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'''Dose limits help ensure that no person is exposed to an excessive amount of [[ICRPædia Guide to the Basics of Ionising Radiation|radiation]] in normal, planned situations.'''

Dose limits alone are not enough to ensure adequate protection. They function in combination with the [[System_Of_Radiation_Protection_Overview#Fundamental Principles of Radiological Protection | fundamental principles]] of justification and optimisation. These limits apply only to doses received above the normal local [[Sources of Radiation Exposure | natural background radiation]]. Limits on [[System_of_radiation_protection_module_2#Effective Dose | effective dose]], combined with optimisation of protection, are designed to avoid a risk of [[Effects of Exposure | stochastic effects]] that would be considered intolerable in a [[System_of_radiation_protection_module_2#Exposure Categories and Situations | planned exposure situation]]. Limits on [[System_of_radiation_protection_module_2#Equivalent Dose | equivalent dose to an organ]], combined with optimisation of protection, are designed to prevent the occurance of [[Effects of Exposure | deterministic effects]].

These limits apply only to doses received above the normal local [[Sources of Radiation Exposure | natural background radiation]].  Limits on [[System_of_radiation_protection_module_2#Effective Dose | effective dose]], combined with optimisation of protection, are designed to avoid a risk of [[Effects of Exposure | stochastic effects]] that would be considered intolerable in a [[System_of_radiation_protection_module_2#Exposure Categories and Situations | planned exposure situation]]. Limits on [[System_of_radiation_protection_module_2#Equivalent Dose | equivalent dose to an organ]], combined with optimisation of protection, are designed to prevent the occurance of [[Effects of Exposure | deterministic effects]]. Dose limits apply only in [[System_of_radiation_protection_module_2#Exposure Categories and Situations | planned exposure situations]]. In other situations, restrictions on individual dose are called reference levels. They provide the additional flexibility needed in [[System_of_radiation_protection_module_2#Exposure Categories and Situations | emergency and existing exposure situations]] to make sure protection is optimised. Dose limits do not apply to [[System_of_radiation_protection_module_2#Exposure Categories and Situations | medical exposures]]. If they did, the effectiveness of diagnosis or treatment might be reduced, doing more harm than good for the patient. The emphasis is on justification of medical procedures and optimisation of protection.