Built through a collaboration of researchers, engineers, and clinicians at CATEA, interface and laser detection software by Mark Duckworth and Shawn Lankton.
Description
A low-cost and high-precision wound measurement device that offers an option
to current low- and high-tech devices. A prototype based upon a commercial
cell phone platform has been clinically tested. The system uses off-the-shelf
electronics and is programmed in C++.
Background
Chronic wounds such as pressure ulcers, stasis ulcers, and diabetic ulcers are a
critical healthcare issue that affects approximately 20% of the hospitalized
population in the US. Including home care patients, elders and persons with
disabilities, overall estimates of chronic wound care exceed $20 billion
annually.
Current methods and devices for wound measurement are diverse. At the lower
end of the spectrum are simple ruler and tracing-based methods which are easy
to use, but lack accuracy and involve undesirable contact with the wound. At
the higher end are devices using structured light and stereophotogrammetry
methods which are accurate and repeatable, but very expensive.
Goals of the System
• Low cost. (System hardware cost in the range $100).
• Ease of use. The system will be usable with minimal training and no
specialized knowledge.
• Non-contact. Measurement will be taken without placing anything on the
skin or wound bed.
• Fast. The total time needed for processing the wound image and retracing
(if needed) will be <1min/wound.
• Portable. The system will be hand held and battery operated.
Secondary Benefits
• Time saving – combines wound measurement and photo-documentation into a single step. This translates to healthcare savings.
• Offers increased intra- and inter-rater reliability.
Market Opportunity
Sales of such a device would be primarily to hospitals, nursing homes and home health agencies. Current practice at 90% of
these point-of-care locations is to use rulers and paper traces, techniques with poor accuracy and reliability. The market
opportunity for such a system in the US is estimated to be on the order of tens of thousands of units. A full series of product
offerings is ultimately envisioned, incorporating the enhanced features mentioned below, which would further expand the
overall market opportunity. Low estimates of cost coupled with the device’s distinct advantages over current practice suggest
attractive margin expectations. Functional prototype systems are currently in limited use to confirm clinical utility and
provide real-time information to complete product development.
Design Features
Border Detection
• Calculation of wound border is done by an iterative edge
detection method
Area Calculation and Skew Correction
• Laser pointers and computer vision techniques permit distance
measurement and skew correction
• Distance measurement and known camera properties allow for
accurate calculation of area
Touch Screen Interface
• Permits the user to
o accept the area
o modify the wound boundary by dragging the outline
using a stylus on the touch screen
o reject the wound boundary and re-trace the wound
manually using the stylus
Quality of Measurement
Repeatability
• Coefficient of variation <7% for well defined ulcer
• <10% for poorly defined ulcer
Accuracy at Different Distances and Skew
• ≈ 6%
• Exceeds those of photography, tracing, and Kundin gauge
Scalable Functioning
The design lends itself to a variety of products exhibiting additional
features. These include, but are not limited to:
• Interfacing software to upload wound pictures onto a PC via
Bluetooth or USB connection
• Integration of a wound healing scale such as the PUSH to track
wound outcomes
• Addition of spectral imaging of the wound bed to inform
clinicians about tissue types within the wound and potential
identification of spectral indicators of infection or bioburden.
• Addition of spectral detection of erythema which would be based
on the same image acquisition hardware, but different spectral
image analysis.
• Depth measurement: the use of a simple laser may be able to
quantify depth .
• Integration of a patient management system in which a database of
patient and wound information is kept and managed .
Prototypes
The prototypes shown are made from polycarbonate, and finished with white and clear lacquer. They are essentianly glorified cradles for the AT&T Tilt smart phones, and contain a calibrated class-3 laser array, LEDs, power switches, a rechargable battery and charging circuit, and a stylus slot. I built six of them which are in clinical testing in hospitals and nursing homes around Atlanta.
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Iterations from v2.2.2 to version 3.3, tweaking laser patterns and dimensions.
Version 1.2, proof of concept.
Version 2.1, unrepeatable results.
 Version 2.2.1, the first with enclosed housing
Version 2.2.2, final choice of smart phone.
Final test iteration, and final version 3.3 ready for clinical testing. Front side.
Final test iteration, and final version 3.3 ready for clinical testing. Back side.
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