The Lorentz force on an electron is utilised to separate out the electron component from the open beam of a Clinac-18, operating in the X-ray mode. The experimental arrangement is such that the mixed beam (comprising the primary photons, the scattered photons and the contamination electrons) enters an external magnetic field, which is perpendicular t o the central axis of the beam. The electron contribution is analysed as a function of collimator setting, depth and distance. Based on the data, one is led to believe that the shift in dm, with field size is due to a relative enhancement in the soft X-ray component as the collimator jaws are opened.

Knowledge of the normal liver size is essential for making the scintigraphic estimate of hepatomegaly. A nomogram for sonographic liver size versus height of the patient was developed for the normal pediatric patient. Liver size was measured as the longitudinal liver length in the plane midway between the xiphoid and the right lateral liver margin. Scintigraphic and sonographic measurements showed a good correlation. The scintigraphic nomogram was developed using the experimentally determined relationship between the two modalities.

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