In the textbook there are represented the most recent achievements of Medical Radiology, Diagnostic Imaging techniques and its principles, diagnostic imaging of internal organs diseases, diagnostic algorithms in the study of organs and systems, questions for self-control and case studies. In the textbook there are represented the foundations of Medical Radiology, dosimetry of ionizing radiation, biological effects of ionizing radiation. In the part are described the principles, methods and elements of radiotherapy of malignant tumors and non-neoplastic lesions. The part presents the physical principles of Diagnostic Radiology. The last part shows the possibility of X-ray, CT, MRI, ultrasound, nuclear imaging and intervention methods.