Section 120.228 - Control of Access to Very High Radiation Areas(A) In addition to the requirements in 105 CMR 120.227, the licensee or registrant shall institute measures to ensure that an individual is not able to gain unauthorized or inadvertent access to areas in which radiation levels could be encountered at five grays (500 rads) or more in one hour at one meter from a source of radiation or any surface through which the radiation penetrates at this level. This requirement does not apply to rooms or areas in which diagnostic x-ray systems are the only source of radiation.(B) The registrant is not required to control entrance or access to rooms or other areas containing sources of radiation capable of producing a very high radiation area as described in 105 CMR 120.228(A) if the registrant has met all the specific requirements for access and control specified in other applicable parts of 105 CMR 120.000, such as, 105 CMR 120.300 for industrial radiography, 105 CMR 120.430 for x-rays in the healing arts, and 105 CMR 120.700 for particle accelerators.