An accurate method for inversely verifying a therapeutic radiation dose delivered to a patient via an x-ray delivery system without involving any computational iteration was developed. The usage of it includes detecting the transmitted radiation dose image after passage through the patient, imaging the patient during treatment to anatomically record information of the patient, followed by inversely verifying through use of both the detected radiation image and the imaging data, the actual radiation dose delivered to the patient, and comparing the level of the dose delivered to a previously planned dose to determine whether the planned dose was delivered, or whether an overdose or underdose occurred.