Related Experiment Video
Updated: Jun 8, 2026
Characterization of Recombination Effects in a Liquid Ionization Chamber Used for the Dosimetry of a Radiosurgical Accelerator
Published on: May 9, 2014
Enhanced epidermal dose caused by localized electron contamination from lead cutouts used in kilovoltage radiotherapy
J E Lye1, D J Butler, D V Webb
1Australian Radiation and Protection and Nuclear Safety Agency, Yallambie, Melbourne, Australia. jessica.lye@arpansa.gov.au
Purpose:
To investigate and quantify electron contamination from the lead cutouts used in kilovoltage x-ray radiotherapy.
Methods:
The lead cutouts were modeled with the Monte Carlo EGSnrc user codes DOSXYZnrc and DOSRZnrc for x-ray beams ranging from 50 to 300 kVp. The results from the model were confirmed with Gafchromic film measurements. The model and measurements investigated the dose distribution with and without gladwrap shielding under the lead, and dose distributions with round, square, and serrated edge cutouts.
Results:
Large dose enhancement near the edges of the lead was observed due to electron contamination. At the epidermal/dermal border, there is double the dose at the edge of the lead compared to the central dose due to electron contamination for a 150 kVp beam and three times the dose for a 300 kVp beam. gladwrapTM shielding effectively removes the contaminant dose enhancement using ten and four layers for 300 and 150 kVp beams, respectively.
Conclusions:
The contaminant dose enhancement is undesirable as it could cause unnecessary erythema and hyperpigmentation at the border of the treated and untreated skin and lead to a poorer cosmetic outcome. The contamination is easily removed by gladwrap shielding placed under or around the lead cutout.
Related Concept Videos
02:59Biological Effects of Radiation
01:35Mutations
Chromosomal Alterations Are Large-Scale Mutations
While point mutations are changes in a single nucleotide in...
01:38Nucleotide Excision Repair
Cells are regularly exposed to mutagens—factors in the environment that can damage DNA and generate mutations. UV radiation is one of the most common mutagens and is estimated to introduce a significant number of changes in DNA. These include bends or kinks in the structure, which can block DNA replication or transcription. If these errors are not fixed, the damage can cause mutations, which in turn can result in cancer or disease depending on which sequences are...
01:08Nucleotide Excision Repair