A radiation image capturing system (1, 20) comprising: - a radiation generation unit configured to generate X-ray radiation; - a carriage (7, 21) on which the radiation generation unit is mounted, wherein the carriage (7, 21) is a mobile carriage and the generation unit is moveably mounted on the mobile carriage; - at least one detection unit configured to capture a radiation image based on X-ray radiation generated by the radiation generation unit and transmitted and/or reflected by an object; characterized by - a first sensor unit provided at the radiation generation unit and a second sensor unit provided at the detection unit, wherein each of the first and second sensor unit (10, 11) comprises at least one accelerometer sensor configured to capture first information regarding an acceleration of the accelerometer sensor with respect to three spatial directions, at least one gyroscope sensor configured to capture second information regarding an orientation of the gyroscope sensor with respect to the three spatial directions, and at least one magnetic field sensor configured to capture third information regarding a magnetic field surrounding the magnetic field sensor along the three spatial directions; and - a first retaining element configured to accommodate the radiation generation unit in a first reference position and a second retaining element, in particular a receptacle, configured to accommodate the detection unit in a second reference position, and - a processing unit configured to determine an orientation and/or a position of the radiation generation unit and the detection unit relative to each other by considering the first, second and third information captured by the accelerometer, gyroscope and magnetic field sensor, respectively, of the first sensor unit provided at the radiation generation unit, and by considering the first, second and third information captured by the accelerometer, gyroscope and magnetic field sensor, respectively, of the second sensor unit provided at the detection unit), and said processing unit configured to determine calibration values while the radiation generation unit and the detection unit are retained in the first and second reference position, respectively. - a radiation generation unit configured to generate X-ray radiation; - a carriage (7, 21) on which the radiation generation unit is mounted, wherein the carriage (7, 21) is a mobile carriage and the generation unit is moveably mounted on the mobile carriage; - at least one detection unit configured to capture a radiation image based on X-ray radiation generated by the radiation generation unit and transmitted and/or reflected by an object; characterized by - a first sensor unit provided at the radiation generation unit and a second sensor unit provided at the detection unit, wherein each of the first and second sensor unit (10, 11) comprises at least one accelerometer sensor configured to capture first information regarding an acceleration of the accelerometer sensor with respect to three spatial directions, at least one gyroscope sensor configured to capture second information regarding an orientation of the gyroscope sensor with respect to the three spatial directions, and at least one magnetic field sensor configured to capture third information regarding a magnetic field surrounding the magnetic field sensor along the three spatial directions; and - a first retaining element configured to accommodate the radiation generation unit in a first reference position and a second retaining element, in particular a receptacle, configured to accommodate the detection unit in a second reference position, and - a processing unit configured to determine an orientation and/or a position of the radiation generation unit and the detection unit relative to each other by considering the first, second and third information captured by the accelerometer, gyroscope and magnetic field sensor, respectively, of the first sensor unit provided at the radiation generation unit, and by considering the first, second and third information captured by the accelerometer, gyroscope and magnetic field sensor, respectively, of the second sensor unit provided at the detection unit), and said processing unit configured to determine calibration values while the radiation generation unit and the detection unit are retained in the first and second reference position, respectively.