One embodiment of the present disclosure is directed to a mobile X-ray unit. The mobile X-ray unit may include an X-ray applicator for emitting an X-ray beam for irradiating an object. The mobile X-ray unit may further include a phantom-based dosimetry system configured to perform a dosimetry check of the X-ray beam. The phantom-based dosimetry system may include two sets of dose meters, each set being positioned on a surface at a distinct depth. The mobile X-ray unit may also include a dosimetry control unit configured to receive measurements from the two sets of dose meters and determine whether the dosimetry check is passed based on the measurements.