ESTRO 2023 - Abstract Book

S2025

Digital Posters

ESTRO 2023

Conclusion Daily alignment with 3D surface imaging was found to be very useful for reducing setup errors when comparing with patient alignment from skin marks; our next step is to reduce the frequency of routine IGRT.

PO-2251 Using the IntegraBite™ for improved setup and reduced swallowing motion in head and neck treatment

R. Butt 1 , A. Krishnan 1 , D. Quince 2 , K. Chiu 3 , D. Megias 1

1 Mount Vernon Cancer Centre, Radiotherapy, London, United Kingdom; 2 Mount Vernon Cancer Centre, Radiotherapy , London, United Kingdom; 3 Mount Vernon Cancer Centre, Oncology, London, United Kingdom Purpose or Objective The purpose of this study was to quantify the impact of the IntegraBite™ on set-up error for a range of patients receiving radiotherapy to the Head and Neck region. Inter-fraction setup error was evaluated measuring:

• Set-up error in relation to the bony anatomy

• Position of hypopharynx structures

Materials and Methods Two cohorts of 9 patients receiving radical radiotherapy, verified daily using either kV paired images or Cone Beam Computed Tomography (CBCT), were evaluated. 230 treatment verification images in total were reviewed. One cohort consisted of patients planned with IntegraBite™ and the other patients planned without IntegraBite™ or mouthbite in-situ. The treatment verification image match shifts applied relative to bone were used to determine the set-up error, with the aggregate match value representing the residual error in bony match. The position of the hypopharynx structures as an indicator of swallowing motion compared the values between the bony match for setup position and the thyroid cartilage.

The results of the two cohorts were compared using descriptive statistics to evaluate the difference in setup error.

Results Generally, the IntegraBite™ provided an improvement in the aggregate match and swallowing motion for the larynx and other population with a median result of 1.5mm with vs 2.5mm without. However, the oropharynx population had similar results with vs without the IntegraBite™.

The IQR suggest good correspondence with the median values reported suggesting good reliability of the results.

An overview of the results can be found in figure 1.

Conclusion