Effect of Radiation Dose Level on Accuracy and Precision of Manual Size Measurements in Chest Tomosynthesis Evaluated Using Simulated Pulmonary Nodules

Abstract

The aim of the present study was to investigate the dependency of the accuracy and precision of nodule diameter measurements on the radiation dose level in chest tomosynthesis. Artificial ellipsoid-shaped nodules with known dimensions were inserted in clinical chest tomosynthesis images. Noise was added to the images in order to simulate radiation dose levels corresponding to effective doses for a standard-sized patient of 0.06 and 0.04 mSv. These levels were compared with the original dose level, corresponding to an effective dose of 0.12 mSv for a standard-sized patient. Four thoracic radiologists measured the longest diameter of the nodules. The study was restricted to nodules located in high-dose areas of the tomosynthesis projection radiographs. A significant decrease of the measurement accuracy and intraobserver variability was seen for the lowest dose level for a subset of the observers. No significant effect of dose level on the interobserver variability was found. The number of non-measurable small nodules (≤5 mm) was higher for the two lowest dose levels compared with the original dose level. In conclusion, for pulmonary nodules at positions in the lung corresponding to locations in high-dose areas of the projection radiographs, using a radiation dose level resulting in an effective dose of 0.06 mSv to a standard-sized patient may be possible in chest tomosynthesis without affecting the accuracy and precision of nodule diameter measurements to any large extent. However, an increasing number of non-measurable small nodules (≤5 mm) with decreasing radiation dose may raise some concerns regarding an applied general dose reduction for chest tomosynthesis examinations in the clinical praxis.

Iterative scatter correction for grid-less skeletal radiography allows improved image quality equal to an antiscatter grid in adjunct with dose reduction: a visual grading study of 20 body donors

“…The radiographs were presented and rated using the software ViewDEX 2.0 (12-14) on a calibrated medical-grade monitor (Coronis 3MP, Barco, Kortrijk, Belgium). This software was used in several recent studies (15)(16)(17). One single image was displayed at a time.…”

Detection of Pulmonary Nodule Growth with Chest Tomosynthesis: A Human Observer Study Using Simulated Nodules

“…This corresponds to the results in the present study. Another study investigated the effect of dose level on the precision of nodule diameter measurements on nodules (45). The study indicated increased intraobserver variability at 0.04 mSv as compared to 0.12 mSv.…”

The Effect of Dose Reduction on Overall Image Quality in Clinical Chest Tomosynthesis

“…The lowest dose level corresponds to a CTS examination with effective dose equivalent to that from a lateral projection in conventional CXR. The 50% dose level was chosen based on the fact that nodule detectability, as well as accuracy and precision of nodule size measurement, have shown to be unaffected by such a dose reduction (10,13). This resulted in four tomosynthesis data sets for each patient to be analyzed and 96 in total for the 24 patients.…”

“…Also, studies on the detectability of pulmonary mycobacterial disease in CTS have shown that the detection rate appears to be unaffected in low-dose CTS (0.05 mSv) (12). Furthermore, the effect of dose reduction on other important clinical tasks, such as nodule size measurements, has been assessed with results showing that precision and accuracy of nodule size measurements are unaffected when reducing the dose to 50% of the original dose (13). Hence, the results from previous studies strongly indicate that it would be possible to reduce the radiation dose from CTS examinations without compromising the diagnostic information obtained from the examinations.…”