EPID – a useful interfraction QC tool

Klimas, Aleksandra; Grządziel, Aleksandra; Plaza, Dominika; Bekman, B.; Woźniak, Bożena; Dolla, Łukasz; Osewski, Wojciech; Paściak, P.; Wendykier, Jacek; Ślosarek, Krzysztof

doi:10.2478/pjmpe-2019-0029

Cited by 4 publications

(4 citation statements)

References 26 publications

(25 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Previous experiments indicate that such a high degree of maps similarity for (0.5%, 0.5 mm, 99%) gamma criteria are not always obtained and are challenging to achieve. 16 Therefore, the values of (2%, 2 mm, 98%) were adopted. They are sufficient to assure the accuracy of measurement system.…”

Section: Discussionmentioning

confidence: 99%

See 1 more Smart Citation

Portal dosimetry in radiotherapy repeatability evaluation

Ślosarek

Plaza

Nas

et al. 2020

J Applied Clin Med Phys

Self Cite

View full text Add to dashboard Cite

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.

show abstract

Section: Discussionmentioning

confidence: 99%

“…Figure 3 shows the possibility of comparing two fluence maps measured during the therapeutic session. The experience described in the paper of Klimas et al 16 . shows that the repeatability of fluence maps measurements is 2%, 2 mm in 98% of analyzed field points.…”

Section: Introductionmentioning

confidence: 90%

Portal dosimetry in radiotherapy repeatability evaluation

Ślosarek

Plaza

Nas

et al. 2020

J Applied Clin Med Phys

Self Cite

View full text Add to dashboard Cite

show abstract

“…The assessment is based on the gamma index, which verifies compliance with the measurement in the specified range of dose and location. [1][2][3][4][5][6][7][8][9] The gamma index calculates the difference between the dose calculated and measured at the same point (dose difference [DD]) and the distance (distance to agreement [DTA]) between points with the same dose. By determining the acceptable difference (DD) in the dose and the distance (DTA), we define the sphere within which the points located meet the compliance criterion: TPS calculations -measurement; then the value of the coefficient is less than 1 [1][2][3][4][5][6][7].…”

Section: Introductionmentioning

confidence: 99%

Comparison of EPID portal dosimetry verification and RadCalc dose verification for VMAT treatment plans

Gądek,

Plaza,

Sroka

et al. 2024

Nowotwory. Journal of Oncology

View full text Add to dashboard Cite

Introduction. Dosimetry verification is required before starting each treatment. The legal regulations do not clearly define one method of plan verification. Therefore, it is allowed to perform measurements (electronic portal imaging device [EPID]) or calculations using an independent system. Portal dosimetry using EPID matrices was compared with the RadCalcTM system v. 7.1.4.1, performing independent dose distribution calculations. Materials and methods. Treatment plans were made for 150 patients treated with the photon 6MV VMAT technique. Three groups of patients were studied: those treated for breast cancer, those treated for prostate cancer, and those irradiated to the prostate area with nodes. Then, the dosimetry verification was carried out on the accelerator using the EPID portal and compared with the independent RadCalc software calculation results. Results. Comparison of tumor proportion score (TPS) vs. EPID and vs. RC calculations for breast, prostate, and prostate with nodes showed no significant statistical differences. Regardless of the size (volume) of the clinical target volume (CTV) area, no significant difference was observed, although there was a greater agreement for large CTVs compared to small ones. Similarly, there was no significant difference in the compared methods based on depth, but there was a better agreement for small depths than large ones. Conclusions. Verification methods in the study groups showed compliance of the measured (EPID) and calculated (RadCalc) doses with the values planned in the TPS. This confirms that verification for patients treated with radiotherapy can be performed with any of these methods. However, for radiosurgical techniques, it is better to use the EPID method because the RadCalc method may give false negative results.

show abstract

“…The fluence map obtained with EPID was tested to measure the dose in real time [3][4][5], repeated treatment [6][7][8][9], point dose measurement [10] and dose distribution [11][12][13][14]. Fluence maps were also used to verify the correct operation of the MLC [15][16][17][18] or compatibility with the planned dose distribution [19].…”

Section: Introductionmentioning

confidence: 99%