Table 4. Comparison of KIM with other real-time prostate tumor localization modalities.

Localization method	Kilovoltage intrafraction monitoring	Calypso electromagnetic guidance	Navotek radioactive fiducial
Accuracy	0.46 mm	0.54 mm (18)	0.89 mm (8)
Imaging dose	61 mSv at 10 Hz	None	64 mSv (19)
MRI distortion	No	Yes	No
Information type	Image plus 3 points	3 points	1 point
Marker size	1-mm diameter × 3-mm length	1.85-mm diameter × 8-mm length	240-μm diameter × 2-cm length coil that crumples into a smaller size
Rotation information potential	Yes	Yes	No
Intratreatment validation potential	Yes (kV/MV triangulation)	No	No
Image reconstruction potential	Yes	No	No
Accessibility potential	Widespread	Limited	Limited