Fatal dose of radiation is:

Ans: d (500 rads) Ref: Harrison, 16th ed, p. 488Fatal dose of radiation is 500 radslGy=100 radFeatures of acute total body radiationDoseSyndromes associatedFeatures<2 Gy Usually require little or no therapy;Just monitor the counts2-8 GyHaematopoietic syndromeDeath in2-4 weeks due to bone marrow failure5-12 GyGastro intestinal syndromeDeath within days, C/F-nausea, vomiting, diarrhoea, sepsis and death>100 GyCerebrovascular syndromeDeath within 24-48 hours due to neurological and cardiovascular failure.Occupational exposure: maximum permitted5 rem/year or 50 msv/year and 20 msv for 5 years.-Maximum permitted radiation exposure in pregnancy-13 msv in 13 weeks or 0.5 rads-Single X-ray will cause an exposure of 5 radsRemember1. First organ to be involved in radiation toxicity is skin and earliest skin manifestation after radiotherapy is erythema and next is desquamation2. Most common presentation of radiation carditis is -asymptomatic pericardial effusion3. Intra operative radiotherapy is used in pancreatic cancer.4. Hyper fractionated radiotherapy is used in head and neck carcinomas, non-small cell carcinoma5. Most sensitive organ to radiotherapy-bone marrow>gonad>GIT mucosa6. Most sensitive cell cycle phase to radiotherapy-G ,M7. Most sensitive blood cell to radiotherapy -lymphocyte8. Most resistant blood cell to radiotherapy - platelet9. Most radio resistant organ is - vagina10. Most common toxicity of radiotherapy-bone marrow suppression11. Most resistant phase of cell cycle- end of S phase12. Most sensitive period for neonatal death to occur following radiation exposure- 3-5 weeksBRIDGE1. Drug used for radiation induced xerostomia-Amifostine2. Drug used for radiation induced mucositis-Palifermine