Introduction

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

The initial report for a new CRT tube is submitted by a manufacturer. The parts of the initial report to be discussed by this document are the preparation of the data plots for X-radiation limit curves and 36 pAikg isoexposure-rate limit curves. The X-radiation limit cuwe defines the relationship between CRT highvoltage and the X-radiation exposure rate (pNkg) under a constant beam current. The "36 pNkg isoexposure rate limit curve" defines the combinations of CRT anode voltages and beam currents that produce a constant rate, in this case 36 pAikg, of X-radiation emission from the CRT. Usually, such limit curves represent the worst case conditions for X-radiation emission from the CRT. Pertinent parameters to be reported are the registration reference points and limit curve slope factors.

Throughout this document the terms ''CRT high-voltage" and "anode voltage" mean the overall acceleration of the electron beam from cathode to final anode.

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

NOTE—TO conform with the International System of Units (SI) dimensions, the unit for radiation exposure of "pA4g" (picoamperes per kilogram) has replaced "mWh". The SI equivalent of 0.5 mWh is 36 piükg. The relationship between the two measurements scales is:

1 mWh = 72 pNkg