Frequency shifting model for diffuse optical tomography


Creative Commons License

KAZANCI H. Ö., Oral O.

OPTICAL AND QUANTUM ELECTRONICS, cilt.53, sa.11, 2021 (SCI-Expanded) identifier identifier

  • Yayın Türü: Makale / Tam Makale
  • Cilt numarası: 53 Sayı: 11
  • Basım Tarihi: 2021
  • Doi Numarası: 10.1007/s11082-021-03308-w
  • Dergi Adı: OPTICAL AND QUANTUM ELECTRONICS
  • Derginin Tarandığı İndeksler: Science Citation Index Expanded (SCI-EXPANDED), Scopus, Academic Search Premier, Aerospace Database, Communication Abstracts, Compendex, INSPEC, Metadex, Civil Engineering Abstracts
  • Anahtar Kelimeler: Frequency domain (FD), Diffuse optic tomography (DOT), Frequency shifting
  • Akdeniz Üniversitesi Adresli: Evet

Özet

The Diffuse Optical Tomography (DOT) imaging modality is an interesting research field for researchers since it has uncertainties in the solution space. DOT imaging modality is an unsolved scientific problem. Inverse problem solution and image reconstruction have never been of their best quality. Reconstructed images have low spatial resolution. The scattering nature of low-energized diffusive light is the obscuring effect for DOT modality. DOT has 3 functional sub-branches which are Continuous Wave, Time-Resolved, and Frequency-Domain. In this work, one new approach to Frequency Domain Diffuse Optical Tomography (FDDOT) biomedical optic imaging modality is presented to the readers. Frequency shifting data were added to the forward model problem which has source-detector couplings and several imaging voxels. 100 MHz center core light modulation frequency was selected as modulation frequency. 169 source-detector matches were used on back-reflected imaging geometry. Absorption coefficient mu(a) was selected 0.1 cm(-1). Scattering coefficient mu(s) was selected 100 cm(-1). 1-mu m x, y, z cartesian grid coordinates were used in each direction for imaging tissue-like simulation media. A total of 100 frequency shifts were added to the forward model problem which has 5 Hz frequency step. 2 inclusion objects were embedded inside the imaging simulation phantom to be reconstructed. Their optical absorption coefficient mu(a) = 0.7 cm(-)(1). Two inclusion images were successfully reconstructed with the low contrast to noise ratio (CNR) and position error. The frequency shifting technique is first applied for FDDOT here in this work. This technique increased the total number of equations in the forward model problem; hence it is helping to solve the inverse problem more accurately. In this work, the positive effect of using frequency shifting methodology was observed. Differentiation of 2 embedded inclusions was completed and illustrated in this work. Two different scenarios were compared with each other. In the first scenario, only 100 MHz center core frequency was used for one source-detector match. In the second scenario, 100 additional shifted frequencies over 100 MHz center core frequency were added. It was seen that the second scenario which has more frequency shifts is superior to the general concept FDDOT methodology. This work shows that the frequency shift technique might be used for future FDDOT devices.