Robert Steven Ledley

6/28/1926–

AMERICAN

PROFESSOR, PHYSIOLOGY AND BIOPHYSICS

Robert Ledley was the inventor of the first full body computer axial tomography (also called CT, computed axial tomography or CAT scans). The CAT scan is a imaging device that uses conventional x-rays to create an image of the entire body of the subject. The scan is produced in three dimensions, as the x-rays are taken through rotation around the body at varying angles in cross sections.

Prior to the technology developed by Ledley, CAT scans were restricted to the subject's head, and precautions had to be taken through the use of water as an insulator to protect the subject from over exposure to x-rays. Ledley developed x-ray detectors and he redesigned the methods by which x-rays were emitted in the course of perfecting his CAT scanner.

During the early 1970s, enhanced digital capabilities spurred the development of computed tomography (derived from the Greek tomos meaning slice) imaging, invented by English physician Godfrey Hounsfield. CT scans use advanced computer-based mathematical algorithms to combine different reading or views of a patient into a coherent picture usable for diagnosis. Hounsfield's innovative use of high energy electromagnetic beams, a sensitive detector mounted on a rotating frame, and digital computing to create detailed images earned him the Nobel prize. As with x-rays, CT scan technology progressed to allow the use of less energetic beams and vastly decreased exposure times. CT scans increased the scope and safety of imaging procedures that allowed physicians to view the arrangement and functioning of the body's internal structures on a small scale.

The impact of CAT scan technology upon sports medicine has been profound. CAT scans are a useful diagnostic tool in the detection of blood clots that often arise as a result from blows to the head of athletes in contact sports. CAT scans are regarded as being a better method than either conventional x-rays or magnetic resonance imaging (MRI) with which to determine such deformities and injuries within the body as the extent and definition of fracture lines on bony structures, small calcified objects within the joints, and loose bodies such as cartilage that has become dislodged within the joint. CAT scans are also useful in the assessment of bone erosion (often due to structural deformities within the joint), and general losses of bone mineral and bone density.

CAT scans are also commonly employed to assess structural problems such as those that occur in the patellar tendon and femur that underlie the condition known as Osgood-Schlatter disease (OSD), a condition that arises due to unequal rate of growth between the patellar tendon and the femur in adolescents.

Like the MRI, the CAT scan has the advantages of speed and relative certainty when used to assess athletic injuries. Decisions regarding the treatment and management of the athlete can be made with greater speed. In a professional sports context, the quicker a definitive decision can be made regarding an athletic injury, the better a decision the team may make concerning a replacement to the team roster.