A comparison of the dosimetric properties of The Electronic Portal Imaging Devices (EPIDs) LC250 and aS500

Woźniak, Bożena; Ganowicz, M.; Bekman, Adam; Maniakowski, Z.

doi:10.1016/s1507-1367(05)71097-x

Cited by 7 publications

(5 citation statements)

References 7 publications

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“…Dosimetry using EPIDs or portal dosimetry has received considerable attention recently due to its relatively high-resolution of 0.392mm amorphous silicon (a-Si) flat-panel detector [15][16][17][18]. Several authors have extensively studied the dosimetric properties of a-Si 500 and a-Si 1000 EPID and its application in IMRT [19][20][21][22][23][24][25]. Varian has recently released a-Si 1200 portal imager with larger area, high resolution of 0.336 mm and improved backscatter for dosimetry.…”

Section: Introductionmentioning

confidence: 99%

Dosimetric Comparison of a-Si 1200 and a-Si 1000 Electronic Portal Imager for Intensity Modulated Radiation Therapy (IMRT)

Mhatre¹,

Pilakkal²,

Chadha³

et al. 2018

J Nucl Med Radiat Ther

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Section: Introductionmentioning

confidence: 99%

Dosimetric Comparison of a-Si 1200 and a-Si 1000 Electronic Portal Imager for Intensity Modulated Radiation Therapy (IMRT)

Mhatre¹,

Pilakkal²,

Chadha³

et al. 2018

J Nucl Med Radiat Ther

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“…of matrices to control the patient treatment position and regular use for pretreatment dosimetry, EPID matrices allow to register a signal that can later be reconstructed, as a dose distribution during the therapeutic session with the patient. [1][2][3][4][5][6] The signal measured by the EPID matrix is called the fluence map.…”

Section: Introductionmentioning

confidence: 99%

“…Modern C‐arm accelerators are equipped with real‐time dose‐monitoring systems, that is, portal matrices (EPID — Electronic Portal Imaging Device). Therefore, in addition to the old‐fashioned use of matrices to control the patient treatment position and regular use for pretreatment dosimetry, EPID matrices allow to register a signal that can later be reconstructed, as a dose distribution during the therapeutic session with the patient 1–6 . The signal measured by the EPID matrix is called the fluence map.…”

Section: Introductionmentioning

confidence: 99%

Portal dosimetry in radiotherapy repeatability evaluation

Ślosarek

Plaza

Nas

et al. 2020

J Applied Clin Med Phys

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The accuracy of radiotherapy is the subject of continuous discussion, and dosimetry methods, particularly in dynamic techniques, are being developed. At the same time, many oncology centers develop quality procedures, including pretreatment and online dose verification and proper patient tracking methods. This work aims to present the possibility of using portal dosimetry in the assessment of radiotherapy repeatability. The analysis was conducted on 74 cases treated with dynamic techniques. Transit dosimetry was made for each collision‐free radiation beam. It allowed the comparison of summary fluence maps, obtained for fractions with the corresponding summary maps from all other treatment fractions. For evaluation of the compatibility in the fluence map pairs (6798), the gamma coefficient was calculated. The results were considered in four groups, depending on the used radiotherapy technique: stereotactic fractionated radiotherapy, breath‐hold, free‐breathing, and conventionally fractionated other cases. The chi2 or Fisher's exact test was made depending on the size of the analyzed set and also Mann–Whitney U‐test was used to compare treatment repeatability of different techniques. The aim was to test whether the null hypothesis of error‐free therapy was met. The patient is treated repeatedly if the P‐value in all the fluence maps sets is higher than the level of 0.01. The best compatibility between treatment fractions was obtained for the stereotactic technique. The technique with breath‐holding gave the lowest percentage of compliance of the analyzed fluence pairs. The results indicate that the repeatability of the treatment is associated with the radiotherapy technique. Treated volume location is also an essential factor found in the evaluation of treatment accuracy. The EPID device is a useful tool in assessing the repeatability of radiotherapy. The proposed method of fluence maps comparison also allows us to assess in which therapeutic session the patient was treated differently from the other fractions.

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“…Electronic portal devices were proposed for clinical practice at the turn of the 20 th and 21 st centuries. They were dedicated for the verification of patient setup during the therapeutic session [1,2], as well as for the dose estimation [3][4][5][6][7][8]. Initially, only a megavolt beam was used both for planar images and volumetric reconstructions CBCT (Cone Beam Computed Tomography).…”

Section: Introductionmentioning

confidence: 99%

EPID – a useful interfraction QC tool

Klimas

Grządziel

Plaza

et al. 2019

Polish Journal of Medical Physics and Engineering

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Biomedical accelerators used in radiotherapy are equipped with detector arrays which are commonly used to obtain the image of patient position during the treatment session. These devices use both kilovolt and megavolt x-ray beams. The advantage of EPID (Electronic Portal Imaging Device) megavolt panels is the correlation of the measured signal with the calibrated dose. The EPID gives a possibility to verify delivered dose. The aim of the study is to answer the question whether EPID can be useful as a tool for interfraction QC (quality control) of dose and geometry repeatability. The EPID system has been calibrated according to the manufacturer’s recommendations to obtain a signal and dose values correlation. Initially, the uncertainty of the EPID matrix measurement was estimated. According to that, the detecting sensitivity of two parameters was checked: discrepancies between the planned and measured dose and field geometry variance. Moreover, the linearity of measured signal-dose function was evaluated. In the second part of the work, an analysis of several dose distributions was performed. In this study, the analysis of clinical cases was limited to stereotactic dynamic radiotherapy. Fluence maps were obtained as a result of the dose distribution measurements with the EPID during treatment sessions. The compatibility of fluence maps was analyzed using the gamma index. The fluence map acquired during the first fraction was the reference one. The obtained results show that EPID system can be used for interfraction control of dose and geometry repeatability.

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A comparison of the dosimetric properties of The Electronic Portal Imaging Devices (EPIDs) LC250 and aS500

Cited by 7 publications

References 7 publications

Dosimetric Comparison of a-Si 1200 and a-Si 1000 Electronic Portal Imager for Intensity Modulated Radiation Therapy (IMRT)

Dosimetric Comparison of a-Si 1200 and a-Si 1000 Electronic Portal Imager for Intensity Modulated Radiation Therapy (IMRT)

Portal dosimetry in radiotherapy repeatability evaluation

EPID – a useful interfraction QC tool

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