What effect does a wedge filter have on the isodose curve?

A wedge filter is used in radiation therapy to modify the distribution of the dose delivered to the tissue. Specifically, it is designed to create a gradient in the dose distribution, which results in a tilt of the isodose curves. This means that one side of the treatment area receives a higher dose while the opposite side receives a lower dose.

The principle behind the wedge filter is to compensate for anatomical variations, such as when the treatment area includes a sloped or irregular surface, or when it is necessary to achieve a uniform dose across an uneven target volume, like in the case of breast or head and neck treatments. By tilting the isodose curve, the wedge allows for better coverage of the target tumor while minimizing excess radiation to surrounding healthy tissues.

This ability to tilt the isodose curves makes it possible to adapt the radiation treatment plan to the specific geometry of the target area, ensuring that the intended dose is delivered more accurately and effectively.