A group of Japanese medical societies has established the country's first diagnostic reference levels (DRLs) for radiation dose.
The DRLs have been established based on the results of the latest nationwide surveys conducted by liaison organizations of the Japan Network for Research and Information on Medical Exposures (J-RIME) and advice from experts belonging to international bodies.
The Japan Medical Imaging and Radiological Systems Industries Association (JIRA) and the National Institute of Radiological Sciences (NIRS) were involved in the effort.
According to the new reference levels, the effective radiation dose for an adult is about 3 mSv for a head CT exam or about 8 mSv for a chest exam.
![Images show the pectoralis muscles of a healthy male individual who never smoked (age, 66 years; height, 178 cm; body mass index [BMI, calculated as weight in kilograms divided by height in meters squared], 28.4; number of cigarette pack-years, 0; forced expiratory volume in 1 second [FEV1], 97.6% predicted; FEV1: forced vital capacity [FVC] ratio, 0.71; pectoralis muscle area [PMA], 59.4 cm2; pectoralis muscle volume [PMV], 764 cm3) and a male individual with a smoking history and chronic obstructive pulmonary disorder (COPD) (age, 66 years; height, 178 cm; BMI, 27.5; number of cigarette pack-years, 43.2, FEV1, 48% predicted; FEV1:FVC, 0.56; PMA, 35 cm2; PMV, 480.8 cm3) from the Canadian Cohort Obstructive Lung Disease (i.e., CanCOLD) study. The CT image is shown in the axial plane. The PMV is automatically extracted using the developed deep learning model and overlayed onto the lungs for visual clarity.](https://img.auntminnie.com/mindful/smg/workspaces/default/uploads/2026/03/genkin.25LqljVF0y.jpg?auto=format%2Ccompress&crop=focalpoint&dpr=2&fit=crop&h=167&q=70&w=250)
