F. Kelcz et al., CONVENTIONAL CHEST RADIOGRAPHY VS DUAL-ENERGY COMPUTED RADIOGRAPHY INTHE DETECTION AND CHARACTERIZATION OF PULMONARY NODULES, American journal of roentgenology, 162(2), 1994, pp. 271-278
OBJECTIVE. We evaluated a single-exposure, phosphor-plate, dual-energy
imaging device that produces, in addition to conventional chest radio
graphs, both tissue- and bone-selective images. Our purpose was to det
ermine whether dual-energy radiography was more accurate than routine
chest radiography for detection and characterization of pulmonary nodu
les. SUBJECTS AND METHODS. Two hundred patients undergoing chest CT we
re asked to volunteer to have dual-energy and conventional chest radio
graphs obtained immediately before or after their CT scan. Radiographs
from a subset of 50 of these patients with 116 CT-detected nodules an
d 10 patients with normal findings on CT scans of the chest were prese
nted to the observers for the nodule detection study. Similarly, radio
graphs from a subset of 29 patients with 20 calcified and 20 uncalcifi
ed nodules were presented to five observers to determine nodule calcif
ication. Dual-energy images were produced by filtering the X-ray tube
output with a gadolinium sheet while using a multiple phosphor plate r
eceptor. A dual-energy triad of images consisting of a conventional im
age, a tissue-selective image, and a bone-selective image were produce
d. The conventional chest radiographs and dual-energy image sets were
presented to observers in random order. Data from a free response rece
iver operating curve and a receiver operating curve were generated for
nodule detection and characterization, respectively. RESULTS. By usin
g the dual-energy images, all five observers improved their ability to
diagnose pulmonary nodules (p = .0005) and to characterize nodules as
calcified (p = .005). CONCLUSION. By eliminating rib shadows with tis
sue-selective images and enhancing calcified structures with bone-sele
ctive images, dual-energy chest radiography improved the ability of al
l observers, regardless of expertise, to detect and characterize pulmo
nary nodules.