X-ray vision.
Recent correspondence initiated by Dr. Cochrane Shanks' account of the sensation of light experienced during a CAT scan recalls an article on vision by X rays by R. R. Newell (1948).
SI units in radiotherapy.
We note with concern recent correspondence advocating the use of the centigray as a unit of dose (Halnan 1978, Martin-Smith 1978). Considering the reasoning and history behind the introduction of the SI system, it would be a retrograde step to introduce a unit such as the centigray. As the Australian Metric Conversion Board recommended that Australians adopt the SI units in radiotherapy by January 1978, the Cancer Institute, Melbourne changed to these units (rad to gray and centimetre to millimetre) on October 3, 1977.
Why does kidney size change during I.V. urography?
Meglumine iothalamate (280 ml I/ml) and sodium iothalamate (400 mg I/ml) in doses of 700 mg I/kg bw, were injected i.v. as a bolus in dogs. Renal size, urine flow rate, arterial pressure, renal blood flow and mean transit time and renal blood volume were measured before and after injection. All changes were qualitatively and quantitatively identical for both drugs. They produced a small transient renal shrinkage followed by a greater and prolonged renal enlargement. During the period of renal enlargement, urine flow increased. The time course of the enlargement paralleled the increase of urine flow rate. Renal blood flow also increased but both the mean transit time and renal vascular volume decreased. Therefore, the kidney size increase after i.v. injection of large doses of urographic contrast media cannot be attributed to an increased volume of the vessels. Most likely it is caused by diuresis-induced increase in the volume of the tubules.