Diagnostic Reference Level (DRL) is needed as an effort for dose optimization on aircraft modalities that use radiation. One modality that has a high radiation dose is CT-scan. CT-scan has a high dose compared to other radiation modalities. Given this, DRL is needed so that the benefits received by patients are greater than the risks. With the DRL, it can help in avoiding excessive doses that are not needed due to inaccuracy in giving doses to patients. This study aims to determine the DRL value at X hospital. The DRL value is obtained from the 3rd quartile of the average CT-scan dose value, namely CTDIvol and total Dose Length Product (DLP). DRL grouping was based on 3 types of CT-scan examinations, namely head, thorax and abdomen. Each type of examination is grouped by age following the reference of the Indonesian Nuclear Energy Regulatory Agency (BAPETEN), namely infants (0–4 years), children (5–14 years) and adults (≥ 15 years) and grouping by gender. Then the results of the DRL value obtained from hospital X will be compared with the Indonesian Diagnostic Reference Level (IDRL). The results obtained for the DRL value CTDIvol are still below the IDRL value or still within safe limits. The results of the DRL (DLP) value in the head examination for all age groups are above the IDRL value. In the abdominal examination, the DRL (DLP) value for children (5–14 years) and adults (≥ 15 years) are above the IDRL values, while the DRL value in the thorax examination for adults (≥ 15 years) is above the IDRL value.