Abstract:
:Andreo and Benmakhlouf (2017 Phys. Med. Biol. 62 1518-32) have disputed a finding of Scott et al (2012 Phys. Med. Biol. 57 4461-76) that the variation with field-size of the response of small ion chambers and solid-state dosimeters in small megavoltage photon radiation fields can largely be attributed to density. Further evidence for this finding was provided by Fenwick et al (2018 Phys. Med. Biol. 63 125003), but Andreo and Benmakhlouf (2018 Phys. Med. Biol. 63 125003) have now challenged the methodology used in that study. Specifically, Andreo and Benmakhlouf suggest that mass stopping-powers of fictitious materials used in Monte Carlo radiation transport calculations should be adjusted with material density according to the polarization effect, as if the materials were real and created by compressing other real materials. In this reply, we observe that fictitious materials are not real, and therefore their densities, mass stopping-powers and microscopic radiation interaction cross-sections can be freely and independently chosen to provide the clearest answers to the questions being studied. And we note that the key role played by density in small field detector response was further confirmed by our group back in 2013, using fictitious materials in which mass stopping-powers were adjusted with density, as preferred by Andreo and Benmakhlouf, as well as being held fixed, with very similar results being obtained in both circumstances (Underwood et al 2013a Med. Phys. 40 082102).
journal_name
Phys Med Bioljournal_title
Physics in medicine and biologyauthors
Fenwick JD,Georgiou G,Rowbottom CG,Underwood TSA,Kumar Sdoi
10.1088/1361-6560/aae0e4subject
Has Abstractpub_date
2018-10-03 00:00:00pages
198002issue
19eissn
0031-9155issn
1361-6560journal_volume
63pub_type
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