Adaptation and validation of a commercial head phantom for cranial radiosurgery dosimetry end-to-end audit

Dimitriadis, Alexis; Palmer, A.L.; Thomas, Russell; Nisbet, Andrew; Clark, Catharine H.

doi:10.1259/bjr.20170053

Cited by 25 publications

(29 citation statements)

References 23 publications

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“…The measured point doses were observed to measure systematically less than the TPS predicted doses. Similar results using Gafchromic film have previously been reported in the literature for E2E dosimetric verification of SRS plans . Liu, et al .…”

Section: Discussionsupporting

confidence: 88%

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Development of a dedicated phantom for multi‐target single‐isocentre stereotactic radiosurgery end to end testing

Poder

Brown

Porter

et al. 2018

J Applied Clin Med Phys

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PurposeThe aim of this project was to design and manufacture a cost‐effective end‐to‐end (E2E) phantom for quantifying the geometric and dosimetric accuracy of a linear accelerator based, multi‐target single‐isocenter (MTSI) frameless stereotactic radiosurgery (SRS) technique.MethodA perspex Multi‐Plug device from a Sun Nuclear ArcCheck phantom (Sun Nuclear, Melbourne, FL) was enhanced to make it more applicable for MTSI SRS E2E testing. The following steps in the SRS chain were then analysed using the phantom: magnetic resonance imaging (MRI) distortion, planning computed tomography (CT) scan and MRI image registration accuracy, phantom setup accuracy using CBCT, dosimetric accuracy using ion chamber, planar film dose measurements and coincidence of linear accelerator mega‐voltage (MV), and kilo‐voltage (kV) isocenters using Winston‐Lutz testing (WLT).ResultsThe dedicated E2E phantom was able to successfully quantify the geometric and dosimetric accuracy of the MTSI SRS technique. MRI distortions were less than 0.5 mm, or half a voxel size. The average MRI‐CT registration accuracy was 0.15 mm (±0.31 mm), 0.20 mm (±0.16 mm), and 0.39 mm (±0.11 mm) in the superior/inferior, left/right and, anterior/posterior directions, respectively. The phantom setup accuracy using CBCT was better than 0.2 mm and 0.1°. Point dose measurements were within 5% of the treatment planning system predicted dose. The comparison of planar film doses to the planning system dose distributions, performed using gamma analysis, resulted in pass rates greater than 97% for 3%/1 mm gamma criteria. Finally, off‐axis WLT showed MV/kV coincidence to be within 1 mm for off‐axis distances up to 60 mm.ConclusionA novel, versatile and cost‐effective phantom for comprehensive E2E testing of MTSI SRS treatments was developed, incorporating multiple detector types and fiducial markers. The phantom is capable of quantifying the accuracy of each step in the MTSI SRS planning and treatment process.

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Section: Discussionsupporting

confidence: 88%

“…Liu, et al . reported gamma pass rates of greater than 99% for 3%/2 mm gamma criteria, and Dimitriadis, et al . found an average gamma pass rate of 96.7% for 2%/2 mm gamma criteria.…”

Section: Discussionmentioning

confidence: 99%

Development of a dedicated phantom for multi‐target single‐isocentre stereotactic radiosurgery end to end testing

Poder

Brown

Porter

et al. 2018

J Applied Clin Med Phys

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“…For stereotactic techniques the key areas of interest in the dosimetry audit lie in the accuracy of the small field and potential FFF modelling, as well as the targeting accuracy. Stereotactic Body Radiotherapy (SBRT) and Stereotactic Radiosurgery (SRS) dosimetry audits have been performed by means of measurements in anthropomorphic phantoms [41] , [42] , [43] , [44] . Audit results are included in 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

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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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“…There are different types of audit from postal to an on-site visit and from basic measurements in reference conditions through to a full end-to-end audit where an anthropomorphic phantom takes the place of the patient and follows the full pathway from imaging, through planning and to complex dose distribution delivery [1] . The development of techniques for dosimetry audit can include the development of new materials [26] , development of anthropomorphic phantoms [27] , [28] as well as characterisation of detectors prior to audit use [29] , [30] .…”

Section: Introductionmentioning

confidence: 99%

The role of dosimetry audit in achieving high quality radiotherapy

Clark

Jornet

Muren

2018

Physics and Imaging in Radiation Oncology

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Adaptation and validation of a commercial head phantom for cranial radiosurgery dosimetry end-to-end audit

Cited by 25 publications

References 23 publications

Development of a dedicated phantom for multi‐target single‐isocentre stereotactic radiosurgery end to end testing

Development of a dedicated phantom for multi‐target single‐isocentre stereotactic radiosurgery end to end testing

Novel methodologies for dosimetry audits: Adapting to advanced radiotherapy techniques

The role of dosimetry audit in achieving high quality radiotherapy

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