Optimization of frequency domain measurement technique and development of a clinical prototype optical tomography system (original) (raw)

Intrumentation for fast functional optical tomography

2001

In this article, we describe the design rationale and performance features of an integrated multichannel continuous wave ͑cw͒ near-infrared ͑NIR͒ optical tomographic imager capable of collecting fast tomographic measurements over a large dynamic range. Fast data collection ͑ϳ70 Hz/channel/wavelength͒ is achieved using time multiplexed source illumination ͑up to 25 illumination sites͒ combined with frequency encoded wavelength discrimination ͑up to four-wavelength capability͒ and parallel detection ͑32 detectors͒. The described system features a computerized user interface that allows for automated system operation and is compatible with various previously described measuring heads. The results presented show that the system exhibits a linear response over the full dynamic measuring range ͑180 dB͒, and has excellent noise ͑ϳ10 pW noise equivalent power͒ and stability performance ͑Ͻ1% over 30 min͒. Recovered images of laboratory vessels show that dynamic behavior can be accurately defined and spatially localized.

Instrumentation for fast functional optical tomography

Review of Scientific Instruments, 2002

In this article, we describe the design rationale and performance features of an integrated multichannel continuous wave ͑cw͒ near-infrared ͑NIR͒ optical tomographic imager capable of collecting fast tomographic measurements over a large dynamic range. Fast data collection ͑ϳ70 Hz/channel/wavelength͒ is achieved using time multiplexed source illumination ͑up to 25 illumination sites͒ combined with frequency encoded wavelength discrimination ͑up to four-wavelength capability͒ and parallel detection ͑32 detectors͒. The described system features a computerized user interface that allows for automated system operation and is compatible with various previously described measuring heads. The results presented show that the system exhibits a linear response over the full dynamic measuring range ͑180 dB͒, and has excellent noise ͑ϳ10 pW noise equivalent power͒ and stability performance ͑Ͻ1% over 30 min͒. Recovered images of laboratory vessels show that dynamic behavior can be accurately defined and spatially localized.

Jurnal Teknologi A Review of the Optical Tomography System

2014

Process Tomography and Instrumentation Engineering Research Group (PROTOM-i), Infocomm Research Alliance, Faculty of Electrical Engineering, Universiti Teknologi Malaysia, 81310 UTM Johor Bahru, Johor Malaysia Tomography Imaging Research Group, School of Mechatronic Engineering, Universiti Malaysia Perlis, 02600 Arau, Perlis, Malaysia Faculty of Electrical and Electronic Engineering, Universiti Tun Hussein Onn Malaysia, 86400 Parit Raja, Batu Pahat, Johor Malaysia Faculty of Science and Technology, Universiti Sains Islam Malaysia, 71800 Bandar Baru Nilai, Negeri Sembilan, Malaysia

Sensitivity Analysis for Frequency-Domain Optical Tomography of Small Tissue Volumes

Biomedical Optics, 2006

We perform numerical and experimental sensitivity analyses for the imaging problem in small-volume optical tomography with the frequency-domain equation of radiative transfer as light propagation model. Varying the optical properties, tissue geometries, and contrast, we show that source modulation frequencies in the range of 300-600MHz yield maximal signal-to-noise ratios and therefore maximal sensitivity to tissue inhomogeneities.

A fast versatile instrument for dynamic optical tomography

Biomedical Optical Spectroscopy and Diagnostics, 2000

Instrumentation suitable for acquiring fast (up to 150 Hz) multi-source, multi-detector optical measurements from tissues having arbitrary geometries is described. The design rationale and measured performance features of first-and second-generation systems are given. Also shown are representative images derived from experimental studies.

Spectral domain optical coherence tomography

Saudi Journal of Ophthalmology

Optical coherence tomography (OCT) allows high-resolution cross-sectional images of the neurosensory retina to be obtained in a non-invasive manner and has become an important tool for the diagnosis and management of vitreoretinal disease. OCT works by measuring the properties of light waves backscattered by tissue (analogous to ultrasonography) using an interferometer. In conventional OCT systems, light traveling in the reference path of the interferometer is reflected from a mobile reference mirror located within the instrument. OCT instruments that adopt this approach are often termed "time domain" as movement of the reference mirror allows assessment of the interference patterns generated as a function of time. Stratus OCT (Carl Zeiss Meditec, Dublin, CA), the most commonly used OCT system worldwide, is based on time domain technology. The requirement for a mobile reference mirror limits the image acquisition speed of time domain systems (Stratus OCT: 400 A-scans/second). As a result, only sparse sampling of the macular area is possible in a single time domain OCT image set for any given patient. More recently however, the next generation of commercial OCT systems, boasting greatly increased image acquisition speed, has been released. These systems, termed spectral domain OCT, are based on the assessment of interference patterns as a function of frequency rather than that of time. With spectral domain OCT, A-scans can be acquired 50-100 times more quickly than in time domain systems, allowing dense sampling of the retina, volumetric rendering, and the generation of OCT fundus images. Spectral domain OCT is likely to supplant time domain OCT as the standard of care for retinal specialists, as it allows earlier detection of morphological changes in disease states and improved monitoring of disease progression over time.

A Review of the Optical Tomography System

Jurnal Teknologi, 2014

Tomography is a method that has been used for image reconstruction in the medical and engineering fields. Optical tomography is one of the various methods applied in tomography systems. This tomography method is widely used in the medical and processing industries fields because of its special characteristics, such as immunity to electrical noise and interference, high resolution and its hard field sensors. The basic principle of the optical tomography system in measuring an object is based on its wave and radiation source. This article is a review of the characteristics of light and its interaction with matter, the types of optical tomography system, the basic construction of an optical tomography system, types of optoelectronic sensors and image reconstruction.