This application discloses configurations for arranging transducer arrays on a person's head to impose tumor treating fields (TTFields) in the brain at field strengths that are as uniform as possible throughout the entire brain. In some embodiments, L-shaped sets of electrodes are positioned near the right and left ears, each with a horizontal arm above the ear and a vertical arm behind the ear. Optionally, these embodiments may be combined with a second pair of electrodes positioned on top of the head and behind the neck. In other embodiments, one pair of electrodes is positioned above the right ear and on the left/rear portion of the neck; and a second pair of electrodes is positioned above the left ear and on the right/rear portion of the neck. These configurations improve the uniformity of the electric fields imposed throughout the brain, and are particularly useful for preventing and/or treating metastases.