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Wound Area Measurement with Digital Planimetry: Improved Accuracy and Precision with Calibration Based on 2 Rulers.

Foltynski P, Ladyzynski P, Ciechanowska A, Migalska-Musial K, Judzewicz G, Sabalinska S - PLoS ONE (2015)

Bottom Line: It was also showed that wound area range and camera type do not influence the precision of area measurement with digital planimetry based on two ruler calibration, however the measurements based on smartphone camera were significantly less accurate than these based on D-SLR or compact cameras.Area measurement on flat surface was more precise with the digital planimetry with 2 rulers than performed with the Visitrak device, the Silhouette Mobile device or the AreaMe software-based method.The calibration in digital planimetry with using 2 rulers remarkably increases precision and accuracy of measurement and therefore should be recommended instead of calibration based on single ruler.

View Article: PubMed Central - PubMed

Affiliation: Nalecz Institute of Biocybernetics and Biomedical Engineering, Polish Academy of Sciences, Warsaw, Poland.

ABSTRACT

Introduction: In the treatment of chronic wounds the wound surface area change over time is useful parameter in assessment of the applied therapy plan. The more precise the method of wound area measurement the earlier may be identified and changed inappropriate treatment plan. Digital planimetry may be used in wound area measurement and therapy assessment when it is properly used, but the common problem is the camera lens orientation during the taking of a picture. The camera lens axis should be perpendicular to the wound plane, and if it is not, the measured area differ from the true area.

Results: Current study shows that the use of 2 rulers placed in parallel below and above the wound for the calibration increases on average 3.8 times the precision of area measurement in comparison to the measurement with one ruler used for calibration. The proposed procedure of calibration increases also 4 times accuracy of area measurement. It was also showed that wound area range and camera type do not influence the precision of area measurement with digital planimetry based on two ruler calibration, however the measurements based on smartphone camera were significantly less accurate than these based on D-SLR or compact cameras. Area measurement on flat surface was more precise with the digital planimetry with 2 rulers than performed with the Visitrak device, the Silhouette Mobile device or the AreaMe software-based method.

Conclusion: The calibration in digital planimetry with using 2 rulers remarkably increases precision and accuracy of measurement and therefore should be recommended instead of calibration based on single ruler.

No MeSH data available.


Two rulers placed above and below the wound at approximately equal distances (d) from the wound edges.There are 2 line segments (denoted as A and B) of the same length in cm drawn at the upper and the lower ruler which are used in wound area measurement for linear distance calibration.
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pone.0134622.g001: Two rulers placed above and below the wound at approximately equal distances (d) from the wound edges.There are 2 line segments (denoted as A and B) of the same length in cm drawn at the upper and the lower ruler which are used in wound area measurement for linear distance calibration.

Mentions: Printed sheet of paper with the wound shape was placed in a support similar to standard photo frame and a paper ruler sticker was attached below or above the wound shape. In the enhanced procedure (two ruler technique) there were 2 ruler stickers placed at both sides (usually at top and bottom) of the wound shape. The rulers were placed parallel to each other and at short distance (5–10 mm) from the wound shape edge (Fig 1). In each ruler position a separate photograph of wound shape and ruler or rulers was taken. Each wound shape was photographed 3 times with 3 cameras: a compact digital camera (point-and-shot camera), a digital single-lens reflex camera (D-SLR), and a smartphone camera. We used the 14 megapixel D-SLR Nikon D3100, the 5 megapixel compact Canon PowerShot A610, and the 13 megapixel Samsung Galaxy S4 cameras. The position of the camera was no closer than 30 cm apart from the wound shape and the wound shape was visible in the middle of the picture. The picture was taken after focusing onto the wound shape. An optical zoom-in function was used in the point-and-shot and the D-SLR cameras in order to narrow the viewing angle of lens, to get lower spatial distortion, and to better fill the image with main objects e.g. wound shape and rulers. The smartphone camera had only digital zoom-in function, but it was not used.


Wound Area Measurement with Digital Planimetry: Improved Accuracy and Precision with Calibration Based on 2 Rulers.

Foltynski P, Ladyzynski P, Ciechanowska A, Migalska-Musial K, Judzewicz G, Sabalinska S - PLoS ONE (2015)

Two rulers placed above and below the wound at approximately equal distances (d) from the wound edges.There are 2 line segments (denoted as A and B) of the same length in cm drawn at the upper and the lower ruler which are used in wound area measurement for linear distance calibration.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4529141&req=5

pone.0134622.g001: Two rulers placed above and below the wound at approximately equal distances (d) from the wound edges.There are 2 line segments (denoted as A and B) of the same length in cm drawn at the upper and the lower ruler which are used in wound area measurement for linear distance calibration.
Mentions: Printed sheet of paper with the wound shape was placed in a support similar to standard photo frame and a paper ruler sticker was attached below or above the wound shape. In the enhanced procedure (two ruler technique) there were 2 ruler stickers placed at both sides (usually at top and bottom) of the wound shape. The rulers were placed parallel to each other and at short distance (5–10 mm) from the wound shape edge (Fig 1). In each ruler position a separate photograph of wound shape and ruler or rulers was taken. Each wound shape was photographed 3 times with 3 cameras: a compact digital camera (point-and-shot camera), a digital single-lens reflex camera (D-SLR), and a smartphone camera. We used the 14 megapixel D-SLR Nikon D3100, the 5 megapixel compact Canon PowerShot A610, and the 13 megapixel Samsung Galaxy S4 cameras. The position of the camera was no closer than 30 cm apart from the wound shape and the wound shape was visible in the middle of the picture. The picture was taken after focusing onto the wound shape. An optical zoom-in function was used in the point-and-shot and the D-SLR cameras in order to narrow the viewing angle of lens, to get lower spatial distortion, and to better fill the image with main objects e.g. wound shape and rulers. The smartphone camera had only digital zoom-in function, but it was not used.

Bottom Line: It was also showed that wound area range and camera type do not influence the precision of area measurement with digital planimetry based on two ruler calibration, however the measurements based on smartphone camera were significantly less accurate than these based on D-SLR or compact cameras.Area measurement on flat surface was more precise with the digital planimetry with 2 rulers than performed with the Visitrak device, the Silhouette Mobile device or the AreaMe software-based method.The calibration in digital planimetry with using 2 rulers remarkably increases precision and accuracy of measurement and therefore should be recommended instead of calibration based on single ruler.

View Article: PubMed Central - PubMed

Affiliation: Nalecz Institute of Biocybernetics and Biomedical Engineering, Polish Academy of Sciences, Warsaw, Poland.

ABSTRACT

Introduction: In the treatment of chronic wounds the wound surface area change over time is useful parameter in assessment of the applied therapy plan. The more precise the method of wound area measurement the earlier may be identified and changed inappropriate treatment plan. Digital planimetry may be used in wound area measurement and therapy assessment when it is properly used, but the common problem is the camera lens orientation during the taking of a picture. The camera lens axis should be perpendicular to the wound plane, and if it is not, the measured area differ from the true area.

Results: Current study shows that the use of 2 rulers placed in parallel below and above the wound for the calibration increases on average 3.8 times the precision of area measurement in comparison to the measurement with one ruler used for calibration. The proposed procedure of calibration increases also 4 times accuracy of area measurement. It was also showed that wound area range and camera type do not influence the precision of area measurement with digital planimetry based on two ruler calibration, however the measurements based on smartphone camera were significantly less accurate than these based on D-SLR or compact cameras. Area measurement on flat surface was more precise with the digital planimetry with 2 rulers than performed with the Visitrak device, the Silhouette Mobile device or the AreaMe software-based method.

Conclusion: The calibration in digital planimetry with using 2 rulers remarkably increases precision and accuracy of measurement and therefore should be recommended instead of calibration based on single ruler.

No MeSH data available.