Selection of the bony landmarks relevant for breast cancer RT. The bony landmarks (open white boxes) chosen in a) anterior reference image and b) lateral reference image. The landmarks were chosen at the presented levels with respect to the target and the humeral head. Notice that the UPPER_V and MID_V are not at the same level in a) and b). The distances between the landmarks were within ± 2 cm for all the patients enabling the comparison of patient rotation. The projection of the target covering the whole breast and lymph node region is illustrated with a dashed line.