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Evaluation of LiF:Mg,Ti (TLD-100) for Intraoperative Electron Radiation Therapy Quality Assurance.

Liuzzi R, Savino F, D'Avino V, Pugliese M, Cella L - PLoS ONE (2015)

Bottom Line: In the dose range of 0-10 Gy, the calibration curve was confirmed to be linear for the conventional photon beam.In the same dose region, the quadratic model performs better than the linear model when high dose-per-pulse electron beams were used (F test; p<0.05).This study demonstrates that the TLD dose response, for doses ≤10 Gy, has a parabolic behavior in high dose-per-pulse electron beams.

View Article: PubMed Central - PubMed

Affiliation: Institute of Biostructure and Bioimaging, National Research Council (CNR), Naples, Italy.

ABSTRACT

Background: Purpose of the present work was to investigate thermoluminescent dosimeters (TLDs) response to intraoperative electron radiation therapy (IOERT) beams. In an IOERT treatment, a large single radiation dose is delivered with a high dose-per-pulse electron beam (2-12 cGy/pulse) during surgery. To verify and to record the delivered dose, in vivo dosimetry is a mandatory procedure for quality assurance. The TLDs feature many advantages such as a small detector size and close tissue equivalence that make them attractive for IOERT as in vivo dosimeters.

Methods: LiF:Mg,Ti dosimeters (TLD-100) were irradiated with different IOERT electron beam energies (5, 7 and 9 MeV) and with a 6 MV conventional photon beam. For each energy, the TLDs were irradiated in the dose range of 0-10 Gy in step of 2 Gy. Regression analysis was performed to establish the response variation of thermoluminescent signals with dose and energy.

Results: The TLD-100 dose-response curves were obtained. In the dose range of 0-10 Gy, the calibration curve was confirmed to be linear for the conventional photon beam. In the same dose region, the quadratic model performs better than the linear model when high dose-per-pulse electron beams were used (F test; p<0.05).

Conclusions: This study demonstrates that the TLD dose response, for doses ≤10 Gy, has a parabolic behavior in high dose-per-pulse electron beams. TLD-100 can be useful detectors for IOERT patient dosimetry if a proper calibration is provided.

No MeSH data available.


Related in: MedlinePlus

Experimental setup used to irradiate the Thermoluminescent Dosimeters (TLDs) with the 5, 7 and 9 MeV electron beams from the intra-operative linear accelerator Novac7.SSD: Source Surface Distance.
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pone.0139287.g002: Experimental setup used to irradiate the Thermoluminescent Dosimeters (TLDs) with the 5, 7 and 9 MeV electron beams from the intra-operative linear accelerator Novac7.SSD: Source Surface Distance.

Mentions: Next, the TLDs were irradiated with the electron beams (5-7-9 MeV) produced by the Novac7 at the depth of maximum dose of each electron energy (Table 1). The distance between the source and the upper surface of the phantom was of 100 cm (source surface distance technique), and the field diameter was of 10 cm (Fig 2). Each beam operates at different dose-rate (7.8, 8.1 and 9.3 GY/min for 5, 7 and 9 MeV energy beam). All beams characteristics are described in Table 1. Before each set of irradiation, the beam output (Gy/UM) was verified using an Advanced Markus chamber type (PTW type 34045, Freiburg, Germany) according to the protocol previously described in [11]. During any TLD irradiation measurement, the delivered dose was separately measured by a ionization chamber to check the accuracy of the delivered dose (Fig 2).


Evaluation of LiF:Mg,Ti (TLD-100) for Intraoperative Electron Radiation Therapy Quality Assurance.

Liuzzi R, Savino F, D'Avino V, Pugliese M, Cella L - PLoS ONE (2015)

Experimental setup used to irradiate the Thermoluminescent Dosimeters (TLDs) with the 5, 7 and 9 MeV electron beams from the intra-operative linear accelerator Novac7.SSD: Source Surface Distance.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4591127&req=5

pone.0139287.g002: Experimental setup used to irradiate the Thermoluminescent Dosimeters (TLDs) with the 5, 7 and 9 MeV electron beams from the intra-operative linear accelerator Novac7.SSD: Source Surface Distance.
Mentions: Next, the TLDs were irradiated with the electron beams (5-7-9 MeV) produced by the Novac7 at the depth of maximum dose of each electron energy (Table 1). The distance between the source and the upper surface of the phantom was of 100 cm (source surface distance technique), and the field diameter was of 10 cm (Fig 2). Each beam operates at different dose-rate (7.8, 8.1 and 9.3 GY/min for 5, 7 and 9 MeV energy beam). All beams characteristics are described in Table 1. Before each set of irradiation, the beam output (Gy/UM) was verified using an Advanced Markus chamber type (PTW type 34045, Freiburg, Germany) according to the protocol previously described in [11]. During any TLD irradiation measurement, the delivered dose was separately measured by a ionization chamber to check the accuracy of the delivered dose (Fig 2).

Bottom Line: In the dose range of 0-10 Gy, the calibration curve was confirmed to be linear for the conventional photon beam.In the same dose region, the quadratic model performs better than the linear model when high dose-per-pulse electron beams were used (F test; p<0.05).This study demonstrates that the TLD dose response, for doses ≤10 Gy, has a parabolic behavior in high dose-per-pulse electron beams.

View Article: PubMed Central - PubMed

Affiliation: Institute of Biostructure and Bioimaging, National Research Council (CNR), Naples, Italy.

ABSTRACT

Background: Purpose of the present work was to investigate thermoluminescent dosimeters (TLDs) response to intraoperative electron radiation therapy (IOERT) beams. In an IOERT treatment, a large single radiation dose is delivered with a high dose-per-pulse electron beam (2-12 cGy/pulse) during surgery. To verify and to record the delivered dose, in vivo dosimetry is a mandatory procedure for quality assurance. The TLDs feature many advantages such as a small detector size and close tissue equivalence that make them attractive for IOERT as in vivo dosimeters.

Methods: LiF:Mg,Ti dosimeters (TLD-100) were irradiated with different IOERT electron beam energies (5, 7 and 9 MeV) and with a 6 MV conventional photon beam. For each energy, the TLDs were irradiated in the dose range of 0-10 Gy in step of 2 Gy. Regression analysis was performed to establish the response variation of thermoluminescent signals with dose and energy.

Results: The TLD-100 dose-response curves were obtained. In the dose range of 0-10 Gy, the calibration curve was confirmed to be linear for the conventional photon beam. In the same dose region, the quadratic model performs better than the linear model when high dose-per-pulse electron beams were used (F test; p<0.05).

Conclusions: This study demonstrates that the TLD dose response, for doses ≤10 Gy, has a parabolic behavior in high dose-per-pulse electron beams. TLD-100 can be useful detectors for IOERT patient dosimetry if a proper calibration is provided.

No MeSH data available.


Related in: MedlinePlus