Postal dosimetry audit test for small photon beams

Espinosa, María del Mar Benavides; Núñez, Luis A.; Muñiz, J.L.; Lagáres, J.I.; Embid, M.; Gómez-Ros, J.M.

doi:10.1016/j.radonc.2011.06.012

Cited by 10 publications

(7 citation statements)

References 30 publications

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“…IC = ionisation chamber; DD = dose difference. Reference Audited systems Treatment technique Dosimeter Phantom Dosimetric/Gamma Criteria Results/success rate Clark et al [26] 43 VMAT, Tomotherapy Planar array Commercial phantom >95% for 3%/3 mm global gamma Test plan: 79,1% Clinical plan: 97,6% Schiefer et al [48] 20 Tomotherapy TLD, IC Cylindrical Perspex phantom <5% DD <3% DD 100% 93,3% Lafond et al [23] 13 IMRT, VMAT IC, film Commercial phantom >95% for 5%/3 mm 3%3 mm Local gamma IC dose within 3% Sag/cor plane 100%/100% 80%/93% Palmer et al [39] 12 Conformal, IMRT, VMAT film Respiratory motion lung-phantom 3%2 mm Global gamma Static phantom: 98,7% Moving-phantom: 88,2% Miri et al [79] 6 IMRT, VMAT Portal dosimetry none 3%/3 mm 3%,/2 mm 2%/2 mm 3 Varian/3 Elekta 99.5%/99.7% 98.9%/97.8% 95.9%/95.3% Nakamura et al [40] 44 IMRT, VMAT, Tomotherapy IC, film In-house developed phantom IC: <3% DD Film:<2 mm positional difference 100% 100% (1,0 ± 0,4 mm) Espinosa et al [45] 14 IMRT, SRS TLD Cylindrical PMMA phantom <5% DD 1 × 1 cm 2 : 69% 3 × 3 cm 2 : 64% Izewska et al …”

Section: Phantom Based Methods For Dosimetry Auditsmentioning

confidence: 99%

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Novel methodologies for dosimetry audits: Adapting to advanced radiotherapy techniques

Pasler¹,

Hernández

Jornet

et al. 2018

Physics and Imaging in Radiation Oncology

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With new radiotherapy techniques, treatment delivery is becoming more complex and accordingly, these treatment techniques require dosimetry audits to test advanced aspects of the delivery to ensure best practice and safe patient treatment. This review of novel methodologies for dosimetry audits for advanced radiotherapy techniques includes recent developments and future techniques to be applied in dosimetry audits. Phantom-based methods (i.e. phantom-detector combinations) including independent audit equipment and local measurement equipment as well as phantom-less methods (i.e. portal dosimetry, transmission detectors and log files) are presented and discussed. Methodologies for both conventional linear accelerator (linacs) and new types of delivery units, i.e. Tomotherapy, stereotactic devices and MR-linacs, are reviewed. Novel dosimetry audit techniques such as portal dosimetry or log file evaluation have the potential to allow parallel auditing (i.e. performing an audit at multiple institutions at the same time), automation of data analysis and evaluation of multiple steps of the radiotherapy treatment chain. These methods could also significantly reduce the time needed for audit and increase the information gained. However, to maximise the potential, further development and harmonisation of dosimetry audit techniques are required before these novel methodologies can be applied.

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Section: Phantom Based Methods For Dosimetry Auditsmentioning

confidence: 99%

“…The phantom and the audit methodology have been tested in multi-centre studies and found to be adequate and feasible for meeting the audit objectives. Other dosimetry audit approaches have focused on verifying the beam output for small fields [45] , see Table 2 .…”

Section: Phantom Based Methods For Dosimetry Auditsmentioning

confidence: 99%

Novel methodologies for dosimetry audits: Adapting to advanced radiotherapy techniques

Pasler¹,

Hernández

Jornet

et al. 2018

Physics and Imaging in Radiation Oncology

View full text Add to dashboard Cite

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“… Small field dosimetric measurements should be verified independently, either through measurements or through an independent external audit, such as that carried out by IROC‐Houston 325,326 or in European countries with postal dosimetry services as described by del Mar Espinosa et al 327 referring to published data would also be helpful. A phantom test from CT simulation through treatment delivery, known as an end‐to‐end test, should be performed and may involve an independent assessment of the delivered dose (Section 6.6). …”

Section: Key Recommendations and Summarymentioning

confidence: 99%

Report of AAPM Task Group 155: Megavoltage photon beam dosimetry in small fields and non‐equilibrium conditions

et al. 2021

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Abbreviations: %dd(10) x , The photon component of the percent depth dose at 10 cm depth in water for a 10 cm 2 × 10 cm 2 field; L∕ w air , Restricted mass collision stopping power ratio of water to air; en ∕ , Spectrum-averaged mass energy-absorption coefficient; AAPM, American Association of Physicists in Medicine; CPE, Charged Particle Equilibrium; DLG, Dosimetric leaf gap; D f msr w,Q msr , Absorbed dose to water at the reference depth z ref in water in the absence of the detector in a field specified by f msr and beam quality Q msr .; f clin , Clinical (clin) non-reference radiation field; f msr , Machine-specific reference (msr) field; f ref , Reference field (ref) specified in dosimetry protocols for which the calibration coefficient of an ionization chamber in terms of absorbed dose to water is provided by a standards laboratory; FWHM, Full-width at half-maximum; GUM, Guide to the expression of Uncertainty in Measurements.; IAEA, International Atomic Energy Agency; ICRU, International Commission on Radiation Units and Measurements; IMRT, Intensity-modulated radiation therapy; k Q,Q 0 , The beam-quality correction factor, which corrects for the differences between the response of an ionization chamber in the reference beam of quality Q o used for calibrating the chamber and the beam of quality Q (defined as k Q . in TG-51 4 ); k f ref Q,Q 0 , Correction factor that accounts for the differences between the response of a detector in field f ref in a beam of quality Q and reference beam quality Q 0 as defined in TRS-483. 1 and Palmans et al 2 ; k fclin,fmsr Qclin,Q msr , The detector-specific correction factor that accounts for the difference between the responses of the detector in fields f clin in a beam of quality Q clin and in fields f msr in beam of quality Q msr as defined by Alfonso et al. 3 ; LCPE, Lateral charged particle equilibrium; M fmsr Qmsr , Detector reading in field f msr and beam quality Q msr corrected for influence of changes in pressure and temperature, incomplete charge collection, polarity effect and electrometer correction factor (TRS-483 1 ); MU, Monitor unit; N D,w,Q 0 , This is N D,w in TG-51, 4 and defined as the calibration coefficient in terms of absorbed dose to water for an ionization chamber at a reference beam of quality,Q 0 and field size f ref ; N f ref D,w,Q 0

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“…The accuracy is probably limited to 5% (117,118). The use of ionisation chambers is not recommended due to poor positioning possibilities.…”

Section: Point Dose Verification Near Organsmentioning

confidence: 99%

NCS Report 22: Code of practice for the quality assurance and control for intensity modulated radiotherapy

Wal¹,

Wiersma²,

Ausma³

et al. 2013

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Postal dosimetry audit test for small photon beams

Cited by 10 publications

References 30 publications

Novel methodologies for dosimetry audits: Adapting to advanced radiotherapy techniques

Novel methodologies for dosimetry audits: Adapting to advanced radiotherapy techniques

Report of AAPM Task Group 155: Megavoltage photon beam dosimetry in small fields and non‐equilibrium conditions

NCS Report 22: Code of practice for the quality assurance and control for intensity modulated radiotherapy

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