In vivo evaluating skin doses for lung cancer patients undergoing volumetric modulated arc therapy treatment

Tseng, Hsien-Chun; Pan, Lung‐Kwang; Chen, Hsin-Yu; Liu, Wen-Shan; Hsu, Chang-Chieh; Chen, Chien-Yi

doi:10.3233/bme-151467

Cited by 2 publications

(4 citation statements)

References 14 publications

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“…So far, techniques could be applied within the scope of patient QA but it requires additional equipment or longer evaluation phases (EBT3, HD-V2, TLD). As TLDs are routinely used for in vivo dosimetry, 27 an increased uncertainty must be expected using protons. In our study, the statistical uncertainty U a was 2.9%.…”

Section: Discussionmentioning

confidence: 99%

“…Further, we used thermoluminescent dosimeters (TLDs) to determine the surface dose. As TLDs are routinely used for in vivo dosimetry, 27 their potential application for a clinical assessment of surface dose would be straight-forward. In addition, we applied the Monte Carlo code TOol for PArticle Simulation (TOPAS) to assess the predictive power of Monte Carlo simulations.…”

Section: Introductionmentioning

confidence: 99%

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Determination of surface dose in pencil beam scanning proton therapy

et al. 2020

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Purpose/objective Quantification of surface dose within the first few hundred water equivalent µm is challenging. Nevertheless, it is of large interest for the proton therapy community to study dose effects in the skin. The experimental determination is affected by the detector properties, such as the detector volume and material. The International Commission on Radiation Units and Measurements in its report 39 recommends assessing the skin dose at a depth of 0.07 mm. The aim of this study is the estimation of the absorbed dose at and around a depth of 70 µm. We used various dosimetric approaches in conjunction with proton pencil beam scanning delivery to determine the skin dose in a clinical setting. Material/methods Five different detectors were tested for determining the surface dose in water: EBT3 and HD‐V2 GAFCHROMIC™ radiochromic film, LiF:Mg,Ti thermoluminescent dosimeter, IBA PPC05 plane‐parallel ionization chamber, and PTW 23391 extrapolation chamber. The irradiation setup consisted of quasi‐monoenergetic scanned proton pencil beams with kinetic energies of 100, 150, and 226.7 MeV, respectively. Radiochromic films were placed within a vertical stack and in wedge geometry and were analyzed with FilmQA Pro™ adopting triple channel dosimetry. The extrapolation chamber PTW 23391, which served as a reference in the current work, was used in a conventional ionization chamber setup with a fixed electrode gap of 2 mm. Three Kapton® entrance windows with thicknesses of 25, 50, and 75 µm were employed. Thermoluminescent dosimeters were provided as powder and were pressed onto a sheet of aluminum. Furthermore, the Monte Carlo code TOol for PArticle Simulation (TOPAS) in version 3.1.p2 was used to model an IBA pencil beam scanning nozzle and score dose to water in a water phantom. Results The resulting depth dose curves were normalized to their 100% dose at the reference depth of 3 cm. We obtained the skin doses with the extrapolation chamber and with TOPAS. For the experimental approach this resulted in 79.7 ± 0.3%, 86.0 ± 0.6%, and 87.1 ± 0.1% for the proton energies 100, 150, and 226.7 MeV, respectively. The results for TOPAS were 80.1 ± 0.2% (100 MeV), 87.1 ± 0.5% (150 MeV), and 86.9 ± 0.4% (226.7 MeV), respectively. Based on the experimental results of the skin dose, we provided a clinically relevant surface extrapolation factor for the common measurement methods. This allows the result of the first measurement depth of a detector to be scaled to the dose at the skin depth. Most practical would be the use of the surface extrapolation factor for the PPC05 chamber, due to its direct reading, the wide availability in clinics and the low uncertainties. The calculated factors were 0.986 ± 0.004 for 100 MeV, 0.961 ± 0.008 for 150 MeV, and 0.963 ± 0.003 for 226.7 MeV. Conclusions In this study, dissimilar experimental approaches were evaluated with respect to measurements at depths close to the surface. The experimental depth dose curves are in good agreement with the simulation with TOPAS Monte Carlo. To the author's...

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Determination of surface dose in pencil beam scanning proton therapy

et al. 2020

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“…Radiation doses were read out from a glow curve Harshaw 3500 analyser (Harshaw, Cleveland, Ohio) after 24 hours of exposure. TLDs were preheated to 70 C at a heating rate of 10 C per sec and further heated to a maximum temperature of 300 C [6].…”

Section: Accuracy and Calibration Of Tldsmentioning

confidence: 99%

“…An Alderson-Rando anthropomorphic phantom (Radiology Support Devices, Long Beach, British Columbia, Canada) was used to assess exposure to radiation. Organ or tissue doses were measured using TLDs that were implanted inside, and on the surface of the phantom [6]. H E values were calculated from the computed tomography dose index (CTDI vol ) and the dose length product (DLP), displayed on the console monitor of 128-slice CT scanner, and the conversion coefficient (k) recommended by the American Association of Physicists in Medicine (AAPM) 96.…”

Section: Introductionmentioning

confidence: 99%

Evaluating doses of multi-slice CT in brain examinations using various methods

Lin

Lai

Tseng

et al. 2017

Computer Assisted Surgery

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H were calculated using ICRP 60 and 103 at 2.67 ± 0.18 and 1.89 ± 0.23 mSv based on an axial scan, and 4.70 ± 0.38 and 4.39 ± 0.37 mSv based on a helical scan, respectively. In the DLP method, H was estimated from CTDI that was recorded directly from the console display of the CT unit and then calculated using AAPM 96. Finally, experimental results are compared with those in literature. Radiologists should choose and adjust protocols to prevent unnecessary radiation to patients and satisfying the as low as reasonably achievable (ALARA) principle. These findings will be valuable to patients, physicians, radiologists, and the public.

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In vivo evaluating skin doses for lung cancer patients undergoing volumetric modulated arc therapy treatment

Cited by 2 publications

References 14 publications

Determination of surface dose in pencil beam scanning proton therapy

Determination of surface dose in pencil beam scanning proton therapy

Evaluating doses of multi-slice CT in brain examinations using various methods

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