There are three phases of the person's radiotherapy treatment journey.23
- Treatment planning and preparation
- Treatment delivery
- Treatment completion and management of responses to radiotherapy
Treatment planning and preparation
Treatment planning is essential to ensure accuracy and reproducibility of the radiotherapy.1, 23 This procedure determines the dimensions, shape, and appropriate number of radiation beams (or treatment fields) required to treat the tumour while limiting the dose to the surrounding normal tissues. Through this process, radiotherapy treatments are tailored to the individual.24
Positioning and stabilisation
The chosen treatment position depends on the site of the person's tumour. Individuals are positioned to avoid unnecessary irradiation of normal tissues. The position needs to be easily reproducible each day. Stabilisation devices include face masks and custom made positioning supports for different areas of the body (e.g. neck, arms, pelvis, and knees). Such devices help the person maintain the required position during treatment.25
Simulation
A simulator 'simulates' the movement and set-up parameters of the linear accelerator involved in radiotherapy treatment delivery.26, 27 Virtual simulation may be completed using results from imaging procedures imported into a 3D treatment planning computer. Virtual representation of the person may be generated through:
- Computed tomography image (also called a planning CT)
- Magnetic resonance imaging (MRI) or positron emission tomography (PET) scans (provides enhanced anatomical or metabolic tumour information, supplementing the planning CT scan through the process of image fusion)28
- 4D or respiratory-gated planning CT scans (tracks the movement of a lung or abdominal tumour during breathing to ensure the tumour is always in the path of the treatment fields)29
The simulation process determines placement of external marks on a person that are used to accurately direct the treatment fields each day of the person's treatment. External treatment marks are often small tattoos, usually the size of a small freckle. Some stabilisation devices such as face masks also allow for the treatment marks to be placed on the device rather than the person's skin to avoid embarrassing marks on the face.25
Once the simulation process is complete, dose calculations determine the amount of radiation to be delivered each day. The isodose curve is the basis of all calculations,14 and is used:
- to determine the daily dose
- to show the total distributed radiation dose in an individual for the intended course of treatment
- to act as a record of the treatment delivered14
Information provision and education
Planning and preparation may be a lengthy process that adds to the anxiety and concerns of people undergoing radiotherapy. Providing an orientation to the treatment area, information and education, and assessment of levels of anxiety and depression before radiotherapy may reduce anxieties and enhance adherence with therapy.30 Tools have been developed by eviQ to ensure a consistent approach to assessment and education:
- Radiation Therapy Patient Education Checklist. eviQ, 2014
- Radiation Therapy Nursing Assessment. eviQ, 2012
Learning activities
Discuss the role of the SCN during the radiotherapy treatment planning and preparation processes.
Outline supportive care interventions you could give to a person affected by cancer to prepare them for a course of radiotherapy.