Systems, methods, and computer program products that are configured to account for tilt of a radiation measurement system are disclosed. In one embodiment, a system includes a scanning system with a radiation detector, the scanning system configured to enable movement of the radiation detector. The system also includes a non-transitory machine-readable medium storing instructions which, when executed by at least one programmable processor, cause the at least one programmable processor to perform various operations including moving the radiation detector through a first, second, and third vertical calibration path and recording a first, second, and third radiation detector response within 3 cm of a water surface, and controlling the scanning system to move the radiation detector through at least one measurement path that takes into account a scanning system tilt, the at least one measurement path determined based on at least the first, second, and third radiation detector responses.