[Radiation Biology] Ep 2 – X-ray Interactions with Matter
This episode covers how x-rays are produced in the tube and how the two primary exposure factors — kVp and mAs — shape the energy and quantity of the x-ray beam. Listeners will explore core terminology including primary radiation, exit radiation, transmission, and attenuation, and learn how four key tissue properties — photon energy, thickness, atomic number, and density — determine how much of the beam is absorbed versus transmitted. The episode establishes the foundational relationship: Primary minus Exit equals Attenuation. The five types of x-ray interactions with matter are examined in detail — coherent scattering, Compton scattering, photoelectric absorption, pair production, and photodisintegration — with clear explanation of which interactions are relevant to diagnostic radiography and why. Special emphasis is placed on comparing Compton scattering and photoelectric absorption: how each behaves across energy ranges and atomic numbers, their opposing effects on image contrast and patient dose, and the clinical concept of differential absorption that makes diagnostic radiographs possible. Content is structured to support radiologic technology programs preparing for imaging coursework and ARRT certification review. This episode aligns with the Safety content category — Radiation Physics and Radiobiology subcategory — of the ARRT Radiography Examination Content Specifications. Audio content is adapted from original instructional material developed by Professor Sanjay Arya, M.S., R.T.(R)(MR) for radiologic technology education. Part of the Radiation Biology series — Quantum Imaging Lab. © 2026 Quantum Imaging Lab. All rights reserved.