MicroReview: Types of Brachytherapy (Internal Radiotherapy)
Editorial Office, Open Medscience, County Armagh, BT62 2LG, United Kingdom
Brachytherapy techniques have been a powerhouse in the treatment of cancer since the beginning of the twentieth century. The advancement of other theranostic treatments has not removed Internal Radiotherapy entirely from the clinician’s armoury war in the ongoing quest to destroy cancer. Currently, one century forward Brachytherapy although in some cases, not always an effective radiotherapy treatment continues to play a fundamental role in cancer therapy. Brachytherapy is most commonly used for prostate, gynaecological, skin and breast cancer treatments and it is believed to will offer continuing treatment possibilities through technological developments in the future.
The definition of Brachytherapy means merely short therapy and it is used in radiotherapy by applying a sealed radiation source inside the human body. The radiation source is usually placed near to where the treatment is required. This type of therapy aims to damage the DNA of cancer cells and ultimately kill them. In the treatment of prostate cancer brachytherapy can be used in the following modes: low dose-rate and high dose-rate.
Low Dose Rate uses a smaller strength radioactive source and is associated with longer treatment times especially for a one-off treatment. The most commonly used Low Dose Rate treatment site is for the prostate, which involves permanent placement of tiny radioactive seeds inside the tissue of the prostate. This Low Dose Rate approach has been used in the treatment of head and neck tumours during which low activity sealed sources are temporarily placed at the cancer source for several days and then removed.
High Dose Rate uses a higher strength radioactive source contained within an after-loader device. The after-loader is capable of delivering the radioactive source for a brief period of time by using catheters and needles placed inside the tumour site.
High Dose Rate treatment is a much shorter procedure – minutes compared to several days of Low Dose Rate treatments. However, High Dose Rate treatment does require multiple sessions and has become the more favourable option to replace Low Dose Rate techniques for the majority of body sites.
In addition, other Internal Radiotherapy techniques include Pulse Dose Rate and Image-Guided Brachytherapy.
Pulsed dose rate brachytherapy treatment combines the physical advantages of high-dose-rate technology with the radiobiological advantages of low-dose-rate brachytherapy. Pulsed brachytherapy consists of using a stronger radiation source than for low-dose-rate brachytherapy and produces a series of short exposures of up to 30 minutes in every hour to approximately the same total dose in the same overall time as with the low-dose-rate brachytherapy.
Modern afterloading equipment offers certain advantages over interstitial or intracavitary insertion of separate needles, tubes, seeds and wires. Automatic removal of the radiation source from the patient into a shielded safe eliminates radiation exposure to staff and visitors. The radiation exposure is also reduced to the staff who formerly loaded and unloaded a multiplicity of radioactive sources into the catheters and tubes.
Image-guided brachytherapy involves the use of advanced imaging techniques to make brachytherapy more accurate, safe, and effective. Internal Radiotherapy consists of four phases: Placement of hollow catheters or hollow carriers; Computed tomography or magnetic resonance imaging of the site; computer calculations of the dose distribution (dosimetry) and robotic radiation treatment delivery with a tiny radiation source. The imaging techniques used for interventional radiology may be used to guide the placement of the Internal Radiotherapy catheters.
The advantages of image-guided brachytherapy include more accurate treatment distribution throughout the targeted area and the reduced risk of injury to healthy tissues. Also, this type of Internal Radiotherapy has the ability to treat a wide variety of cancer lesions such as those that are deep within the body or adjacent to blood vessels which would ordinarily be more dangerous to remove.