Light & X-ray Field testing can be performed using which tools?

• A. Alignment template
• B. 9 pennies and tape measure
• C. None of the above
• D. Both Alignment template and 9 pennies and tape measure

Answer: (D)

Testing light and X-ray field accuracy means making sure the light field used to lay out the image matches the actual radiation field that exposes the patient or phantom. The alignment template is a purpose-built tool with precise marks that line up with the central beam and field edges, so you can verify that the light field and the X-ray field are congruent and centered to the imaging geometry. It provides a clear, repeatable check that’s standard in QA programs.

If a template isn’t available, the pennies and tape measure approach offers a practical, low-cost alternative. Nine pennies placed in known locations create clear reference points at the field edges, and a tape measure lets you determine the field dimensions and how well-centered the field is relative to the central axis. This method is handy for quick field-size checks and for confirming collimation in everyday practice.

Using both methods, when possible, gives you a robust assessment: the alignment template gives precise, controlled verification of alignment, while the pennies method provides a simple, accessible way to monitor field size and centering in routine checks.