Investigation of Imaging Properties of Mouse Eyes Using X-ray Phase Contrast Tomography

Abstract

Abstract. The structure of a whole eye of mouse was studied with an X-ray Talbot grating interferometer. The distribution of crystallin concentration in the lens was quantitatively measured by X-ray phase contrast tomography. A new technique to measure the crystallin concentration in the lens is proposed. By using the proposed method, the gradient of crystallin concentration in the lens was estimated. A ray-trace of a mouse whole eye was performed with the refractive indices derived from the crystallin concentration.

Phase-contrast X-ray microtomography of mouse fetus

“…The highest density in the lens of the 15 day fetus was about 1.12 g/cm 3 . This is still much lower than the density at the center of an adult lens (1.27 g/cm 3 (Hoshino et al, 2010; Hoshino et al, 2011)). Thus, the protein (crystallin) is still being concentrated.…”

“…Eye is one of the organs that are best visualized by phase-contrast X-ray imaging (Hoshino et al, 2010; Hoshino et al, 2011). The density of lens increases with gestational days (Table 1) and the cross-sections of lenses at 11, 13 and 15 days (Fig.…”

“…Since the phase-shifts by the materials are added along the X-ray path, it is possible to apply the tomographic technique (Radon transformation). After tomographic reconstruction, the value of X-ray refractive index in each cubic voxel was determined by the calibration procedure with salt solutions of known density as described (Hoshino et al, 2010; Hoshino et al, 2011). In the present study, the calibration was made with five solutions: water (1.000 g/cm 3 ), normal saline (1.006 g/cm 3 ), and salt solutions of 1.051, 1.110, 1.143 g/cm 3 .…”

“…Since the X-ray phase-shift cross sections are about 1000 times larger than the X-ray absorption cross-sections for low Z elements such as hydrogen, carbon, nitrogen, and oxygen, phase-contrast X-ray CT enables us to visualize the density distribution in biological soft tissues with a much higher contrast than conventional X-ray CT (Momose, 2005; Momose et al, 1996). This technique has been used in structural studies of soft tissues such as brain (McDonald et al, 2009; Noda-Saita et al, 2006; Pfeiffer et al, 2007; Schulz et al, 2010), liver (Wu et al, 2009), atherosclerotic plaque (Shinohara et al, 2008) and eye lens (Hoshino et al, 2010; Hoshino et al, 2011). Since an embryo and a fetus before bone calcification are made mostly of soft tissues, this technique is suitable for these samples.…”

Quantitative and dynamic measurements of biological fresh samples with X-ray phase contrast tomography

“…In this estimation the Z/M value was assumed to be 0.55, which is an average for soft tissues (NIST database, http://physics.nist.gov/PhysRefData/XrayMassCoef/ tab2.html). Á values were calibrated from standard samples (Hoshino et al, 2010). In this case experimentally obtained Á values were multiplied by 1.45, the calibration factor under these measurement conditions.…”