An influential group of government advisers has endorsed lung cancer screening for the first time — but not for everybody. The U.S. Preventive Services Task Force is proposing annual CT scans, a type of X-ray, for certain current and former smokers.

To be considered for screening, the task force says people should:

—Be ages 55 through 79.

—Have smoked a pack of cigarettes a day for 30 years or the equivalent, such as two packs a day for 15 years.

People who should not be screened include:

—Those younger than 55 or older than 79.

—Those who smoked less or less often than those described above.

—Those who quit smoking 15 or more years ago.

—Those too sick or frail to withstand treatment for lung cancer.