Brachytherapy: Radiation Therapy

Brachytherapy
Brachytherapy (also known as internal radiation therapy) is the use of radioactive ‘seeds’ to help destroy cancerous cells. It is commonly used as a treatment for cervical, prostate, breast and skin cancer. How long the treatment will take will depend on where the tumor is and how large it is. Brachytherapy works from the inside of the body by placing the radioactive ‘seeds’ into the body next to the tumor. About 4/10 people with cancer have some type of radiation therapy as their treatment.
History of Brachytherapy
- The earliest use of Brachytherapy was in 1901 at the Curie Institute in Paris by Henri-Alexandre Danlos and at St Lukes and Memorial Hospital in New York by a surgeon called Robert Abbe. It was suggested to Danlos that radioactivity could be used to treat cancer. When Danlos tested this h e found that cancerous tumors shrunk when exposed to radiation.
- In 1970 a machine called an ‘Afterloader’ was developed to stop the doctors from being exposed to
the radiation. The ‘Afterloader’ contains the radiation sources for high dose rate Brachytherapy. It was controlled remotely by the doctors in a separate observation room so that they were not exposed to radiation at all.
- In the 1990’s, advanced imagery techniques were developed and were used to help plan the Brachytherapy treatment. It was also used during the procedure so that the radiation was delivered to the right place.
- In the year 2000, virtual treatment planning was introduced and this helped to enable healthcare professionals to accurately plan the delivery of radiation using a virtual 3D representation of the patient.
- The year 2005 was a year in which robotics were used to accurately deliver the first brachytherapy treatment for prostate cancer. This has helped Brachytherapy become even more effective and safe.

How does it work?

With High-Dose Rate Brachytherapy, thin tubes are placed first in the tumor. The tubes are then connected the Afterloader, which is the machine used so that doctors won’t be directly exposed to radiation. The Afterloader places a single, highly radioactive capsule/tablet, usually containing 125Iodine but can also contain 103Palladium or 131Cesium at the end of a wire. The capsule is then pushed into both tubes, one by one. The computer controls how long each capsule stays in the tubes and where along the tubes it should pause to release its radiation. To ensure the capsule is placed in the perfect position a CT scan is undergone before hand and throughout the initial treatment. 125Iridium is a highly radioactive element with a Decay energy of 185.77KeV. With a half life of 60 days, 90% of the dose will be finished by 204 days which means it will be safe to do most things after then as there is not enough radioactivity to disturb anything. The radioactivity during the first few months will destroy the DNA cells surrounding it. That is why the capsules must be placed well enough so that it only destroys the cancerous cells. After a few treatments the tubes will be removed and there will be no more radioactive substances.

Role of Technology

The role of technology in the treatment is quite significant so that the doctor/s performing the Brachytherapy is safe from the radioactivity. An Afterloader does just this as it lets the doctor/s can safely perform the procedure from another room using the device to implant the radioactive seeds. Initial planning of the treatment must first be done virtually to ensure that the procedure can be carried out with precision. X-Rays, CT scans, Ultrasounds and MRI’s are used in this process to receive a detailed visual of the tumor and the surrounding tissue. This technology works to deliver the most accurate treatment with utmost precision. The initial planning helps to ensure that places in the body with too little irradiation and too much irradiation are avoided as these can result in side effects and treatment failure.

Risks
Being around young children or pregnant women who have developing bodies that are changing at a rapid rate and therefore cells will be more vulnerable to abnormal cell changes after being exposed go radiation. It is possible to stand next to them, but not for any prolonged periods of time. This emitting of radiation that does damage to children and pregnant women will be going on for roughly 2 months after the treatment. A recommended safe distance is 6 feet from the patient as there is no limit to time that one can stand there. Sexual intercourse has not been recommended without the use of a condom for 2 weeks after the implant, after that there is extremely rare that a seed will be released.

Comparison to Alternatives

An alternative for Brachytherapy could be Radiation Therapy.
Though Brachytherapy is one half of radiation therapy, its other half is known as External Beam Radiation Therapy (EBRT). EBRT, just like Brachytherapy, involves radiation entering the body to remove tumorous cells. EBRT uses accurately targeted beams that enter the body from a machine called the linear accelerator. Patients would or lie down on a couch or bed at the hospital and receive the therapy. With Brachytherapy radiated seeds are planted in the body rather than separate doses. EBRT, which uses X-ray radiation, makes its radiation by bombarding a high atomic number material with electrons. If that target is removed an electron beam with high energy is formed. Instead with Brachytherapy the radiation is placed within Radon seeds which are tiny, usually gold containers. They are 4.5mm long and are 0.8mm in width. Both treatments come from the radiation therapy category and are both very commonly used to treat cancer
patients.