title: The dose penumbra of a custom-made shield used in hemibody skin electron irradiation.
abstract: We report our technique for hemibody skin electron irradiation with a custom-made plywood shield. The technique is similar to our clinical total skin electron irradiation (TSEI), performed with a six-pair dual field (Stanford technique) at an extended source-to-skin distance (SSD) of 377 cm, with the addition of a plywood shield placed at 50 cm from the patient. The shield is made of three layers of stan-dard 5/8'' thick plywood (total thickness of 4.75 cm) that are clamped securely on an adjustable-height stand. Gafchromic EBT3 films were used in assessing the shield's transmission factor and the extent of the dose penumbra region for two different shield-phantom gaps. The shield transmission factor was found to be about 10%. The width of the penumbra (80%-to-20% dose falloff) was measured to be 12 cm for a 50 cm shield-phantom gap, and reduced slightly to 10 cm for a 35 cm shield-phantom gap. In vivo dosimetry of a real case confirmed the expected shielded area dose.
authors.affiliation: Roswell Park Cancer Institute. Charlotte.Rivers@RoswellPark.org.
authors.forename: Charlotte I
authors.initials: CI
authors.lastname: Rivers
authors.forename: Ismail
authors.initials: I
authors.lastname: AlDahlawi
authors.forename: Iris Z
authors.initials: IZ
authors.lastname: Wang
authors.forename: Anurag K
authors.initials: AK
authors.lastname: Singh
authors.forename: Matthew B
authors.initials: MB
authors.lastname: Podgorsak
mesh_terms: D004583:Electrons / Q000627:therapeutic use*; D005373:Film Dosimetry; D006801:Humans; D019047:Phantoms, Imaging; D011835:Radiation Protection / Q000379:methods*; D011879:Radiotherapy Dosage; D011880:Radiotherapy Planning, Computer-Assisted / Q000379:methods*; D050397:Radiotherapy, Intensity-Modulated; D012871:Skin Diseases / Q000532:radiotherapy*