ECIA TEP197-A

Introduction

In accordance with the Radiation Control for the Health andSafety Act of 1968, cathode ray tube (CRT) manufacturers arerequired to submit an initial report to the Center for Devices andRadiological Health (CDRH), an agency of the U.S. Department ofHealth and Human Services (DHHS). The initial report for cathoderay tubes must provide results of the testing and measuring of theX-radiation emissions from a cathode ray tube.

The initial report for a new CRT tube is submitted by amanufacturer. The parts of the initial report to be discussed bythis document are the preparation of the data plots for X-radiationlimit curves and 36 pAikg isoexposure-rate limit curves. TheX-radiation limit cuwe defines the relationship between CRThighvoltage and the X-radiation exposure rate (pNkg) under aconstant beam current. The “36 pNkg isoexposure rate limit curve”defines the combinations of CRT anode voltages and beam currentsthat produce a constant rate, in this case 36 pAikg, of X-radiationemission from the CRT. Usually, such limit curves represent theworst case conditions for X-radiation emission from the CRT.Pertinent parameters to be reported are the registration referencepoints and limit curve slope factors.

Throughout this document the terms ”CRT high-voltage” and”anode voltage” mean the overall acceleration of the electron beamfrom cathode to final anode.

Two limit curves should be developed, one for the entire CRT andone for the anode contact. The following instruction for thepreparation of the X-radiation characteristic curves is recommendedto insure uniformity throughout the CRT industry.

NOTE—TO conform with the International System of Units (SI)dimensions, the unit for radiation exposure of “pA4g” (picoamperesper kilogram) has replaced “mWh”. The SI equivalent of 0.5 mWh is36 piükg. The relationship between the two measurements scalesis:

1 mWh = 72 pNkg

Edition:

A

Published:

10/01/1997

Number of Pages:

21

File Size:

1 file , 770 KB