Abstract: This study aims to examine and verify the accuracy of entrance radiation dose it is given to the patient by using the diode system and adopt it as a quality assurance protocol. Diode response was calibrated and tested to ensure that the objective of the study was achieved by using a radiotherapy device used to treat malignant diseases, four p-type Isorad diode were tested and calibrated. The diodes measured the entrance dose in each field in D max depth and were compared with the calculated dose from TPS at D max depth for every single beam. Approximately 97.77% of the 136 measurement for the head and neck treatment were within the action level set ±5%. In this study the entrance dose measurements were performed for total of 45 treatment fields of head and neck cancer patients, and 22 patients.