Implementation of a Novel Uncertainty Budget Determination Methodology for Small Field Dosimetry

Tolabin, David Eduardo; Laguardia, Rodolfo Alfonso; Bianchini, Sebastian

doi:10.1007/978-981-10-9023-3_113

Cited by 5 publications

(9 citation statements)

References 1 publication

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“…) as was expected, and in general solid state detectors yield smaller uncertainties compared to the micro and mini‐ ionization chambers (10–50 mm circular fields and all square field sizes) (Fig. ), which agrees with the budget prepared by Tolabin . This is most evident for the 1 cm × 1 cm square fields with the microDiamond/unshielded diodes having a combined relative uncertainty of 0.78%, shielded diodes 0.88%, while the micro and mini‐ionization chambers yield 1.31 and 2.53%, respectively.…”

Section: Discussionsupporting

confidence: 86%

“…The largest sources of uncertainty were; k small (which is the uncertainties in the output correction factors stated in the protocol) and ranged between 0.30–3.60% for circular fields (Table ) and 0.30–2.50% for square fields (Table ). Tolabin also reported this in their small field uncertainty budget for square fields (0.5 cm × 0.5 cm to 4 cm × 4 cm) using two mini‐ionization chambers (IBA CC13, CC01), one micro‐ionization chamber (Razor NanoChamber) and one unshielded diode (IBA Razor). The other main source of uncertainty in our budget was the CAX positioning error (0.3 mm), which was determined using the in‐line and cross‐line profiles for each detector type scanned at each field or cone size.…”

Section: Discussionmentioning

confidence: 77%

“…Its magnitude for each detector type ranged between 0.10–0.98% for circular fields (Table ) and 0.14–0.67% for square fields (Table ). Interestingly, Tolabin estimated this uncertainty (called µ scan ) as much lower with a range between 0.001 and 0.012% uncertainty for all four detector types investigated. As Tolabin does not state the CAX positioning limit, this difference could be due to applying a smaller positioning error (0.1 mm), which would yield lower uncertainties particularly for steep gradient profiles.…”

Section: Discussionmentioning

confidence: 99%

“…8), which agrees with the budget prepared by Tolabin. 22 This is most evident for the 1 cm × 1 cm square fields with the microDiamond/unshielded diodes having a combined relative uncertainty of 0.78%, shielded diodes 0.88%, while the micro and mini-ionization chambers yield 1.31 and 2.53%, respectively.…”

Section: C | the Small Field Uncertainty Budgetmentioning

confidence: 96%

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Evaluation of the IAEA‐TRS 483 protocol for the dosimetry of small fields (square and stereotactic cones) using multiple detectors

Smith

Montesari

Oliver³

et al. 2019

J Applied Clin Med Phys

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The IAEA TRS 483 protocol1 for the dosimetry of small static fields in radiotherapy was used to calculate output factors for the Elekta Synergy linac at the Australian Radiation Protection and Nuclear Safety Agency (ARPANSA). Small field output factors for both square and circular fields were measured using nine different detectors. The “corrected” output factors (ratio of detector readings multiplied by the appropriate correction factor from the protocol) showed better consistency compared to the “uncorrected” output factors (ratio of detector readings only), with the relative standard deviation decreasing by approximately 1% after the application of the relevant correction factors. Comparisons relative to an arbitrarily chosen PTW 60019 microDiamond detector showed a reduction of maximal variation for the corrected values of approximately 3%. A full uncertainty budget was prepared to analyze the consistency of the output factors. Agreement within uncertainties between all detectors and field sizes was found, except for the 15 mm circular field. The results of this study show that the application of IAEA TRS 4831 when measuring small fields will improve the consistency of small field measurements when using multiple detectors contained within the protocol.

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Section: Discussionsupporting

confidence: 86%

Section: Discussionmentioning

confidence: 77%

Section: Discussionmentioning

confidence: 99%

Section: C | the Small Field Uncertainty Budgetmentioning

confidence: 96%

See 2 more Smart Citations

Evaluation of the IAEA‐TRS 483 protocol for the dosimetry of small fields (square and stereotactic cones) using multiple detectors

Smith

Montesari

Oliver³

et al. 2019

J Applied Clin Med Phys

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show abstract

“…This study presents a detailed calculation of uncertainty for ionization chambers and diode. The positional uncertainty, as proposed by Lechner et al .,[ 18 ] along with the overall methodology by Tolabin et al .,[ 17 ] was used to calculate total uncertainty in output factors. As expected, the positional uncertainty in both the diode and ionization chamber reduces with an increase in field size.…”

Section: Discussionmentioning

confidence: 99%

Implementation and Challenges of International Atomic Energy Agency/American Association of Physicists in Medicine TRS 483 Formalism for Field Output Factors and Involved Uncertainties Determination in Small Fields for TomoTherapy

Kinhikar

Kaushik

Tambe

et al. 2021

Journal of Medical Physics

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Purpose International Atomic Energy Agency published TRS-483 to address the issues of small field dosimetry. Our study calculates the output factor in the small fields of TomoTherapy using different detectors and dosimetric conditions. Furthermore, it estimates the various components of uncertainty and presents challenges faced during implementation. Materials and Methods Beam quality TPR20,10(10) at the hypothetical field size of 10 cm × 10 cm was calculated from TPR20,10(S). Two ionization chambers based on the minimum field width required to satisfy the lateral charge particle equilibrium and one unshielded electron field diode (EFD) were selected. Output factor measurements were performed in various dosimetric conditions. Results Beam quality TPR20,10(10) has a mean value of 0.627 ± 0.001. The maximum variation of output factor between CC01 chamber and EFD diode at the smallest field size was 11.80%. In source to surface setup, the difference between water and virtual water was up to 9.68% and 8.13%, respectively, for the CC01 chamber and EFD diode. The total uncertainty in the ionization chamber was 2.43 times higher compared to the unshielded EFD diode at the smallest field size. Conclusions Beam quality measurements, chamber selection procedure, and output factors were successfully carried out. A difference of up to 10% in output factor can occur if density scaling for electron density in virtual water is not considered. The uncertainty in output correction factors dominates, while positional and meter reading uncertainty makes a minor contribution to total uncertainty. An unshielded EFD diode is a preferred detector in small fields because of lower uncertainty in measurements compared to ionization chambers.

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Determination of correction factors in small MLC‐defined fields for the Razor and microSilicon diode detectors and evaluation of the suitability of the IAEA TRS‐483 protocol for multiple detectors

McGrath

Golmakani

Williams

2022

J Applied Clin Med Phys

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Small field output factors for Multileaf collimator (MLC)‐defined field sizes between 0.5 × 0.5 cm2 and 3 × 3 cm2 were measured with six different detectors for a Varian TrueBeam in 6‐MV, 6‐FFF, 10‐MV, and 10‐FFF photon beams. Correction factors kQclin,Qreffclin,fref$k_{{Q_{{\rm{clin}}}},{Q_{{\rm{ref}}}}}^{{f_{{\rm{clin}}}},{f_{{\rm{ref}}}}}$ from the IAEA publication TRS‐483 were used to correct the measured output factors. The corrected output factors from the six detectors were used to calculate correction factors for the PTW microSilicon T60023 (PTW, Freiburg, Germany) and IBA Razor (IBA Dosimetry, Schwarzenbruck, Germany) detectors. The uncertainty of the output and correction factors in this study was calculated and the calculations presented in detail. The application of the TRS‐483 correction factors significantly reduced the variation in output factors between the various detectors, with the exception of the PTW 60016 diode in 6‐MV and 6‐FFF beams, and the IBA PFD in 10‐MV and 10‐FFF beams. Correction factors calculated for the Razor agreed within 2.9% of existing literature for all energies, while the microSilicon correction factors agreed within 1.6% to the literature for 6‐MV beams. The uncertainty in the microSilicon and Razor correction factors was calculated to be less than 0.9% (k = 1). This study shows that TRS‐483 correction factors reduce the variation in output factors between the detectors used in this study and presents a suitable method for determining correction factors for detectors with unpublished values.

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Implementation of a Novel Uncertainty Budget Determination Methodology for Small Field Dosimetry

Cited by 5 publications

References 1 publication

Evaluation of the IAEA‐TRS 483 protocol for the dosimetry of small fields (square and stereotactic cones) using multiple detectors

Evaluation of the IAEA‐TRS 483 protocol for the dosimetry of small fields (square and stereotactic cones) using multiple detectors

Implementation and Challenges of International Atomic Energy Agency/American Association of Physicists in Medicine TRS 483 Formalism for Field Output Factors and Involved Uncertainties Determination in Small Fields for TomoTherapy

Determination of correction factors in small MLC‐defined fields for the Razor and microSilicon diode detectors and evaluation of the suitability of the IAEA TRS‐483 protocol for multiple detectors

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