When the word X-ray is used as a verb, it means “to examine”. When we go to a doctor, the doctor examines us to determine if we are of good health or if we are sick. Likewise, we are to ask the LORD to examine us. In other words, we are to ask the LORD to X-ray us, so that there are no wicked ways in us, and to lead us in the way everlasting (Psalm 139:23-24)

In addition to the doctor examining us, we often check ourselves at home to make sure that we are healthy. As Christians we need to do the same. We have to take time to introspect ourselves regarding our spiritual health. In other words we need to X-ray (examine) ourselves to ensure that we keep the faith (2 Corinthians 13:5) for the just(ified) shall live by faith (Habakkuk 2:4), as many in the latter days will depart (fall away) from the faith, giving heed to seducing spirits, and doctrines of devils; (1 Timothy 4:1).

2 Corinthians 13:5 (KJV)
5 Examine yourselves, whether ye be in the faith; prove your own selves. Know ye not your own selves, how that Jesus Christ is in you, except ye be reprobates?

Psalm 26:2 (KJV)
2 Examine me, O LORD, and prove me; try my reins and my heart.

Psalm 139:23-24 (KJV)
23
Search me, O God, and know my heart: try me, and know my thoughts:
24
And see if there be any wicked way in me, and lead me in the way everlasting.