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Radiation Oncology

When a patient has been diagnosed with cancer, radiation oncology is one of the treatment options. During this treatment, the patient is exposed to a specific amount of radiation delivered in carefully planned, focussed fields. The radiation is delivered either via teletherapy [the radiation is directed at the patient from a distant source] or brachytherapy [the radiation source is on or near the patient]. Most teletherapy and brachytherapy is applied remotely from the console of sophisticated, electronically controlled units.

Once a treatment unit is installed, it is commissioned by the Medical Physicist in order to ensure compliance with radiation safety legislation, technical and clinical performance specifications. Treatment planning systems [TPS] are used for planning of radiation treatments. TPS are computers that are capable of predicting the distribution of the radiation dose from a therapeutic procedure using sophisticated algorithms.The Medical Physicist performs quality control and oversees the quality assurance and radiation safety aspects of all the treatment machines and TPS computers, as well as the treatment techniques used.


Teletherapy device called a Linear Accelerator

In radiation oncology a patient generally receives a daily radiation dose over a few weeks. The patient therefore needs to be immobilized and repositioned to ensure that the treatment is exactly reproducible. Personalised devices are manufactured in the Medical Physics Mould Room for this purpose. The staff performing this are the Radiation Laboratory Technologists (RLT). The Charlotte Maxeke Johannesburg Academic Hospital Medical Physics Division has an HPCSA-accredited 3-year fulltime training program for the RLT profession.

Examples of devices made by RLT's:


Shielding blocks.
Shielding blocks are used to protect sensitive organs from radiation during treatment or to shape the radiation field.


Lead Cut-Out.
A personalized lead cut-out is used to shape the radiation field.


Patient Mask.
This is used to immobilise the patient to ensure reproducible radiation treatment of the head and neck area.

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