Kilovoltage peak and half value layer relationships of a dental X-ray machine

This study compares the recorded kilovoltage peak (kVp) on the control panel versus actual kVp measured by the Photon Physics instrument and Non-invasive Evaluator of Radiation Output (NERO) System. The study also measures the effects of kVp and milliampere (mA) on Half Value Layer (HVL). Kilovoltage peak was measured using a photon physics instrument and the NERO system. Half value layer was measured using aluminum as the absorber. The kVp and HVL were measured from 50 to 100 kVp at 5 kVp intervals using both 10 mA and 15 mA. Results show a 2 to 6 kVp difference between recorded kVp on the control panel of the dental x-ray machine and measured kVp using the photon physics instrument. There was 10-15 kVp difference between the recorded kVp on the control panel and kVp measured with the NERO Quality Assurance System. The measured kVp on photon physics or NERO system was always greater than the recorded kVp on the control panel. The HVL increased as the kVp increased for both 10 mA and 15 mA settings. However, above 80 kVp, the HVL increase was not significant.