Quantifying construction vibration effects on daily radiotherapy treatments.

The existing two-story parkade is being replaced by a four-story parkade on a hospital campus. The parkade is across a two-lane access road from a cancer center with a nine-linear accelerator radiotherapy department in the basement. The new parkade is supported by over 280 drilled and cased pilings installed at depths between 10 and 25 m depending on the underlying soil strata and varying diameters, up to 1.5 m. The construction work in such close proximity to the radiation therapy department resulted in significant vibrations being felt in the simulation and treatment vaults. The amplitude and frequency of the vibration was measured. Using vendor supplied documentation, the total vibratory amplitude of the linear accelerators in use within the department was calculated. The results fell outside of specification, resulting in changes to the way the project preceded following discussion with the project management team.