This International Standard applies to RADIOTHERAPY SIMULATORS which use diagnostic X-RAY EQUIPMENT tO geometrically simulate a RADIOTHERAPY RADIATION BEAM SO that the TREATMENT VOLUME to be irradiated during RADIOTHERAPY can be localized and the position and size of the therapeutic RADIATION FIELD can be confirmed. This standard applies to RADIOTHERAPY SIMULATORS using HIGH VOLTAGE GENERATORS operating at a voltage not exceeding 400 kV complying with IEC 601-2-7. This standard applies to RADIOTHERAPY SIMULATORS intended exclusively for RADIOTHERAPY simulation as a prelude to intended RADIOTHERAPY and not for any other purposes such as general diagnostic purposes. The requirements in this standard are based on the assumption that the RADIOTHERAPY SIMULATOR consists of: a) a system for producing a beam of X-RADIATION not exceeding 400 kV which simulates the geometry of the RADIOTHERAPY RADIATION BEAM; b) a system for producing images of the transmitted X-RAY BEAM, either by RADIOGRAPHY Or by RADIOSCOPY; c) an assembly which controls the size of the RADIATION BEAM and which delineates the intended treatment area; d) a mechanical structure that physically simulates the geometry and motions of a RADIOTHERAPY EQUIPMENT, and which suppo rts an imaging system; e) a PATIENT SUPPORT system. This standard applies to EQUIPMENT intended for use under the supe rv ision of a QUALIFIED PERSON. Except where otherwise stated this standard assumes that the RADIOTHERAPY SIMULATOR has an ISOCENTRIC GANTRY with no pitch or roll movement of the RADIATION HEAD. This standard specifies TYPE TESTS to be performed by the MANUFACTURER at the design and construction stages of a RADIOTHERAPY SIMULATOR but does not specify SITE TESTS t0 be performed after installation at the USER'S site. The accompanying technical report IEC 1170, however, does suggest that many of the test procedures are appropriate for SITE TESTS. During the course of any test procedure only those adjustments of the RADIOTHERAPY SIMULATOR are permissible that can be carried out using controls normally accessible to the OPERATOR and which are regarded as forming part of the normal operation of the RADIOTHERAPY SIMULATOR.