. Radiography, X-ray therapeutics and radium therapy . ndicates the intensity of the current,so that we can compare the relative strength of the closing and breakingcurrents. There are several varieties of tube but the diagram illustrates thegeneral type in use. The instrument is useful. It recordsthe current passing in one directionthrough the tube. If reverse currentis present it represents the differencebetween the two currents. When bothare equal then no reading is the reverse is greater than the currentin the right direction, then it recordson the wrong side of the zero
. Radiography, X-ray therapeutics and radium therapy . ndicates the intensity of the current,so that we can compare the relative strength of the closing and breakingcurrents. There are several varieties of tube but the diagram illustrates thegeneral type in use. The instrument is useful. It recordsthe current passing in one directionthrough the tube. If reverse currentis present it represents the differencebetween the two currents. When bothare equal then no reading is the reverse is greater than the currentin the right direction, then it recordson the wrong side of the zero the oscilloscope tube showsthat reverse current is present, thenvalve tubes must be used to check thereverse. The combination of milliam-peremeter, valve, and oscilloscope tubesis a most useful one, helping greatly toregulate the exposures. The X-ray tube affords an excellentindication of the presence of reversecurrent. The change in the appearanceof the tube which has reverse current passing through it is illustrated inthe coloured Fia. 50.—Oscilloscope tube in action.(Schall.) a, The appearance of a tube with the run-cutpassing in the right direction with a traceof reverse current. //, The appearance with the current passingin both directions in almosl equal pro-portions. 54 RADIOGRAPHY Secondary Radiations, Cause, and Methods of Suppression.— Secondary rays are produced by the reverse current. All those X-rayswhich do not emanate from the focus of the anti-cathode are called secondaryrays. They have the same penetrating power as the primary rays and areplentiful in hard tubes, but they project the outlines of the objects in otherdirections than the primary rays, and a loss of sharpness results. When they are present it is necessary to do something to preventdeterioration of the negative. Secondary rays are also produced, or adiffusion of the primary rays takes place in the patients body. It is probable
Size: 1503px × 1663px
Photo credit: © Reading Room 2020 / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bo, bookauthorknoxrobert18681928, bookcentury1900, bookdecade1910
