Comparison of low-dose and standard-dose helical CT in the evaluation of pulmonary nodules

Abstract

The purpose of this study was to investigate the diagnostic accuracy of low-dose helical computed tomography by comparing the number of nodules detected at low-and standard-dose CT. The prospective study included 25 patients who were referred to CT scan for the assessment of pulmonary metastases. All patients underwent CT examinations at both standard-(200 mA, 120 kV, collimation 5 mm, table feed 10 mm per rotation) and low-dose (50 mA, 120 kV, collimation 5 mm, table feed 10 mm per rotation). The number of nodules detected at each protocol was recorded. The size of the nodules was measured electronically and categorized as <3, 3-4.9, 5-6.9, 7-9.9, and ≥10 mm. Finally, the nodules detected at only standard-or low-dose CT were assessed for the underlying causes of discrepancy. In 25 patients, 533 nodules were detected at standard-dose, whereas 518 nodules were observed at lowdose CT. There were no statistically significant differences in the number of nodules detected at standard-or low-dose CT (p>0.05). Four hundred ninety-one (87.7%) nodules were detected at both standard-or low-dose CT, 42 (7.5%) nodules were observed only at standard-dose CT, and 27 (4.8%) nodules were seen only at low-dose CT. The sensitivity of lowdose CT was 92.5% for all nodules, 88.1% for nodules <5 mm, and 97.4% for nodules ≥5 mm. No significant image artifact interfering with nodule detection was observed at low-dose CT. The low-dose CT protocol used in this study provided images of adequate quality; thus, it can be used reliably in the detection or exclusion of pulmonary nodules.

Low dose chest CT protocol (50 mAs) as a routine protocol for comprehensive assessment of intrathoracic abnormality

“…There are several investigations on the radiation dose reduction for specific abnormal findings including pulmonary nodules [9], [10], emphysema severity [11], [12], [13] and bronchiectasis [14]. There are also several studies on the radiation dose reduction for CT pulmonary angiography [15], [16], [17].…”

Standard-dose vs. low-dose CT protocols in the evaluation of localized lung lesions: Capability for lesion characterization—iLEAD study

“…The application of low dose CT technique has been facilitated by various techniques, including automatic exposure systems and imaging filters [13], [14], [16], [17], [18], [19], [20]. As chest CT examinations are frequently used for lung lesion detection, detection of lung nodules using low dose CT images has been investigated by several groups [1], [2], [3], [4], [5], [21]. These results showed that detection of pulmonary nodules is possible with low dose CT images obtained with 20–50 mAs.…”

“…Low dose CT examinations are currently employed to detect lung nodules and to find treatable lung cancer cases [1], [2], [3], [4], [5], [6], [7], [8]. Low dose CT is much more effective as a screening process than chest X-ray, but the drawback is that low dose CT examinations uncover many nodules or larger localized lesion which should be differentiated from lung cancers.…”

Ultra-Low-Dose MDCT of the Chest: Influence on Automated Lung Nodule Detection

“…Theoretically, quantum noise increases inversely in proportion to the square root of the amperage. However, because the lungs are aerated, they generate more contrast than solid organs, and the detection of pathological changes in the lung are less dependent on image noise than for those in solid organs (3). …”

“…Although low- to ultra-low-dose chest CT has been used, conventional 50 mA low-dose CT is normally used for lung cancer screening (3, 6, 13). Moreover, previous studies on low-dose or ultra-low-dose CT were performed without a CAD system (3, 5, 6, 13), and no comparative information is available in the English language clinical literature on low-dose and ultra-low-dose CT supported by a CAD system. In the present study, we assessed the rationale and feasibility of the use of ultra-low-dose helical CT using a CAD system.…”