Internal radiation therapy
The radiation delivered from radiation sources namely radioactive material placed inside or on the body is known as internal radiation therapy. Brachytherapy techniques are commonly used in cancer treatment. A radiation source placed within tumor tissue namely within a prostate tumor is known as Interstitial brachytherapy. A source placed within a surgical cavity or a body cavity, such as the chest cavity, near a tumor is known as Intracavitary brachytherapy.
Episcleral brachytherapy is used to treat melanoma within the eye. It uses a source that is attached to the eye. Brachytherapy involves using radipactive isotopes seales in pellets or seeds. Delivery devices such as catheters, needles or some other types of carriers are used to place these seeds within the patients. The isotopes decay naturally and give off radiation that destroys the nearby cancerous cells. The isotopes decay completely and do not give off radiation if they are left for a few weeks and months.
Brachytherapy is used to deliver higher doses of radiation to certain cancers other than external-beam radiation therapy without causing much damage to normal tissues. Brachytherapy can imparted at lower dose or at higher dose treatment.
Continuous low dose radiation are given from the source over a time period of several days in the low dose rate treatment.
A robotic machine attached to delivery tubes inserted in the body directs the radioactive sources close to a tumor and then removes the source at the end of each treatment session in high dose rate treatment. The treatment is given in one or more sessions. MammoSite system is an example of a high dose rate treatment which is being used on breast cancer patients who have undergone breast conserving surgery.
The placement of brachytherapy sources can be temporary or permanent.
- In permanent brachytherapy the sources are sealed surgically inside the body and left inside the body even after all the radiation has been given. The remaining material containing the sealed radioactive isotopes does not cause any damage to the patient’s body. Permanent brachytherapy is a kind of low-dose-rate brachytherapy.
- Tubes or catheters or other kinds of carriers are used to impart the radiation source in temporary brachtherapy and the radiation source is removed after treatment. This can be either low dose rate or high dose rate treatment.
Brachytherapy is used along or in conjunction with external-beam radiation therapy by doctors to provide a radiation boost to a tumor while not harming the surrounding tissues.–