Development of Radiation Therapy 2.development of radiobiology The primary understand of radiobiology were from the injure and the diseases like leukaemia. 1950,cell technique developed.Cell cycle revealed. 1960,radiobiology in molecular level:target thesis
◼ 2. development of radiobiology ◼ The primary understand of radiobiology were from the injure and the diseases like leukaemia. ◼ 1950, cell technique developed. Cell cycle revealed. ◼ 1960, radiobiology in molecular level: target thesis. Development of Radiation Therapy
Radiation Cellular Effects Approximately 20%is a direct effect. Ionizing radiation causes breakage among the strands of the DNA helix,causing cell lysis,which leads to cell death. Works on the DNA of cancer normal cells. Approximately 80%is an indirect effect. Ionizing can also ionize body fluids,especially water in the cell,leading to the formation of free radicals,which cause irreversible damage to the DNA by breaking the strands. This causes cell lysis and cell death
Radiation Cellular Effects ◼ Approximately 20% is a direct effect. ◼ Ionizing radiation causes breakage among the strands of the DNA helix, causing cell lysis, which leads to cell death. ◼ Works on the DNA of cancer & normal cells. ◼ Approximately 80% is an indirect effect. ◼ Ionizing can also ionize body fluids, especially water in the cell, leading to the formation of free radicals, which cause irreversible damage to the DNA by breaking the strands. ◼ This causes cell lysis and cell death
Radiation cellular Effects Cellular death may occur immediately if DNA repair does not occur,or at the time of cellular division when the damaged cell attempts mitosis(有丝分裂) and dies. Finally,a tumor cell may become sterile by the effects of radiation and die a natural death without the ability to produce progeny(offspring)
Radiation cellular Effects ◼ Cellular death may occur immediately if DNA repair does not occur, or at the time of cellular division when the damaged cell attempts mitosis（有丝分裂） and dies. ◼ Finally, a tumor cell may become sterile by the effects of radiation and die a natural death without the ability to produce progeny (offspring)
Cellular Factors Influencing Response to Radiation Therefore the most sensitive cells to radiation are rapidly dividing,well oxygenated, more vascular cells
Cellular Factors Influencing Response to Radiation ◼ Therefore the most sensitive cells to radiation are rapidly dividing, well oxygenated, more vascular cells
Development of Radiation Therapy 3.RT development in China 97-98,450 hospitals have RT,about 10000,radiation oncologists,technician,physicists 1998,about 500 units accelerators and 500 cobalt 60 and 400 afterload system served in hospitals. 1999,about 30 r knifes and 60 x-knife Now:we can't imagine how many RT equipments served in different clinic unit
◼ 3. RT development in China ◼ 97-98,450 hospitals have RT, about 10000, radiation oncologists , technician, physicists ◼ 1998, about 500 units accelerators and 500 cobalt 60 and 400 afterload system served in hospitals. ◼ 1999,about 30 r knifes and 60 x-knife ◼ Now: we can’t imagine how many RT equipments served in different clinic unit. Development of Radiation Therapy