Radiopharmacy 2 dist 2021 MO ANDD ppt.pptx

Radiopharmacy biosafety labs are the major targets for these peripheral tissue products and they may be activated by class II MHC molecules

1. Units of Radioactivity Radioactivity is expressed in units called curies. Historically, it was initially defined as the disintegration rate of 1 g radium, which was considered to be 3.7 x 10 10 disintegrations per second. The System Internationale (SI) unit for radioactivity is becquerel ( Bq ), which is defined as one disintegration per second. Thus, 1 - - - -

2. Radioactive decay: The rate of decay can be described by: N = N o e - λ t where N is the number of atoms at elapsed time t الوقتُ المُسْتَغْرَق , N o is the number of atoms when t = 0, and λ is the disintegration constant characteristic of each individual radionuclide. T 1/2 = 0.693 / λ The intensity of radiation can be described by: I = I e - 0.693/ T1/2 Half life  — symbol t 1/2  — The time in which a given quantity of a radionuclide decays to half its initial value is termed the half-life (T 1/2 ). 2

3. Radioactive Decay Law 4

4. Detection of Radioactivity and the Concept of Half-life Geiger-Muller counter – instrument which measures radioactive decay by registering the ions and electrons produced as a radioactive particle passes through a gas-filled chamber 5

5. Detection of Radioactivity and the Concept of Half-life Scintillation counter – instrument which measures the rate of radioactive decay by sensing flashes of light that the radiation produces in the detector 6

6. Radiation Units There are three basic units related to radiation: the roentgen (R) for exposure, the rad (radiation absorbed dose) for absorbed dose, and the rem (roentgen equivalent man) for dose equivalent. The roentgen is the amount of x or γ radiation that produces ionization of one electrostatic unit of either positive or negative charge per cubic centimeter of air at 0°C and 760 mmHg (STP). C : coulomb 7

7. the roentgen applies only to air and to x or γ radiations. the R unit is applicable only to photons of less than 3 MeV energy. The rad is a more universal unit. It is a measure of the energy deposited in unit mass of any material by any type of radiation. 8

8. In SI units, the gray ( Gy ) is the unit of radiation absorbed dose and is given By: It can be shown that the energy absorbed per kilogram of air due to an exposure of 1 R is : Therefore, 9

9. In SI units, the dose equivalent Hr is expressed in sievert ( Sv ), which is defined as : The dose equivalent unit , Hr, in rem , has been developed to account for the differences in effectiveness of different radiations in causing biological damage. In radiobiology, the dose equivalent Hr for a particular radiation is defined as : where ( RBE ) r is the relative biological effectiveness of the radiation. 10

10. Quality factors for different radiations. 11

11. Effects of Radiation Energy of the radiation Penetrating ability of the radiation Ionizing ability of the radiation Factors Determining Biological Effects of Radiation Chemical properties of the radiation source 12

12. Effects of Radiation 13

13. Effects of Radiation 14

14. RADIATION HEALTH SAFETY The Nuclear Regulatory Commission (NRC) adopts many of the recommendations and guidelines set by the International Council on Radiation Protection (ICRP) and the National Council on Radiation Protection and Measurement. The Code of Federal Regulations , IOCFR20 , was revised and were effective as of January I, 1994. This revision incorporates advances in the science and concepts of radiation protection and principal recommendations of the ICRP. The principles of radiation protection from external sources are based on the factors of time , distance , shielding , and activity . 15

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20. The total radiation exposure is directly proportional to the time of exposure to the radiation source. Therefore, to decrease exposure, one should work quickly and efficiently to reduce the amount of time spent near radiation sources . The intensity of the radiation source varies inversely as the square of the distance from the source to the point of exposure. This principle is more commonly known as the " Inverse Square Law " and can be written, 22

21. By doubling the distance, the radiation dose is reduced to one-fourth of the original intensity . High atomic number (Z) materials can be used to absorb radiation . Lead is used to shield gamma radiation in nuclear medicine departments because of economic reasons. Plastic should be used for radionuclides that emit beta particles (e.g. 32P), because in high Z containers such as lead, they produce highly penetrating bremsstrahlung radiations . Radiation exposure increases with the intensity of the radioactive materials being used . 23

22. Whenever possible, avoid working with large amounts of radioactivity or placing yourself in an environment when large amounts are stored. In addition, laboratory coats and gloves should always be worn when working with radioactive materials. Familiarity with receiving and monitoring radioactive packages, radioactive waste disposal, and the records that must be maintained for the receipt, storage, and disposal of radioactive materials is essential. 24