Yes, it's possible.

You start out by first checking if a point/circle is behind the player. You do this by getting the dot product between the direction player is facing (a unit vector) and the direction vector to the circle (normalize it so that it's also a unit vector). If the values dotProduct <= 0 then the circle is behind your player.

(unit vector means that your vector has a magnitude of one. Which is a fancy way of saying your x/y/z will never go beyond 1)

Code example

// Let's assume that the following code is in some sort of loop, yes

// Get the direction vector to the circle
const directionVect = circle.position.clone().sub(player.position).normalize();

// If your player is a camera you can get the direction like so
const playerFacing = player.getWorldDirection(new THREE.Vector3());

// Orientation
if (playerFacing.dot(directionVect) <= 0) {
    // Circle is behind the player
    // ...to be continued...
} else {
    return;
}

Now that you know which circles are behind your player, you can get the circles within the cone. This is done by getting the angle between the player's position and the circle's position. Then check that the angle fits some criteria (e.g. the angle can't be more than 45deg from back of player).

// ...

// Orientation
if (playerFacing.dot(directionVect) <= 0) {
    // Circle is behind the player
    const angle = player.position.angleTo(circle.position);
    
    if (angle < Math.PI * 0.25) {
        // Do something with circle
    }
} else {
    return;
}