Radiation Therapy

Radiotherapy or radiation therapy is one of the effective cancer treatments that using ionizing radiation to kill cancer cells and shrink tumors.

Radiotherapy can be administered externally in the form of high energy x-ray or electron. The machine used to deliver this treatment is called Linear Accelerator.

A Linear accelerator uses electricity to form a stream of fast-moving subatomic particles. This creates high-energy radiation that will be used to treat cancer.

Below is video courtesy from Elekta shows how the Linear Accelerator works.

The radiation injures or destroys the tumor cells in the area being treated (target tissue). Radiotherapy does not hurt and will take several minutes to complete the treatment. Although radiation may damage both cancer cells and normal cells surrounding the area, most normal cells can recover from the effect of radiation and function properly within 24 hours. While cancer cells have little means of recovering from radiation damages, the goal of radiation therapy is to damage as many cancer cells as possible while limiting harm to nearby healthy tissue. Hence, it is given in many fractions, allowing healthy tissue to recover between fractions.

Conventional and Conformal Radiation Therapy

Conventional radiation therapy is a technique that applies to basic and simple cases. It is using one or two beam directions to irradiate the target without complex shielding, ie whole brain, spine metastases etc. It applies multiple beams directions to conform as closely as possible to the target volume to deliver adequate dose to the tumor while minimizing dose to normal tissues. Both conventional and conformal radiation therapy technique are based on 3D anatomic information to gather dose distributions.

Intensity Modulated Radiation Therapy (IMRT)

IMRT is a state of the art radiation therapy technique which enables non-uniform fluence of radiation to be delivered to the patient from any given position of beam to optimize the composite dose distribution. IMRT treatment techniques has a superior to conventional 3-dimensional conformal radiotherapy (3DCRT) in terms of sparing of normal tissues and organs enabling higher doses to be delivered to the cancer without increasing the side effects. This has been shown to translate into better cancer cure in many clinical studies.

Stereotactic Radiosurgery (SRS)

SRS is a highly precise form of radiation therapy used primarily to treat tumours and other abnormalities of the brain. It is also used to treat extracranial lesions called stereotactic body radiation therapy (SBRT). Stereotactic radiosurgery is a procedure using, focused radiation beams targeting a well-defined tumour relying on detailed imaging, computerized treatment planning and precise treatment set-up with extreme accuracy. It is delivered single or several times depending on the dose prescribed by Oncologist.

Despite its name, stereotactic radiosurgery is a non-surgical procedure that uses highly focused x-rays to treat certain types of tumours, inoperable lesions and as a post-operative treatment to eliminate any leftover tumour tissue or to obliterate abnormal blood vessels in congenital arteriovenous malformations.

Image Guided Radiation Therapy (IGRT)

Human body is unique in a way that it is always moving and this movement reflects the behaviour of the organs, since organs do that, the tumors can also move between treatments due to differences in organ filling or movements while breathing. IGRT is an imaging method on a real time basis where an image of the patient is taken and compared to the planning image prior the delivery of the treatment. The advantage of doing an IGRT is the accuracy of the treatment delivery.

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	Screening for Cancer Screening for cancer is essentially indentifying the presence of a cancer before an individual has any symptoms relating to the cancer itself.
	Radiation Therapy Process Before any radiotherapy treatment, patient will undergo a treatment simulation. Simulation process is done in either Manual or CT Simulator.