Which tolerance is described with angular units rather than linear millimeters?

• A. Table travel maximum range tolerance (all directions) ±2 mm
• B. Table angle tolerance 1°
• C. Annual couch rotation isocenter tolerance ±1 mm
• D. Table top sag tolerance 2 mm

Answer: (B)

Tolerances can be given in either distance (millimeters) or angle (degrees) depending on whether we’re controlling position or orientation. The only option described with an angular unit is the table angle tolerance, specified as 1°. This uses degrees because it’s about how far the table is rotated (its orientation), not how far it moves linearly.

The other tolerances specify linear displacements: table travel range in millimeters, couch rotation isocenter tolerance in millimeters (a positional error at the isocenter), and table top sag in millimeters. While angular rotation can impact where the beam hits, those values are expressed in linear terms as displacements.