Using a golden angle radial sampling technique (Siemens WIP#1104), the motion range detection capabilities of 4D-MRI were compared to 4D-CT simulating lung tumour motion using a MODUS QA 4D MRI phantom. Thirteen patient respiratory patterns were used to simulate realistic breathing motion. Repeated measures ANOVA (F=0.052, p=0.948), a post-hoc paired t-test (all p>0.677) and the RMSE (RMSE12 = 1.9 mm) were used to evaluate differences between the detected motion ranges. Results showed no statistically significant difference between the motion range detection capabilities of 4D-CT and 4D-MRI in the phantom. This observation provides evidence for further evaluation in a patient population.