A SIMPLE TEST FOR X-RAY TUBE FILTRATION

To determine the total filtration of an X ray beam the user measures t he half-value layer (HVL). The HVL is one of the parameters to be chec ked regularly in a Quality Assurance programme. Its value is an index of the spectral quality of the X ray beam and its experimental measure ment requires narrow beam geometry, a condition which is often difficu lt to achieve in practice. The beam quality, at fixed tube potential, is therefore better represented by the ratio between the tenth-value l ayer (TVL) and HVL measured in the same conditions. The present work s hows the results of measurements of the TVL/HVL ratio under different conditions for different X ray equipment. This test has many advantage s: its execution is quick and easy, it does not require sophisticated instrumentation, and it is unaffected by the measurement conditions.