Abstract
Background The effects of dose reduction in lung nodule detection need better understanding. Purpose To compare the detection rate of simulated lung nodules in a chest phantom using different computed tomography protocols, low dose (LD), ultralow dose (ULD), and conventional (CCT), and to quantify their respective amount of radiation. Materials and Methods A chest phantom containing 93 simulated lung nodules was scanned using five different protocols: ULD (80 kVp/30 mA), LD A (120 kVp/20 mA), LD B (100 kVp/30 mA), LD C (120 kVp/30 mA), and CCT (120 kVp/automatic mA). Four chest radiologists analyzed a selected image from each protocol and registered in diagrams the nodules they detected. Kruskal–Wallis and McNemar's tests were performed to determine the difference in nodule detection. Equivalent doses were estimated by placing thermoluminescent dosimeters on the surface and inside the phantom. Results There was no significant difference in lung nodules' detection when comparing ULD and LD protocols (p=0.208 to p=1.000), but there was a significant difference when comparing each one of those against CCT (p < 0.001). The detection rate of nodules with CT attenuation values lower than −600 HU was also different when comparing all protocols against CCT (p < 0.001 to p=0.007). There was at least moderate agreement between observers in all protocols (κ-value >0.41). Equivalent dose values ranged from 0.5 to 9 mSv. Conclusion There is no significant difference in simulated lung nodules' detection when comparing ULD and LD protocols, but both differ from CCT, especially when considering lower-attenuating nodules.
Highlights
Lung cancer represents the main cause of cancer-related deaths in the world [1]
E National Lung Screening Trial (NLST) was the first large multicentric study to show a reduction of 20% in lung cancer mortality in patients enrolled in a screening program using low-dose computed tomography (LDCT) [4]
E pursuit for lower doses led to the creation of ultralowdose (ULD) protocols, performed in modern CT equipment with iterative reconstruction [8] which expose the patient to amounts of X-rays as low as chest radiography [9]
Summary
Lung cancer represents the main cause of cancer-related deaths in the world [1]. Conventional chest radiographs used to be a screening tool for early diagnosis [2], but low-dose computed tomography (LDCT) proved to be superior [3].e National Lung Screening Trial (NLST) was the first large multicentric study to show a reduction of 20% in lung cancer mortality in patients enrolled in a screening program using LDCT [4]. Conventional chest radiographs used to be a screening tool for early diagnosis [2], but low-dose computed tomography (LDCT) proved to be superior [3]. E main issue regarding lung cancer screening is the systematic exposition of patients to ionizing radiation, which is potentially carcinogenic [6]. E pursuit for lower doses led to the creation of ultralowdose (ULD) protocols, performed in modern CT equipment with iterative reconstruction [8] which expose the patient to amounts of X-rays as low as chest radiography [9]. Radiology Research and Practice is study aims to quantify the amount of radiation the patients are exposed to during a specific ultralow-dose protocol and different low-dose protocols and to determine how those doses impact the detection of simulated lung nodules in a phantom
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