1. A method comprising: determining a first projection image of a phantom based on first imaging geometry parameters associated with a first radiation-based imaging system and on a virtual model of the phantom; acquiring a second projection image of the phantom based on radiation emitted from the first radiation-based imaging system, the phantom located at a first position; determining a difference between the first projection image and the second projection image; determining second imaging geometry parameters based on the first imaging geometry parameters and the difference between the first projection image and the second projection image; determining a third projection image of the phantom based on the second imaging geometry parameters and on the virtual model of the phantom; acquiring a fourth projection image of the phantom located at the first position based on radiation emitted from the first radiation-based imaging system; determining a difference between the third projection image and the fourth projection image; and determining that the difference between the third projection image and the fourth projection image is less than a threshold.