Principles of Radiation Therapy

TOPIC: PRINCIPLES OF RADIATION THERAPY(TIME, DISTANCE AND SHIELDING)

Radiation Therapy uses ionizing radiation to kill or limit the growth of cancer cells, may be internal or external. It not only injures the cell membrane but destroys or alters DNA so that the cells cannot reproduce. Like chemotherapy, effect cannot be limited to cancer cells only; all exposed cells, including normal ones, will be injured, causing side effects. Localized effects are related to area of body being treated; generalized effects may be related to cellular breakdown products.

Factors Controlling Exposure

A.   Half-life: time required for half of radioactive atoms to decay

1.    Each radioisotope has a different half-life.

2.    At the end of the half-life, the danger from exposure decreases.

B.    Time: the shorter the duration, the less the exposure

C.   Distance: the greater the distance from the radiation source the less the exposure

D.   Shielding: all radiation can be blocked; rubber gloves stop alpha and usually beta rays; thick lead or concrete stops gamma rays

E.    These factors affect health care worker’s exposure as well as client’s.

1.    Health care worker at greater risk from internal than external sources

a.    Limit visitors to 30 mins. per day; visitors should be at least 6 feet from the source.

2.    Film badge can measure the amount of exposure received

3.    No pregnant nurses or visitors permitted near radiation source

HYPERTHYROIDISM

DISEASE: HYPERTHYROIDISM- is a hyperthyroid state resulting from hypersecretion of thyroid hormones(T3 and T4), characterized by an increased rate of body metabolism, common cause is Grave’s disease also known as toxic diffuse goiter, clinical manifestations are referred to as thyrotoxicosis.

SIGNS & SYMPTOMS: Enlarged thyroid gland(goiter), palpitations, cardiac dysrhythmias, such as tachycardia or atrial fibrillation, protruding eyeballs(exophthalmos), hypertension, heat intolerance, diaphoresis, weight loss, diarrhea, smooth, soft skin and hair, pliable nails, nervousness and fine tremors of hands, personality changes, irritability and agitation, mood swings.

PATIENT TEACHINGS: Provide adequate rest. Provide cool and quiet environment. Obtain weight daily. Avoid administration of stimulants.

 TREATMENTS: Administer sedatives as prescribed. Administer antithyroid medications(propylthiouracil(PTU) and methimazole(Tapazole)) that block thyroid synthesis, as prescribed. Administer iodine preparations that inhibit the release of thyroid hormone as prescribed. Administer propranolol(Inderal) for tachycardia as prescribed. Prepare the client for radioactive iodine therapy as prescribed to destroy thyroid cells. Prepare the client for thyroidectomy if prescribed.

DIET: Provide a high-calorie diet.

HYPOTHYROIDISM

DISEASE: HYPOTHYROIDISM(myxedema) is a hypothyroid state resulting from a hyposecretion of the thyroid hormones T4 and T3, characterized by a decreased rate of body metabolism.

SIGNS & SYMPTOMS: Lethargy and fatigue, weakness, muscle aches, paresthesia, Intolerance to cold, weight gain, dry skin and hair, loss of body hair, bradycardia, anorexia, constipation, generalized puffiness and edema around the eyes and face, forgetfulness and loss of memory, menstrual disturbances, cardiac enlargement, tendency to develop congestive heart failure.

PATIENT TEACHINGS: Instruct the client about thyroid replacement therapy.

 TREATMENTS: Monitor VS, including heart rate and rhythm. Administer thyroid replacement; levothyroxine sodium(Synthroid) is most commonly prescribed. Assess the client for constipation; provide roughage and fluids to prevent constipation. Provide a warm environment. Avoid sedatives and narcotics because of increased sensitivity to these medications.

DIETS AND DRUGS: Instruct client in low-calorie, low cholesterol, low saturated fat diet. Levothyroxine(Synthroid), Thyroglobulin(Proloid), Dessicated thyroid, Liothyronine(Cytomel) Thyroid hormone replacements are taken daily in the morning to prevent insomnia.

ADDISONIAN CRISIS

DISEASE: ADDISONIAN CRISIS – a life threatening disorder caused by acute adrenal insufficiency. Crisis precipitated by stress, infection, trauma or surgery. It can cause hyponatremia, hyperkalemia, hypoglycemia and shock.

SIGNS & SYMPTOMS: Severe headache, severe abdominal, leg and lower back pain, Generalized weakness, Irritability and confusion, Severe hypotension, Shock.

PATIENT TEACHINGS: Maintain bed rest and provide a quiet environment.

 TREATMENTS: Prepare to administer glucocorticoids intravenously as prescribed; hydrocortisone sodium succinate(Solu-Cortef) usually is prescribed initially. Following resolution of the crisis, administer glucocorticoid and mineralocorticoid orally as prescribed. Monitor vital signs, particularly BP. Monitor neurological status, noting irritability and confusion. Monitor I & O. Monitor lab values, particularly sodium, potassium and blood glucose. Administer IV fluids as prescribed to restore electrolyte balance. Protect the client from infection.

DIETS AND DRUGS: High protein, carbohydrate, & sodium intake. Dexamethasone, Hydrocortisone and Fludrocortisone.

ADDISON DISEASE

ADDISON DISEASE – hyposecretion of adrenal cortex hormones (glucocorticoids & mineralocorticoids). Fatal if left untreated.

SIGNS & SYMPTOMS: Lethargy, fatigue & muscle weakness, GI disturbances, wt. loss, menstrual changes in women, impotence in men, hypoglycemia, hyperkalemia, postural hypotension, dehydration, emotional disturbances

PATIENT TEACHINGS: Avoid individuals with infection, strenuous exercise & stressful situations. Need for lifelong glucocorticoid therapy. Avoid OTC meds. Wear medic-alert bracelet.

 TREATMENTS: Monitor VS, BP, wt. and I & O. Monitor blood glucose, and potassium. Administer glucocorticoid or mineralocorticoid medications as prescribed.

DIETS AND DRUGS: High protein, carbohydrate, & sodium intake. Dexamethasone, Hydrocortisone and Fludrocortisone.