Monaco 2

Question 1

Monaco is a

Answer 1

Voxel based planning system

Question 2

What is the advantage of voxel based planning

Answer 2

Can define the voxels you want to control instead of controlling the structure

Question 3

What is a possible disadvantage voxel based planning?

Answer 3

If 50% or more voxels are inside the contour, the planning system considers it to be part of the structure (e.g. rectum in prostate)

Question 4

What are the voxels dependant on?

Answer 4

Grid size and thickness of slices

Question 5

Stage 1 Op

Answer 5

Fluence optimisation

Question 6

Stage 2 Op

Answer 6

Segmentation and dose calculation

Question 7

What energy would you use to treat pancreas?

Provide (2) reasons why this energy is ideal

Answer 7

6MV - small volume and close proximity to bowel (has air) the pneumbra increases
- can consider Monaco planning system (6MV is faster computation)

Question 8

How many arcs?

Answer 8

2 Arcs

Question 9

What collimator angles to use?

Answer 9

Complement angles (5-15 degrees)

Question 10

How does increasing arc increment affect the plan quality?

Answer 10

Degrades plan quality

Question 11

What happens when you decrease arc increment size>

Answer 11

Introduces more sectors and increases planning time (doesn’t necessarily improve quality)

Question 12

SSO?

Answer 12

Segment shape optimisation

Question 13

What does SSO do?

Answer 13

Improves plan quality and deliverability

Question 14

What does SSO increase (3)

Answer 14

Optimization time
Plan quality
MUs

Question 15

What does SSO decrease (2)

Answer 15

Delivery time

Segment #

Question 16

For a complex plan what fluence smoothing option would you use?

Answer 16

Low as this creates more segments

Question 17

What is the effect of increasing statistical uncertainty?

Answer 17

increases noise and degrades plan quality

3% is the recommendation

Question 18

Pareto mode

Answer 18

Prioritizes target underdoses on tumour volumes and relax constraints on healthy tissue

OARS>Targets

Question 19

Constrained mode

Answer 19

Sets constraints on healthy tissue while administers dose to target volumes.

Targets>OARs

Question 20

What cost function can be used for target structures

Answer 20

Target EUD & Target penalty (works as a minimum dose)
Quadratic overdose (works as a maximum dose with RMS allowing for leeway with dose excess)

Question 21

What cost functions can be used for OARs

Answer 21

Biological parallel and serial

Tradiational DVH

Question 22

What cost functions are used for dose outside of targets and OARs

Answer 22

Quadratic overdose

Conformality

Question 23

Define EUD

Answer 23

Dose that causes the same effect if applied homogenously to the entire organ volume (any two or more dose distributions that yield the same radiobiological effect)

Question 24

Isoconstraint?

Answer 24

Value defined by user

Question 25

Isoeffect?

Answer 25

Calculated EUD

Question 26

Rule of thumb for determining k value in serial

Answer 26

k = 0.15 x D50

Question 27

When is conformality cost function useful (2)

Answer 27

Single target volumes and steroetactic volumes where there are large areas of unspecified tissue Shaping high dose volume tightly around one or more target volumes

Question 28

When would conformality cost function not be useful

Answer 28

Complex plans where there is several overlapping structures (head and neck) When hotspot is outside of margin >8cm away

Question 29

What is batch optimisation?

Answer 29

Automatic Stage 1 to Stage 2 (can pause)

Question 30

Define a control point

Answer 30

Defines the movement of MLC during treatment delivery from start to end of each segement