Ellipse Hit Area

You can set an ellipse as shape for the hit area of an object. Select the ELLIPSE option in the Shape parameter and changes the ellipse properties in the Hit Area (Ellipse) section:

Ellipse hit area

Also, you can change the ellipse properties with the Edit Hit Area Tool (I):

Edit ellipse hit area tool.

The scene compiler generates the hit are shape code like this:

// chicken
const chicken = this.add.image(684, 126, "budbrain_chick");
chicken.setInteractive(
    new Phaser.Geom.Ellipse(30, 70, 66, 133),
    Phaser.Geom.Ellipse.Contains);