A method of measuring a parameter of a structure (212) on a medical image (200) comprises a measurement tool (220) displayed on a slice of the image. An automated point detection function identifies a point within at least one region (250) of the image that optimizes the placement of the respective end of the measurement tool (220). The region may be 2-d or 3-d. The identified point(s) are then used to calculate the parameter, which may be distance, angle, area or volume. The measurement tool (320) may move to the identified points (330, 340). A system (2000), computer program and computer-readable medium are also provided. The invention may make the measurement of tumors, and measurements of the spacing within or between various structures on a medical image, more accurate and/or more consistent.