Matching intraoperative electron-beam fields: dosimetric and clinical considerations

Journal Article · Tue Sep 01 04:00:00 EDT 1987 · Int. J. Radiat. Oncol., Biol. Phys.; (United States)

DOI:https://doi.org/10.1016/0360-3016(87)90220-3· OSTI ID:6072985

Shaw, E G; Blackwell, C R; McCullough, E C; Gunderson, L L

In the setting of a large or irregularly shaped tumor, adjacent or intentionally overlapped intraoperative electron fields may be required to give adequate coverage of the intraoperative target volume. The matching of such intraoperative electron fields present special dosimetric problems because of the divergence of electron isodose curves with depth. In the intraoperative setting, where large, single-fraction doses are delivered, the low- and high dose areas which result from gaps or overlaps between the diverging isodose curves of electron fields matched at depth or the surface may translate into decreased local tumor control or excessive normal tissue toxicity. This study examines the dosimetry of gapped, adjacent, and overlapped 8 X 9 cm2 rectangular intraoperative fields, for 9 to 18 MeV electrons, using film densitometry. ''Ideal'' methods of matching rectangular intraoperative electron fields are presented, and include: 1) a 2-mm gap plus surface bolus for adjacent fields, and 2) placing a tenth-value layer shaped lead cutout in the overlap region for intentionally overlapped fields.

• Research Organization: Mayo Clinic, Rochester, MN
• OSTI ID: 6072985
• Journal Information: Int. J. Radiat. Oncol., Biol. Phys.; (United States), Journal Name: Int. J. Radiat. Oncol., Biol. Phys.; (United States) Vol. 13:9; ISSN IOBPD
• Country of Publication: United States
• Language: English

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