Increasing the irradiation dose also improves local control. However, local toxicity, especially rectal and bladder complications, restrict the dose which can be given with conformal external beam irradiation with population based uncertainty margins. Setup inaccuracy and organ movement determine the irradiation margins needed. Modern position verification techniques, e.g. using fiducial markers in the prostate in combination with megavoltage imaging techniques, allow a reduction of the margins and offer the possibility for dose escalation in the prostate. Studies of IMRT have utilised these sophisticated position verification techniques and this approach appears feasible. A further reduction of the margins, and thus a possible further increasing of the irradiation dose, can be expected from improving the delineation of the prostate contour. Imaging can be performed to delineate anatomic structures or biological processes within the intraprostatic malignant lesion.