Table 1.

Comparing prostate intrafraction motion magnitude. Prostate intrafraction motion results from multiple institutional trials using an endorectal balloon (ERB) for immobilization compared to the current study using an EIS. Patients treated with the EIS showed significantly reduced 3D intrafraction motion for treatment times longer than 6 min. EM = Electromagnetic

Study	Sample size (n)	Technique	Immobilization	Motion Evaluation	3D intrafraction motion	Treatment time (min)
Current study	20	VMAT	EIS	Pre-post CBCT	0 % > 3 mm	>6
Chiang et al. 2014 [36]	30	VMAT	ERB	Pre-post CBCT	3.7 % > 4.5 mm	>6
Smeenk et al. 2012 [15]	30	IMRT	ERB	Real-time EM tracking	7.0 % > 3 mm	<6
Wang et al. 2012 [34]	30	IMRT or VMAT	ERB	Real-time EM tracking	5.0 % > 3 mm	≤6
Both et al. 2011 [14]	24	IMRT or VMAT	ERB	Real-time EM tracking	5.2 % > 3 mm	<6