Planning Individualized Radiation Treatment
Radiation is delivered to patients either by directing a radiation beam at the cancerous tumour from an external radiation source ("external beam therapy"), or, by placing a radioactive source temporarily or permanently inside the patient or on the patient's skin ("brachytherapy"). 


In both types of treatment, it is important to ensure that sufficient radiation reaches the tumour without delivering too much radiation to nearby healthy tissues. To achieve this, every radiation treatment must be carefully planned, individually for each patient, using detailed information about the location, size, and shape of the patient's tumour and neighbouring tissues.

Patient receiving external beam radiation from a linear accelerator.
Patient receiving external beam radiation from a linear accelerator. Image used with permission
of Varian Medical Systems.
The planning requires accurate calculations of the dose at each point in the patient. Much of this work is done by radiation therapists using a treatment planning computer system. 


Radiotherapy physicists must understand the theory behind the calculations, so that they can advise radiation therapists and radiation oncologists on how to make the best use of the treatment equipment and the treatment planning computer.

The radiotherapy physicists are also responsible for checking each plan for accuracy and to ensure that it provides the best possible treatment for the patient.
Patient receiving high dose rate brachytherapy to the right lung.
Patient receiving high dose rate brachytherapy to the right lung. Image used with permission of Nucletron.