Implications of respiratory motion for small animal image-guided radiotherapy.

Mark A Hill,Borivoj Vojnovic

doi:10.1259/bjr.20160482

Abstract

Image-guided small animal irradiators have the potential to make a significant impact on facilitating the translation of radiobiological research into the clinic. To fully exploit the improved precision in dose delivery to the target/tumour while minimizing dose to surrounding tissues, minimal positional error in the target is required. However, for many sites within the thorax and abdomen, respiratory motion may be a critical factor in limiting the accuracy of beam delivery and until now, very little attention has been paid to the impact and management of this motion. We report on the implications of respiratory motion with respect to the negative impact of delivered dose distributions and their assessment, ways being developed to effectively manage this motion, so that beam delivery only occurs during the stationary resting phase of the breathing cycle, and comment on the need to effectively integrate these developments into the software used to plan and control beam delivery. Altogether, the implementation of respiratory-gated imaging and beam delivery will lead to significant improvements in the precision in dose delivery and constitutes an important development for preclinical radiotherapy studies.

Highlights

The recent development of image-guided small animal irradiators has the potential to make a significant impact on facilitating the translation of radiobiological research into the clinic.[1,2] These devices are useful when targeting and treating orthotopic tumours at internal sites, with imaging at treatment time to determine the size and location of the tumour and precise treatment with tightly collimated beams
The effects of respiratory motion are likely to become more significant with increasing breathing rates, owing to a decrease in the fraction of time during the breathing cycle taken by the stationary resting phase
Four-dimensional cone-beam CT (CBCT) imaging is not presently available on current-generation image-guided small animal irradiators and would be difficult to perform without a significant increase in the imaging dose

Summary

Introduction

The recent development of image-guided small animal irradiators has the potential to make a significant impact on facilitating the translation of radiobiological research into the clinic.[1,2] These devices are useful when targeting and treating orthotopic tumours at internal sites, with imaging at treatment time to determine the size and location of the tumour and precise treatment with tightly collimated beams. The effects of respiratory motion are likely to become more significant with increasing breathing rates, owing to a decrease in the fraction of time during the breathing cycle taken by the stationary resting phase.

Results

Conclusion