The procedure that makes use of high-energy radiation that usually involves x-rays for treating cancer is known as radiation therapy. The calculation of the amount and type of radiation is done carefully so as to destroy cancer or abnormal cells. This entire procedure properly divides these cells for destroying them and causes little or no damage to the surrounding healthy cells. Radiotherapy is used for treating different types of cancer in any part of the body.
Precise radiation doses are delivered on the particular areas inside the tumor or to a cancerous tumor by using computer controlled linear accelerators is known as intensity-modulated radiation therapy (IMRT). This is considered as an advanced mode of high-precision radiotherapy that shapes radiotherapy beams so that they can fit the outline of the tumor more accurately. These radiation beams are given from many angles. Higher doses can also be targeted inside the tumor so as to minimize the dose to nearby healthy significant structures. The dose intensity pattern is determined by using magnetic resonance (MRI) or 3-D computed tomography (CT) images in order to best conform to the tumor shape. The risk of damage to nearby healthy tissue is reduced and it also reduces the chance of long-term side effects.
IMRT (Intensity-modulated radiation therapy) is primarily used for treating those tumors that were earlier untreatable as they were located close to some significant structures and organs. Computer-generated images are used for delivering tightly focused radiation beams to the malignant tumors. The x-rays or photons are generated by using LINAC (linear accelerator).
Treatment Planning: IMRT is planned in such a way that it works in a best possible way. Some 3D pictures of the area that is going to be treated are taken with the help of MRI scan and CT scan. The location and shape of the tumor is determined with the help of these pictures. Permanent marks or small tattoos of pinpoint size can also be drawn on the skin that helps in placing the patient accurately while performing the treatment. A doctor will also instruct a patient about how to look after their skin.
A patient may also be required to wear a plastic mask if they are also having radiotherapy treatment including IMRT for head and neck cancer. This plastic mask helps to keep the head of a patient firm while giving radiotherapy treatment. Here the tattoos or marks are not necessary on the skin as they can be drawn on the mask itself.
A radiographer or a mould technician will prepare the mask in the mould room that takes about 30 minutes. There are two techniques that are considered for making the face mask- first by using a type of mesh plastic that is molded so as to fit the shape of face. In other technique, the impression of the face is taken by using wet plaster bandages along with the finished mask that is prepared of Perspex.
Treatment sessions : The painless IMRT treatment sessions begins that takes 10-30 minutes to complete. The type of cancer determines the number of treatment sessions.
There are some benefits of IMRT that include –