Patent Number: 06021175&
Section: abstract

An x-ray filter is used to permit higher intensity x-ray exposure to the upper thoracic spine while maintaining a normal level of x-ray exposure to the cervical spine. The resulting x-ray image allows a viewer to count the seven cervical vertebrae in order to identify the position of the first and second thoracic vertebrae. The filter is formed by a pair or mating blocks of x-ray absorbing material. The filter has a first region for absorbing x-ray radiation to decrease exposure of the cervical spine and has a second region with a V-shaped opening which allows higher x-ray transmission to the thoracic spine while reducing exposure on areas adjacent to the thoracic spine. The filter is formed by two shaped filter blocks which fit together to create the first and second regions. The edges of the filter blocks which form the V-shaped opening are beveled to create a generally trapezoidal exposure region which is aligned with the upper thoracic spine. A similar x-ray filter for use in a lateral view of the hip reduces exposure to areas commonly overexposed adjacent to the head and neck of the femur in a lateral projection.