Processes in Radiotherapy

Summary of Radiotherapy processes

Summary of Radiotherapy processes

Following the consultation with your Radiation Oncologist, you are usually given appointments for the following processes:

  1. Simulation: This is the process whereby the radiation fields to be used in your treatment is determined. It can be performed with the use of projected light fields to simulate the real radiation fields (2-dimensional planning). Nowadays, it is more common to scan your body into the computer to allow these fields to be determined on an exact 3-dimensional model of your body reconstructed from the CT-scans (3D-conformal radiotherapy)
  2. Plan Verification: In this process, usually 1-2 weeks after simulation, you may be asked to return to check that the individualized plan that had been created for you in 3D-conformal planning fits your body exactly.
  3. Treatments: The first fraction of your 4 to 6 weeks of radiation usually starts about 2 to 3 weeks after simulation. Usually, you will be treated on a daily basis, every weekday for about 30 to 45 minutes per session. Most of these times is spent ensuring your treatment position is exactly the same as that captured during your simulation. Actual treatment lasts only minutes and is completely painless. You will not experience the passage of the x-rays through your body, what-so-ever.

2-Dimensional Planning 

Patient on a Conventional (2D) simulator

Patient on a Conventional (2D) simulator

A patient lying on her back with the arm (on the side of the treated breast) elevated on specialized holders.

Projected lights fields on patient's chest to simulate the direction, angle and position of the actual radiation fields.

Simulated radiation fields

Projected lights fields on patient’s chest to simulate the direction, angle and position of the actual radiation fields.

Cross-section outline of treated breast reproduced with wires

Taking the breast outlines

The outline of the patient’s treated breast or chest wall is reproduced using a pliable wire.

Outline of breast transferred onto graph paper

The outline of the breast is then transferred onto graph paper before being digitized into the planning computer for dose calculation and planning.

The finalized 2-dimensional plan is produced. It needs to be approved by a specialist radiation oncologist before it can be used for patient treatment. The typical dose of radiation delivered in the post-operation patient is 50Gy over 5 to 6 weeks. Your doctor may sometimes choose a faster fractionation regimen that delivers the treatment over a shorter time.

Now, let’s have a look at 3-Dimensional planning which is much more commonly practiced today.

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