Screening for lung cancer using low dose CT scanning

Abstract

Background: Lung cancer is the most common cause of cancer related death in Ireland. The majority of lung cancers are inoperable at the time of diagnosis and consequently the overall 5 year survival is less than 10%. The objective of the ProActive Lung Cancer Detection (PALCAD) study was to evaluate whether low dose chest computed tomographic scanning (LDCCT) can detect early stage asymptomatic lung cancer in a high risk urban population. Methods: Four hundred and forty nine subjects of median age 55 years (range 50-74) with a median pack year smoking history of 45 years (range 10-160), with no previous cancer history and medically fit to undergo thoracic surgery were recruited. After informed consent, LDCCT was performed on all subjects. Non-calcified nodules (NCNs) of >10 mm in diameter were referred for biopsy. Follow up with interval LDCCT at 6, 12 and 24 months to exclude growth was recommended for NCNs ,10 mm in diameter. Results: Six (1.3%) NCNs of >10 mm were detected of which one (0.23%) had non-small cell lung cancer stage 1; 145 NCNs of ,10 mm were detected in 87 (19.4%) subjects. Mediastinal masses were detected in three subjects (0.7%)-one small cell lung cancer and two benign duplication cysts. Incidental pathology was noted in 276 patients (61.5%), most commonly emphysema and coronary artery calcification. Conclusion: The prevalence of resectable lung cancer detected by LDCCT at baseline screening was low at 0.23%, but there was a high rate of significant incidental pathology.

Thoracic low-dose CT image processing using an artifact suppressed large-scale nonlocal means

“…n denotes the pixel number in n , and is used as a normalization parameter to make the processing independent of the different size settings of n . denotes the standard deviation of the Gaussian kernel. Parameter h is used to control the smoothing effect in the attenuating exponent function in (2). The application of the LNLM method is based on the assumption that in clinical CT images the pixels representing different tissue attenuation often distribute over a large scale, ad pixels of similar surrounding distribution have a higher probability to belong to the same tissues.…”

“…Other scanning parameters were: kVp, 120; Slice thickness, 2 mm; Gantry rotation time, 0.5 s; detector configuration (number of detector rows section thickness),16 mm 1.5 mm  ; table feed per gantry rotation, 24 mm; pitch, 1:1; reconstruction method: Filtered Back Projection (FBP) algorithm with convolution kernel "B70f" and "B31f" ("B31f" is the smoothing reconstruction kernel for mediastinal window illustration in Siemens CT). The CT dose index volume (CTDI vol ) is a linear function of the tube currents [2]. We recorded the accumulated doses from the workstation for each scan with 40 slices.…”

“…Computed tomography (CT) is widely used for lung cancer screening because it is more sensitive than chest radiography in the detection of small nodules and lung carcinoma at an early stage [2][3]. Nevertheless, a trouble spot is the x-ray dose delivered by the scanner.…”

The clinical effectiveness and cost-effectiveness of computed tomography screening for lung cancer: systematic reviews

“…53 A further three of the studies included a subgroup (2-14% of the total study population) within the study who had a history of asbestos exposure. 30,40,52 None of these papers quantified the extent of asbestos exposure.…”

“…27,28 Time since smoking cessation was incorporated into three of the studies by restricting screening to those who were smokers within the 10 years before recruitment. 28,46,52 In the studies, participants were interviewed about smoking history after volunteering to participate. A screening programme in the UK could be mediated via GPs who could restrict invitation to those patients with a recorded history of smoking.…”