Patent ID: 8704519

Claim:
A magnetic resonance tomography apparatus comprising: a magnetic resonance data acquisition unit configured to acquire magnetic resonance data from an examination subject located in an opening in said magnetic resonance data acquisition unit that has a longitudinal axis along which the examination subject is moved through the opening, said longitudinal axis coinciding with the z-direction of a Cartesian coordinate system in which the x-direction is substantially horizontal and the z-direction is substantially vertical; said magnetic resonance data acquisition unit comprising a local coil configured to receive a magnetic resonance signal during acquisition of said magnetic resonance data; a detector system configured to detect a position of the local coil on the examination subject using electromagnetic waves that are differentiatable from said magnetic resonance signal, said detector system comprising a source that emits said electromagnetic waves in a radiation field, and a reflection device located in said radiation field, on which said electromagnetic waves are incident with a direction of incidence, and that reflects said electromagnetic waves in a reflection direction that substantially coincides with, but is opposite to, said direction of incidence; said signal source and said reflector being located at respective locations relative to each other that cause said reflected electromagnetic waves to be affected by the position of the local coil as said examination subject, with the local coil thereon, is moved into the data acquisition unit; and said signal source being configured to emit a beam of said electromagnetic waves having a first aperture angle in said x-direction and a second aperture angle in said z-direction, thereby causing said detector system to detect a peak of the reflected electromagnetic waves as coinciding with the position of the coil as the examination subject is moved into the magnetic resonance data acquisition unit.