The combination of the error correction methods of GAFCHROMIC EBT3 film

Li, Yinghui; Chen, Lixin; Zhu, Jinhan; Liu, Xiaowei

doi:10.1371/journal.pone.0181958

Cited by 15 publications

(18 citation statements)

References 33 publications

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“…To simulate the actual patient simulation procedure, the phantom was immobilized with the head and neck immobilization equipment. The irradiated films were scanned and imported into an in-house analysis software (QAchart) which used a verified triple-channal dose analysis method 22 . At commonly used gamma evaluation criteria (3% dose difference (DD) and 3 mm distance to agreement (DTA)), the global gamma analysis was performed for evaluate the dose accuracy of patient Plan+.…”

Section: Methodsmentioning

confidence: 99%

Dosimetric Effects of Head and Neck Immobilization Devices on Multi-field Intensity Modulated Radiation Therapy for Nasopharyngeal Carcinoma

Chen

Peng

et al. 2018

J. Cancer

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Background: In practice, the dose perturbation effect of head and neck immobilization devices is often overlooked in intensity-modulated radiation therapy (IMRT) for nasopharyngeal carcinoma (NPC). Purpose of this study is to verify and analyze the dosimetric effect of head and neck immobilization devices on NPC multi-field IMRT.Methods: Ten patients with nasopharyngeal carcinoma were randomly selected. Two sets of body contours were established for each patient. One set of body contours did not contain the immobilization device, and the other contour set included the immobilization device. For each patient, dose calculations were conducted for the two sets of contours using the same 9-field IMRT plan, which were recorded as Plan- and Plan+. The dose difference caused by the head and neck immobilization devices was assessed by comparing the dose-volume histogram (DVH) parameter results and by plan subtraction. The gafchromic EBT3 film and anthropomorphic phantom were used to verify the calculated doses.Results: The target coverage and average dose of Plan+ were lower than those of Plan- : the prescription dose coverage rates for PTVnx, PTVnd, PTV1 and PTV2 decreased by 2.4%, 9.9%, 1.5%, and 3.6%, respectively, and the mean doses were reduced by 0.9%, 1.9%, 1.1%, and 1.5%, respectively. Doses in the organs at risk showed no significant differences or slight reductions (the maximum reduction in mean dose was 1.7%). From the EBT3 measurements, the skin dose on the posterior neck was increased by approximately 53%.Conclusion: The attenuation and bolus effects of the head and neck immobilization device reduce dose coverage rate and average dose of the planning target volumes in nasopharyngeal carcinoma and lead to an increase in the skin dose. During treatment planning and dose calculation, the immobilization device should be included within body contour to account for the dose attenuation and skin dose increment.

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Section: Methodsmentioning

confidence: 99%

Dosimetric Effects of Head and Neck Immobilization Devices on Multi-field Intensity Modulated Radiation Therapy for Nasopharyngeal Carcinoma

Chen

Peng

et al. 2018

J. Cancer

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“…Radiochromic films have a relatively large dose range (0.1 cGy–10 Gy for EBT3), however the analysis process is slow, requiring a minimum of 24 hr for self‐development post‐irradiation . At lower dose levels (less than 0.1 Gy) noise becomes more significant. This typically necessitates two separate sets of irradiations for the same set of microbeams, in order to be able to increase the accuracy of the assessment of the dose distribution in the regions with lower dose range (valleys) without saturating the high dose region of the microbeam peaks.…”

Section: Introductionmentioning

confidence: 99%

Evaluation of a pixelated large format CMOS sensor for x‐ray microbeam radiotherapy

et al. 2020

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Purpose Current techniques and procedures for dosimetry in microbeams typically rely on radiochromic film or small volume ionization chambers for validation and quality assurance in 2D and 1D, respectively. Whilst well characterized for clinical and preclinical radiotherapy, these methods are noninstantaneous and do not provide real time profile information. The objective of this work is to determine the suitability of the newly developed vM1212 detector, a pixelated CMOS (complementary metal‐oxide‐semiconductor) imaging sensor, for in situ and in vivo verification of x‐ray microbeams. Methods Experiments were carried out on the vM1212 detector using a 220 kVp small animal radiation research platform (SARRP) at the Helmholtz Centre Munich. A 3 x 3 cm2 square piece of EBT3 film was placed on top of a marked nonfibrous card overlaying the sensitive silicon of the sensor. One centimeter of water equivalent bolus material was placed on top of the film for build‐up. The response of the detector was compared to an Epson Expression 10000XL flatbed scanner using FilmQA Pro with triple channel dosimetry. This was also compared to a separate exposure using 450 µm of silicon as a surrogate for the detector and a Zeiss Axio Imager 2 microscope using an optical microscopy method of dosimetry. Microbeam collimator slits with range of nominal widths of 25, 50, 75, and 100 µm were used to compare beam profiles and determine sensitivity of the detector and both film measurements to different microbeams. Results The detector was able to measure peak and valley profiles in real‐time, a significant reduction from the 24 hr self‐development required by the EBT3 film. Observed full width at half maximum (FWHM) values were larger than the nominal slit widths, ranging from 130 to 190 µm due to divergence. Agreement between the methods was found for peak‐to‐valley dose ratio (PVDR), peak to peak separation and FWHM, but a difference in relative intensity of the microbeams was observed between the detectors. Conclusions The investigation demonstrated that pixelated CMOS sensors could be applied to microbeam radiotherapy for real‐time dosimetry in the future, however the relatively large pixel pitch of the vM1212 detector limit the immediate application of the results.

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“…Each of them is dedicated for film scanning, calibration, dose map creation, gamma evaluation, and for image processing. 22 , 23 , 24 , 25 , 26 …”

Section: Methodsmentioning

confidence: 99%

Comparison of three film analysis softwares using EBT2 and EBT3 films in radiotherapy

Pócza

Zongor

Melles-Bencsik

et al. 2020

Radiology and Oncology

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Introduction The purpose of the study was to compare the results of gamma value based film analysis according to the used type of self-developer film and software product. Material and methods The films were irradiated with different treatment techniques such as 3D conformal and intensity modulated radiotherapy with static and rotational delivery. Stereotactic plans with conformal and intensity modulated arc techniques, using coplanar and non-coplanar beam setup were also evaluated. The data of irradiated film were compared with the planned planar dose distribution exported from the treatment planning system. Three film analysis software programs were evaluated: PTW Mephysto (PTW), FilmQA Pro (FQP) and radiohromic.com(RC). Both EBT2 and EBT3 types of films were examined. The comparisons of dose distributions were performed with gamma analysis using 10% cut-off level. Results The results of the gamma analysis for larger fields were between 78.3% and 98.3%, 75.7% and 100%, 80.2% and 98.8% with PTW, FQP and RC, respectively. The results of evaluation in case of stereotactic measurements were 76.8%–99.2% for PTW, 95.7%–100% for FQP and 91.2%–99.9% for RC. Conclusions All the three software programs are suitable for calibrating and evaluating films, performing gamma analysis, and can be used for patient specific quality assurance measurements. There is no direct connection between gamma passing rate and absolute accuracy or software quality, it is just a feature of the software. The interpretation of own results has to be defined on an institutional level according to given workflow and preliminary results.

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The combination of the error correction methods of GAFCHROMIC EBT3 film

Cited by 15 publications

References 33 publications

Dosimetric Effects of Head and Neck Immobilization Devices on Multi-field Intensity Modulated Radiation Therapy for Nasopharyngeal Carcinoma

Dosimetric Effects of Head and Neck Immobilization Devices on Multi-field Intensity Modulated Radiation Therapy for Nasopharyngeal Carcinoma

Evaluation of a pixelated large format CMOS sensor for x‐ray microbeam radiotherapy

Comparison of three film analysis softwares using EBT2 and EBT3 films in radiotherapy

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