Prac 2 Breast Tans + Boost

Question 1

What is the dose prescription for left breast + boost?

Answer 1

50Gy in 25 fractions

Boost 16Gy/ 8# (100% Dmax), 12MeV

Question 2

What structures need to be contoured?

Answer 2

CTV boost
PTV boost
Electron wire and scar wire if placed during CT simulation

Question 3

What beam energy can be used?

Answer 3

6MV- 10MV, 100% to RP

Question 4

What arrangement can be used?

Answer 4

non-divergent post jaw

1. ED wedges (with no FIF)
2. FIF approach (2-6 beams)
3. Mono-isocentric technique (FIF)

Question 5

What are the OAR for breast?

Answer 5

Ipsilateral Lung
Heart
Non-target tissue

Question 6

What algorithm is used?

Answer 6

CC Convolution

Question 7

What might shielding result in?

Answer 7

collimator rotation

Question 8

What determines the choice of energy for the boost?

Answer 8

depth to which dose is being prescribed

e.g. using Central Axis Dose Information

Question 9

What is the dose limit of the ipsilateral lung?

Answer 9

V20 < 20%

Question 10

What determines the choice of energy for the boost?

Answer 10

depth to which dose is being prescribed
e.g. using Central Axis Dose Information

(CHECK)

Question 11

What determines the size of the electron cone?

Answer 11

size of tumour bed to be treated

CHECK

Question 12

What is the dose limit of the whole heart?

Answer 12

V25 <10%

Mean Heart Dose (MHD) <5 Gy

Question 13

Where is the E-SSD placed?

Answer 13

E-SSD (SSD for electron field) auto placed in the centre of the wire