IGRT (Image guided Radiotherapy)
IGRT is the use of daily imaging during a course of radiation therapy to guide in the precise and accurate delivery of radiation therapy. Machines equipped with IGRT technology allow the physician to image the tumor before or during the time radiation is being delivered while the patient is on the treatment table in treatment position. Specialized software is then used to compare the images to the reference images taken at the time of simulation. These daily images allow any necessary adjustments to be made to the patient’s position prior to the delivery of radiation therapy.
A benefit of IGRT is increased dosage levels of radiation to the tumor while sparing the surrounding healthy tissues. Additionally, it reduces the possible side effects of radiotherapy.
SRS (Stereotactic radiosurgery)
SRS is a non-surgical radiation therapy used to treat small tumors. Each patient’s plan is created using precisely targeted radiation fields which are used to destroy cancerous cells while preserving and minimizing radiation to healthy surrounding tissue. Due to its accuracy and small fields, SRS is ideal for tumors in the brain or spinal cord. When SRS is used to treat tumors in the body, it is called Stereotactic Body Radiotherapy (SBRT). SRS and SBRT are typically performed on an outpatient basis. Unlike conventional external beam radiation therapy, SRS and SBRT are normally provided in 1 to 5 treatments.
IMRT (Intensity Modulated Radiation Therapy)
IMRT is a high-precision mode of radiotherapy that delivers precise doses of radiation to a tumor. IMRT allows for the radiation dose to conform more precisely to the three-dimensional shape of the tumor with the use of collimation and multi-leaf collimators (MLC). MLC’s are a device that consists of a number of ‘fingers’ or ‘leaves’ which project into the primary beam to create the required shape.
IMRT also allows higher radiation doses to be distributed to the tumor while sparing the surrounding organs and tissues.
Combinations of multiple intensity-modulated fields coming from multiple beam directions produce a custom radiation dose that maximizes tumor dose while minimizing the dose to adjacent normal tissues. Lower doses to healthy normal tissues may result in fewer complications or side effects. Types of tumors that may be treated with IMRT include head & neck cancer, brain, prostate, spinal cord or tumors very close to radiosensitive normal tissues.
Brachytherapy is the temporary or permanent placement of a radioactive source either on or within body tissues or cavities. Brachytherapy allows the delivery of a high dose of radiation to a small area while sparing the amount of surrounding normal tissue that is irradiated, additionally it allows a physician to use a higher total dose of radiation to treat a smaller area in a shorter amount of time.
The implant may be temporary or permanent.
During temporary brachytherapy, a radioactive material is placed inside a catheter for a specific amount of time and then withdrawn. Temporary brachytherapy can be administered at a low-dose rate (LDR) or high-dose rate (HDR).
Permanent brachytherapy is an interstitial implant. It is a radioactive source that is contained within a needle, seed, wire or catheter which is placed directly in the tumor or tumor bed. Permanent implants, also known as seed implantation, are LDR brachytherapy treatments that utilize radioactive materials, seeds, or pellets, that are implanted permanently within the tumor to provide highly localized radiation. After several months, the radioactivity level of the implants eventually diminishes to nothing. The inactive seeds remain in the body but have no lasting effect on the patient.
A form of partial breast radiation using HDR brachytherapy for select cases only. Utilizes a catheter device that can be custom fitted to the lumpectomy cavity at the time of surgery, regardless of shape or size. Restricts the radiation to tumor bed, sparing radiation to healthy surrounding tissue. Reduces the potential for side effects. Advantage is that it can be completed in five days utilizing treatment in the morning and in the afternoon with at least six hours in between. FDA approved in 2006.