Fundamentals Principles

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Radiation Protection refers to protecting humans and the environment from harmful effects of exposure to ionizing radiation. Ionizing radiation includes gamma rays, X-rays and the radiation from radioactive materials. It is widely used in medicine for diagnosis and treatment of patients and it has brought enormous benefits when used safely. However, direct exposure to radiation in the course of medical procedures, work or research can cause microscopic damage to living tissue. Hence need of implementing safety measures.

General principles of radiation protection based on International Commission on Radiological Protection (ICRP) recommendations:

i. Justification: No practice involving exposures to radiation should be adopted unless it produces sufficient benefit to the exposed individual.

ii. Optimization: A process or method used to make a system of protection as effective as possible within the given criteria and constraints.

iii. Dose limit: Limitation of radiation exposure to an individual.

These principles should be followed by each and every person who is directly or indirectly in the way of radiation protection.  The principles are explained below.


No use of ionizing radiation is justified if there is no benefit.  All applications must be justified. This implies all, even the smallest exposures are potentially harmful and the risk must be offset by a benefit. Justification need to evaluate the benefits of radiation and doing in easy way especially in the case of radiotherapy.  Assessment of the risks requires the knowledge of the dose received by persons.


Optimization of the procedure is crucial phenomenon. When radiation is to be used then the exposure should be optimized to minimize any possibility of detriment. Optimization is “doing the best you can under the prevailing conditions”.  Need to be familiar with techniques and options to optimize the application of ionizing radiation - this is really the main objective of the present course.

Principle of Optimization:

AS Low As Reasonably Achievable (ALARA) is the main principle of optimization. Whatever be the procedure the optimization should be there to minimize the risk of the effects of radiation. Optimization can be divided into two types one is optimizing the tumor and normal structures and another one is optimizing the protection of Occupational workers, patients, and Public’s.

Both the justification and optimization are include in a part of strategies when handling the potential situations or procedure.

Dose & Dose limits:

Dose limits are one of the three principles of protection as introduced by ICRP and BSS. Fixed dose limits are recommended by ICRP and often enforced by a national regulatory body. Dose constraints are used in an optimization process to guide Treatment planning. Constraints and the importance thereof may be subject to change to achieve the optimum solution to a problem.

“No dose limitation for medical exposure of the patient - it is always assumed that the benefits for the patient outweigh the risks”

“Limits need to be applied for public and occupational exposures.”


1. What is the principle of optimization?

a) Distance

b) Time

c) Shielding


2) Dose limits are applied only for,

a) Patients

b) Public and Occupational 

c) Non radiation workers

d) ll



b) Public and Occupational


  • International Basic Safety Standards for protection against Ionizing Radiation and for the Safety of  Radiation Sources. Safety Series:115
  • ICRU History, policies and Procedures.
  • IAEA Training material on Radiation Protection in Radiotherapy.

Home > Radiation Protection and Quality AssuranceRadiation Protection > Fundamental Principles

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