Tham khảo tài liệu 'recent advances in biomedical engineering 2011 part 7', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | Hyperspectral Imaging a New Modality in Surgery 229 Fig. 6. A spectral signature in blue and corresponding white reference in red and dark current in black. Wavelength nm Fig. 7. Reflectance spectra using visible and near infrared camera the horizontal axis shows different wavelengths in nanometers and the vertical axis shows the reflectance. Then the raw data are corrected to reflectance using the following equation R M ww Idark Iwhite Idark 1 where R is the calculated reflectance value for each wavelength Iraw X is the raw data radiance value of a given pixel and Idark and Iwhite are respectively the dark current and the white board radiance acquired for each line and spectral band of the sensor. The dark current and white reference in the ImSpector N17E sensor is separately captured and included in the main .raw data file. However in the ImSpector V10E it was captured in a separate file in .drk format. The white reference board should be placed in the 230 Recent Advances in Biomedical Engineering capturing field when the ImSpector V10E is used. However the dark current should be captured separately. Figure 7 and Figure 8 show the reflectance spectra of the abdominal organs. Fig. 8. Reflectance spectra using near infrared and infrared camera the horizontal axis shows different wavelengths in nanometers and the vertical axis shows the reflectance. 3. Segmentation of Abdominal Organs Due to the ambiguity between the organ and its adjacent tissues it is difficult to segment the organs and tissues during surgeries. Due to the movements of the object dynamic situations such as in live and or moving subjects will worsen the detection Liu et al. 2007 . In special situations such as anatomic variations ectopic tissues and tissue abnormalities this problem becomes more challenging. Hyperspectral imaging is used to segment the abdominal organs during the surgeries on two pigs. Two approaches are utilized to classify the hyperspectral data. In the first approach the data .
