Factors influencing pulmonary nodule detection on a postero-anterior chest radiograph

Abstract

Lung cancer deaths are predicted to double by 2035, and with 60% of these deaths occurring in the Western Pacific and South East Asia regions, chest radiography remains an important modality in the detection of non-small cell lung cancers (NSCLC). The interplay of visual perception and cognition on the detection of a lung nodule is studied and demonstrates that it is moderated by the radiologists’ specialisation. The thesis focuses on three studies investigating: priming action via a word association (nodule) on the radiologists’ cognition and visual perception; the influence of radiologists’ expertise on detecting nodules and the impact of grey-scale inversion on the detection of subtle nodules. Additionally, when the location of false-positives (FP) in the word association study were mapped on a CXR, a distinct pattern emerged. The concluding study identified that grey-scale inversion can be utilised to enhance nodule detection on primary class monitors. The thesis has established a link through the priming action of the word association. The priming actions results in a significant increase in the FPs on nodule-free and nodule-containing images with an overall significant reduction in the JAFROC figure-of-merit (FOM). The FP locations marked by the radiologists closely matches where common lung cancers are typically missed on a CXR and NSCLC occur. Further, the thesis has identified that thoracic radiologists can detect more subtle nodules than general radiologists. The thesis concludes that the wording of the clinical history can have a variable effect on CXR reporting. It increases the FPs in the case of searching for nodules creating a priming bias. Grey-scale inversion is a useful tool for radiologists to employ to assist them with identification of lung nodules of relatively low luminance value. Further education for radiologists is necessary to better understand the effects of priming upon their interpretation of CXRs.