Plaque Therapy and Scatter Dose Using {sup 252}Cf Sources

摘要: As melanomas are radioresistant to conventional low-linear energy transfer (LET) radiations such as photons and electrons, {sup 252}Cf (high-LET due neutrons) may offer more promising clinical results. Although also emits the majority of absorbed dose is imparted by high-LET radiation. This study examines impact scattering material on neutron distributions for plaque therapy (used treat surface lesions like melanoma). Neutrons were transported through a 10-cm-diam water phantom with thickness either 5 or 10 cm using MCNP radiation transport code. The was surrounded vacuum; spectrum modeled Maxwellian distribution; source bare point positioned at 1.0, 0.5, {epsilon} above below water/vacuum interface. These positions chosen mimic case where locates skin's surface, e.g., 2{pi} geometry, if layers tissue-equivalent bolus materials placed atop implant provide backscatter, 4{pi} geometry. Differences between geometries maximized closest farthest from Therefore, maximum radiationmore » (closest source) be minimized not including therapy. However, nonrelativistic, elastic protons neutrons, proton range increases energy. result expected since degrades increasing depth proportion fast total in Future studies will examine this effect function energy, consider synergy low-LET component include experimental measurements, assess technique possibly improve vivo distributions.« less