Title: Idealizing Sonodynamic: the coupling problem

Photodynamic therapy (PDT) offers advantages such as non-invasiveness, non-ionizing properties, and shorter recovery times. However, its limited tissue penetration, particularly in pigmented areas like melanoma, remains a challenge. Sonodynamic therapy (SDT) addresses this limitation by using ultrasound, which penetrates deeper and is unaffected by tissue color. Combining PDT and SDT, known as sono-photo dynamic therapy (SPDT), could enhance therapeutic outcomes. This study explores methods to manipulate ultrasound beams using metallic cones to optimize focal depth and beam distribution. Variables such as cone diameter, height, curvature, and material were tested in a water tank, with hydrophones mapping ultrasound pressure in 2D. Results showed output diameter as the most significant factor for focal depth, while cone height had moderate effects. Curvature influenced beam shape, and material impacted overall performance. These findings support the development of SDT for precise clinical applications, enabling targeted energy delivery to treated regions.