Delta Medix Patient General Information

Cancer Treatment Options

IGRT - Image Guided Raditation Therapy

Image-guided radiation therapy (IGRT) is a process using various imaging technologies such as a CT scan to locate a tumor target prior to a radiation therapy treatment. This process is aimed to improve the treatment accuracy. It is often used to treat cancers in organs that move such as prostate or lung. The use of highly precise IGRT treatments result in the surrounding healthy tissue receiving less exposure to radiation minimizing the incidence of side effects. At The Center for Comprehensive Cancer Care, physicians apply advanced imaging techniques using CT, and PET/CT to accurately delineate the treatment target. IGRT is complementary to IMRT. IMRT is used to improve the radiation delivery precision and IGRT is used to improve the radiation delivery accuracy.

What is IGRT?

IGRT is Image-Guided Radiation Therapy - a method of using images taken immediately before treatment to use extreme accuracy to target a tumor. Accurate targeting is essential to resolve daily tumor location changes due to internal organ motion and body position variation on the treatment couch. IGRT increases radiation to the tumor and spares normal surrounding tissue.

Why use implanted markers?

To assist with IGRT, three tiny implanted markers become visible landmarks for tumor location on pre-treatment images. They provide a permanent method for quick and accurate daily tumor alignment.

Implanted Markers

Implanted markers are typically, pure gold rods—crosscut to prevent movement—that permanently remain in the prostate. Non-metallic markers are also used on occasion.
Note:  Gold markers do not contain iron and do not set off metal detectors.

Implant procedure

The 10-minute office procedure under ultrasound guidance is very similar to a prostate biopsy or other image-guided techniques, and only slightly uncomfortable. Typically, three markers are placed in the prostate.

CT scan

After marker implantation, the radiation oncologist and planning team obtain a CT scan and create the unique treatment plan.

Daily image guidance

Each day, just before treatment, images are taken to confirm the exact tumor location.
IGRT images are obtained by the treatment machine itself (port films), electronic portal imaging devices (EPID images), real-time low-energy systems (kV x-rays) or computed radiography.
Implanted markers show up clearly on all image types, providing internal landmarks for tumor position.
Using localization software, the radiation therapist registers the markers on the pretreatment images and calculates the exact couch moves for high accuracy tumor alignment.

Summary

IGRT uses implanted markers, pre-treatment images, and localization software to provide advanced tumor targeting accuracy for radiotherapy. IGRT increases radiation to the tumor and spares normal surrounding tissue.

Please contact your physician or nurse to discuss your treatment and review any questions you might have about your care.

IMRT - Intensity Modulated Radiation Therapy

Intensity Modulated Radiation Therapy (IMRT) is an advanced type of radiotherapy, which uses a computer-controlled device, called a linear accelerator, to deliver precise doses of radiation to tumors or specific areas within the tumors.

Using 3-D computed tomography (CT) images of the patient along with computerized dose calculations, IMRT allows for the radiation dose to conform more precisely to the three-dimensional shape of the tumor by controlling — or modulating — the intensity of the radiation beam. The therapy allows higher radiation doses to be delivered to regions within the tumor while minimizing the dose to the surrounding area.

IMRT involves a complicated treatment planning process (called inverse planning) and a dedicated delivery process using dynamic multi-leaf collimator (MLC). A comprehensive quality assurance program specific for both machine and individual patient is very critical and has been developed at The Center for Comprehensive Cancer Care to ensure the quality treatment of IMRT.

The advantages of IMRT therapy are  higher and more effective radiation doses can safely be delivered to tumors with fewer side effects and it reduces treatment toxicity.

Stereotactic Radiotherapy

Stereotactic radiotherapy (SRS) involves delivering a high dose of radiation very precisely to a tumor. SRS uses focused radiation beams targeting a well-defined tumor, relying on detailed imaging, computerized three-dimensional treatment planning and precise treatment set-up to deliver the radiation dose with extreme accuracy (i.e., stereotactically). Stereotactic radiotherapy delivers radiation from numerous different angles to focus the radiation at one small point, like a magnifying glass. By using a large number of unique beam angles to deliver the radiation, stereotactic radiotherapy minimizes the effects on the normal tissue, which the radiation passes through, but delivers a large dose of radiation to a single point where all of the beams converge. However, since the dose of radiation to that single point is so high, very precise targeting of the tumor is required. Due to these constraints, the most common use of radiosurgery involves tumors of the brain. The brain does not move and hence does not have the problems with motion that other tumors sites can have, and the skull serves as a stable landmark for the location of the tumor.

There are two types of stereotactic radiation:

Gated Therapy

Treatment to tumors located in the head and neck and abdominal regions, such as lung and liver, is always a challenging task because of respiratory organ motions. Respiratory gating technology allows physicians at The Center for Comprehensive cancer Care to synchronize the delivery of radiation with a patient's own breathing cycle. This allows for a high dose of radiation to be directly administered more safely.