Radiation information for patientsAn overview of radiation and why you will see a dentistRadiation therapy (sometimes abbreviated to XRT) is the medical use of radiation as part of cancer treatment to control cancer cells (not to be confused with radiology, the use of radiation in medical x-rays and diagnosis). Radiotherapy is used for the treatment of malignant tumors (cancer), and may be used as the primary therapy. It is also common to combine radiotherapy with surgery, chemotherapy, hormone therapy or some mixture of the three. Most common cancer types can be treated with radiotherapy in some way. Radiation therapy is commonly applied to the cancerous tumour. The radiation fields (the amount of tissue to be treated) may also include the draining lymph nodes if they are involved with tumour, or if there is a risk of spread to them. It is necessary to include a margin of normal tissue around the tumour to allow for uncertainties in daily set-up and internal tumour or patient motion (breathing, swallowing). To try to spare normal tissues (such as skin, saliva glands or organs which radiation must pass through in order to treat the tumour), shaped radiation beams are aimed from several angles of exposure to intersect at the tumour, much like using multiple beams of light to illuminate a single object. Radiation therapy works by damaging the DNA of the cancer cells. The amount of radiation used in radiation therapy is measured in gray (Gy. For cancer treatment, the typical dose for a solid epithelial tumor (most head and neck cancers) ranges from 60 to 80 Gy. The total dose is fractionated (spread out over time) for several important reasons. Fractionation allows normal cells time to recover, while tumor cells are generally less efficient in repair between fractions. In some cases, two fractions per day are used near the end of a course of treatment. Before treatment, a CT scan is often performed to identify the tumor and surrounding normal structures. During this time, the patient is sent to see the cancer centre’s department of dentistry for a pre treatment assessment. The patient is then sent for a simulation so that molds can be created to be used during treatment. These molds hold the patient in the same spot when they are receiving radiation treatment. Radiation is delivered in many different ways; two that are highlighted are conventional external beam radiotherapy and Intensity Modulated Radiation Therapy. Conventional external beam radiotherapy consists of a single beam of radiation delivered to the patient from several directions: often front or back, and both sides. Intensity-Modulated Radiation Therapy (IMRT) is an advanced type of high-precision radiation. The radiation dose intensity is elevated near the cancer while radiation among the surrounding normal tissue is decreased or avoided completely. This may result in better tumor targeting, lessened side effects, and improved treatment outcomes. Radiation therapy is in itself painless. Treatment to higher doses causes varying side effects during treatment (acute side effects), in the months or years following treatment (long-term side effects), or after re-treatment (cumulative side effects). The nature, severity, and longevity of side effects depend on the organs that receive the radiation, the treatment itself (type of radiation, dose, fractionation, concurrent chemotherapy), and the patient. Most side effects are predictable and expected. Side effects from radiation are usually limited to the area of the patient's body that is under treatment. One of the aims of modern radiotherapy is to reduce side effects to a minimum, and to help the patient understand and to deal with those side effects which are unavoidable. Acute side effectsTypically the skin starts to become pink and sore several weeks into treatment. Skin reactions tend to be worse in areas where there are natural folds in the skin, such as underneath the female breast, behind the ear, and in the groin. If the head and neck area is treated, temporary soreness and ulcers commonly occur in the mouth and throat. If severe, this can affect swallowing, and the patient may need painkillers and nutritional support/food supplements. A feeding tube may be placed if the patient cannot swallow. Tissues which have been irradiated tend to become less elastic over time. This can affect the ability to open the mouth as the jaw joint may be affected. DrynessThe salivary glands and tear glands have a radiation tolerance of about 30 Gy in 2 Gy fractions, a dose which is exceeded by most radical head and neck cancer treatments. Dry mouth (xerostomia) and dry eyes (xerophthalmia) can become irritating long-term problems and severely reduce the patient's quality of life. Xerostomia can lead to rampant decay of all remaining teeth over a short time. FatigueFatigue is among the most common symptoms of radiation therapy. Lack of energy, reduced activity and overtired feelings are common symptoms. Why does the patient see a dentist before and after Head and Neck Radiation?
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