. Journal of radiology . herapy has beenthe main topic at all meetings, bothstate and national. All other subjectshave been displaced for the time beingat least, and most of the time has beengiven to the subject of higher is no longer sufficient to state thespark gap used. The potential mustbe definitely measured. For measuringhigher accurately, a sphere gapis used, constructed according to thestandards of the American Institute ofElectrical Engineers. The sphere gap Chicago, Illinois must be placed in the high tension cir-cuit as near the tube as possible. Bythis method
. Journal of radiology . herapy has beenthe main topic at all meetings, bothstate and national. All other subjectshave been displaced for the time beingat least, and most of the time has beengiven to the subject of higher is no longer sufficient to state thespark gap used. The potential mustbe definitely measured. For measuringhigher accurately, a sphere gapis used, constructed according to thestandards of the American Institute ofElectrical Engineers. The sphere gap Chicago, Illinois must be placed in the high tension cir-cuit as near the tube as possible. Bythis method the peak voltage at thetube is definitely measured. With the higher voltages (he sub-ject of protection to the patient, theoperator, and persons adjacent to thedepartment is of importance. Duringthe past four months, numerous experi-ments have been carried out with spe-cial reference to protection. Bv the useof dental films and the electroscope thefollowing conclusions were use of a lead screen, regardless of. Fig. 2 Figure I.—Lateral view of II.—Posterior view of III.—End view of table, showing tilting of IV.—End view of table, showing lateral tilting of tube. the thickness, is inadequate. The ide^that the rays travel only in a directline does not apply when using a volt-age of two hundred thousand or radiation is given cfT by thewalls and all objects in the room. Theprimary rays are deflected. It ;s, there-fore, imperative that the operator beentirely enclosed in a lead booth—thispoint must be emphasized. The leadmust be at least one-quarter of an inchthick. One quarter of an inch of leadwill supply ample protection for twohundred thousand volts. For thevoltages above two hundred andtwenty thousand, three-eighths of aninch should be used. It is not sufficientto line a booth with lead, as a largeamount of secondary rays which areharmful to the operator are given covering the lead with pulp boardo
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Keywords: ., bookauthoramerican, bookcentury1900, bookdecade1920, bookyear1922
