Comparing Absorbed Doses of Properly and Improperly Collimated Abdominal Exposures

摘要

During a radiography examination, the beam should be restricted, or collimated, to the anatomy in question. If a repeat exposure is necessary because an anatomical area was clipped or missed in the original exposure, the beam should be collimated to the clipped or missing anatomy to limit the radiation dose to the patient. It the repeated exposure is not properly collimated, the patient potentially is exposed to another full dose of ionizing radiation. The purpose of this study was to calculate and compare the absorbed doses of properly and improperly collimated repeat examination exposures and to measure the anode heel effect to determine the difference in intensity between the cathode and anode ends of the x-ray beam. The investigators wanted to document the amount of additional radiation a patient receives due to improper collimation techniques and determine whether the difference in intensity between the anode and cathode ends of the x-ray beam was large enough to cause concern for increased patient absorbed doses for specific rad iography examinations. The researchers obtained radiographs of the abdomen using different coiiimation techniques and then measured and compared the entrance skin exposures. They also examined the anode heel effect, which causes a difference in energy between the cathode and anode ends of the x-ray beam, and the reduction of beam intensity proportional to the inverse of the distance squared.