Correct.
Although there are risks of up to 0.45% or 1 in 220 this is likely to be less than the value gained from undertaking an appropriate examination of a sick child.

Correct. 
The risk of inducing cancer will be the only effect observed provided that the dose is sufficiently low.

Correct.
Foetal dose from a head scan is extremely small and could be somewhat reduced by shielding the abdomen. Hence there is negligible risk to the foetus. However the radiologist should be warned so that appropriate precautions can be taken.

Correct.
A plain abdominal x-ray gives a dose of approximately 0.5 mSv which gives a risk of 0.0025% or 1 in 40,000.

Correct.
You selected the correct responses.

Correct.

Provided the benefit outweighs the risk and there is no non-ionizing method which will provide equal or better diagnostic imaging, then the additional scan is indicated. Previous scans have no bearing on the proposed course of action. Of course , the ALARA principle should always be followed (dose should be As Low As Reasonably Achievable).

Correct.

If a CT scan is unlikely to provide useful information it should not be undertaken no matter what the patient thinks. Explanation of the possibility of getting cancer from the scan may be sufficient to deter the patient.

Correct. 
A single CT scan of the head gives a dose of approximately 2 mSv which has a risk of 0.01% or 1 in 10,000.

Correct. 
The patient has ‘red flags’ (age, continuous nature of the pain, without positional component, heavy smoker). Imaging is therefore indicated. It is reasonable to perform plain x-rays initially to look for possible metastatic tumour.

Correct. 
CXR is performed to exclude other pathology such as pneumothorax or pneumonia. Given the history a clinical risk assessment (eg Well’s Score) would indicate a high pre-test probability for pulmonary embolism and therefore the patient can proceed to CT pulmonary angiography or Ventilation/Perfusion scan without D-Dimer assay. If the CXR was abnormal and pulmonary embolism suspected CT pulmonary angiogram is preferred to Ventilation/Perfusion scan.

Correct. 
Ultrasound will show acute appendicitis and gynae disease in a high percentage of patients especially when combined with transvaginal ultrasound. Better than CT for gynae disease.

Correct.
A non-contrast CT is the preferred initial imaging. A solitary kidney needs to be confirmed and if there is obstruction due to a stone or other pathology, this needs to be treated urgently before renal failure and/or infection complicate the clinical picture.

Correct.
MRI is contra-indicated due to the presence of a cardiac pacemaker, but would otherwise be the preferred examination, if available. X-ray tomography has been superseded by CT which is widely accepted as effective in diagnosing occult fractures. Nuclear medicine bone scan is very sensitive for fracture but has lower specificity than MRI and CT.

Correct. 

The patient’s age puts her into a high risk category for breast cancer. Mammogram and ultrasound are the preferred examinations. MRI may be considered by a specialist in limited cases where the mammography and ultrasound are negative and there is persisting clinical concern

Correct. 
An abdominal aneurysm larger than 5cm (even if asymptomatic) requires urgent further assessment and referral to a specialist vascular surgeon.

Correct.
Review of previous films, if available, is always the most cost-effective option. If the raised hemidiaphragm is longstanding, usually no further action may be necessary. If previous films are not available or the raised diaphragm is noted to be a new finding, then ultrasound (or decubitus chest radiograph) should be done to exclude pleural effusion. If an effusion is suspected, this can be subjected to diagnostic aspiration. If no effusion is present, diaphragmatic movement can be assessed with fluoroscopy and/or ultrasound. The latter may also exclude a subphrenic collection. If diaphragmatic movement is impaired, a CT scan will need to be considered to diagnose a hilar or mediastinal mass.