More on the latest Radiation technology which I will be undergoing - Intensity Modulated Radiation Therapy (IMRT). But firstly, let's take a look at its most immediate predecessor.
(3D-CRT)
3-dimensional conformal radiotherapy (3D-CRT) combines multiple radiation treatment fields to deliver precise doses of radiation to the affected area. Tailoring each of the radiation beams to accurately focus on the patient's tumor allows coverage of the cancer while at the same time keeping radiation away from nearby healthy tissue.
(IMRT)
Intensity modulated radiation therapy (IMRT) is a form of 3D-CRT that further modifies the radiation by varying the intensity of each radiation beam. This technique allows a precise adjustment of radiation doses to the tissue within the target area. IMRT may allow doctors to direct a higher radiation dose to the affected area and keep more radiation away from nearby healthy tissue.
Important Note
Radiation therapy works by damaging the DNA within cancer cells and destroying the ability of the cancer cells to reproduce. When these damaged cells die, the body naturally eliminates them. Normal cells are also affected by radiation, but they are able to repair themselves in a way that cancer cells cannot.
How it Works
In intensity modulated radiation therapy (IMRT), very small beams, or beamlets, are aimed at a tumor from many angles. During treatment, the radiation intensity of each beamlet is controlled, and the beam shape changes hundreds of times during each treatment. As a result, the radiation dose bends around important healthy tissues in a way that is impossible with other techniques.
Because of the complexity of these motions, physicians use special high-speed computers, treatment-planning software, diagnostic imaging and patient-positioning devices to plan treatments and control the radiation dose during therapy.
For IMRT to be effective, the anatomical position of the tumor and surrounding healthy tissues must be accurately defined. Computed tomography (CT), positron emission tomography (PET) and magnetic resonance (MR) imaging provide the necessary three-dimensional anatomical information. It's also important to accurately position and immobilize the patient during treatment.
This may be done with special head frames (if the head or brain is being treated), or with advanced imaging devices such as electronic portal imaging and scanning ultrasound, which provide daily information about the location of internal organs. Some organs, such as the prostate, move due to normal daily volume changes in the bladder and rectum. Gold seeds may be placed into the prostate to track prostate movement daily and ensure more precise targeting.
A device called a multileaf collimator adjusts the size and shape of the computer-determined radiation beams. The collimator, a computer-controlled mechanical device, consists of up to 120 individually adjusted metal leaves. These leaves move across the irradiated tissue while the beam is on, blocking out some areas and filtering others to vary the beam intensity and precisely distribute the radiation dosage.
Radiation oncologists usually administer a regimen of IMRT treatments over four to eight weeks. The total dose of radiation and the number of treatments given depend on the size, location and type of cancer; the patient's general health; and other medical therapy the patient is receiving.
As can be seen in the following image, IMRT permits the delivery of a high dose of radiation to the cancer while minimizing dose to other sensitive organs. Here multiple beams are all focused on the prostate. Each of these beams has a number of sub-beams or segments, and the intensity of each segment is varied according to the treatment plan.
(3D-CRT)
3-dimensional conformal radiotherapy (3D-CRT) combines multiple radiation treatment fields to deliver precise doses of radiation to the affected area. Tailoring each of the radiation beams to accurately focus on the patient's tumor allows coverage of the cancer while at the same time keeping radiation away from nearby healthy tissue.
(IMRT)
Intensity modulated radiation therapy (IMRT) is a form of 3D-CRT that further modifies the radiation by varying the intensity of each radiation beam. This technique allows a precise adjustment of radiation doses to the tissue within the target area. IMRT may allow doctors to direct a higher radiation dose to the affected area and keep more radiation away from nearby healthy tissue.
Important Note
Radiation therapy works by damaging the DNA within cancer cells and destroying the ability of the cancer cells to reproduce. When these damaged cells die, the body naturally eliminates them. Normal cells are also affected by radiation, but they are able to repair themselves in a way that cancer cells cannot.
How it Works
In intensity modulated radiation therapy (IMRT), very small beams, or beamlets, are aimed at a tumor from many angles. During treatment, the radiation intensity of each beamlet is controlled, and the beam shape changes hundreds of times during each treatment. As a result, the radiation dose bends around important healthy tissues in a way that is impossible with other techniques.
Because of the complexity of these motions, physicians use special high-speed computers, treatment-planning software, diagnostic imaging and patient-positioning devices to plan treatments and control the radiation dose during therapy.
For IMRT to be effective, the anatomical position of the tumor and surrounding healthy tissues must be accurately defined. Computed tomography (CT), positron emission tomography (PET) and magnetic resonance (MR) imaging provide the necessary three-dimensional anatomical information. It's also important to accurately position and immobilize the patient during treatment.
This may be done with special head frames (if the head or brain is being treated), or with advanced imaging devices such as electronic portal imaging and scanning ultrasound, which provide daily information about the location of internal organs. Some organs, such as the prostate, move due to normal daily volume changes in the bladder and rectum. Gold seeds may be placed into the prostate to track prostate movement daily and ensure more precise targeting.
A device called a multileaf collimator adjusts the size and shape of the computer-determined radiation beams. The collimator, a computer-controlled mechanical device, consists of up to 120 individually adjusted metal leaves. These leaves move across the irradiated tissue while the beam is on, blocking out some areas and filtering others to vary the beam intensity and precisely distribute the radiation dosage.
Radiation oncologists usually administer a regimen of IMRT treatments over four to eight weeks. The total dose of radiation and the number of treatments given depend on the size, location and type of cancer; the patient's general health; and other medical therapy the patient is receiving.
As can be seen in the following image, IMRT permits the delivery of a high dose of radiation to the cancer while minimizing dose to other sensitive organs. Here multiple beams are all focused on the prostate. Each of these beams has a number of sub-beams or segments, and the intensity of each segment is varied according to the treatment plan.
The image below shows an IMRT plan for treating prostate cancer. The area in red is the prostate gland; the area in blue, the rectum. IMRT focuses high doses of radiation on the prostate while keeping the dose to the rectum at a minimum.
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