title: On the use of fields of negative weight to simulate blocks in radiotherapy calculations.
mesh_terms: D003037:Cobalt Radioisotopes / Q000627:therapeutic use; D005720:Gamma Rays / Q000627:therapeutic use; D006801:Humans; D009369:Neoplasms / Q000532:radiotherapy*; D011879:Radiotherapy Dosage; D011882:Radiotherapy, High-Energy; D014964:X-Ray Therapy
chemical_list: D003037:Cobalt Radioisotopes