A method for medical imaging may include determining a posture of an object and obtaining a first parameter of a pulse sequence to be applied to the object. The method may also include determining, based on the posture and the first parameter, a SAR distribution model and estimating, based on the SAR distribution model and a second parameter of the pulse sequence to be applied, a SAR distribution associated with the object under the pulse sequence to be applied. The second parameter is associated with calibration of the pulse sequence to be applied. The method may further include determining whether the estimated SAR distribution meets a condition and causing, in response to a result of the determination that the estimated SAR distribution associated with the object meets the condition, a scanner to perform an MR scan on the object according to the pulse sequence.