Lecture 5 B: Electrons

Electrons are generally used to treat:

1. Skin lesions

2. boost to surgical scars

Where is the patient simulated?

1. Simulation is most often performed on the treatment unit

2. On occasion, a CT Sim is performed

Why is Simulation is most often performed on the treatment unit?

1. if there is no conventional simulator available

2. or if the particular gantry or table angle required is not possible on a simulator.

Why is a CT SIM performed?

to get the depth of the lesion → to select the proper electron energy

Basic simulation of a skin lesion includes:

1. Position patient with immobilization devices in a reproducible way

2. Dr. draws field size & shape on the patient’s skin

3. Position gantry en face to tx area

4. 100 SSD (as close as possible)

5. trace shape onto an insert in the electron cone

   

6. On the insert, note anatomical direction in relation to the insert

7. Photograph

8. Create a skin template using film or plastic sheeting

9. take skin measurement

10. Notate

Mnemonic: People Drive Fast. Speeding In Peaceful, Safe & Modest Neighborhoods.

shape Dr drew traced on electron cone insert & anatomical directions in direction to the insert

1. Position patient with proper immobilization devices in a reproducible way. How do we position them in a reproducible way?

With as few of the following as possible:

1. immobilization devices

2. table angles

3. gantry angles

term. en face

dfef. the plane of the beam is parallel to the plane of the surface to be treated

How many photos do we take? What photos

1. patient-cone interface

2. gantry position

3. the field

4. general position

What materials do we use to create a skin template?

1. film

2. other plastic sheeting

What do we note on the skin template? Why?

1. direction

2. 3 landmarks (e.g. mole, tattoo, scar, eye, ear, mask, edge etc)

to reorient in subsequent days

What skin measurement must we obtain?

Measure the size of the field on the skin in 2 axis: long and wide

notate

name

what we are treating

orientation

ssd

gantry angle

collimator angle

table angle

hint: Never wait or stay