Flashcards in Imaging in Cancer Deck (24):
1
Name 5 Imaging techniques used in cancer
PET, CT, MRI, Barium studies and radiographs
2
What is usually used for cancer imaging
Endoscopy and biopsy or barium examination
3
What does barium sulphate do
Outline GI tract and does not react with tissues
High atomic number absorbs more xrays and appears white
4
Barium swallow
Oesophagus
5
Barium meal
Stomach and duodenum (1.5mSv) and fast for 4-6 hours
6
Barium follow through/ small bowel study
Small bowel
7
Barium enema
Large bowel (7mSv) and have a low residue diet for 48 hours and lie on left hand side
8
CT
Xray Produce slice of tissue in axial plane
Fan shape beam of xray
9
Hounsfield (HU)
Attenuation coefficient measurement
10
HU of distilled water
0HU
11
Sate some HU values
lung = -700
Fat = -100
blood = 40
muscle = 40
Calcium = 150
12
Voxel
Value on a regular grid in 3D and position relative to other voxel
13
Pixel
Physical point on an image (2D)
14
Contrast agent
Oral ( dilute iodine to outline GI) or IV ( iodine for vascularity of tissues) but IV can have problems with anaphylaxis
15
Explain the ways in which imaging can help with the diagnosis and staging of cancer
- Presence of distant metastases and spread to lymph nodes
- Relationship to adjacent structure
- Position and depth of tumour and penetration
16
CT radiation dose for chest
8mSv
17
CT radiation dose for abdomen and pelvis
10mSv
18
MRI and H+
Align H+ by strong magnetic fields in one direction
Radio frequency displaces protons and images created during the time protons take to relax and realign
19
What is MRI used to see
Bone and fat
Soft tissue
Vessels and heart
20
Drawback of MRI
Loud, noisy and claustrophobic
Can create a "ghost" due to fluid movement which can mimic pathology
Cannot image patients with pacemakers or aneurysm clips
21
MRI contrast agent
Gadolinium DTPA (IV)
Changes local magnetic field and allows vascularisation and tumours to be seen easier
22
Screening
Diagnose at earlier stage when asymptomatic eg cervix, lung, breast - mammography before lump felt but can give false positives
23
WHO principles
The condition should be a important health problem and used at latent stage of disease
24