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A study of the effect of cone shielding in intraoperative radiotherapy
Author(s) -
Papanikolaou Nikos,
Paliwal Bhudatt
Publication year - 1995
Publication title -
medical physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.473
H-Index - 180
eISSN - 2473-4209
pISSN - 0094-2405
DOI - 10.1118/1.597584
Subject(s) - electromagnetic shielding , imaging phantom , percentage depth dose curve , monte carlo method , nuclear medicine , dosimetry , materials science , radiation therapy , intraoperative radiation therapy , shielding effect , ionization chamber , medicine , physics , radiology , mathematics , ionization , ion , statistics , quantum mechanics , composite material
The primary goal of intraoperative radiation therapy is to irradiate the intraoperatively determined tumor target volume with a single fraction of tumoroidal dose while minimizing the dose to all adjacent healthy tissues. To reduce dose outside the treatment volume, lead sheets are often used to cover the external surface of the cone tip thus providing a shielding for the tissues outside the field. In this paper, the effect of the shielding on the depth dose distributions and dose profiles at different depths is studied based on experimental data. The results were also compared against an EGS4 Monte Carlo code for the same geometry as the measurements. The cones varied in size having diameters of 5 cm, 7 cm, and 9 cm, and the electron energies ranged from 6 MeV to 22 MeV. The depth dose curves and dose profiles (at two different depths in the phantom) were measured and computed with and without the lead shielding for the various combinations of cone sizes and electron energies using a water phantom to simulate the patient. It was found that the presence of lead increases on average across the treatment area the dose to the tumor from 2% up to 5%, while the dose outside the cone was reduced by as much as 75%. Both measurements and calculations were found to be in agreement.