[The efficacy of surface-guidance technique in positioning of stereotactic radiotherapy of the lung].

[INTRODUCTION] Surface-guided radiotherapy is an increasingly widely used technique that can monitor patient body surface movement in real time in a non-invasive manner.

[OBJECTIVE] To evaluate the setup accuracy of surface-guided radiotherapy in lung stereotactic body radiotherapy compared to conventional cone-beam CT-based positioning.

[METHOD] A retrospective single-center analysis was performed on 12 patients treated with lung surface-guided radiotherapy between 2022 and 2025. 6 patients were positioned using surface guidance with cone beam CT verification, while 6 were treated using cone-beam CT alone. Table couch corrections in three translational (vertical, longitudinal, lateral) and three rotational axes (pitch, roll, rotation) were recorded. Group differences were analyzed using the independent-samples Mann-Whitney U-test.

[RESULTS] The resultant 3D translational displacement was significantly lower in the surface-guided group (median: 0.40 cm) compared to the control group (0.63 cm; p = 0.002). Among individual translational components, only the vertical axis showed a significant reduction in the surface-guided group (p<0.001), while longitudinal and lateral shifts did not differ significantly (p>0.05). In contrast, the resultant 3D rotational displacement was higher with surface-guided radiotherapy (median: 2.19° vs. 1.13°; p = 0.013). None of the individual rotational axes (pitch, roll, rotation) showed statistically significant differences (p>0.05).

[DISCUSSION] These findings are consistent with previous literature demonstrating that surface guidance improves translational accuracy in thoracic radiotherapy, particularly in the vertical direction. The slightly increased rotational deviations observed in the surface-guided group may be attributed to the absence of a 6D treatment couch, as the system primarily optimizes translational alignment. Given the small sample size, further multicenter studies with larger cohorts and different surface guidance platforms are warranted.

[CONCLUSION] Surface-guided radiotherapy enhances positioning accuracy in lung sterotactic radiotherapy, mainly by reducing translational displacements. However, optimal control of rotational errors may require the integration of 6D couch capabilities or dedicated rotational correction techniques. Orv Hetil. 2026; 167(5): 171-179.