MDCB PRACTICE QUESTIONS 2025

MDCB PRACTICE QUESTIONS 2025 A patient is to receive 55 Gy to a tumor in the mediastinum. In order to meet the acceptable dose limits for the spinal cord, you could: a. use high energy photon beams to decrease the entrance dose. b. block the spinal cord out of all treatment fields after 40 Gy is delivered. c. use a BID treatment technique to achieve greater repair time for the normal tissue cells. d. utilize a 3DCRT beam arrangement including oblique beam angles. - answer-d. utilize a 3DCRT beam arrangement including oblique beam angles. Which of the following statements are true for Iodine-125? a. half-life 86.4 days. b. has life-long radiation protection issues. c. energy of 0.412 MeV. d. decays exclusively by electron capture. - answer-d. decays exclusively by electron capture. The most significant effect(s) of an air cavity in a megavoltage beam treatment is: a. a change in the spectral energy distribution within the cavity. b. an increased primary photon transmission through the cavity. c. an enhanced absorption of dose in and beyond the cavity. d. a partial gain of electronic equilibrium at the cavity interface. - answer-b. an increased primary photon transmission through the cavity.