Abstract: A helmet-like medical diagnostic apparatus that is fixed or worn has motorized gimbals that automatically swivel to positions around a patient's head. An end effector extends radially from the gimbals toward the head to place a coil or other directional sensor snugly against the scalp. A coil sensor can be part of a sensitive circuit to measure eddy currents within the brain. Accelerometers, or other tilt-measuring gauges, are compared between those on the sensor and those on the apparatus's base to determine the precise 3D orientation of the sensor when resting against the head. The orientation can compensate coil measurements, find an exact spot again, or map opposing sides of the patient's cranium, even with a fidgeting unconscious patient. The head can be scanned in its entirety, or a spot scan may be prompted from other diagnostic data.