Imaging in Cancer Flashcards Preview

Principles of disease JK > Imaging in Cancer > Flashcards

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

Screening principles

Detect at early stage with no harm caused and should be highly sensitised and specific