Determination of the intrinsic energy dependence of LiF:Mg,Ti thermoluminescent dosimeters for 125I and 103Pd brachytherapy sources relative to 60Co

Reed, Joshua L.; Rasmussen, B; Davis, Stephen D.; Micka, J; Culberson, Wesley S.; DeWerd, Larry A.

doi:10.1118/1.4901300

Cited by 8 publications

(24 citation statements)

References 50 publications

(103 reference statements)

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“…X-ray transitions are listed after the elemental symbol for the daughter nuclide (i.e., Xe). Subgroups are enumerated for the K a and K b transitions, while the mean energies and total intensities are given for the other transitions, e.g., While these results are well within the range of corresponding findings of studies [41][42][43] employing x-ray beams, they are significantly higher than corresponding findings of Reed et al 45 On average, the measured Λ values (as revised by Rodriquez and Rogers 44 to include their f rel , P phant , and k rel bq corrections) were 4.3% and 5.9% lower than the original values for 103 Pd and 125 I seeds, respectively. As expected, a closer agreement was observed between these revised Λ values and their corresponding MC calculations.…”

Section: D Tld Dosimetry Correctionsmentioning

confidence: 66%

“…38 Since the publication of the 2004 TG-43U1 report 2 and its 2007 supplement, 4 a terminology has been introduced to rigorously describe dosimeter characteristics, 39,40 and important work has been reported on the complexity of using TLD dosimetry for low-energy sources. [41][42][43][44][45] In this terminology, 39,44 D med (Q) is the absorbed dose to the medium med at the point of measurement (normally the detector midpoint) in the absence of the detector for a given radiation quality Q. This is related to the detector measurement for the same radiation quality M(Q) and the absorbed dose calibration coefficient for the detector N D,med (Q) according to:…”

Section: D Tld Dosimetry Correctionsmentioning

confidence: 99%

“…37 The hypothesis of k rel bq equal to unity prevailed in TLD dosimetry studies of low-energy sources until the work of Davis et al and subsequent high-quality determinations of k bq reported in the literature. [42][43][44][45] See reference 37 for a review. Davis et al 41 reported a TLD over-response under 200 keV relative to 60 Co (k bq decrease) up to 10% (0.6% Type A uncertainty, k = 1) for LiF:Mg,Ti TLD chips using low-energy x-ray beams.…”

Section: D Tld Dosimetry Correctionsmentioning

confidence: 99%

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Supplement 2 for the 2004 update of theAAPMTask Group No. 43 Report: Joint recommendations by theAAPMandGEC‐ESTRO

et al. 2017

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Cs (IsoRay Medical model CS-1 Rev2). Observations are included on the behavior of these dosimetry parameters as a function of radionuclide. Recommendations are presented on the selection of dosimetry parameters, such as from societal reports issuing consensus datasets (e.g., TG-43U1, AAPM Report #229), the joint AAPM/IROC Houston Registry, the GEC-ESTRO website, the Carleton University website, and those included in software releases from vendors of treatment planning systems. Aspects such as timeliness, maintenance, and rigor of these resources are discussed.Links to reference data are provided for radionuclides (radiation spectra and half-lives) and dose scoring materials (compositions and mass densities). The recent literature is examined on photon energy response corrections for thermoluminescent dosimetry of low-energy photon-emitting brachytherapy sources. Depending upon the dosimetry parameters currently used by individual physicists, use of these recommended consensus datasets may result in changes to patient dose calculations. These changes must be carefully evaluated and reviewed with the radiation oncologist prior to their implementation.

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Section: D Tld Dosimetry Correctionsmentioning

confidence: 66%

Section: D Tld Dosimetry Correctionsmentioning

confidence: 99%

Section: D Tld Dosimetry Correctionsmentioning

confidence: 99%

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Supplement 2 for the 2004 update of theAAPMTask Group No. 43 Report: Joint recommendations by theAAPMandGEC‐ESTRO

et al. 2017

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“…In addition to absorbed‐dose energy dependence, an intrinsic energy response has been reported for most radiochromic film models as well as other solid‐state and chemical dosimeters . Intrinsic energy response, denoted k bq , refers to the phenomenon in which different beam energies delivering the same absorbed dose to the film active layer produce different dosimeter responses.…”

Section: Introductionmentioning

confidence: 99%

Experimental investigation of GafChromic^® EBT3 intrinsic energy dependence with kilovoltage x rays, ¹³⁷Cs, and ⁶⁰Co

Hammer

Rosen

Fagerstrom³

et al. 2017

Medical Physics

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Purpose: To determine experimentally the intrinsic energy response, k bq , of EBT3 GafChromic â radiochromic film with kilovoltage x rays, 137 Cs, and 60 Co in therapeutic and diagnostic dose ranges through direct measurement with an accompanying mathematical approach to describe the physical processes involved. Methods: The EBT3 film was irradiated with known doses using 60 Co, 137 Cs, and 13 NIST-matched kilovoltage x-ray beams. Seven dose levels, ranging from 57 to 7002 mGy, were chosen for this work. Monte Carlo methods were used to convert air-kerma rates to dose rates to the film active layer for each energy. A total of 738 film dosimeters, each measuring (1.2 9 1.2) cm 2 , were cut from three film sheets out of the same lot of the latest version of EBT3 film, to allow for multiple dosimeters to be irradiated by each target dose and beam quality as well as unirradiated dosimeters to be used as controls. Net change in optical density in excess of the unirradiated controls was measured using the UWMRRC Laser Densitometry System (LDS). The dosimeter intrinsic energy response, k bq , for each dose level was determined relative to 60 Co, as the ratio of dosimeter response to each beam quality relative to the absorbed dose to the film active volume at the same dose level. A simplified, single-hit mathematical model was used to derive a single-free-parameter, b, which is a proportionality constant that is dependent on beam quality and describes the microdosimetric interactions within the active layer of film. The response of b for each beam quality relative to 60 Co was also determined. Results: k bq was determined for a wide range of doses and energies. The results show a unique variation of k bq as a function of energy, and agree well with results from other investigations. There was no measurable dose dependence for k bq within the 500-7002 mGy range outside of the expanded measurement uncertainty of 3.65% (k = 2). For doses less than 500 mGy, the signal-to-noise ratio was too low to determine k bq accurately. The single-free-parameter, b, fit calculations derived from the single-hit model show a correlation with k bq that suggests that b, at least in part, characterizes the microdosimetric interactions that determine k bq . Conclusions: For the beam qualities investigated, a single energy-dependent k bq correction can be used for doses between 500 and 7002 mGy. Using the single-hit model with the single-free-parameter fit to solve for b shows promise in the determination of the intrinsic energy response of film, with b being the mathematical analog of the measured k bq .

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“…In particular, kilovoltage x‐ray units, such as the Xstrahl (Camberley, UK) small animal radiation research platform (SARRP) or the Precision x‐ray (North Brandford, CT, USA) X‐RAD SmART, are increasingly used to perform image‐guided preclinical irradiations . In brachytherapy, TLDs have been instrumental in providing basic dosimetric data for the TG‐43 brachytherapy dose calculation formalism …”

Section: Introductionmentioning

confidence: 99%

Characterization of nanoDot optically stimulated luminescence detectors and high‐sensitivity MCP‐N thermoluminescent detectors in the 40–300 kVp energy range

2017

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Purpose: To investigate empirically the energy dependence of the detector response of two in vivo luminescence detectors, LiF:Mg,Cu,P (MCP-N) high-sensitivity TLDs and Al 2 O 3 :C OSLDs, in the 40-300-kVp energy range in the context of in vivo surface dose measurement. As these detectors become more prevalent in clinical and preclinical in vivo measurements, knowledge of the variation in the empirical dependence of the measured response of these detectors across a wide spectrum of beam qualities is important. Method: We characterized a large range of beam qualities of three different kilovoltage x-ray units: an Xstrahl 300 Orthovoltage unit, a Precision x-Ray X-RAD 320ix biological irradiator, and a Varian On-Board Imaging x-ray unit. The dose to water was measured in air according to the AAPM's Task Group 61 protocol. The OSLDs and TLDs were irradiated under reference conditions on the surface of a water phantom to provide full backscatter conditions.To assess the change in sensitivity in the long term, we separated the in vivo dosimeters of each type into an experimental and a reference group. The experimental dosimeters were irradiated using the kilovoltage x-ray units at each beam quality used in this investigation, while the reference group received a constant 10 cGy irradiation at 6 MV from a Varian clinical linear accelerator. The individual calibration of each detector was verified in cycles where both groups received a 10 cGy irradiation at 6 MV. Results: The nanoDot OSLDs were highly reproducible, with AE1.5% variation in response following >40 measurement cycles. The TLDs lost~20% of their signal sensitivity over the course of the study.The relative light output per unit dose to water of the MCP-N TLDs did not vary with beam quality for beam qualities with effective energies <50 keV (~150 kVp/6 mm Al). At higher energies, they showed a reduced (~75-85%) light output per unit dose relative to 6 MV x rays.The nanoDot OSLDs exhibited a very strong (120-408%) dependency of the light output relative to 6 MV x rays. Variations up to 15% between different x-ray units with equivalent effective energies were also observed. Conclusions: While convenient for clinical use, nanoDot OSLDs exhibit a strong variation in their measured light output per unit dose relative to 6 MV in the 40-300 kV x-ray range. This variability differs unit-to-unit, limiting their effective use for in vivo dosimetry applications in the kilovoltage x-ray energy range. MCP-N TLDs offer a much more stable response, but suffer from variations in sensitivity over time dependent on radiation history, which requires careful experimental handling.

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Determination of the intrinsic energy dependence of LiF:Mg,Ti thermoluminescent dosimeters for ¹²⁵I and ¹⁰³Pd brachytherapy sources relative to ⁶⁰Co

Cited by 8 publications

References 50 publications

Supplement 2 for the 2004 update of theAAPMTask Group No. 43 Report: Joint recommendations by theAAPMandGEC‐ESTRO

Supplement 2 for the 2004 update of theAAPMTask Group No. 43 Report: Joint recommendations by theAAPMandGEC‐ESTRO

Experimental investigation of GafChromic^® EBT3 intrinsic energy dependence with kilovoltage x rays, ¹³⁷Cs, and ⁶⁰Co

Characterization of nanoDot optically stimulated luminescence detectors and high‐sensitivity MCP‐N thermoluminescent detectors in the 40–300 kVp energy range

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Determination of the intrinsic energy dependence of LiF:Mg,Ti thermoluminescent dosimeters for 125I and 103Pd brachytherapy sources relative to 60Co

Cited by 8 publications

References 50 publications

Supplement 2 for the 2004 update of theAAPMTask Group No. 43 Report: Joint recommendations by theAAPMandGEC‐ESTRO

Supplement 2 for the 2004 update of theAAPMTask Group No. 43 Report: Joint recommendations by theAAPMandGEC‐ESTRO

Experimental investigation of GafChromic® EBT3 intrinsic energy dependence with kilovoltage x rays, 137Cs, and 60Co

Characterization of nanoDot optically stimulated luminescence detectors and high‐sensitivity MCP‐N thermoluminescent detectors in the 40–300 kVp energy range

Contact Info

Product

Resources

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Determination of the intrinsic energy dependence of LiF:Mg,Ti thermoluminescent dosimeters for ¹²⁵I and ¹⁰³Pd brachytherapy sources relative to ⁶⁰Co

Experimental investigation of GafChromic^® EBT3 intrinsic energy dependence with kilovoltage x rays, ¹³⁷Cs, and ⁶⁰Co