Imaging in cancer Flashcards
What are some of the image technique that can be used in diagnosing and staging cancer? (5)
- plan radiographs
- barium studies
- CT
- MRI
- PET
What are the conventional diagnostic modalities? (2)
- endoscopy and biopsy
2. barium examinations
What is the radio-opaque contrast used for outlining the gastro-intestinal tract?
barium sulphate
why is barium used especially?
it has a high atomic number which means it absorbs more x ray photons than surrounding tissues
what colour does barium appear on a radiograph?
white
what does barium swallow and meal outline in the barium studies?
oesophagus, stomach and duodenum
What does barium follow-through or small bowel study outline in the barium studies?
small bowel
what does barium enema outline in the barium studies?
large bowel (large intestine)
how long does the patient have to fast for to have barium studies?
4-6 hours
What 2 things need to be done before a barium enema?
- low reside diet for 48 hours
2. bowel cleansing with Picolax
Outline the steps of a barium enema (8)
- tube inserted into rectum
- barium, water and air is run into descending colon/small int. to splenic flexure
- barium coats the colon
- patient turned onto right side
- barium is let out though the tube
- bowel is inflated with air
- column of contrast is pushed forward to caecum (pouch between large and small intestine) by air 8. imagine in different planes take can be taken as contrast shows clear images
What other, more invasive procedure is avoided by doing barium enema?
Colonoscopy
What can barium enema diagnose?
- lower GI tract disorders e.g. can detect rectal carcinoma
- can also explain pain, constipation or blood in stool
what are main advantages of a barium enema? (5)
- more invasive procedures like colonoscopy avoided (it’s less invasive)
- less complications (e.g. allergic reactions)
- no radiation in body after x ray examination
- barium not absorbed into blood
- x rays usually have no side effects
What are some disadvantages of a barium enema? (4)
- still chance of cancer development since little exposure to radiation
- Ba could leak into surrounding tissues if hole in GI tract causing inflammation
- barium impaction (obstruction) in GI tract can occur
- effect of radiation dose varies from patient
what are the 3 main cross sectional imaging techniques?
- CT
- MRI
- PET
what can cross sectional imaging reveal? (5)
- Initial DIAGNOSIS and STAGING of cancer
- monitoring response to treatment
- evaluation of residual mass after treatment
- recognition of complications of treatment
- when there is concern for disease relapse
In a CT, x -rays produce a digital image of a slice of tissue using computing, in what plane?
Transverse plane (axial)
What units does CT scanning use?
Hounsfield Unit
What is a Hounsfield unit?
attenuation values of voxels expressed as a CT number relating to attenuation value of water
What is attenuation number of water?
0
what is attenuation number of blood and muscle?
+40
what is attenuation number of calcium?
+150
what is attenuation number of bone?
700-3000
what is attenuation number of air?
-1000