Icru

Question 1

Treatment planning process?

Answer 1

Patient positioning
Imaging
Anatomy definition
Beams
Dose
Plan evaluation 
Implementation
Review
Treat

Question 2

What types of treatment planning are there?

Answer 2

1-4 dimensions of planning

Question 3

What is 2D planning?

Answer 3

Just use one slice of CT scan

Question 4

What is 3D planning?

Answer 4

Using multiple slices of CT

Question 5

What is 4D planning?

Answer 5

Same as 3D plan but takes into account movement

Question 6

What is parallel opposed pair?

Answer 6

Two beams which overlap at the centre giving a higher dose to the tumour

Question 7

Is the attenuation compensated by the opposing beam?

Answer 7

Yes if one beam has attenuated to 30% the other will have an intensity of 70%

Question 8

Advantages of POP?

Answer 8

Simple reproducible

Homogenous dose to tumour

Question 9

What is SSD?

Answer 9

Set up lasers to the surface of patient

Beam is wider for SSD disadvantage machine can’t be moved outside of the room
You have to set up every field
100cm on skin

Question 10

What is SAD?

Answer 10

Set up to a point in the patient isocentric

100cm at isocentre within patient

Question 11

Are electron beams fixed

Answer 11

Yes they have a fixed SSD

Question 12

What does homogeneity and dose uniformity mean?

Answer 12

Means uniformity deliver a homogenous dose to tumour

Question 13

What are the factors of homogeneities?

Answer 13

Patient size
Tumour position
Beam energy
Different tissue densities

Question 14

Does dose uniformity change at deeper depths?

Answer 14

Yes it does

Question 15

What is beam weighting?

Answer 15

Each field contributes different amount of the dose

Question 16

What are the benefits of beam weighting?

Answer 16

Improve dose uniformity
The PTV may not be centrally located
Different tissue densities in the volume
Reduce dose to organs at risk etc

Question 17

Aim of treatment planning?

Answer 17

Maximum dose to tumour while sparing normal tissue

By changing field size, number of fields, beam angles, beam weights and beam modifiers

Question 18

What is the GTV?

Answer 18

Gross tumour

Question 19

What is the CTV?

Answer 19

For microscopic disease

Question 20

What is the PTV?

Answer 20

Is the CTV with a margin for variations in size, shape and position

Question 21

What is the treated volume?

Answer 21

Volume that receives a dose that is considered important for local cure or palliation close to PTV

Question 22

What is the purpose of ICRU 50/62

Answer 22

For prescribing therapy
Recording therapy
Reporting therapy

Question 23

What are internal margins?

Answer 23

Inter fraction variations

Intra fraction variations

Question 24

What are set up margins?

Answer 24

Systematic variations

Random variations

Question 25

What is a hotspot?

Answer 25

Volume outside the PTV which receives a dose larger than 100% must be greater than 1.5cm