Radiology: Definition, Imaging Modalities & Clinical Role

Definition

Radiology is the medical specialty using ionizing and non-ionizing radiation for diagnosis and treatment.

Diagnostic Imaging Modalities

• X-ray radiography – planar projection imaging
• Fluoroscopy – real-time X-ray "movie"
• Computed Tomography (CT) – cross-sectional X-ray reconstruction
• Magnetic Resonance Imaging (MRI) – magnetic fields + radio waves (non-ionizing)
• Ultrasound – high-frequency sound waves
• Nuclear Medicine – radioactive tracers (PET, SPECT)

Therapeutic Applications

• Radiation Oncology (Radiotherapy): External beam, brachytherapy, stereotactic radiosurgery for cancer
• Interventional Radiology: Image-guided minimally invasive procedures (embolization, ablation, stenting, biopsy)

Key Professionals

• Radiologists: MD/DO + 4–5 yr residency + fellowship; interpret images, perform interventions
• Radiologic Technologists: Acquire images
• Medical Physicists: QA, dose calculation, safety
• Radiation Therapists: Deliver radiotherapy

Safety & Regulation

ALARA principle (As Low As Reasonably Achievable), shielding, dose monitoring, appropriateness criteria (ACR Select), and strict credentialing.