Activated Components

During direct irradiation by the proton beam or through exposure to secondary neutrons within the facility, equipment, beamline components and other materials may become radioactive. Most of this activity is of a relatively short half-life and does not pose a significant exposure hazard. The following is a brief summary of requirements:

Handling Activated Components - Care should be taken in handling activated components:

• The maximum time practical to facility operation should be taken after shutdown before handling such items. For example, in the patient treatment room, post irradiation tasks which do not involve handling activated items should be done first. The effective half-life of most activation is short enough that a minute or two of extra time will result in an exposure reduction of 50 percent or more.
• When handling the component, minimize the time during which you have direct contact with the surface.
• All activated materials must be labeled as "Radioactive." Until such items are declared non-radioactive, they must be kept in secured storage when not in use.

Bolus Blocks - Bolus made of plastic or wax decay to non-radioactive very quickly. These blocks must be held for decay for 24 hours. At the end of the decay period, a confirmatory survey must be made with a suitable instrument, after which the blocks may be released for unrestricted use or disposal.

Patient Apertures - Apertures or collimators made of standard eutectic alloys must be held for a period of not less than two weeks for decay. At the end of the decay period, a confirmatory survey must be made with a suitable instrument, after which the blocks may be released for unrestricted use or disposal, providing all subsidiary hazards (such as lead or cadmium) are considered.

Accelerator Beamline Components - All accelerator beamline components are considered to be radioactive until a survey with a suitable instrument proves otherwise. No activated components may be removed from interlocked areas without special arrangements through the Office of Radiation Safety.

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