Imaging in Cancer Flashcards
What imaging techniques can be used in diagnosing and staging cancer?
Plain radiographs, barium studies, CT, MRI, PET
What other practical techniques can be used?
Endoscopy, biopsy
What is a barium study?
A radio-opaque contract for outling GI tract (high atomic no of barium absorbs more x-ray photons than surrounding tissues)
What can imaging achieve?
Initial diagnosis, staging of disease, monitoring respone to treatment, evaluation of mass after treatment, recognition of complications of treatment, concern for relapse
What is the Hounsfield Unit?
Attenuation values expressed as numbers related to the attentuation value to that of water
What is looked at when staging a tumour?
Position of tumour, depth of penetration of tumour, relationship to adjacent tissues, involvement of regional lymph nodes, presence of distant metastases
What is the TNM system?
Used to stage tumours:
T - size and extent of main tumour
N - number of nearby lymph nodes that have cancer
M - whether the cancer has metastasised
What is CT imaging used for in cancer?
Diagnosis and staging (assessing local and distant spread), monitoring disease
What is the ALARA principle?
To give as low a dose as is reasonably achievable
How does MRI work?
Strong magnetic field aligns protons in the body in one direction, radiofrequency pulse displaces protons and images created by time taken for protons to relax back to orignial alignment
What are the contraindications of MRI?
Claustophobic, noisy, blurring from movement, cannot image those with metal
What are the WHO principles of screening?
Should be important health problem, should be latent stage of disease, should be test/examination for condition, should be acceptable in population, should be treatment, facilities for diagnosis and treatment should be available, should cause no harm, should have high sensitivity and specifitiy, benefit should outway cost
