Addendum to the IPEMB code of practice for the determination of absorbed dose for x-rays below 300 kV generating potential (0.035 mm Al–4 mm Cu HVL)

Aukett, R J; Burns, J E; Greener, A.; Harrison, R. M.; Moretti, C; Nahum, Alan E.; Rosser, K E

doi:10.1088/0031-9155/50/12/001

Cited by 85 publications

(80 citation statements)

References 19 publications

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“…9,10 An ionization chamber with a flat energy response (better that 65% between 40 and 300 kV) and suitable size which allows measurement at shallow depths is recommended. 3,6,11,12 Some dosimetry protocols recommend only liquid water for relative dosimetry, 6,12 whereas others do not discourage the use of non-water-equivalent plastics in the low-kV energy region. 3,4,13 Based on the findings by Hill et al, 9 some, but not all commercially available solid phantoms, are water-equivalent within 62% in kV beams and data measured in some plastics can differ from those measured in water by up to 7%, and this depends on beam quality and field size.…”

Section: Introductionmentioning

confidence: 99%

Acceptance, commissioning and clinical use of the WOmed T-200 kilovoltage X-ray therapy unit

Aspradakis¹,

Zucchetti²

2015

BJR

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Objective: The objective of this work was to characterize the performance of the WOmed T-200-kilovoltage (kV) therapy machine. Methods: Mechanical functionality, radiation leakage, alignment and interlocks were investigated. Half-value layers (HVLs) (first and second HVLs) from X-ray beams generated from tube potentials between 30 and 200 kV were measured. Reference dose was determined in water. Beam start-up characteristics, dose linearity and reproducibility, beam flatness, and uniformity as well as deviations from inverse square law were assessed. Relative depth doses (RDDs) were determined in water and water-equivalent plastic. The quality assurance program included a dosimetry audit with thermoluminescent dosemeters. Results: All checks on machine performance were satisfactory. HVLs ranged between 0.45-4.52 mmAl and 0.69-1.78 mmCu. Dose rates varied between 0.2 and 3 Gy min 21 with negligible time-end errors. There were differences in measured RDDs from published data. Beam outputs were confirmed with the dosimetry audit. The use of published backscatter factors was implemented to account for changes in phantom scatter for treatments with irregularly shaped fields. Conclusion: Guidance on the determination of HVL and RDD in kV beams can be contradictory. RDDs were determined through measurement and curve fitting. These differed from published RDD data, and the differences observed were larger in the low-kV energy range. Advances in knowledge: This article reports on the comprehensive and novel approach to the acceptance, commissioning and clinical use of a modern kV therapy machine. The challenges in the dosimetry of kV beams faced by the medical physicist in the clinic are highlighted.

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Section: Introductionmentioning

confidence: 99%

Acceptance, commissioning and clinical use of the WOmed T-200 kilovoltage X-ray therapy unit

Aspradakis¹,

Zucchetti²

2015

BJR

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“…For the INTRABEAM and Papillon units, the 0.02-cm 3 PTW23342 chamber (PTW Freiburg, Freiburg, Germany) has been used following the Institute of Physics and Engineering in Medicine very low energy code of practice. 35,36 Air kerma calibration was derived from the UK National Physical Laboratory free air chamber, and the chamber correction factor for the difference between measurement in air and in phantom, k ch , was found to be 1.06-1.07. 37,38 The main uncertainties in this approach are positioning accuracy and the energy dependence of any solid water materials used.…”

Section: Output Calibrationmentioning

confidence: 99%

Electronic brachytherapy—current status and future directions

Eaton¹

2015

BJR

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In the past decade, electronic brachytherapy (EB) has emerged as an attractive modality for the treatment of skin lesions and intraoperative partial breast irradiation, as well as finding wider applications in intracavitary and interstitial sites. These miniature X-ray sources, which operate at low kilovoltage energies (,100 kV), have reduced shielding requirements and inherent portability, therefore can be used outside the traditional realms of the radiotherapy department. However, steep dose gradients and increased sensitivity to inhomogeneities challenge accurate dosimetry. Secondly, ease of use does not mitigate the need for close involvement by medical physics experts and consultant oncologists. Finally, further studies are needed to relate the more heterogeneous dose distributions to clinical outcomes. With these provisos, the practical convenience of EB strongly suggests that it will become an established option for selected patients, not only in radiotherapy departments but also in a range of operating theatres and clinics around the world.

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“…The "very low energy" dosimetry range (,1 mm Al) from the Codes of Practice (CoPs) 9,10 were used in 5 centres (10%), "low energy" range (1-8 mm Al) in 46 centres (92%) and the "medium energy" range (0.5-4 mm Cu) in 31 centres (62%).…”

Section: Kilovoltage Equipment Profile In the Ukmentioning

confidence: 99%

“…All responding centres were using the recommended CoPs for kV radiation dosimetry in the UK, either the Institute of Physics and Engineering in Medicine (IPEM) 1996 or IPEM 2005 addendum codes. 9,10 The "very low energy" dosimetry ranges from the CoPs were used in 9 centres (19%), "low energy" range in 43 centres (90%) and the "medium energy" range in 27 centres (56%). Of those using the medium energy range, 13 centres were using the 1996 CoP incorporating an in-water measurement, and 14 centres were using the 2005 CoP incorporating an in-air measurement.…”

Section: Kilovoltage Equipment Profile In the Ukmentioning

confidence: 99%

Current status of kilovoltage (kV) radiotherapy in the UK: installed equipment, clinical workload, physics quality control and radiation dosimetry

Palmer

Pearson

Whittard

et al. 2016

The British Journal of Radiology

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Objective: To assess the status and practice of kilovoltage (kV) radiotherapy in the UK. Methods: 96% of the radiotherapy centres in the UK responded to a comprehensive survey. An analysis of the installed equipment base, patient numbers, clinical treatment sites, quality control (QC) testing and radiation dosimetry processes were undertaken. Results: 73% of UK centres have at least one kV treatment unit, with 58 units installed across the UK. Although 35% of units are over 10 years old, 39% units have been installed in the last 5 years. Approximately 6000 patients are treated with kV units in the UK each year, the most common site (44%) being basal cell carcinoma. A benchmark of QC practice in the UK is presented, against which individual centres can compare their procedures, frequency of testing and acceptable tolerance values. We propose the use of internal "notification" and "suspension" levels for analysis. All surveyed centres were using recommended Codes of Practice for kV dosimetry in the UK; approximately the same number using in-air and in-water methodologies for medium energy, with two-thirds of all centres citing "clinical relevance" as the reason for choice of code. 64% of centres had hosted an external dosimetry audit within the last 3 years, with only one centre never being independently audited. The majority of centres use locally measured applicator factors and published backscatter factors for treatments. Monitor unit calculations are performed using software in only 36% of centres. Conclusion: A comprehensive review of current kV practice in the UK is presented. Advances in knowledge: Data and discussion on contemporary kV radiotherapy in the UK, with a particular focus on physics aspects.

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Addendum to the IPEMB code of practice for the determination of absorbed dose for x-rays below 300 kV generating potential (0.035 mm Al–4 mm Cu HVL)

Cited by 85 publications

References 19 publications

Acceptance, commissioning and clinical use of the WOmed T-200 kilovoltage X-ray therapy unit

Acceptance, commissioning and clinical use of the WOmed T-200 kilovoltage X-ray therapy unit

Electronic brachytherapy—current status and future directions

Current status of kilovoltage (kV) radiotherapy in the UK: installed equipment, clinical workload, physics quality control and radiation dosimetry

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