Development of a dynamic phantom and investigation of mobile target imaging and irradiation in preclinical small animal research

Objective:Progress made in preclinical radiotherapy makes respiratory gating reachable. Nevertheless, technical means are still needed, as well as accurate investigations of the effect of motion on small animal treatment plans.Methods:An animal-scaled dynamic phantom (0.3–11.1-mm motion peak-to-peak amplitude, 30–120 cycles per minute) was developed and characterized. It was used to evaluate respiratory monitoring and high resolution imaging (μPET/CT scans). The width and position variations of a fluorine-18 solution were measured for various motions and gating configurations. The phantom was finally used to measure the impact of motion on dose distribution for vertical irradiation using 2.5- and 5-mm collimations.Results:Phantom motions accurately reproduced original waveforms with good rate and amplitude linearity (R2 = 1 and R2 = 0.9995, respectively). µPET/CT acquisitions showed an increase of 92% of the target size caused by a 4.9-mm sine motion and reduced to <12% by gating. Target motion measuremen...