An apparatus for imaging a patient comprises a magnetic-resonance imager (MRI), a breath control device (e.g. an active breathing control or ABC device or face-mask) having a selectively closable valve adapted to prevent breath flow in at least one direction and a control apparatus which is adapted to (i) obtain a scan of the patient utilising the MRI device to yield a 1D/2D output image, (ii) analyse the said output image and (iii) close the valve to prevent breathing if the image meets a defined criterion. In another embodiment the apparatus may be combined with a radiotherapy device for delivering therapeutic radiation to a user. In this embodiment the control apparatus is used to trigger delivery of radiation while the valve is shut.
