[en] Mould room techniques are necessary to get the best from teletherapy treatment. They are directed at: Ensuring that the part of the patient being treated remains in the same position from start to end of a fraction of radiotherapy. Ensuring that the fields, as originally imaged and planned, can be accurately reproduced for each fraction. Ensuring that, if more than one planned volume is treated, these volumes maintain a constant, reproducible relationship to each other. Deriving contours for planning teletherapy. Facilitating accuracy of setting up individual fields with respect to position on the patient and treatment unit. Fabricating and mounting blocks or shields within any field that will adequately and reproducibly shield healthy tissue or sensitive organs. Fabricating and mounting compensators and bolus material within any field that will adequately and reproducibly modify the beam as required. Immobilisation is approached initially by assessing an anatomical region, the disease and the favoured treatment machine. The versatility of each technique to accomplish immobilisation for various purposes is addressed. Immobilisation is most commonly used in the head and neck region for the treatment of cancers of the oral and nasal passages and the treatment of brain tumours. As this part of the anatomy is very flexible, the immobilisation device must not only ensure that the head is kept in a symmetrical position, but also that the degree of flexion or extension of the neck (needed for treating a pituitary as opposed to a larynx) is maintained. Sensitive structures in that region are predominantly the eyes and spinal cord but on occasions a parotid salivary gland or part of the brain may require limitation of the dose. This may be achieved by planning the teletherapy beams with shielding blocks within selected fields