The person who helps plan and calculate the radiation dose and delivery scheme to be used for radiation therapy.
Found on http://www.encyclo.co.uk/local/20892
dosimetrist 1. A person who performs medical dose measurements. 2. In radiation therapy, a person trained to make radiation measurements and also performs treatment-planning calculations. Found on http://www.wordinfo.info/words/index/info/view_unit/670/2