X-Ray Certification Cheat Sheet 2026

The 30 highest-yield X-Ray Certification facts, distilled from real exam questions. Print it, save it as a PDF, or study it here — free, no sign-up.

1. Approximately what percentage of radiation-induced biological damage occurs through indirect action via water radiolysis? → 70–80%
2. On a standard PA hand radiograph, which joint space is assessed for calcium pyrophosphate deposition disease in the triangular fibrocartilage region? → Distal radioulnar joint
3. To demonstrate an air-fluid level in the abdomen, which position and projection should be used? → Left lateral decubitus abdomen
4. What is the purpose of contrast media in CT scans? → To enhance the visibility of specific structures and pathology
5. What is the purpose of an 'artifact analysis' QC test in computed radiography? → To identify recurring image artifacts (e.g., lines, ghost images) from the reader or plate
6. The 'double bubble' sign on a neonatal abdominal radiograph indicates obstruction at which level? → Duodenum
7. Which structure is identified as the 'sentinel loop' sign on an abdominal radiograph and what does it indicate? → A localized dilated bowel loop indicating adjacent inflammation
8. Which law states that the most radiosensitive cells are those that are rapidly dividing and least differentiated? → Bergonié-Tribondeau law
9. A patient states they have a latex allergy. Which action should the radiologic technologist take? → Document and notify the radiologist, and use latex-free supplies
10. When performing a KUB (kidneys, ureters, bladder) radiograph, the lower border of the IR should be placed at the level of: → The symphysis pubis
11. What is the primary purpose of the half-value layer (HVL) measurement in X-ray QC? → To assess beam quality and filtration adequacy
12. What process decomposes water molecules through radiation exposure, producing free radicals that can damage DNA? → Radiolysis
13. What is the term used to describe the basic radiographic position for imaging the chest? → Posteroanterior (PA)
14. On a lateral skull radiograph, the sella turcica is located within which bone? → Sphenoid bone
15. Which oblique position requires the patient to rotate so the right side is closest to the IR? → RPO
16. A radiographer increases the SID from 100 cm to 150 cm. Using the inverse square law, if the original intensity was 100 mR, what is the new intensity? → 44 mR
17. What is the primary mechanism by which low-LET radiation such as diagnostic x-rays damages DNA? → Indirect action via free radicals produced from water radiolysis
18. What does CT stand for in medical imaging? → Computed Tomography
19. What are standard precautions in healthcare? → Treating all blood and body fluids as potentially infectious
20. What is the function of red blood cells? → To transport oxygen from lungs to tissues and CO2 back
21. The AP axial projection of the coccyx requires a central ray angle of: → 10 degrees caudad
22. What does the term 'effective focal spot size' refer to in X-ray equipment? → The projected focal spot size as seen from the image receptor
23. On a lateral knee radiograph, which structure appears as a teardrop-shaped density posterior to the distal femur? → Fabella
24. What is a Hounsfield unit? → A quantitative measurement of tissue density on CT images
25. For a geriatric patient who cannot stand for an upright chest, the BEST alternative is: → PA chest with the patient seated at the end of the table using an upright grid device
26. Which shielding material is most commonly used for structural radiation protection in X-ray rooms? → Lead
27. Which anatomical structure divides the thorax into right and left pleural cavities on a PA chest radiograph? → Mediastinum
28. What is the purpose of contrast media in CT scans? → To enhance the visibility of specific structures and pathology
29. A grid is primarily used to reduce which image quality problem? → Scatter radiation fog
30. What is characteristic radiation? → Radiation emitted when an outer-shell electron fills an inner-shell vacancy