Cancer of the Head and Neck
Head and neck cancers can be of many types, based on the area where they are found.
Symptoms of head and neck cancer can range from a lump in the neck to hoarseness of voice to even a growth in the mouth. A person may notice a change in voice. A person suffering from mouth and tongue can lead to sores. Basal cell cancer of the skin is another form of head and neck cancer. Early detection of head and neck cancer is vital to timely treatment. Most of these cancers lead to identifiable symptoms. Blood in the saliva or phlegm can indicate mouth, nose or throat cancer. Persistent earache and difficulty in swallowing can be due to infection or tumor in the throat. Cancer of the nasal cavity can result in nose blockage, pain in the forehead and face numbness.
Most common causes for head and neck cancers are smoking, chewing tobacco and alcohol. Other probable factors for head and neck cancer are are HPV infection, asbestos exposure and excessive sun exposure. A person suffering from Epstein Barr virus is at higher risk for developing head and neck cancer. Do not ignore a persistent lump on the neck or tongue or jaw. Consult a doctor when you notice difficulty in swallowing for more than a few weeks.
A doctor will conduct a physical examination and probably take a biopsy of any suspicious lymph nodes or tissues. If a cancer of the head or neck is detected, further tests will be needed to judge the extent of spread. The type of treatment usually depends on the extent of spread of the tumor.
PET - Positron Emission Tomography scan is a non-invasive test that aids in imaging the cellular functions and body tissues. It helps in observing the blood flow, oxygen use, and glucose metabolism. A PET scan is of immense help in the diagnosis of cancer, heart disease and brain disorders. The PET scan has been of particular help in the diagnosis of brain tumors, head and neck cancer and esophageal cancer. Since the PET scan reveals metabolic changes in the cells, it aids in early detection of certain conditions such as epilepsy. A PET scan involves injection of a small amount of radioactive tracer drug such as FDG-18. After an hour when the radioactive tracer has spread to the body, the scan is taken. The tracer emits tiny positively charged particles (positrons) that produce signals. A PET scan produces three-dimensional color images from the images taken by a camera that records the tracer as it travels through the body. It is often combined with a CT scan to study a particular body area. Lactating mothers must not breast feed their babies for a few hours after the PET scan.
Intensity Modulated Radiation Therapy
Intensity modulated radiation therapy or IMRT is one of the most effective and precise methods of therapy administered in the treatment of cancer and tumors of various origins. This method was first employed in San Francisco at PAMF - Palo Alto Medical Foundation center in California. PAMF used this technique for the treatment of cancers of neck and prostate soft tissues.
Mechanism and clinical aspects of IMRT
Intensity modulated radiation therapy is an advanced version of the three dimensional conformal radiation therapy. The technique is administered with the integrated software and hardware to determine the amount of radiation required on a specific target. The IMRT team consists of clinicians, radiologists and physicists to evaluate the specific site and the radiation dose on the cancer cells in the specific location. The doses of radiation are determined by the clinicians after identifying the location of the target and also the normal tissues adjacent to it. These factors are further evaluated by the physicist through a specified computer software to calculate the effective dose proportion and also to reduce the side effects. IMRT technique involves the usage of dynamic multi leaf collimators (DMLC) which determine size and shape of the target site in relation to therapy that can be administered.
DMLC enables the radiation to be administered in different intensity levels through variations created in the single beam. This method helps in calculated release of radiation based on the requirement, whether high or low on the target site. The IMRT technique avoids the speculations of trial and error methods through its inverse planning technique in association with computer programmed release of the radiation. This prevents the normal surrounding tissues from getting damaged. IMRT technique has gained in importance because of its effective tumor control and cost saving factor. This method is also efficient as it not does involve different energies derived from photons or combinations associated with photons and electrons.
IMRT technique involves important requirements such as patient immobilization. This is to prevent the missing of target site during radiation therapy. IMRT for moving organ systems is considered as a sensitive and significant factor as the moving organs can affect the delivery of radiation to the target sites. Immobilization tools of invasive fixation systems (peacock talon system) and non-invasive fixation systems (reinforced mask) are used in the IMRT technique. In case of head cancer and neck cancer, oral stents and bite blocks are used to prevent the surrounding tissue damage. In conditions such as prostate cancer, patient immobilization is very difficult and hence, immobilization box is used.
Advantages of the IMRT technique
IMRT has potentially produced many advantages in the field of radiation therapy and oncology. It enables in the identification of multiple target sites in conditions such as brain metastases. The therapy affects the target sites while avoiding other normal tissues of the brain. This facilitates the prevention of CNS toxicity. The radiation thresholds of the IMRT are effective in the determination of normal tissue tolerance surrounding the target area. This helps minimizing complications such as vision loss and impairment associated with sensory organs.
Side effects of IMRT
The side effects of IMRT are predominantly associated with the equipment. These leakages often affect the intensity of the radiation related to the target site. The most common leakage are found in the multi leaf collimators. Another factor is the administration IMRT in children. Children are extremely sensitive to radiation therapies and subsequently if radiation therapies are administered in children, there may be incidences of mutated genes which may cause other complications. Studies specify the increase in the onset on secondary cancers in elderly population. This is predominantly noticed in case of prostate cancers.
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Bibliography / Reference
Collection of Pages - Last revised Date: January 21, 2020