Biological Effects of Ionizing Biological Effects of Ionizing Radiation Radiation Deterministic effects Deterministic effects Effects of partial body Effects of partial body irradiation irradiation Lecture Lecture A Post Graduate Educational Course Radiation Protection and Safe Use of Radiation Sour IAEA Post Graduate Educational Course in Radiation Protection and Safety of Radiation Sources
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Biological Effects of Ionizing Radiation Deterministic effects Effects of partial body irradiation Lecture IAEA Post Graduate Educational Course Radiation.
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Biological Effects of Ionizing RadiationBiological Effects of Ionizing RadiationDeterministic effectsDeterministic effects
Effects of partial body irradiationEffects of partial body irradiationLectureLecture
IAEA Post Graduate Educational Course Radiation Protection and Safe Use of Radiation Sources
IAEA Post Graduate Educational Course in Radiation Protection and Safety of Radiation Sources
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IntroductionIntroduction
Partial body irradiation may cause local Partial body irradiation may cause local radiation injury of the part of the bodyradiation injury of the part of the body
Sources of data for deterministic effects in Sources of data for deterministic effects in man:man: side effects of radiotherapyside effects of radiotherapy effects on the early radiologistseffects on the early radiologists effects amongst survivors of the atomic effects amongst survivors of the atomic
bombs at Hiroshima and Nagasaki in Japan bombs at Hiroshima and Nagasaki in Japan consequences of severe accidentsconsequences of severe accidents
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ContentContent
TThreshold doses for deterministic hreshold doses for deterministic effects in different organseffects in different organs
Radiation-induced damage of the:Radiation-induced damage of the: SkinSkin EyeEye LungLung GonadsGonads ThyroidThyroid SkeletonSkeleton
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OverviewOverview
Partial body irradiation may cause Partial body irradiation may cause local radiation injury of the part of local radiation injury of the part of the bodythe body
mmoderate doses ( > 20 Gy): oderate doses ( > 20 Gy): eepidermal cell depletion pidermal cell depletion (denudation) due to the mitotic death of the(denudation) due to the mitotic death of the epidermal epidermal cells basal and viable upper layers with consecutive dry cells basal and viable upper layers with consecutive dry oror moist desquamation, blistering of the epidermis and moist desquamation, blistering of the epidermis and secondary dermal secondary dermal uulcerationlceration
vvery high doses (>100 Gy surface dose): ery high doses (>100 Gy surface dose): aacute dermal cute dermal necrosis within 2-3 weeks (interphase death of necrosis within 2-3 weeks (interphase death of endothelial and fibroblast type cells; sometimesendothelial and fibroblast type cells; sometimes moist moist desquamation and blisters)desquamation and blisters)
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Radiation injury of the skin: late Radiation injury of the skin: late phasephase
Epidermal and dermal atrophy: (Epidermal and dermal atrophy: (fragilefragile skin) skin) Insufficient blood supplyInsufficient blood supply Late necrosis with skin ulcerationLate necrosis with skin ulceration Occlusion of lymphatic vessels with local lymph Occlusion of lymphatic vessels with local lymph
stagnation: stagnation: pain, late oedemapain, late oedema Hyperkeratotic and fibrotic degeneration of the Hyperkeratotic and fibrotic degeneration of the
skinskin Decreased immunological defence of the skin Decreased immunological defence of the skin
with increased sensitivity against infectionswith increased sensitivity against infections, etc, etc Persistent or recurring pain Persistent or recurring pain Increased risk of skin malignanciesIncreased risk of skin malignancies
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Radiation injury of the eyeRadiation injury of the eye
Observations:Observations: X-ray treatment of eye tumorsX-ray treatment of eye tumors
Radiation injuries:Radiation injuries: Lid erythemaLid erythema ConjunctivitisConjunctivitis CataractCataract RetinopathyRetinopathy
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CataractCataract
Cataract Cataract - - any detectable change of the any detectable change of the normally transparent normally transparent llens of the eyeens of the eye
Reason of development:Reason of development: SSome abnormal metabolic disorderome abnormal metabolic disorder CChronic ocular infectionhronic ocular infection TraumaTrauma Old ageOld age Ionizing radiation (radiation-induced cataract)Ionizing radiation (radiation-induced cataract)
TThe threshold dose following a single exposure he threshold dose following a single exposure of low-LET radiation is 2 Gy, for neutrons 0.2 Gyof low-LET radiation is 2 Gy, for neutrons 0.2 Gy
Lowering the dose rate or extending the exposure Lowering the dose rate or extending the exposure period increases the EDperiod increases the ED5050 value to an average of value to an average of 9.3 Gy9.3 Gy
Estimated latency periods: 6 month to 35 yearsEstimated latency periods: 6 month to 35 years Doses of less than 0.1 Sv/year are not thought to Doses of less than 0.1 Sv/year are not thought to
present appreciable risk for detectable visual present appreciable risk for detectable visual impairmentimpairment
OOccupational exposure limit for the eye is 0.15 Sv ccupational exposure limit for the eye is 0.15 Sv (ICRP-60)(ICRP-60)
Latency period: 6 months to 3 yearsLatency period: 6 months to 3 years Clinical manifestation:Clinical manifestation:
mmicroaneurysms of the capillariesicroaneurysms of the capillaries ““cotton-wool spots”cotton-wool spots” intraretinal haemorrhages, and intraretinal haemorrhages, and leakage of retinal vessels with exudatesleakage of retinal vessels with exudates
Threshold dose – 5 Gy of acute Threshold dose – 5 Gy of acute exposure within 2 daysexposure within 2 days
Latent period – yearsLatent period – years Pathophysiological mechanism Pathophysiological mechanism
involved:involved: direct lesions to follicular cellsdirect lesions to follicular cells alterations of vascular systemalterations of vascular system immunological reactionsimmunological reactions
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Deterministic radiation injury of Deterministic radiation injury of the lungthe lung
PheumonitisPheumonitis Threshold dose – 8 Gy of acute Threshold dose – 8 Gy of acute
exposureexposure Latent period – 1-3 monthsLatent period – 1-3 months
Fibrosis Fibrosis At the late stage and as a consequence At the late stage and as a consequence
of acute pneumonitisof acute pneumonitis Latent period – 6 monthsLatent period – 6 months
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Radiation-induced pulmonary Radiation-induced pulmonary reactionsreactions Phases of development:Phases of development:
LatencyLatency degenerative changes of pneumocytes and of
Deterministic radiation injury of Deterministic radiation injury of the skeletonthe skeleton
Threshold dose – 5-10 GyThreshold dose – 5-10 Gy Children bones are more sensitiveChildren bones are more sensitive The severity of radiation-induced damage The severity of radiation-induced damage
to growing bone depends on:to growing bone depends on: the total radiation dosethe total radiation dose fractionationfractionation dose homogeneitydose homogeneity volume irradiatedvolume irradiated symmetry of the volume irradiatedsymmetry of the volume irradiated patient's age, etcpatient's age, etc
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SummarySummary
This lecture presented materials about This lecture presented materials about effects of partial body irradiationeffects of partial body irradiation
The following topics were covered in The following topics were covered in the lecture: threshold doses for the lecture: threshold doses for deterministic effects in different deterministic effects in different organs, radiation-induced damage of organs, radiation-induced damage of the skin, eye, lung, gonads, thyroid and the skin, eye, lung, gonads, thyroid and skeleton skeleton
Comments are welcomedComments are welcomed
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Where to Get More InformationWhere to Get More Information UNSCEAR, Sources and Effects of UNSCEAR, Sources and Effects of
Ionizing Radiation, 2000 Report to the Ionizing Radiation, 2000 Report to the General Assembly with Scientific General Assembly with Scientific Annexes, United Nations, New York,2000Annexes, United Nations, New York,2000
IAEAIAEA - WHO. Diagnosis and treatment of - WHO. Diagnosis and treatment of radiation injuries, Safety Reports Series radiation injuries, Safety Reports Series No. 2, IAEA, Vienna, 1998No. 2, IAEA, Vienna, 1998
Hopewell JW. The skin: It's structure and Hopewell JW. The skin: It's structure and response to ionizing radiation. Int J response to ionizing radiation. Int J Radiat Biol 1990; 57:751-73Radiat Biol 1990; 57:751-73