= Ryozo Omoto
{c}
\b[Ryozo Omoto] was a cardiovascular surgeon and a coauthor of the 1985 real-time <Color Doppler> paper with <Chihiro Kasai>, <Koroku Namekawa> and <Akira Koyano>. Its author biography identifies his surgical work at Saitama Medical School. The paper includes cardiac flow images alongside instrument and phantom experiments.<Real-Time Two-Dimensional Blood Flow Imaging Using an Autocorrelation Technique by Chihiro Kasai and others>[Printed pp. 458, 461–462 and 464: full name, clinical tests and author biography]{ref}
A central interpretive distinction is between the displayed beam-direction component and the full <blood flow> velocity. In an ideal projection model, $v_{\rm beam}=v\cos\theta$. For a constructed speed $v=0.40\,\mathrm{m\,s^{-1}}$, a beam at $60\,{}^\circ$ measures a $0.20\,\mathrm{m\,s^{-1}}$ component, whereas a perpendicular beam has zero component. \b[Zero Doppler shift does not imply zero flow.]
Likewise, a sign-coded color indicates motion relative to the <ultrasound> beam, rather than automatically identifying oxygenated blood or a particular vessel. Turning a frequency estimate into a cardiac observation therefore requires geometry and timing, not just a color scale. Omoto's coauthored work connects that measurement problem with observing intracardiac flow; the paper's case observations do not by themselves establish universal diagnostic accuracy.
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