HPA-CRCE-032 - The Measurement of X-Ray Beam Size from Dental Panoramic Radiography Equipment

Synopsis

Dental panoramic X-ray equipment provides a challenge for the accurate measurement of dose area product (DAP) values, which are utilised to help ensure radiation doses to patients are kept as low as reasonably practicable.

This report describes a quick and accurate automated method using digitised images for the measurement of the dimensions of panoramic X-ray beams. The accuracy of the method is assessed by comparing its results against those obtained using a transmission densitometer and micrometer to precisely measure the optical density profile across radiographic images of panoramic X-ray beams. The method is also compared to two established alternative methods: using a ruler alone and using a ruler in combination with a light box and magnifying glass.

Both the digitised images method (average error of 7%) and the use of a ruler in combination with a light box method (average error of 6%) were found to show good agreement with the densitometer method. Comparing the ruler-only method to the densitometer method showed that the ruler method underestimates the beam width by on average 29%, but that this method could be accurately used for measuring the beam height.

Digitised images can be used to measure panoramic beam profiles as accurately as using a transmission densitometer, and with significantly improved speed compared to both this method and use of a ruler with a light box and magnifying glass. The use of a ruler alone is neither accurate nor consistent and should not be used to make these measurements.

Last reviewed: 2 May 2012