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.
Permanent implants put radioactive seeds directly in the tumor using a special delivery device. Temporary implants use needles, catheters or special applicators. After the device's accurate position is confirmed, the radiation sources are inserted. This is called "afterloading. Or, the oncologist may use a computer-controlled remote afterloading machine to insert the material. Medical imaging helps position the material to treat the tumor in the most effective way. A computer calculates the source position and the amount of time needed to deliver the desired radiation dose.
A medical physicist, licensed dosimetrist or radiation oncologist operates the equipment. The oncologist creates the overall treatment plan. Permanent brachytherapy inserts needles pre-filled with radioactive seeds into the tumor.
The doctor will remove the needle and leave the seeds behind. Seeds may also be implanted using a device that inserts them individually at regular intervals.
The procedure may use medical imaging to help position the seeds. The doctor may do more imaging tests later to verify seed placement. Temporary brachytherapy places a delivery device, such as a catheter, needle, or applicator into the tumor. Medical imaging helps position the radiation sources. The doctor may insert the delivery device into a body cavity such as the vagina or uterus intracavitary.
Or, the doctor may insert an applicator needle or catheter into body tissues interstitial.
High dose-rate HDR treatments deliver radiation over 10 to 20 minutes per session. Low dose-rate LDR treatments deliver radiation over 20 to 50 hours. Pulsed dose-rate PDR treatments deliver radiation in periodic pulses. HDR treatment is usually an outpatient procedure. However, some patients are admitted to the hospital for one to two days to have several HDR treatments using the same applicator. HDR treatment delivers a specified dose of radiation to the tumor in a short burst using a remote afterloading machine.get link
Brachytherapy - Macmillan Cancer Support
The machine stores a powerful source of radioactive isotopes Iridium and protects personnel from unnecessary radiation exposure. The HDR treatment lasts about 10 to 20 minutes. The entire procedure including placement of the delivery device may take up to several hours. This may be repeated a couple times in a day before the delivery device is removed. Patients may receive up to 10 separate HDR treatments over one or more weeks.
LDR treatment delivers radiation at a continuous rate over one to two days. It requires an overnight stay at the hospital. This allows the delivery device to remain in place throughout the treatment period. PDR treatment delivers radiation similarly using periodic pulses usually one per hour.
The doctor may insert the material through the delivery device by hand and remove it later once treatment is complete. Or, the patient may be moved to a shielded room for HDR treatment using a remote afterloading unit. The unit inserts the material into the delivery device within the tumor.
It automatically removes the material when someone enters the room and when the treatment is complete. Before treatment begins, the doctor may place an intravenous IV line into your arm or hand to deliver medication. If anesthesia or heavy sedation is used, you will be moved to a recovery room afterwards.
Depending on the type of treatment, you may return home the same day or be moved to a hospital room. Patients who have an afterloaded implant for temporary brachytherapy may hear a clicking or humming noise from the treatment machine. This occurs as the machine pushes the radioactive material into the treatment device previously placed at the tumor site. You will be alone during the procedure. However, you will be able to speak with your treatment team via a microphone.
The team will be located nearby, where they can see and hear you. PDR treatment will allow you to have visitors between the treatment pulses. LDR treatment will require you to stay in the hospital. Visits are usually limited to about 30 minutes per visitor per day.
Children and pregnant women may not visit. No radiation remains in your body after temporary brachytherapy, so there is no risk to others. This may be due to the catheters or applicators and having to stay relatively still for a prolonged period. Your doctor will prescribe medication to relieve your pain. After permanent brachytherapy, the implanted seeds' radioactivity decays with time, depending on which radioactive isotope is used.
Ask your doctor if you should limit close contact with others, such as pregnant women or children.
With temporary implants, the doctor removes all radioactive material before you return home. There is no risk of exposure after the doctor removes the delivery device and radiation sources. You may have tenderness and swelling in the treatment area or other symptoms. This will depend on your specific treatment. Most patients are able to resume normal activities within days or weeks.
However, you may have some long-term side effects.
Who will be involved in this procedure?
Talk to your treatment team about how to manage them. Your doctor may recommend a series of follow-up exams after treatment.
These may include a physical check-up, imaging exam s and blood or other lab tests. Intracavitary applicators are also used to treat cervical cancer and the most commonly used applicator is a tandem and ovoid applicator. An example of 2D based planning using a tandem and ovoid applicator can be seen below. An example of 3D based planning can be seen below with an axial image on the left and a coronal image on the right.
Once again one can immediately appreciate how much additional detail in the anatomy and distribution of the radiation dose can be appreciated on the CT scan versus the X-ray. An example of when this might be used is shown in the following illustrations. In the picture on the left there is an oval uterus narrowing down to the rectangular cervix which has a red cervical cancer and a larger rectangular vagina. Ideally after an initial course of external beam radiation therapy and concurrent chemotherapy this red cervical tumor will shrink and allow for a tandem and ovoid applicator green figures to fit into the vaginal fornices and cervix so the appropriate distribution of dose orange can be achieved image on left.
Sometimes a lesion does not regress at the end of external beam radiation and may not allow the tandem and ovoid applicator to properly fit as in the picture on the right. In other cases the tandem and ovoid applicator would fit but the residual lesion is larger than the standard distribution of dose with this applicator and so some of the tumor would be underdosed if this approach were used as is illustrated below on the left.
So in these cases an interstitial approach is best so that the residual disease can be appropriately encompassed as can be seen on the right.
Types of Image Guided Brachytherapy
Below is a 3D rendering of the distribution of radiation dose and normal tissues from a gynecologic interstitial implant:. An axial CT slice showing the distribution of small hollow brachytherapy tubes and the distribution of radiation dose for a gynecologic interstitial brachytherapy implant.
Toggle navigation. Types of Image Guided Brachytherapy. Share this. CET Demanes-Rodriguez cylinder and ovoids applicator.