ARWorldTrackingConfiguration vs ARImageTrackingConfiguration

I'm trying to make an app with ARKit in iOS swift where a QR code can be detected and then I can constantly measure the 3D position between the detected QR code and the camera, even when the QR code leaves the screen Is ARWorldTrackingConfiguration or ARImageTrackingConfiguration better suited to this? Can ARImageTrackingConfiguration keep track if image anchors even when the reference image leaves the screen or is ARWorldTrackingConfiguration better for this? I should also mention that the reference image will stay static and unmoving. Thanks!