Quality assurance of the dose delivered by small radiation segments.

2.50
Hdl Handle:
http://hdl.handle.net/10541/91978
Title:
Quality assurance of the dose delivered by small radiation segments.
Authors:
Hansen, V N; Evans, P M; Budgell, Geoff J; Mott, Judith; Williams, Peter C; Brugmans, M J; Wittkämper, F W; Mijnheer, B J; Brown, K
Abstract:
The use of intensity modulation with multiple static fields has been suggested by many authors as a way to achieve highly conformal fields in radiotherapy. However, quality assurance of linear accelerators is generally done only for beam segments of 100 MU or higher, and by measuring beam profiles once the beam has stabilized. We propose a set of measurements to check the stability of dose delivery in small segments, and present measured data from three radiotherapy centres. The dose delivered per monitor unit, MU, was measured for various numbers of MU segments. The field flatness and symmetry were measured using either photographic films that are subsequently scanned by a densitometer, or by using a diode array. We performed the set of measurements at the three radiotherapy centres on a set of five different Philips SL accelerators with energies of 6 MV, 8 MV, 10 MV and 18 MV. The dose per monitor unit over the range of 1 to 100 MU was found to be accurate to within +/-5% of the nominal dose per monitor unit as defined for the delivery of 100 MU for all the energies. For four out of the five accelerators the dose per monitor unit over the same range was even found to be accurate to within +/-2%. The flatness and symmetry were in some cases found to be larger for small segments by a maximum of 9% of the flatness/symmetry for large segments. The result of this study provides the dosimetric evidence that the delivery of small segment doses as top-up fields for beam intensity modulation is feasible. However, it should be stressed that linear accelerators have different characteristics for the delivery of small segments, hence this type of measurement should be performed for each machine before the delivery of small dose segments is approved. In some cases it may be advisable to use a low pulse repetition frequency (PRF) to obtain more accurate dose delivery of small segments.
Affiliation:
Joint Department of Physics, Royal Marsden NHS Trust and Institute of Cancer Research, Sutton, Surrey, UK.
Citation:
Quality assurance of the dose delivered by small radiation segments. 1998, 43 (9):2665-75 Phys Med Biol
Journal:
Physics in Medicine and Biology
Issue Date:
Sep-1998
URI:
http://hdl.handle.net/10541/91978
DOI:
10.1088/0031-9155/43/9/017
PubMed ID:
9755953
Type:
Article
Language:
en
ISSN:
0031-9155
Appears in Collections:
All Christie Publications

Full metadata record

DC FieldValue Language
dc.contributor.authorHansen, V Nen
dc.contributor.authorEvans, P Men
dc.contributor.authorBudgell, Geoff Jen
dc.contributor.authorMott, Judithen
dc.contributor.authorWilliams, Peter Cen
dc.contributor.authorBrugmans, M Jen
dc.contributor.authorWittkämper, F Wen
dc.contributor.authorMijnheer, B Jen
dc.contributor.authorBrown, Ken
dc.date.accessioned2010-02-12T12:47:08Z-
dc.date.available2010-02-12T12:47:08Z-
dc.date.issued1998-09-
dc.identifier.citationQuality assurance of the dose delivered by small radiation segments. 1998, 43 (9):2665-75 Phys Med Biolen
dc.identifier.issn0031-9155-
dc.identifier.pmid9755953-
dc.identifier.doi10.1088/0031-9155/43/9/017-
dc.identifier.urihttp://hdl.handle.net/10541/91978-
dc.description.abstractThe use of intensity modulation with multiple static fields has been suggested by many authors as a way to achieve highly conformal fields in radiotherapy. However, quality assurance of linear accelerators is generally done only for beam segments of 100 MU or higher, and by measuring beam profiles once the beam has stabilized. We propose a set of measurements to check the stability of dose delivery in small segments, and present measured data from three radiotherapy centres. The dose delivered per monitor unit, MU, was measured for various numbers of MU segments. The field flatness and symmetry were measured using either photographic films that are subsequently scanned by a densitometer, or by using a diode array. We performed the set of measurements at the three radiotherapy centres on a set of five different Philips SL accelerators with energies of 6 MV, 8 MV, 10 MV and 18 MV. The dose per monitor unit over the range of 1 to 100 MU was found to be accurate to within +/-5% of the nominal dose per monitor unit as defined for the delivery of 100 MU for all the energies. For four out of the five accelerators the dose per monitor unit over the same range was even found to be accurate to within +/-2%. The flatness and symmetry were in some cases found to be larger for small segments by a maximum of 9% of the flatness/symmetry for large segments. The result of this study provides the dosimetric evidence that the delivery of small segment doses as top-up fields for beam intensity modulation is feasible. However, it should be stressed that linear accelerators have different characteristics for the delivery of small segments, hence this type of measurement should be performed for each machine before the delivery of small dose segments is approved. In some cases it may be advisable to use a low pulse repetition frequency (PRF) to obtain more accurate dose delivery of small segments.en
dc.language.isoenen
dc.subject.meshBiophysical Phenomena-
dc.subject.meshBiophysics-
dc.subject.meshHumans-
dc.subject.meshParticle Accelerators-
dc.subject.meshQuality Control-
dc.subject.meshRadiometry-
dc.subject.meshRadiotherapy Dosage-
dc.subject.meshRadiotherapy, High-Energy-
dc.subject.meshTechnology, Radiologic-
dc.titleQuality assurance of the dose delivered by small radiation segments.en
dc.typeArticleen
dc.contributor.departmentJoint Department of Physics, Royal Marsden NHS Trust and Institute of Cancer Research, Sutton, Surrey, UK.en
dc.identifier.journalPhysics in Medicine and Biologyen

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