What actually happens when you get an X-ray? This explainer walks through the full journey—from how the tube generates X-rays and how your body’s tissues absorb them, to how detectors capture data and software turns signals into a diagnostic image. You’ll also see where the technologist’s expertise shapes image quality and safety through ALARA principles and smart positioning.
From Beam to Image: The Hidden Process Behind Every X-ray
Behind each quick click in the X-ray room is a precise series of steps—physics, positioning, dose control, and image processing—all coordinated by a trained radiologic technologist.
Curious about how radiography really works? Explore the science and patient care behind X-ray imaging—and how training turns technology into accurate diagnosis.
X-ray imaging is one of the most common—and essential—tools in modern medicine. It’s fast, widely available, and excellent for showing bones, joints, and certain soft-tissue patterns. But the magic isn’t magic at all: it’s a Controlled beam of energy, thoughtful positioning, and pattern recognition turned into a viewable image. Here’s how the full process works from start to finish.
The Physics, Briefly: How X-rays Are Made
Inside the X-ray tube, electrons accelerate across a tiny gap and strike a metal target (often tungsten). That impact converts kinetic energy into X-rays. The technologist sets exposure factors—commonly kVp (beam energy) and mAs (beam quantity over time)—to match the anatomy being imaged. Higher kVp penetrates more, while mAs influences how much signal reaches the detector.
- kVp (kilovolt peak): Controls beam energy and affects subject contrast and penetration.
- mAs (milliampere-seconds): Controls beam quantity and influences image brightness and noise.
- Filtration & collimation: Filters remove low-energy photons; collimators shape the beam to the area of interest.
Attenuation: Why Different Tissues Look Different
As X-rays pass through your body, tissues absorb or scatter them to different degrees—this is called attenuation. Dense structures like bone attenuate more (appearing lighter), while air-filled spaces attenuate less (appearing darker). Soft tissues sit between those extremes. The contrast you see is the map of how much of the beam made it to the detector.
The Detector & Image Formation: From Photons to Pixels
Modern systems most often use digital detectors (flat-panel or computed radiography plates). When X-rays strike the detector, they produce an electrical signal proportional to the exposure that passed through the patient. Software then processes this raw data—applying algorithms to adjust brightness, contrast, and noise—so clinicians can interpret fine detail.
- Automatic Exposure Control (AEC): Helps optimize exposure by sensing when enough signal has reached the detector.
- Post-processing: Edge enhancement, noise reduction, and window/level adjustments improve diagnostic visibility.
- Metadata: Patient ID, body part, view, and dose indicators are stored with the image for safety and quality tracking.
Step-by-Step: What Happens During Your X-ray Exam
- Verification: The technologist confirms patient identity, exam type, and the side/body part to image.
- Preparation: Jewelry or objects are removed; shielding is used where appropriate.
- Positioning: The body part is aligned precisely (e.g., AP/Lateral). Correct positioning reduces repeats.
- Technique Selection: The technologist sets kVp/mAs (or uses AEC) based on anatomy and patient size.
- Exposure: The beam is collimated to the smallest necessary field; the exposure is made.
- Quality Check: The image is reviewed for positioning, sharpness, and appropriate contrast.
- Documentation: Images and technical factors are saved and sent to the radiologist for interpretation.
Safety & ALARA: Built Into Every Decision
Safety isn’t a separate step—it’s embedded in the process. Radiologic technologists apply the ALARA principle (“As Low As Reasonably Achievable”) to keep exposure minimal while achieving diagnostic quality. That includes careful collimation, appropriate technique, using shielding when indicated, and avoiding unnecessary repeats.
For a focused overview of safety habits and tools, see our explainer:
Safety First: Understanding Radiation Protection in Radiography.
Image Quality Factors: What Pros Look For
- Contrast: Can the structures of interest be distinguished?
- Sharpness: Are edges crisp (minimal motion/blur, correct focal distance)?
- Noise: Is the image grainy or appropriately smooth for diagnosis?
- Coverage: Does the field include the full region of interest?
- Markers & Metadata: Proper left/right markers and patient/exam info.
Balancing these factors is where technologist expertise shines—choosing techniques that achieve clarity at the lowest reasonable dose.
Special Cases: Pediatrics, Pregnancy, and Portable Imaging
- Pediatrics: Size-specific techniques, immobilization strategies, and strict collimation help reduce dose and motion.
- Pregnancy: Screening questions and shielding/alternative imaging pathways may be considered based on clinical need.
- Portable/Bedside: Extra attention to staff/patient shielding and environment to minimize scatter to others.
Quick FAQ
Will I feel anything? No—X-rays are invisible and painless. You may need to hold still briefly.
How long does it take? Many exams finish in minutes, though complex studies or multiple views take longer.
Who reads my images? A radiologist interprets the images and sends a report to your provider.
Find Out More
Interested in the science and care behind medical imaging? Explore our Diagnostic Medical Imaging Radiography program, or Request Information.
The Diagnostic Medical Imaging Radiography program is offered at MCC’s Chicago Main Campus and Cleveland Campus. Students at both locations train on digital imaging systems under experienced instructors in modern clinical settings.
Katherine R. Lieber, Director of Enrollment Technology at Midwestern Career College, is a technology and digital strategy leader who has driven student engagement and content innovation across industries. Her expertise in enrollment technology, strategic systems, and AI-optimized content strategies ensures that prospective students connect with the right career insights.
