Department of Biomedical Engineering Posters and Presentations

Title

Breast Cancer Detection by an Infrared Imager: Evaluating the Thermal Resolution

Document Type

Poster

Keywords

Breast Cancer; Thermography; medical imaging; infrared camera; digital image analysis

Publication Date

4-2017

Abstract

Early detection of breast cancer is the key to higher survival rates for breast cancer patients. We are investigating infrared thermography as a noninvasive adjunct to mammography for breast cancer screening. Thermography detects elevated skin temperatures that arise from increased blood flow as a consequence of the angiogenesis that accompanies tumor growth. Previous work indicates that differences of as little as 0.1 K can be clinically important [1]. This study assesses the suitability for thermography of the N2 Imager thermal infrared camera by measuring its thermal resolution and determining the effect of automatic gain control (AGC).

To measure the thermal resolution, a blackbody (BB) thermal radiator, was imaged with the N2 Imager at temperatures ranging from 32oC to 42oC, 60 images were recorded at each temperature. The line of best fit between temperature and the count value for each pixel was computed, and the mean line of best fit was found. The thermal resolution was calculated by dividing the mean standard deviation (across all pixels) by the mean slope and was found to be 47.5 mK/digital count, using a 95% (± 2σ) confidence interval derived from the mean line of best fit. To test AGC, a cup of water at 44oC was allowed to cool to room temperature; 60 images were taken every minute for 25 minutes. The experiment was repeated with AGC OFF and ON. When AGC is ON, the digital count is saturated at all temperatures, because AGC maintains a fixed gain by distributing the detected temperature range over the entire grayscale (14-bits). Therefore, the cool-down curve of the water cup was not observed with AGC ON, but clearly seen when AGC was OFF.

The results confirm that the N2 Imager is suitable for a preliminary clinical study that began in September 2016. Patients diagnosed with breast cancer are imaged with the camera for a total time of 15 minutes. This is done to observe the cool-down of the breast tissue. Therefore, for our purposes, AGC must be kept off; otherwise valuable data related to the cool-down of breast tissues [1] would be lost. Current work includes acquiring images from breast cancer patients, as well as developing a software to analyze images and locate warm regions on the breast.

References:

[1] L. Jiang, W. Zhan, and M. H. Loew, "Modeling static and dynamic thermography of the human breast under elastic deformation," Phys. Med. Biol., Vol. 56, No.1, 2011, pp. 187-202.

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Creative Commons License
This work is licensed under a Creative Commons Attribution-Noncommercial-No Derivative Works 4.0 License.

Open Access

1

Comments

To be presented at GW Annual Research Days 2017.

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Breast Cancer Detection by an Infrared Imager: Evaluating the Thermal Resolution

Early detection of breast cancer is the key to higher survival rates for breast cancer patients. We are investigating infrared thermography as a noninvasive adjunct to mammography for breast cancer screening. Thermography detects elevated skin temperatures that arise from increased blood flow as a consequence of the angiogenesis that accompanies tumor growth. Previous work indicates that differences of as little as 0.1 K can be clinically important [1]. This study assesses the suitability for thermography of the N2 Imager thermal infrared camera by measuring its thermal resolution and determining the effect of automatic gain control (AGC).

To measure the thermal resolution, a blackbody (BB) thermal radiator, was imaged with the N2 Imager at temperatures ranging from 32oC to 42oC, 60 images were recorded at each temperature. The line of best fit between temperature and the count value for each pixel was computed, and the mean line of best fit was found. The thermal resolution was calculated by dividing the mean standard deviation (across all pixels) by the mean slope and was found to be 47.5 mK/digital count, using a 95% (± 2σ) confidence interval derived from the mean line of best fit. To test AGC, a cup of water at 44oC was allowed to cool to room temperature; 60 images were taken every minute for 25 minutes. The experiment was repeated with AGC OFF and ON. When AGC is ON, the digital count is saturated at all temperatures, because AGC maintains a fixed gain by distributing the detected temperature range over the entire grayscale (14-bits). Therefore, the cool-down curve of the water cup was not observed with AGC ON, but clearly seen when AGC was OFF.

The results confirm that the N2 Imager is suitable for a preliminary clinical study that began in September 2016. Patients diagnosed with breast cancer are imaged with the camera for a total time of 15 minutes. This is done to observe the cool-down of the breast tissue. Therefore, for our purposes, AGC must be kept off; otherwise valuable data related to the cool-down of breast tissues [1] would be lost. Current work includes acquiring images from breast cancer patients, as well as developing a software to analyze images and locate warm regions on the breast.

References:

[1] L. Jiang, W. Zhan, and M. H. Loew, "Modeling static and dynamic thermography of the human breast under elastic deformation," Phys. Med. Biol., Vol. 56, No.1, 2011, pp. 187-202.