In a pre-employment health setting, eliminating the lateral radiographs in the screening of patients with positive purified protein derivative (PPD) results would substantially reduce radiation exposure without adversely affecting patient care, according to a study in this month’s Radiology.
By undertaking the study, Ronald L. Eisenberg, MD, from the department of radiology at Beth Israel Deaconess Medical Center in Boston, and colleagues sought to test their hypothesis that lateral radiography adds no clinically relevant information to that acquired with posteroanterior radiography in individuals with positive PPD skin test results.
As part of routine practice, all 875 adults with positive PPD skin test results at pre-employment exams performed at a medical center during 2007 underwent posteroanterior and lateral chest radiography. In this study, the patient informed consent requirement was waived. Two radiologists retrospectively and independently interpreted each radiograph for evidence of abnormalities that were indicative of acute or chronic tuberculosis infection.
First, they only analyzed the posteroanterior radiograph. Thereafter, both the posteroanterior radiograph and the lateral radiograph were analyzed together to determine if any observed finding was identified on only the lateral radiograph. If a finding was seen on both images, a determination was made as to whether the finding on the lateral radiograph changed the radiologist's decision based on the posteroanterior radiograph alone.
The posteroanterior radiograph revealed abnormalities in all 91 subjects with positive findings at radiography, according to the authors. The lateral radiograph revealed no abnormality in 75 subjects. They reported that all abnormalities seen on lateral radiographs were also seen on posteroanterior radiographs.
“When abnormalities were seen on both images, the information on the lateral image never caused the radiologist to change the decision he or she made on the basis of the posteroanterior image alone,” the investigators noted.
In a pre-employment setting, Eisenberg and colleagues said that one posteroanterior radiograph is sufficient for tuberculosis screening of individuals with positive PPD skin test results, adding that this would “substantially reduce radiation exposure.”