Patient's cross infection with bite block of orthopantamograph machine is prevented by

Panoramic  and  cephalometric  equipment  should  receive  the same maintenance for decontamination and disinfection as other equipment. Panoramic bite-blocks, chin rest, and patient handgrips should be cleaned with detergent-iodine disinfectant and covered with a plastic bag. Disposable bite-blocks may be used. The head-positioning guides, control panel, and exposure switch should be carefully  wiped  with  a  paper  towel  that  is  well  moistened  with disinfectant. Note: disposable bite-blocks are the preferred method, although they may not be cost effective. Oral radiology ; White and Pharaoh 7th edition page no: 256