**A Comparison of Physical vs. Nonphysical Wedge Modalities in Radiotherapy**

Hiroaki Akasaka, Naritoshi Mukumoto, Masao Nakayama, Tianyuan Wang, Ryuichi Yada, Yasuyuki Shimizu, Saki Osuga, Yuki Wakahara and Ryohei Sasaki

Additional information is available at the end of the chapter

http://dx.doi.org/10.5772/67057

#### **Abstract**

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This chapter discusses the clinical application and implementation of wedge techniques in radiation therapy. Coverage of the target region with a curative dose is critical for treating several cancer types; to that end, wedge filters are commonly used to improve dose uniformity to the target volume. Initially, wedges designed for this purpose were physical and were made of high-density materials such as lead or steel. Subsequently, nonphysical wedges were introduced; these improved the dose uniformity using computer systems in lieu of physical materials. As wedge systems evolve, however, they each continue to have their advantages and disadvantages. When using physical wedges, it is difficult to control the generation of secondary radiation resulting from the collision of the radiation beam with the wedge body; conversely, nonphysical wedges do not create any secondary radiation because there is no physical interference with the beam. On the other hand, nonphysical wedges are less suitable for treating moving tumors, such as those in the lung, and physical wedges have better dose coverage to the target volume than nonphysical wedges. This chapter aims to guide decision-making regarding the choice of wedge types in various clinical situations.

**Keywords:** physical wedge, nonphysical wedge, radiotherapy
