بایگانی برچسب برای: Radiation

Radiation.Oncology.for.Pediatric.CNS.[taliem.ir]

Radiation Oncology for Pediatric CNS Tumors

Childhood brain tumors are the most common form of pediatric solid tumors. Signifcant improvements over the decades in the treatment of brain tumors in children have improved outcomes but mortality and morbidity are still high. Pediatric brain tumors are clinically and biologically distinct from those that occur in adults. Our understanding of risk factors in childhood brain tumors remains limited to several exposures of the head and neck to ionizing radiation and well-described hereditary cancer predisposition syndromes. In this chapter ,we review the descriptive and analytic epidemiology of childhood brain tumors, including a discussion of the roles of radiation exposure, established predisposing syndromes, and other suspected risk factors.
Radiation.Therapy.for.Extranodal.[taliem.ir]

Radiation Therapy for Extranodal Lymphomas

Radiotherapy (RT) after systemic chemotherapy including high-dose (HD) methotrexate is widely accepted as the standard treatment for primary central nervous system lymphoma (PCNSL). Treatment must consider the blood brain barrier as it characterizes the clinical behavior of PCNSL. For consolidation RT in patients with complete remission (CR) after chemotherapy, 23.4–30 Gy of whole-brain radiotherapy (WBRT) is recommended. For salvage RT in patients with non-CR or recurrent disease (RD) after chemotherapy, 36–45 Gy of WBRT or 30 Gy of WBRT followed by 10–20 Gy of boost irradiation is recommended. The reported 5-year survival rate of PCNSL patients is 30–50%; it is worse than for patients with other extranodal lymphomas. Late neurological toxicity is a major problem in long survivors after HD methotrexate and WBRT. Chemotherapy alone may be considered in elderly PCNSL patients who are at high risk for radiation- induced neurocognitive dysfunction.
Radiation.Therapy.for.Liver.Tumors.[taliem.ir]

Radiation Therapy for Liver Tumors

The liver is the central clearing house for most metabolic functions in the body . These functions include lipid, carbohydrate, and protein metabolism; coagulation factor production; albumin production; detoxification of xenobiotics; storage of vitamins and glycogen; and bile processing and secretion. The liver is situated at the receiving end, via the portal circulation, of the intestines, which provide metabolic substrates to the liver. Blood flows out of the liver, carrying away the fruits of its metabolic labor, into the inferior vena cava. Bile flows out of the liver via the bile ducts to aid in digestion and dispose of certain waste products. The liver is for the most part composed of hepatocytes, bile ducts, and blood vessels. Diseases typically target one of these principal components. But, as this is a functional system, injury to one component generally affects other components of the system. The liver has an enormous functional reserve: approximately 80–90% of the liver needs to be destroyed before its essential functions can no longer be adequately performed. Fortunately, the liver is one of the few organs with a high regenerative capacity; this is seen in the ancient Greek story of Prometheus, the giver of fire to humans, who was punished with an endless cycle of having his newly regenerated liver eaten by a bird each day.