Fig 4. Pictorial representation of the problem of clearing the shoulders of the patient and proposed solutions. A, Due to side shielding and dead area at the borders of the FOV of the detector, collimators do not reach the side of the detector and prevent positioning the camera head next to the patient's head. B, If a parallel-hole with slant holes is used, the camera can be tilted inwards to allow clearance. C, The camera head can be redesigned to minimize side dead space. D and E, The same problem is present for cone-beam collimation, even with minimal side shielding. A possible solution is to tilt the collimator as in B. F, An alternative is to shift caudally the focal point of the collimator. The case in which the shift equals half the size of the collimator, resulting in a half-cone-beam collimator, is shown.