Section 18 Optical, photographic, cinematographic, measuring, checking, precision, medical or surgical instruments and apparatus; clocks and watches; musical instruments; parts and accessories thereof 90 Optical, photographic, cinematographic, measuring, checking, precision, medical or surgical instruments and apparatus; parts and accessories thereof 90 22 Apparatus based on the use of X-rays or of alpha, beta, gamma or other ionising radiations, whether or not for medical, surgical, dental or veterinary uses, including radiography or radiotherapy apparatus, X-ra y tubes and other X-ray generators, high tension generators, Commodity Code Description 90 22 12 Computed tomography apparatus 90 22 13 Other, for dental uses 90 22 14 Other, for medical, surgical or veterinary uses 90 22 19 For other uses 90 22 21 For medical, surgical, dental or veterinary uses 90 22 29 For other uses 90 22 30 X-ray tubes 90 22 90 Other, including parts and accessories