Radiation-Emitting Products

Focal Spot Selection

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900.12(b)(7)(i),(ii),(iii): Focal spot selection.

(i) When more than one focal spot is provided, the system shall indicate, prior to exposure, which focal spot is selected.

(ii) When more than one target material is provided, the system shall indicate, prior to exposure, the preselected target material.

(iii) When the target material and/or focal spot is selected by a system algorithm that is based on the exposure or on a test exposure, the system shall display, after the exposure, the target material and/or focal spot actually used during the exposure.

Approved Alternative Standard:


  1. For x-ray systems with multiple focal spot sizes and target materials that are automatically selected by the system, how is it possible for the system to indicate the selected focal spot or target material before the exposure is taken?
  2. A facility’s x-ray unit has automatic exposure control of the mAs but does not automatically select the focal spot or the target material. Are the requirements of 900.12(b)(7)(iii) applicable to that unit?


Page Last Updated: 01/22/2015
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