{
  "annotation_id": "d848be62-3591-4d9b-8875-1dc2643a7010",
  "date_created": "2026-03-02T18:00:56.870000Z",
  "date_modified": "2026-03-02T18:00:56.870000Z",
  "file_hash": "e60165df7069077106df4d14fa3aea9e796dfd5fc86065e87cda1e964f5b473b",
  "private": false,
  "record": {
    "abstract": "Homogeneity for highly asymmetric fields has been studied for a Siemens\nPRIMUS linear accelerator. The flattening filter has a radius smaller than the\nprimary collimator one, creating inhomogeneities that affect large fields in\nareas far from the collimator axis, and asymmetric fields with large offset.\nProfiles and absolute dose have been measured in fields with two jaws at\nmaximal position (20 cm) and the other two at maximal overtravel (10 cm.),\ncorresponding to 10 x 10 fields with extreme offset. Profiles have a remarkable\ngradient decreasing towards the beam edge, making these fields unsuitable for\ntreatments. Results show that the design of the primary collimator and\nflattening filter assembly has direct consequences in homogeneity. This can\nhave clinical consequences for treatments involving fields that include these\ninhomogeneous areas. Comparisons with the treatment planning system (Philips\nPinnacle) calculations, that computes under the hypotheses of a uniformly\nflattened beam, result in severe discrepancies.",
    "arxiv_id": "physics/0501077",
    "authors": [
      "F. Cutanda",
      "S. T. Vargas-Castrillon"
    ],
    "categories": [
      "physics.med-ph"
    ],
    "title": "The effect of the primary collimator and flattening filter on asymmetric   fields for a Siemens PRIMUS linear accelerator",
    "url": "https://arxiv.org/abs/physics/0501077"
  },
  "schema_id": "dorsal/arxiv",
  "source": {
    "execution_id": "fb6bd5c1-a81c-4bb5-8a73-3587b5857acd",
    "id": "arXiv Dataset IDs",
    "type": "Model",
    "variant": "snapshot-2026-03-01",
    "version": "0.1.0"
  },
  "user_id": 1000002
}