[Safety management activities of Yokohama City University Hospital--safety management is the platform of quality improvement]

Four years have passed since mistaking patients for operations occurred at Yokohama city university hospital (YCU hosp) on January 11, 1999. The accident was not just a simple mistake such as the patients happened to have the same name. Its root seemed to be a system error that deeply related to health care delivery at YCU hosp. Based on the trying experience, YCU hosp started to construct a new system for health care safety management. From 2001 the system development entered the second phase. The activities of this phase included promoting interdisciplinary projects on a variety of topics, implementing a systematic educational program, and activating risk managers. As a whole, autonomous activities by health care professionals regarding patient safety started to take place in the hospital as a new approach for safety management. The next step will be to expand these activities into a movement for hospital-wide quality improvement and establishing clinical governance.