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Article: The effect of the nasopharyngeal air cavity on x-ray interface doses

TitleThe effect of the nasopharyngeal air cavity on x-ray interface doses
Authors
Issue Date1998
PublisherInstitute of Physics Publishing. The Journal's web site is located at http://www.iop.org/journals/pmb
Citation
Physics In Medicine And Biology, 1998, v. 43 n. 3, p. 529-537 How to Cite?
AbstractWe investigated the impact of air cavities in head and neck cancer patients treated by photon beams based on clinical set-ups. The phantom for investigation was constructed with a cubic air cavity of 4 x 4 x 4 cm3 located at the centre of a 30 x 30 x 16 cm3 solid water slab. The cavity cube was used to resemble an extreme case for the nasal cavity. Apart from measuring the dose profiles and central axis percentage depth dose distribution, the dose values in 0.25 x 0.25 x 0.25 cm3 voxels at regions around the air cavity were obtained by Monte Carlo simulations. A mean dose value was taken over the voxels of interest at each depth for evaluation. Single-field results were added to study parallel opposed field effects. For 10 x 10 cm2 parallel opposed fields at 4, 6 and 8 MV, the mean dose at regions near the lateral interfaces of the cavity cube were decreased by 1 to 2% due to the lack of lateral scatter, while the mean dose near the proximal and distal interfaces was increased by 2 to 4% due to the greater transmission through air. Secondary build-up effects at points immediately beyond the air cavity cube are negligible using field sizes greater than 4 x 4 cm2. For most bead and neck treatment, the field sizes are usually 6 x 6 cm2 or greater, and most cavity volumes are smaller than our chosen dimensions. Therefore, the influence of closed air cavities on photon interface doses is not significant in clinical treatment set-ups.
Persistent Identifierhttp://hdl.handle.net/10722/71885
ISSN
2015 Impact Factor: 2.811
2015 SCImago Journal Rankings: 1.577
ISI Accession Number ID
References

 

DC FieldValueLanguage
dc.contributor.authorKan, WKen_HK
dc.contributor.authorWu, PMen_HK
dc.contributor.authorLeung, HTen_HK
dc.contributor.authorLo, TCen_HK
dc.contributor.authorChung, CWen_HK
dc.contributor.authorKwong, DLWen_HK
dc.contributor.authorSham, STen_HK
dc.date.accessioned2010-09-06T06:36:06Z-
dc.date.available2010-09-06T06:36:06Z-
dc.date.issued1998en_HK
dc.identifier.citationPhysics In Medicine And Biology, 1998, v. 43 n. 3, p. 529-537en_HK
dc.identifier.issn0031-9155en_HK
dc.identifier.urihttp://hdl.handle.net/10722/71885-
dc.description.abstractWe investigated the impact of air cavities in head and neck cancer patients treated by photon beams based on clinical set-ups. The phantom for investigation was constructed with a cubic air cavity of 4 x 4 x 4 cm3 located at the centre of a 30 x 30 x 16 cm3 solid water slab. The cavity cube was used to resemble an extreme case for the nasal cavity. Apart from measuring the dose profiles and central axis percentage depth dose distribution, the dose values in 0.25 x 0.25 x 0.25 cm3 voxels at regions around the air cavity were obtained by Monte Carlo simulations. A mean dose value was taken over the voxels of interest at each depth for evaluation. Single-field results were added to study parallel opposed field effects. For 10 x 10 cm2 parallel opposed fields at 4, 6 and 8 MV, the mean dose at regions near the lateral interfaces of the cavity cube were decreased by 1 to 2% due to the lack of lateral scatter, while the mean dose near the proximal and distal interfaces was increased by 2 to 4% due to the greater transmission through air. Secondary build-up effects at points immediately beyond the air cavity cube are negligible using field sizes greater than 4 x 4 cm2. For most bead and neck treatment, the field sizes are usually 6 x 6 cm2 or greater, and most cavity volumes are smaller than our chosen dimensions. Therefore, the influence of closed air cavities on photon interface doses is not significant in clinical treatment set-ups.en_HK
dc.languageengen_HK
dc.publisherInstitute of Physics Publishing. The Journal's web site is located at http://www.iop.org/journals/pmben_HK
dc.relation.ispartofPhysics in Medicine and Biologyen_HK
dc.subject.meshAiren_HK
dc.subject.meshBiophysical Phenomenaen_HK
dc.subject.meshBiophysicsen_HK
dc.subject.meshComputer Simulationen_HK
dc.subject.meshHead and Neck Neoplasms - radiotherapyen_HK
dc.subject.meshHumansen_HK
dc.subject.meshNasopharynxen_HK
dc.subject.meshPhantoms, Imagingen_HK
dc.subject.meshPhotons - therapeutic useen_HK
dc.subject.meshRadiotherapy Planning, Computer-Assisteden_HK
dc.subject.meshRadiotherapy, High-Energyen_HK
dc.titleThe effect of the nasopharyngeal air cavity on x-ray interface dosesen_HK
dc.typeArticleen_HK
dc.identifier.openurlhttp://library.hku.hk:4550/resserv?sid=HKU:IR&issn=0031-9155&volume=43&spage=529&epage=537&date=1998&atitle=The+effect+of+the+nasopharyngeal+air+cavity+on+x-ray+interface+dosesen_HK
dc.identifier.emailKwong, DLW:dlwkwong@hku.hken_HK
dc.identifier.authorityKwong, DLW=rp00414en_HK
dc.description.naturelink_to_subscribed_fulltext-
dc.identifier.doi10.1088/0031-9155/43/3/005en_HK
dc.identifier.pmid9533132-
dc.identifier.scopuseid_2-s2.0-0031929807en_HK
dc.identifier.hkuros35424en_HK
dc.relation.referenceshttp://www.scopus.com/mlt/select.url?eid=2-s2.0-0031929807&selection=ref&src=s&origin=recordpageen_HK
dc.identifier.volume43en_HK
dc.identifier.issue3en_HK
dc.identifier.spage529en_HK
dc.identifier.epage537en_HK
dc.identifier.isiWOS:000072502300005-
dc.publisher.placeUnited Kingdomen_HK
dc.identifier.scopusauthoridKan, WK=18334754400en_HK
dc.identifier.scopusauthoridWu, PM=8663653900en_HK
dc.identifier.scopusauthoridLeung, HT=19234693500en_HK
dc.identifier.scopusauthoridLo, TC=19234805700en_HK
dc.identifier.scopusauthoridChung, CW=19233652200en_HK
dc.identifier.scopusauthoridKwong, DLW=15744231600en_HK
dc.identifier.scopusauthoridSham, ST=6603618508en_HK

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