parts in expertise. It shows the same problems like Lund Browder Chart, but has often major financial and juristic impact.

3D – computer assisted evaluation

Sage II, Burn Vision 3D [50], BurnCase 3D [19] are existing systems that are currently in use. Sage II is a two-dimensional system, the others are three-di- mensional.

To overcome the drawbacks of existing estimation methods, the three-dimensional structure of the human body surface must be taken into account when determining the TBSAB (Total Body Surface Area Burned) of an individual patient. Modern computer graphics software is an effective, user-friendly way of dealing with three-dimensional surfaces. As already proposed by [39], the estimation and documentation of burned surface area on three-dimen- sional virtual models qualify to overcome difficulties in burn documentation.

It has been shown, that by the use of computerassisted assessment procedures, the variability of results among different observers can be reduced [50]. Discussion:

Three dimensional systems help to avoid of system immanent error: Only a three-dimensional model can ensure a sufficient documentation of the burn injury and its interpretation. In the two dimensional anterior – posterior view it is nearly impossible to classify and to illustrate burns of the lateral part of the body.

Exact documentation needs appropriate graphic resolution. The resolution of BurnVision is too low to get details. Only BurnCase3D has a sufficient resolution of 1 cm2 to illustrate height and weight as well as type of physique sufficiently.

Optical resolution of SageII is not described.

Computer aided three-dimensional documentation systems

Software-based diagnostics and documentation in modern medicine is a growing field, becoming very popular nowadays. In contrast, classification and documentation of human burn injuries and their

follow-up is still a manually performed procedure, based on paper estimation charts, free text records and most of all strongly dependent on individual impression and medical experience of the physician involved.

The exploitation of modern computer graphics technology is an effective and user-friendly way of dealing with 3D surfaces. As stated above, the estimation and documentation of burned surface area by means of 3D computer graphics is appropriate for mastering the difficulties of burn diagnostics and treatment. Electronic systems like BurnCase 3D take the three-dimensional structure of the human body surface into account when determining the TBSA of an individual patient. BurnCase 3D also regards different body shapes caused by sexual differences, age, weight, size and corpulence.

The usage of computer-aided methods can tremendously reduce error rates, but still the problem of incorrect input of burn areas resides. A major reason for input errors by chance or intended is clearly the fact of “subjective cognition” of wound areas for different reasons and the complexity of transferring the three-dimensional wound surface onto a twodimensional estimation chart. Another reason is the fact that every patient is an individual, not exactly fitting the mean human body shape and surface proposed by all common estimation methods; even by models of BurnCase3D. The only way to change this would be the creation of individual models from 3D scanners or tomography, but this till today is not feasible in praxis.

Methods used by BurnCase 3D

To overcome the issues described above, it is essential to find a way to objectively define the burned surface area and link all collected relevant data to be able to reduce the work load on the one hand and support the personnel in making decisions for the further medical treatment on the other hand, with balanced scientific claim and pragmatic feasibility.

A development team consisting of computer scientists and medical scientists has been working on a state-of-the-art software system named BurnCase 3D since 2001. During this research project, which follows the principles of action research, many chal-

lenges of modern burn care have been taken into account by the developers. Its strength is the simple and intuitive user interface; allowing quick data input without the need of sophisticated training (Fig. 1).

Technical description

The system operates on a 3D virtual body representing the real patient. This model is build up as a three-dimensional mesh of over 90 000 connected triangles with each smaller than one cm2. By specifying age, sex, height and weight and choosing an appropriate 3D standard model the system is able to

generate an automatically adapted virtual body surface which accurately fits the patient’s individual body shape. The standard model is precisely adapted to the patient’s height by scaling in longitudinal direction. Afterwards, a surface adaptation algorithm deor inflates the model until its TBSA exactly reaches the predicted value calculated by an established TBSA estimation formula.

BurnCase 3D incorporates the 12 most widely accepted TBSA estimation formulas in scientific literature. The adaptation algorithm also takes into account the growth behavior of different body regions in order to reach a realistic body expansion.

3D registration

The burned surface area is marked on the 3D body surface by standard mouse interaction. The user simply sketches the burned area with the mouse or pen cursor and BurnCase 3D projects this twodimensional polygon onto the underlying threedimensional body. Consequently, the marked area appears in a significant color and pattern, thus visualizing different burn degrees of injuries or even surgical procedures, dressings or medications. The covered surface area, as well as the affected percentage of the total body surface area (TBSA) and based on these values several medical scored and indices (ASBI, Baux, Baxter-Parkland, etc.) are calculated in real-time and presented on the user interface immediately after drawing. By rotation and zooming of the model all parts of the body can be assessed and documented.

Work reduction by automated creation of codes

The surface areas classified to burn degrees as well as operative procedures are automatically encoded to the different medical codes, which are often needed for reimbursement.

Objectivities by visual verification

In order to further increase the level of accuracy, an integrated digital picture archive provides visual verification by superimposing pictures on the 3D model. In addition, an intuitive model-picture-regis- tration algorithm has been implemented, which allows the physician to easily move the virtual body in the position of the patient on any digital picture. By doing so, the whole burn surface estimation procedure becomes as easy as sketching the border of burn wounds on a picture, however reducing the drawback of subjective influences.

Archiving photos

The system assigns photos in a simple and intuitive way to patients, dates, areas, burn conditions, procedures and even 3D location. Photos can be searched by these criteria after insertion.

Way to objective assessment of burn extent and burn depth

The combination of this 3D surface area information with available burn depth classification methods

Creation of treatment history

An 3D state of the patient can be created and revisited at different points in time throughout the whole treatment. Thus, a comprehensive three-dimension- al track of the complete treatment history is created and stored in the database for every patient.

Additional burnrelated information

Additional burn-related information such as course of accident, first aid, complications, former illnesses, and condition on admission, etc. can also be acquired and stored to the database. In order to be able to supervise all changes to the stored data, BurnCase 3D keeps track of every data acquisition or deletion in a separate change log. The data collection is compatible to the United States’ National Trauma Registry (NTRACS).

Fig. 2. Model-Picture-Alignment procedure with 2D (red) and 3D (blue) reference points

Results

Fig. 3. Mobile version of the burn injury documentation system BurnCase 3D

In contrast to common estimation methods mentioned above, BurnCase 3D uses an accurate threedimensional model of the patient for the surface calculation. Thus, a very high validity regarding the total body surface area can be achieved. Moreover, visual comparison between the real patient and the adapted virtual model enables verification that has not been possible before.

The benefits of using a computer-aided burn classification and documentation procedure over arbitrary paper estimation charts are obvious. A tremendous reduction of work load for documentation purposes for the physician is the major advantage resulting in more time for patient’s treatment. Secondly, this software system lowers the risk of overand underestimation of burn wounds by less experienced physicians. For the first time, an objective diagnostic method for burn injuries is available, which allows comparison studies even of different institutions and countries on a substantiated data basis. Finally, there is an obvious benefit for the hospital’s accounting since all necessary medical encodings like ICD10 are generated automatically.

First results of the BurnCase 3D project have been published by Dirnberger and Diretzlehner.

BurnCase 3D is currently deployed in several burn units in Europe and the US, since 2004a continuously growing number of hospitals in Linz (AUT), Vienna (AUT), Feldkirch (AUT), Halle/Saale (GER), Lübeck (GER), Mannheim (GER), Rotterdam (NED), Galveston (USA), Phoenix (USA), Birmingham (GB), Rome (IT) and Zürich (CH) are using the system for their burn surface estimation and documentation. The system is available as stand-alone and as network version providing a central database of burn cases directly connected to the institution’s hospital information system (HIS). The integration of classification images as described above is easily possible. The software system is ready to be installed on a common Microsoft Windows personal computer and uses the OpenGL technology for 3D visualization.

As most of the physicians possess smartphones, it is quite reasonable to make use of this existing hardware. The research team has already gained experience in the implementation of three-dimension- al documentation systems into mobile platforms. A mobile version of BurnCase 3D for the platform iPhone OS (iPod , iPhone , iPad ) by Apple is already available.