// Center of point by X and Y
var centerX : Number = 150;
var centerY : Number = 150;

// Radius (how far away your object will fly near your center)
var radius : Number = 50;

// Change angle to move by circle path
var angle : Number = 90;

// img it's display object
img.x = centerX + radius * Math.cos(angle);
img.y = centerY + radius * Math.sin(angle);

Using this code you can move your object along radius

Moving object around center

ActionScript 3