What are different kinds of imaging that can be used to diagnose cancer?
What are conventional cancer diagnosis methods?
Endoscopy and biopsy
What is a radio-opaque used from outlining the gastro-intestine tract?
Why is barium used to outline the GI tract?
High atomic number absorbs more X-rays than surrounding tissue and appears white on radiograph
What chance does barium have of developing fatal malignancy after 10 years latent perioid?
What are different kinds of cross sectioning imaging?
What can cross sectioning imaging be used for?
Staging of the disease
Monitoring response after treatment
Evaluation of residual mass after treatment
What does CT stand up for?
What happens during a CT scan?
X-rays produce a digital image of a slice of tissue
What is hounsfield unit?
Attenuation value of voxels are expressed as a CT number which relates to the attenuation value to that of water (ranges from -1000 to +3000
What are some common hounsfield values?
Bone +700 to +3000
What is a voxel?
A value on a grid in a 3D space
What are contrast agents?
Substances used to enhance the visibility of internal structures in X-ray based imaging
What are the two kinds of contrast agents?
What do oral contrast agents do?
Outline the GI tract
What do intra-venous contrast agents do?
Show blood vessels and vascularity of different tissues
What are contrast agents usually made of?
Usually iodine based, oral ones are diluted and known as gastrografin and IV ones are known as omnipaque
What are oral contrast agents known as?
What are IV contrast agents known as?
What do scans show to diagnose and stage a tumour?
Position of tumour
Depth of tumour
Relationship to adjacent structures
Involvment in regional lymph nodes
Presence of distant metastasis
What are different scans used for?
Different kinds of cancers
What kinds of cancers are CT scans used for?
What CT scans have the highest equilvalent dose and what value is this?
CT scans of the abdomen and pelvis which have an equilvalent dose of 10mSv
What should be considered when deciding if a scan is required?
Ensure examination is necessary
Adequate clinical information is essential for appropiate protocol
Avoid repeat examination
What does MRI stand up for?
Magnetic resonance imaging
How do MRIs work?
1) Magnetic fields align protons in the body in one direction
2) Radiofrequency pulse displaces protons and images are created displaying the time they take to reurn to their original position
What is MRI often used for?
Excellent soft tissue detail
Vessels can be demonstrated
Brain, spine and musculoskeletal
Abdomen and pelvis
What are disadvantages of MRI?
Claustrophobic and noisy
Cannot image patients with pacemakers and other electronic implants
What contrast agent can be used in an MRI and what does this do?
Gadolinium DTPA (intravenous agent) which changes local magnetic fields and so alters the tissue signal
What is screening used for?
To diagnose at an earlier stage before symptoms begin, making it more curable