Publication: Adapting a practical EPR dosimetry protocol to measure output factors in small fields with alanine.
cris.virtual.author-orcid | 0000-0002-3911-3403 | |
cris.virtualsource.author-orcid | fb089609-c18a-4ab4-bf39-a2d95248a9a9 | |
dc.contributor.author | Höfel, Sebastian | |
dc.contributor.author | Liebig, Pauline | |
dc.contributor.author | Fix, Michael | |
dc.contributor.author | Drescher, Malte | |
dc.contributor.author | Zwicker, Felix | |
dc.date.accessioned | 2024-10-25T18:27:26Z | |
dc.date.available | 2024-10-25T18:27:26Z | |
dc.date.issued | 2023-12 | |
dc.description.abstract | PURPOSE Modern radiotherapy techniques often deliver small radiation fields. In this work, a practical Electron Paramagnetic Resonance (EPR) dosimetry protocol is adapted and applied to measure output factors (OF) in small fields of a 6 MV radiotherapy system. Correction factors and uncertainties are presented and OFs are compared to the values obtained by following TRS-483 using an ionization chamber (IC). METHODS Irradiations were performed at 10 cm depth inside a water phantom positioned at 90 cm source to surface distance with a 6 MV flattening filter free photon beam of a Halcyon radiotherapy system. OFs for different nominal field sizes (1 × 1, 2 × 2, 3 × 3, 4 × 4, normalized to 10 × 10 cm2 ) were determined with a PinPoint 3D (PTW 31022) IC following TRS-483 as well as with alanine pellets with a diameter of 4 mm and a height of 2.4 mm. EPR readout was performed with a benchtop X-band spectrometer. Correction factors due to volume averaging and due to positional uncertainties were derived from 2D film measurements. RESULTS OFs obtained from both dosimeter types agreed within 0.7% after applying corrections for the volume averaging effect. For the used alanine pellets, volume averaging correction factors of 1.030(2) for the 1 × 1 cm2 field and <1.002 for the larger field sizes were determined. The correction factor for positional uncertainties of 1 mm was in the order of 1.018 for the 1 × 1 cm2 field. Combined relative standard uncertainties uc for the OFs resulting from alanine measurements were estimated to be below 1.5% for all field sizes. For IC measurements, uc was estimated to be below 1.0%. CONCLUSIONS A practical EPR dosimetry protocol is adaptable for precisely measuring OFs in small fields down to 1 × 1 cm2 . It is recommended to consider the effect of positional uncertainties for field sizes <2 × 2 cm2 . | |
dc.description.sponsorship | Universitätsklinik für Radio-Onkologie - Medizinische Strahlenphysik | |
dc.identifier.doi | 10.48350/188577 | |
dc.identifier.pmid | 37922380 | |
dc.identifier.publisherDOI | 10.1002/acm2.14191 | |
dc.identifier.uri | https://boris-portal.unibe.ch/handle/20.500.12422/171131 | |
dc.language.iso | en | |
dc.publisher | American Association of Physicists in Medicine | |
dc.relation.ispartof | Journal of applied clinical medical physics | |
dc.relation.issn | 1526-9914 | |
dc.relation.organization | DCD5A442BAD6E17DE0405C82790C4DE2 | |
dc.relation.organization | DCD5A442BAE6E17DE0405C82790C4DE2 | |
dc.subject | EPR dosimetry alanine density effect output factor small field volume effect | |
dc.subject.ddc | 500 - Science::530 - Physics | |
dc.subject.ddc | 600 - Technology::610 - Medicine & health | |
dc.title | Adapting a practical EPR dosimetry protocol to measure output factors in small fields with alanine. | |
dc.type | article | |
dspace.entity.type | Publication | |
dspace.file.type | text | |
oaire.citation.issue | 12 | |
oaire.citation.startPage | e14191 | |
oaire.citation.volume | 24 | |
oairecerif.author.affiliation | Universitätsklinik für Radio-Onkologie - Medizinische Strahlenphysik | |
unibe.contributor.role | creator | |
unibe.contributor.role | creator | |
unibe.contributor.role | creator | |
unibe.contributor.role | creator | |
unibe.contributor.role | creator | |
unibe.date.licenseChanged | 2023-11-07 02:58:58 | |
unibe.description.ispublished | pub | |
unibe.eprints.legacyId | 188577 | |
unibe.refereed | TRUE | |
unibe.subtype.article | journal |
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