title: The influence of location of the crossing needle on dose distributions from planar implants.
abstract: Three typical planar radium implants with one uncrossed end were investigated for optimization of the crossing needle location. Isodose distributions in a plane 0.5 cm from the plane of the implant were calculated and the sizes and shapes of the areas receiving at least 85% of the maximum dose were evaluated. The merits of each implant geometry are discussed along with certain clinical considerations. As a refinement to the Paterson-Parker rules of geometry, it was found that an optimum distribution is achieved when the crossing needle is located near the physical ends of the parallel needles.
mesh_terms: D001918:Brachytherapy / Q000379:methods*; D003201:Computers; D006801:Humans; D009369:Neoplasms / Q000532:radiotherapy; D011879:Radiotherapy Dosage; D011883:Radium / Q000008:administration & dosage*
chemical_list: D011883:Radium