Absolute dose verification of static intensity modulated radiation therapy (IMRT) with ion chambers of various volumes and TLD detectors

Acun-Bucht, Hediye; Tuncay, Ebru Başpınar; Darendeliler, Emin; Kemikler, Gönül

doi:10.1016/j.rpor.2018.04.001

Cited by 3 publications

(2 citation statements)

References 30 publications

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“…They measured doses of off-axis points 2 cm and 4 cm from the isocenter with TLDs. Acun-Bucht et al (2018) found the difference between TPS and TLD doses at 2cm and 4cm distance from the isocenter of approximately 3% and 4%, respectively (Acun-Bucht et al, 2018). In our current study, the difference between TLD and TPS doses for 2 cm and 4 cm distances from the isocenter is less than 1%.…”

Section: Resultssupporting

confidence: 43%

Accuracy of In-Field and Out-Field Doses Calculated by Analytical Anisotropic and Pencil Beam Convolution Algorithms: A Dosimetric Study

Gül

2023

Gazi University Journal of Science Part A: Engineering and Innovation

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Out-of-field doses may affect the formation of secondary cancers, especially in radiosensitive organs, in patients treated with radiotherapy. The aim of this study is to investigate the in-field dose and out-of-field dose accuracy of Eclipse's analytic anisotropic algorithm (AAA) and pencil beam convolution (PBC) algorithms using TLDs. A tissue equivalent phantom containing a total of 21 measurement points at a depth of 5 cm from the anterior and posterior was created. Using Eclipse AAA and PBC algorithms in TPS, 100 MU for AP/PA fields and 95 cm source-skin distance (SSD) were planned. In-field measurement points including isocenter were 3, 5, 7 and 11 points for 3x3, 5x5, 7x7 and 10x10 cm2, respectively. Measuring points outside the field edge were 38, 36, 34 and 30 points for 3x3, 5x5, 7x7 and 10x10 cm2, respectively. In-field point dose values calculated by TPS for different fields were compared with TLD doses measured at the same location. The difference between in-field dose estimation and TLD measurements of both algorithms was generally below 1%. The difference between TPS and TLD was found to be 4.41% for the 10x10 cm2 irradiation field, due to the field edge at a distance of 5 cm from the isocenter. As the field size decreased, the out-of-field dose calculation performance of the AAA and PBC algorithms was adversely affected. For the 10x10 cm2 irradiation field, the TLD measurements and the out-of-field point dose difference of the PBC algorithm were found to be 39.40%. This difference was at most 12.06% for the AAA algorithm. The Eclipse TPS is good at calculating the in-field dose but underestimates the off-field dose. In out-of-field dose calculation, the AAA algorithm gives more accurate results than the PBC algorithm. Additionally, the smaller the field size, the worse the outfield dose accuracy. The use of in vivo dosimeters is recommended in order to estimate the out-of-field dose with great accuracy in radiotherapy.

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Section: Resultssupporting

confidence: 43%

Accuracy of In-Field and Out-Field Doses Calculated by Analytical Anisotropic and Pencil Beam Convolution Algorithms: A Dosimetric Study

Gül

2023

Gazi University Journal of Science Part A: Engineering and Innovation

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“…Chen et al obtained equivalent doses for organs or tissues of patients with nasopharyngeal carcinoma under the VMAT program and normal doses by inserting a TLD into human molds [22]. Acun-Bucht et al found that the TLD readings were consistent with the TPS calculations with a 3% deviation on the central axis in their dosimetric validation of the intensity-modulated radiotherapy (IMRT) scheme, providing a good accuracy for absolute dosimetry [23]. Lai et al evaluated the therapeutic dose at the nasopharyngeal air-tissue interface using an anthropomorphic model and found that the difference between the calculated TPS dose and measured TLD at the air-tissue interface under a 2 cm × 2 cm field of view was − 4.9% [24].…”

Section: Discussionmentioning

confidence: 99%

TLD calibration and absorbed dose measurement in a radiation-induced liver injury model under a linear accelerator

Xiao

Liu

et al. 2023

NUCL SCI TECH

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The application of a thermoluminescent detector (TLD) for dose detection at the liver irradiation site in mice under linear accelerator precision radiotherapy and the use of a single high dose to irradiate the mouse liver to construct a biological model of a radiation-induced liver injury (RILD) in mice were to determine the feasibility of constructing a precision radiotherapy model in small animals under a linear accelerator. A 360° arc volumetric rotational intensity-modulated radiotherapy (VMAT) plan with a prescribed dose of 2 Gy was developed for the planned target volume (PTV) at the location of the TLD within solid water to compare the difference between the measured dose of TLD and the assessed parameters in the TPS system. The TLD was implanted in the livers of mice, and VMAT was planned based on TLD to compare the measured and prescribed doses. C57BL/6 J mice were randomly divided into control and 25-Gy radiation groups and were examined daily for changes in body weight. They were euthanized at 3 and 10 weeks after radiation, and the levels of liver serum enzymes such as alanine aminotransferase (ALT), aspartate aminotransferase (AST), and alkaline phosphatase (ALP) were measured to observe any pathological histological changes in the irradiated areas of the mouse liver. The measured values of solid underwater TLD were within ± 3% of the Dmean value of the evaluation parameter in the TPS system. The mice in the 25-Gy radiation group demonstrated pathological signs of radiation-induced liver injury at the site of liver irradiation. The deviation in the measured and prescribed doses of TLD in the mouse liver ranged from − 1.5 to 6%; construction of an accurate model of RILD using the VMAT technique under a linear accelerator is feasible.

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Using an on-board cone-beam computed tomography scanner as an imaging modality for gel dosimetry: A feasibility study

Shih

Hsieh

2019

Applied Radiation and Isotopes

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Absolute dose verification of static intensity modulated radiation therapy (IMRT) with ion chambers of various volumes and TLD detectors

Abstract: The 0.125 cc ion chamber measures the absolute dose of the isocenter more accurately compared to the 0.65 cc chamber. TLDs have good accuracy (within 3.0%) for absolute dose measurements of in-field points.

Cited by 3 publications

References 30 publications

Accuracy of In-Field and Out-Field Doses Calculated by Analytical Anisotropic and Pencil Beam Convolution Algorithms: A Dosimetric Study

Accuracy of In-Field and Out-Field Doses Calculated by Analytical Anisotropic and Pencil Beam Convolution Algorithms: A Dosimetric Study

TLD calibration and absorbed dose measurement in a radiation-induced liver injury model under a linear accelerator

Using an on-board cone-beam computed tomography scanner as an imaging modality for gel dosimetry: A feasibility study

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