(HealthDay News) — The estimated sizes of lung nodules and mediastinal lymph nodes vary considerably with the radiation dose of chest computed tomography (CT) examinations, according to a study presented at the annual meeting of the American Roentgen Ray Society, held from April 14 to 19 in Washington, D.C.

Beth Vettiyil, from Massachusetts General Hospital in Boston, and colleagues acquired postmortem chest CT examinations for 20 human cadavers, within six hours of death, at two different radiation doses. They measured the volumes of mediastinal lymph nodes and lung nodules with a three-dimensional lesion segmentation and volumetry tool and compared the sizes on CT images acquired at low and high radiation doses.

The researchers found that on low-dose versus high-dose images the volume of the lung nodules calculated with the three-dimensional image processing tool was 46 percent lower in nine cases and 34 percent higher in 10 cases. In low-dose versus high-dose images the estimated mediastinal lymph node volumes were 30 percent lower in five cases and 10 percent higher in 15 cases. No significant difference was seen between high-dose and low-dose images in average attenuation volumes (P = 0.38 for nodules; P = 0.36 for mediastinal lymph nodes). On low-dose images, noise was higher (14 percent for nodules; 43 percent for mediastinal lymph nodes).

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“The study indicates that radiologists can use these types of quantitative tools to supplement them in their measurements, but the use of such software without the radiologist’s clinical correlation might not be advisable at this stage,” Vettiyil said in a statement.

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