Hygienic regulation of ionizing radiation as a base of radiation Safety

1. Ionizing radiation as a environmental and
occupational factor. Hygienic regulation of ionizing
radiation as a base of radiation safety

2. Plan
1. Radioactive contamination of the environment.
2. Hygienic characteristics of basic methods of
medical usage of active material and sources of
ionizing radiation.
3. Characteristic of ionizing radiation sources
used in medicine
4. Conception of radiation safety, its principles.
5. Objectives and organization of medical control
at work with sources of ionizing radiation.

3. 1. Radioactive contamination of
environment
• also called radiological contamination, is the
deposition of, or presence of radioactive substances on
surfaces or within solids, liquids or gases (including the
human body), where their presence is unintended or
undesirable
• Contamination may affect a person, a place, an animal,
or an object such as clothing. Following an atmospheric
nuclear weapon discharge or a nuclear reactor
containment breach, the air, soil, people, plants, and
animals in the vicinity will become contaminated by
nuclear fuel and fission products.
• Cases of widespread radioactive contamination include
the Rocky Flats Plant in Colorado, the Fukushima
nuclear disaster, the Chernobyl disaster, and the area
around the Mayak facility in Russia.

4. Nuclear power station

5. Sponsored
Medical Lecture Notes – All Subjects
USMLE Exam (America) – Practice

6. Nuclear weapon testing

7. The radiation warning symbol

8. Radioactivity
• is spontaneous transformation of atoms nuclei of
chemical elements with change of their chemical nature
or energy state of nucleus, accompanied by nuclear
radiation
• The radioactive pollution is defined as the
physical pollution of air, water and the other radioactive
materials. The ability of certain materials to emit the
proton, gamma rays and electrons by their nuclei is
known as the radioactivity. The protons are known as the
alpha particle and the electrons are also known as the
beta particle. Those materials are known as the
radioactive elements. The environmental radiations can
be from different sources and can be natural or
manmade.

9. The use of radiation in medicine
• It has led to major improvements in the diagnosis and
treatment of human diseases. Annually, worldwide, more
than 3,600 million X-ray examinations are performed, 37
million nuclear medicine procedures are carried out, and
7.5 million radiotherapy treatments are given. As the
benefits for patients gain recognition, the use of radiation
in medicine increases. While the development of modern
health technology makes new applications safer, their
inappropriate use can lead to unnecessary or unintended
radiation doses, and can cause potential health hazards
for patients and staff.

10. All methods of sources used from hygienic positions can
be relatively represented by the following groups:
• 1. Radiodiagnosis.
• 2. Roentgen and gamma-ray therapy. Therapy with use
of high-energy irradiations
• 3. Intracavitary. Interstitial and application therapy using
of active material in closed form.
• 4. Radiotherapy and diagnostic analysis using of active
material in open form.

11. For receiving of image or picture,
following methods can be marked out:
• 1. Radioscopy- is visual observation using of
strengthening screens
• 2. Radiography- is using of special (roentgen)
films for receiving on image.
• 3. Photofluorography- is photographing the
image on strengthening screens using of
camera
• 4. Radio xerography- is formation of concealed
electrostatic image on the surface of
semiconductor layer of selenium plate under the
action of roentgen radiation and following visible
image on paper.

12. The level of irradiation of the personnel during
radiodiagnosis depends on:
• the way of image acquisition
• location of work place during investigation
(the nearer the more dangerous);
• operating regime;
• type of exploited equipment:
• position of X-ray tube (horizontal, vertical).

13. 2. Hygienic characteristics of basic methods of
medical usage of active material and sources of
ionizing radiation

15. Cone-beam computed tomography

16. Dental radiography

19. 3. Characteristic of ionizing radiation
sources used in medicine
• In medicine open and closed sources of ionizing
radiation are used.
• Closed source is radioactive source of
irradiation, arrangement of which excludes
entrance of active materials in surroundings in
service and deterioration conditions on which it
is counted on.
• It is seen from definition that the closed source
can give only irradiation and work with it is
connected with the possibility of external
irradiation of the personnel.

20. Closed sources
• External irradiation is the irradiation of the body located
out of the source of radiation.
• Closed sources used in medicine can be divided into
isotopic and nonisotopic sources.
• X-ray machines and accelerators of elementary particles
refer to nonisotopic sources. Such sources generate
irradiation occasionally only during period of their use,
when the voltage is in X-ray tube and accelerator
started. These machines represent danger for the
personnel only during period of work.
• Radionuclide sources refer to isotope sources. These
sources will permanently generate ionizing radiation
because of the decay of radioactive substances.

21. Open source
• Open source is radionuclide source of radiation.
Application of this source is connected with
possible entrance of radioactive substances into
environment.
• The open source gives irradiation and
radioactive pollution of environment. Work of the
personnel with the open source can be
connected with hit of radioactive substances
both inside the organism and on the surface of
the body. At the same time danger may be due
not only because of external irradiation but
because of internal irradiation as well..

22. Internal irradiation
• Internal irradiation is the irradiation of the organism,
systems and organs from the sources of ionizing
radiation located inside of the organism.
• Radioactive danger during work with active materials
and sources of ionizing radiation is determined by
radiotoxicity. Radiotoxicity is determined by physical and
biological characteristics of radioactive nuclides. Physical
characteristics of radioactive nuclides are kind and
energy of irradiation, half-value period, scheme of decay,
activity, physical state of isotope etc.
• Biological characteristics are penetration way, solubility
(isotope ability for transfer from environment to the
organism), allocation in the organism (organotropism),
and output speed (biological half-period, effective half-
period).

23. 4. Conception of radiation safety, its principles.
Radiation safety and anti radiation protection in practical
work have to be built with of the following principles:
• Principle of propriety i.e. any practical activity that is
accompanied by irradiation of people must not be
realized if it does not bring more profit than harm to
irradiated people or to society as a whole;
• Principle of optimization i.e. levels of individual doses
and (or) amount of irradiated people regarding to every
source of radiation have to be as much low as it can be
achieved taking into account economic and social
factors.
• Principle of unexceeding i.e. inadmissibility of
exceeding of maximum permissible individual doses of
radiation from sources of ionizing radiation.

24. Categories of irradiated people (by NRSU):
• Category A (personnel) – the persons
that permanently works directly with
sources of ionizing radiation.
• Category B (personnel) – the persons
that do not work directly with the source of
ionizing radiation but because of location
of their work place in premises and in
industry can receive additional irradiation.
• Category C – whole population.

25. Limits of doses Category of irradiated persons
Аab Bа Cа
Dle (limit of effective dose) 20c 2 1
Limits of equivalent dose of
external irradiation
DLlenz
(For crystalline lens)
150 15 15
DLskin
(for skin) 500 50 50
DLextrim
(for hands and feet) 500 50 -
Limits of irradiation dose (mZv/year)
Comments:
distribution of irradiation dose during official year is not regulated;
there are limitations for women of childbearing age (under 45) and for
expectant mothers
for any consistent 5 years work on average but not more than 50mZv per
single year

26. Principles of protection at work with closed
and open sources of ionizing radiation
• Ionizing radiation possesses high activity (biological
one). Its effect appears on every level: molecular,
cellular, tissular, organ and organism. Taking into
account the danger irradiation of organism it is
necessary to use effective protection of the personnel
and patients in case of RS and SIR use.
• At work with sources of ionizing radiation it is necessary
to use principles and methods for protection of the
personnel. There are 4 principles used for the external
irradiation protection:
• Protection by time
• Protection by distance
• Protection by quantity or activity
• Shielding

27. • Protection by time is based on decreasing of contact time
with ionizing radiation. Dose is directly proportional to the
time of influence. Practical realization of this principle is
professional development, decreasing of work time
duration.
• Protection by distance is based on increasing distance
from the source of radiation. There is inversely proportional
dependence between the dose and distance squared i.e.
the larger distance squared the fewer doses. Therefore the
increase of distance in 2 times leads to decrease of dose in
4 times, the increase of distance in 4 times decreases the
dose of irradiation in 16 times etc. Protection by distance is
realized by using of remote control, remote instruments,
master-slave devices etc.
• Dose of irradiation is proportional to dose rate and
therefore to activity. Decrease of the dose rate (activity of
substance) decreases the dose of irradiation. Therefore
that is on what principle of protection by quantity or
activity it is based

28. • Protection by shields is based on ability of materials to
absorb ionizing radiation owing to interaction with atoms
and molecules of environment and to transmission of
energy to them. That’s why it is necessary to select right
shield (screen) material according to the kind of radiation
in order to exclude by-effects, and to determine right
effective sickness of screen according to energy of
radiation. The most effective one is triple shielding:
shielding of source, shielding of the organism and
installation of shield between the source and the worker.

29. The protection from open sources
consists of two principles:
• to exclude the hit of radioactive substances in
the environment;
• to exclude the hit of radioactive substance inside
the organism.
To exclude the hit of radioactive substance
inside the organism by maintenance of
regulations of work with radioactive nuclides, by
use of personal protective equipment, by
effective ventilation and deactivation.

30. Source of ionizing radiation
Activity
Exposure dose its quantitative
characteristic of radiation which
based on ability of radiation to ionized
air
Irradiation of human organism
Absorbed dose
(quantity of energy of
IR that was absorbed
by unit of mass of
medium (Gray, Gy)
Equivalent dose
(dose of any kind of
ionizing radiation that
causes the same
biological effects as
standard (sample)
roentgen radiation
with energy 200 KeV )
Effective dose
(sum of equivalent doses that were
received by separate organs
and tissues during radiation,
multiplied by tissue weighting
factor: for gonads – 0.20, for red
bone marrow, lungs, stomach- 0.12,
for other organs and tissues – 0.05 )

31. Radiation dose units
Radioacti
vity
Absorded
dose
Equivalen
t dose
Exposure
Common
Units
Curie (Ci) rad rem roentgen
(R)
Si units becquer
el (Bq)
gray
(Gy)
sievert
(Sv)
coulomb
/kilogra
m (C/kg)

32. Radiation effects of human irradiation
Determinate Stochastic
Acute radiation
disease
Chronic radiation
disease
Local radiation
injury
Somato - stochastic Genetic
Shortening
average life
Increase of common
sickness rate
Malignant neoplasms
Dominant
genetic mutation
Inherited
carcinogenesis
Chromosomal
aberration

33. Measures of radiation safety
Collective measures are:
• Organizational-legislative – measures that provide correct work
organization with closed and open sources of ionizing radiation,
observance of radiation safety State regulations – NRSU-97, BSRU-
2001.
• Technological measures provide using of radionuclide's with low
toxicity in technological process which do not form aerosols and
radioactive gases.
• Technical-and-engineering measures provide automation,
mechanization of work processes, capsulation of manufacturing
equipment, use of protective constructions made of proper materials
depending on kind and energy of radiation.
• Planning measures provide observance of regulations of radiation
establishments allocation and principles of premises planning. Allocation
of establishments is realized according to the kind of source, its activity
and in case of work with open source – class of work.
• Hygienic and sanitary measures include preventive and current
sanitary inspection of radiological objects.
Individual protective measures include observance of personal
protection rules, use of personal protective equipment: working clothes,
protective footwear, goggles, gloves and other equipment.