根据第一段内容可知需要照X光的物体是偏大的包和行李

Gallery Policies

for Visitors to National Gallery of Art, Washington

Visitors must present all carried items for inspection upon entry. After inspection, all bags, backpacks, umbrellas, parcels, and other things as determined by security officers must be left at the checkrooms, free of charge, close to each entrance. All oversized bags, backpacks and luggage must be left at the checkrooms near the 4th Street entrance of either the East or West Building. These items will have to be x-rayed before being accepted. Items of value, such as laptop computers, cameras, and fur coats, may not be left in the checkrooms but may be carried into the galleries.

We regret that we do not have enough space for visitor items larger than 17×26 inches into the Gallery or its checkrooms.

Additional security procedures and checks may be taken according to the decision of the Gallery.

For the safety of the artworks and other visitors, nothing may be carried on a visitor’s back. Soft front baby carriers are allowed, but children may not be carried on shoulders or in a child carrier worn on the back. Pushchairs are available free of charge near each checkroom.

Smoking is prohibited. Food and drink are not permitted outside the food service areas. Unopened bottled water may be carried only in a visitor’s bag. Cell phones may not be used in the galleries.

Animals, other than service animals, are not permitted in the Gallery.

Skateboarding is prohibited.

Picture-taking (including video) for personal use is permitted except in special exhibitions and where specifically prohibited. Tripods (三角架) are not allowed.

Please do not touch the works of art.