King's of Radiology

X-ray Basics for Radiographers: Principles, Technique & Practical Guide

RadiographerApril 18, 2026Exposure Factors, Image Quality, Radiation Safety, Radiographer Education, Radiography Basics, X-Ray No comments

X-ray Basics for Radiographers: Principles, Technique & Practical Guide

X-ray imaging is the most commonly performed diagnostic investigation in radiology. For a radiographer, understanding both the basic principles and practical factors affecting image quality is essential to produce accurate and diagnostic images while minimizing radiation exposure.

Basic Principle of X-ray

Figure: X-ray attenuation showing density differences

X-rays are a form of electromagnetic radiation
They penetrate the body and are differentially absorbed
Bone → White
Soft tissue → Grey
Air → Black

Components of an X-ray System

Figure: Components of X-ray system

X-ray Tube: Produces X-rays
Control Panel: Adjusts exposure settings
Detector: Captures image
Grid: Reduces scatter radiation

Exposure Factors

Figure: Effect of kVp and mAs on image quality

kVp: Controls penetration (High kVp → low contrast)
mAs: Controls image density
Time: Affects motion blur

Image Quality Factors

Figure: Contrast, sharpness and distortion

Contrast: Black vs white difference
Density: Image brightness
Sharpness: Detail clarity
Distortion: Shape accuracy

Radiation Safety (ALARA)

Figure: Radiation safety practices

Use collimation
Maintain distance
Apply shielding
Avoid repeat exposures

Common Mistakes in X-ray

Figure: Examples of positioning and exposure errors

Improper positioning
Rotation
Motion blur
Over/under exposure
Artifacts

Practical Tips for Radiographers

✔ Confirm patient identity
✔ Ensure correct positioning
✔ Use proper exposure factors
✔ Check for artifacts
✔ Instruct patient clearly

Quick Checklist

✔ Correct patient
✔ Correct view
✔ Proper positioning
✔ Correct exposure
✔ No artifacts

Clinical Relevance

A technically good X-ray is essential for accurate diagnosis. Poor technique may lead to misinterpretation and repeat imaging.

Summary

X-ray depends on tissue density and exposure factors
kVp and mAs are critical
Proper positioning is essential
Avoid common errors
Follow radiation safety principles

Anteater nose sign

SelvaSeptember 05, 2024Anatomy, Signs, X-Ray, xray No comments

The anteater nose sign refers to an anterior tubular prolongation of the superior calcaneus which approaches or overlaps the navicular on a lateral radiograph of the foot. This fancifully resembles the nose of an anteater and is an indication of calcaneonavicular coalition

the appearance on a lateral view of the foot of an abnormal bony fusion of the calcaneus and navicular bones accompanied by a bony bar (tarsal coalition) extending between the two bones, with an elongated tubule-like extension of the anterior and superior process of calcaneus, fancifully likened to an anteater’s elongated nose.

Credits : Vijayakumar Sir

Balloon on a string sign (ureter)

RadiographerAugust 04, 2023Signs, ureter No comments

The balloon on a string sign refers to the appearance of the ureter on intravenous urography in ureteropelvic junction obstruction. It is seen due to the high and eccentric point of the exit of ureter from a dilated renal pelvis.

Angiographic string sign

Carotid stenting under proximal cerebral protection seems to be a feasible and safe procedure to manage patients with severe carotid stenosis in presence of angiographic string sign. Further prospective trials are required to prove efficacy of CAS in larger study populations.

Ball of wool / Yarn sign (hydatid cyst)

SelvaMay 27, 2023Ball of wool, cyst, Signs No comments

The ball of wool sign, also referred to as the yarn sign or congealed water lily sign, is an ultrasound appearance, representing degeneration of hydatid cysts . The inner side of the cyst detaches from the cyst wall and folds on itself, causing a change from anechoic (fluid) to a solid, hyperechoic appearance without internal septations or daughte Renal hydatid infection

Renal hydatid infection is extremely rare and is seen in less than 5% of patients with hydatid disease1. Infection is caused by a parasitic zoonosis with the Echinococcus tape worm. The kidneys are the most commonly affected urinary organs, but bladder, prostate, seminal vesicles and testis can also be involved

Baastrup's disease (kissing spine syndrome)

SelvaMarch 25, 2023Anatomy, Bone, disorders, Radiography, Signs, Spine, Syndrome No comments

Baastrup's sign or kissing spine, is an orthopedic and radiographic disorder that often occurs in elderly humans. It is characterized by enlargement of the posterior spinous projections of the lumbar spine, with normal intervertebral disc height and neuroforamina.

Baastrup's sign, or kissing spine, is an orthopedic and radiographic disorder that often occurs in elderly humans. It is characterized by enlargement of the posterior spinous projections of the lumbar spine, with normal intervertebral disc height and neuroforamina. The reason it is referred to as kissing spine is because the posterior spinous processes 'kiss' and touch one another as the individual goes into lumbar extension, for example when flat on their stomach. The condition has been seen in humans, canines, particularly with boxer breeds, and certain breeds of horses. This disorder is named after Christian Ingerslev Baastrup.