Written by : Dr.Kishore Kumar Das, MD
Internal radiotherapy, also called Brachytherapy, is a procedure in which radioactive sources are placed inside the body very near to the tumor area. High-energy, ionizing rays from the source delivers a high dose of radiation directly to the tumor and helps spare nearby tissues.
The radiation source is usually sealed in a small holder called an implant, which may be in the form of wires, needles or a catheter. It targets the area where the cancer originally grew (called the 'tumor bed') and the tissues closest to the tumor site, killing any possible remaining cancer cells.
The implant may be placed inside the breast at the time of the surgery or soon after.
Brachytherapy may also be used to give an extra dose of radiation to the area of the excision site (called a "boost") after a lumpectomy.
The advantage of brachytherapy is that it suplies radiation very close to the site of the tumor and thus prevents or decreases radiation to the normal tissues of the chest, ribcage and lungs. The skin is also not affected unlike the traditional external radiation.
During brachytherapy, the radiation source in the body may give off radiation during the procedure, especially in high dose brachytherapy. It may be necessarry to be isolated and to avoid meeting with other people while the treatment process is on.
Types of Brachytherapy:
PDR or Pulsed dose-rate (PDR) treatments are a type of LDR Brachytherapy in which radiation is deliverd in periodic pulses, usually one per hour.
During the course of treatment, the catheter or applicator may stay in place, or it may be put in place before each treatment.
Accelerated Partial Breast Irradiation (APBI)
Accelerated partial breast irradiation (APBI) is a type of HDR Brachytherapy in which the radiation is focused on just the tissues around the breast cavity left after a lumpectomy is performed.
Since the majority of recurrences in the breast occur around the site of the original lumpectomy cavity, it is rational to deliver radiation primarily to these tissues. Radiation is not delivered to the whole breast.
APBI reduces the duration of therapy to just five to seven days compared to the six to seven weeks for traditional whole-breast irradiation . It offers better cosmetic results and nearly the same efficacy as whole-breast irradiation. The criteria for receiving APBI are:
Types of APBI
The SAVI system consists of an expandable bundle of tiny, soft and pliable catheters which can be positioned around the lumpectomy cavity and which can expand into a ball-like shape inside the lump. Radiation is delivered through these catheters. They can be inserted through a tiny incision on the breast and remains in position thorughout the course of treatment. They are removed after the treatment is over.
The SAVI device can be placed during the lumpectomy or afterwards in a separate procedure. The latter can be performed as an in-office procedure or in an outpatient clinic.
This is a highly skilled procedure with multiple entry and exit points into and out of the breast.
Procedure of Brachytherapy: The type of radioactive material used (iodine, palladium, cesium or iridium) depends on the type of treatment. In all types, the radiation source is encapsulated. This means it is enclosed within a non-radioactive metallic capsule often referred to as a "seed." This helps prevent the material from moving to other parts of the patient's body.
The initial procedure of simulation is the same as in external radiation therapy . Then, under local or general anesthesia, the device is inserted into the tissues of the breast just over the site of the lumpectomy. After the device's accurate position is confirmed, the radiation wires are inserted into the tubes or a radioactive source is placed in the ballon . This is called "afterloading." The radioactive source may be placed for a few minutes every day or continuously for a few days.
Once treatment is complete, the delivery device is removed from the patient. Internal radiation typically offers fewer noticeable side effects. In nearly all cases, the appropriate method is determined by the radiation oncologist based on the location and size of the tumor.
What to Expect When the Device Is Removed
Once you finish treatment with LDR or HDR implants, the device will be removed. Here are some things to expect:
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Side Effects of Radiotherapy