Calculation of set-up margin in frameless stereotactic radiotherapy accounting for translational and rotational patient positing error.

Context: Rotation corrected set-up margins in stereotactic radiotherapy (SRT).

Aims: This study aimed to calculate the rotational positional error corrected set-up margin in frameless SRT.

Settings And Design: 6D setup errors for the steriotactic radiotherapy patients were converted to 3D translational only error mathematically.