Fig. 1. VCH-based lung model. (a) VCH original lung image; (b) segmented tissue from the (a) image; (c) five lung lobes; (d) 3D image is an arrangement of 200 processed (b) images

Fig. 2. Five lung lobes detect light source positions. (a) Coordinate system corresponding to Fig.2(b); (b) detection of light source positions in the superior lobe of the left lung, the superior lobe of the right lung, and the middle lobe of the right lung; (c) coordinate system corresponding to Fig.2(d); (d) detection of light source positions in the inferior lobe of the left lung and the inferior lobe of the right lung

Fig. 3. Preliminary experiments of light intensity signals in the lungs. Digits 1-5 indicate the positions of the superior lobe of the right lung, the superior lobe of the left lung, the middle lobe of the right lung, the inferior lobe of the left lung, and the inferior lobe of the right lung, respectively. Digit 6 indicates the cell phone application (upper computer). Digit 7 indicates the NIR detection device. (a) Detection of light signals at positions 1, 2, and 3 of volunteers; (b) detection of light signals at positions 4 and 5 of volunteers

Fig. 4. Light fluence distribution images of the five lung lobes. (a) Inferior lobe of the right lung; (b) superior lobe of the left lung; (c) middle lobe of the right lung; (d) inferior lobe of the left lung; (e) superior lobe of the right lung. The dot “0” and arrow indicate the starting point of the light source and the direction of photon emission, respectively

Fig. 5. Changes in photon absorbance of the five lung lobes with source-detector distance L_SD. (a) Photon absorbance of the left lung lobe changes with L_SD; (b) photon absorbance of the right lung lobe changes with L_SD

Fig. 6. DPF and PPF as a function of source-detector distance L_SD for the five lung lobes. (a1)(b1) Inferior lobe of the left lung; (a2)(b2) superior lobe of the left lung; (a3)(b3) inferior lobe of the right lung; (a4)(b4) middle lobe of the right lung; (a5)(b5) superior lobe of the right lung

Fig. 7. Comparison of experimental and simulated light intensities in the lung detection region. (a) Comparison of experimental and simulated light intensities in each lung lobe of 13 volunteers, where “SR” represents superior lobe of the right lung, “IR” represents inferior lobe of the right lung, “MR” represents middle lobe of the right lung, “SL” represents superior lobe of the left lung, and “IL” represents inferior lobe of the left lung; (b) fitting of experimental and simulated values in Fig.7(a), where R² is the coefficient of determination, * represents P<0.05 and ** represents P<0.01; (c) comparison of experimental and simulated light intensities in 5 lung lobes of a male volunteer; (d) fitting of experimental and simulated values in Fig.7(c)