Image guided radio therapy (IGRT) is the use of imaging such as CT scans and X-rays during radiation therapy to help in targeting the cancer and delivering the treatment precisely and accurately by providing high resolution, three dimensional images. These X-rays and scans show the exact position, size and shape of the malignant tumors or lesions along with the surrounding tissues and bones. Patients who need radiotherapy are given high dose to treat these cancerous tumors by damaging and making it hard for them to reproduce. Cancerous tumors can move in some parts of the body during or between the treatments like tumor in lung or liver can move with breathing, tumor in abdomen or pelvis can move due to movement of digestive tract, tumor in prostate gland move depending on whether the bladder is full or not. IGRT takes many images of the tumor during the treatment which ensures the accurate aiming of radiation beam to the exact location of the cancer. By comparing these images with the reference images taken at the time of stimulation, the position of the patient or the radiation beams are adjusted to deliver the radiation dose more precisely to the targeted tumor. Skin markers known as Fiducial markers, transponders or colored tattoos may be used on the skin to help in aligning and targeting the radiation equipment during the IGRT procedure. They are usually placed at least a week before the treatment.
Radiation therapy requires a team of highly trained doctors including a radiation oncologist, therapeutic medical physicist, radiation therapists to evaluate the size, shape, and location of the tumor, other factors such as age, overall health conditions, medical history and techniques to use in delivering the required recommended dose. Patients with pacemaker implanted or has loose metal in their bodies should inform the doctor in case of MRI is used for simulation or IGRT.
Prior to the treatment, simulation (treatment planning procedure) is done to ensure that the treatment area is mapped out, right dose of radiation depending on the shape and size of the tumor, amount of radiation that may harm the surrounding healthy tissue should be as small as possible. Patient may have CT scan, MRI, PET scans on the treatment area. The information from these scans feeds into the radiotherapy computer programme that designs a radiation beams which follow the shape of the tumor closely to focus only on the cancer and avoid harming the healthy tissues. Tattoo marks are made by radiographers on the patient’s skin to ensure that the same location is treated in each session. Simulation may take 2 to 4 hours depending on the treatment planned for the patient.
During the IGRT, patient is set up on the treatment table in the same position as every day; radiation machine will move around the patient and turned on and off. Patient will not feel any radiation. It can take 2-3 hours depending on the treatment plan. Doctor will closely monitor the patient’s breathing and other discomfort. Weekly treatment session and visits may be planned out to evaluate the response to the treatment.
Some people can experience side effects of radiotherapy depending on the area of the treatment such as:
1. Swelling around the treated area
2. Hair loss in the treated area
3. Difficulty in swallowing
6. Change in urine or bladder
There may be some rare side effects that can be seen after months or years like:
1. Lung changes
2. Joint changes
3. Kidney changes
5. Secondary cancer
6. Brain changes
7. Sexual problems
8. Colon or rectal changes
Patient should visit the doctor for checking recurrent or new cancers on regular basis.