Screening for Pneumonia: A Comparison of Ultra Low Dose Chest CT [ULD-CT] and Conventional Chest Radiography [CXR]

* 200 subjects
* Each subject will undergo CXR and ULD-CT at the same day.
* Subjects subdivided into 3 groups \[high, moderate and low risk\], based on a laboratory finding(CRP), symptoms and physical examination.
* 3 different thoracic radiologist will judge the scans on existence of consolidation. Consolidation will be expressed as binary outcomes (Yes or No consolidation)
* Radiologist will be blinded for subjects demographic data.
* All radiologist have to score how confidence they were on the finding of consolidation\[5point likert\].
* The investigators will perform a McNemar's test for evaluation. A two sided p-value of less than 0.05 will be considered to be statistically significant.
* Inter-observer variability will be evaluated by using a Fleiss Kappa test.

• ULD-CT (Radiation), also known as Ultra Low Dose chest CT: Siemens Healthcare SOMATOM FORCE Ultra Low Dose chest CT
• CXR (Radiation), also known as Conventional chest X ray: Conventional chest radiograph

Primary outcomes

• Three different radiologists will be asked to fill in a questionaire on whether or not there is presence of consolidation (yes/no) on both ULD-CT, as well as on CXR. [2 years]: * 3 different thoracic radiologist will judge the scans on existence of consolidation. Consolidation will be expressed as binary outcomes (Yes or No consolidation) * Radiologist will be blinded for subjects demographic data.
• Risk assessment of having a pneumonia for each subject [2 year]: Subjects will be subdivided into 3 groups \[high, moderate and low risk\], based on a laboratory finding(CRP). * CRP levels lower than 20mg/L > low risk * CRP levels between 20 and 100mg/l > medium risk * CRP levels higher than 100mg/l > high risk
• 5 point likert scale to evaluate the "level of confidence" of each radiologist [2 year]: \- As described in "outcome 1" the radiologist judges the scans on existence of consolidation. After each judgement the radiologists has to fill in a questionaire \[5 point likert scale\] to score their level of confidence on the finding on whether or not they saw consolidation on the scan.

Secondary outcomes

• All 3 radiologist will be asked to write down on paper if they see an additional finding on either the ULD-CT or CXR [2 years]: Three different thoracic radiologist will judge the scans and fill in a questionaire if they see any additional finding (Yes/No).
• In case the radiologist observes an additional finding, the radiologist has to fill in a questionaire on paper what kind of additional finding was seen: [2 year]: In case they see an additional finding, they have to fill in what kind of additional finding the have seen and write it down in the questionaire. Example: \[tumoral mass; pleural effusion; atelectasis; lymph nodules\]. \- Additional findings will be subdivided in: atelectasis, pleural effusion, tree in bud, lymph nodes or tumoral mass.
• Reporting the total number of observed additional findings for each modality [ULD-CT and CXR], based on the above mentioned questionaires [2 year]: All additional findings will be presented in a table. for example: Number of subjects with additional finding of atelectasis: * ULD-CT (40 ULD-CT scans with atelectasis out of 100) * CXR (25 CXR radiographs with atelectasis out of 100) Number of subjects with additional finding of tumoral mass: * ULD-CT (2 ULD-CT scans with tumoral mass out of 100) * CXR (1 CXR radiographs with tumoral mass out of 100) Number of subjects with additional finding of pleural effusion: * ULD-CT (15 ULD-CT scans with pleural effusion out of 100) * CXR (33 CXR radiographs with pleural effusion out of 100)

Sex: All, ages: 18 Years to any, accepts healthy volunteers

Inclusion Criteria:

* Suffering from pneumonia and referred by their GP

Exclusion Criteria:

* Younger than 18
* Known pregnancy
* Not able to sign the Informed Consent document
* If not willing to be informed about additional findings

• Marco Das, Dr, Principal investigator, Maastricht University Medical Centre