Given a text passage, come up with an appropriate title for it. The title should accurately represent what the main focus of the passage is. The title of a passage may be present in the first few sentences of the passage and/or be referred to multiple times in the passage. The title should be 1-5 words long.

[Q]: Metrication in Canada began in 1970 and while Canada has converted to the metric system for many purposes , there is still significant use of non-metric units and standards in many sectors of the Canadian economy . This is mainly due to historical ties with the United Kingdom ( before metrication ) , the traditional use of the imperial system of measurement in Canada , proximity to the United States , and to public opposition to metrication during the transition period .
[A]: Metrication in Canada


[Q]: For medical purposes , X-ray filters are used to selectively attenuate , or block out , low - energy rays during x-ray imaging ( radiography ) . Low energy x-rays ( less than 30 keV ) contribute little to the resultant image as they are heavily absorbed by the patient 's soft tissues ( particularly the skin ) . Additionally , this absorption adds to the risk of stochastic ( e.g. cancer ) or non stochastic radiation effects ( e.g. tissue reactions ) in the patient . Thus , it is favorable to remove these low energy X-rays from the incident light beam . X-ray filtration may be inherent due to the X-ray tube and housing material itself or added from additional sheets of filter material . The minimum filtration used is usually 2.5 mm aluminium ( Al ) equivalent , although there is an increasing trend to use greater filtration . Manufacturers of modern fluoroscopy equipment utilize a system of adding a variable thickness of copper ( Cu ) filtration according to patient thickness . This typically ranges from 0.1 to 0.9 mm Cu .
[A]: X-ray filter


[Q]: It is bordered on the west by the Pacific Ocean and on the north and east by the Atlantic Ocean ; North America and the Caribbean Sea lie to the northwest . It includes twelve sovereign states ( Argentina , Bolivia , Brazil , Chile , Colombia , Ecuador , Guyana , Paraguay , Peru , Suriname , Uruguay , and Venezuela ) , a part of France ( French Guiana ) , and a non-sovereign area ( the Falkland Islands , a British Overseas Territory though this is disputed by Argentina ) . In addition to this , the ABC islands of the Kingdom of the Netherlands , Trinidad and Tobago , and Panama may also be considered part of South America .
[A]:
South America