Devotional meditation is a means of awakening and expressing our own inner resources, which are essential for healing.
To heal our minds and bodies, we visualize images of the Buddha. We think of and feel the presence of these Healing Buddhas, the enlightened ones to whom we pray, and believe in their healing power. We invoke and enjoy their blessings.
This may sound like idol worship, but it really is not. In Buddhism, external sources and mental objects are a means to an end. The ultimate source of healing is our minds, not the external objects, which of themselves have no power to save us or change our fate. The Buddha said:
I have shown you
The way that leads beyond the pain of craving. [But] Buddha is [just] a guide.
You are the one who must take the steps.
From Boundless Healing