Clinical Experience with Machine Log File Software for Volumetric-Modulated Arc Therapy Techniques

Vazquez‐quino, L.; Huerta-Hernandez, Claudia Ivette; Rangaraj, D

doi:10.1080/08998280.2017.11929614

Cited by 17 publications

(20 citation statements)

References 17 publications

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“…Any deviation in dose indices, gantry angles, and MLC positions during patients’ treatment can be identified and corrective actions can be implemented as early as possible. Also, degradation related to MLC and gantry can be spotted out earlier with the use of trajectory log analysis in a daily basis, thanks to its superior sensitivity in deviations of MLC leaf positions and gantry angles 26 …”

Section: Discussionmentioning

confidence: 99%

Patient‐specific quality assurance using machine log files analysis for stereotactic body radiation therapy (SBRT)

Chow

Kan

Chan

2020

J Applied Clin Med Phys

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An in-house trajectory log analysis program (LOGQA) was developed to evaluate the delivery accuracy of volumetric-modulated arc therapy (VMAT) for stereotactic body radiation therapy (SBRT). Methods have been established in LOGQA to provide analysis on dose indices, gantry angles, and multi-leaf collimator (MLC) positions. Between March 2019 and May 2020, 120 VMAT SBRT plans of various treatment sites using flattening filter-free (FFF) mode were evaluated using both LOGQA and phantom measurements. Gantry angles, dose indices, and MLC positions were extracted from log and compared with each plan. Integrated transient fluence map (ITFM) was reconstructed from log to examine the deviation of delivered fluence against the planned one. Average correlation coefficient of dose index versus gantry angle and ITFM for all patients were 1.0000, indicating that the delivered beam parameters were in good agreement with planned values. Maximum deviation of gantry angles and monitor units (MU) of all patients were less than 0.2 degree and 0.03 % respectively. Regarding MLC positions, maximum and rootmean-square (RMS) deviations from planned values were less than 0.6 mm and 0.3 mm respectively, indicating that MLC positions during delivery followed planned values in precise manner. Results of LOGQA were consistent with measurement, where all gamma-index passing rates were larger than 95 %, with 2 %/2 mm criteria. Three types of intentional errors were introduced to patient plan for software validation. LOGQA was found to recognize the introduced errors of MLC positions, gantry angles, and dose indices with magnitudes of 1 mm, 1 degree, and 5 %, respectively, which were masked in phantom measurement. LOGQA was demonstrated to have the potential to reduce or even replace patient-specific QA measurements for SBRT plan delivery provided that the frequency and amount of measurement-based machine-specific QA can be increased to ensure the log files record real values of machine parameters.

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Section: Discussionmentioning

confidence: 99%

Patient‐specific quality assurance using machine log files analysis for stereotactic body radiation therapy (SBRT)

Chow

Kan

Chan

2020

J Applied Clin Med Phys

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“…The paper focuses on the methods that the reference dose distribution is compared to the evaluated one. The presentation of dose verification tools, including 2D detectors, 3D phantoms, fluence detectors, machine log files [4][5][6], etc. is out of the scope of the current study.…”

Section: Discussionmentioning

confidence: 99%

“…Therefore, various solutions and dosimetric systems were introduced in clinical routine, incorporating detectors placed in two (2-D) and three (3-D) dimensional layouts, "in silico" machine log files quality control etc [4][5][6]. These solutions are aiming at adequatelycapturing the dosimetric outcome of these complex movements in multiple dimensions.…”

Section: Introductionmentioning

confidence: 99%

Treatment plan verification: A review on the comparison of dose distributions

et al. 2019

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The aim of this review article is to provide a useful reference for dose comparison techniques within the frame of treatment plan verification. Each technique is presented with a general description given along with advantages and disadvantage and the rationale for its development. Methods: The review was conducted in PubMed from 1993 to 2019 including articles referring to the methodology of dose comparison for treatment plan verification. Results: The search identified thirty-one dose comparison methods that were categorized according to the number of physical parameters that take into account for dose comparison. Conclusions: Among the available methods for the comparison of two dose distributions, the γ-analysis (gamma analysis) has been widely adopted as the gold standard in verification procedures. However, due to various intrinsic limitations of gamma index, the development of a better metric taking into account both statistical and in clinical parameters is required.

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“…Existing pretreatment tools for quality assurance (QA) in the MR‐linac are typically time‐consuming solutions which, besides, are not applicable for an online adaptive workflow . Alternative patient‐specific QA solutions have been proposed, such as fast sanity checks on the adapted plan, in vivo geometrical accuracy of the delivery using EPID images, or the use of independent calculations fed with linac log files …”

Section: Introductionmentioning

confidence: 99%

“…[25][26][27][28] Alternative patient-specific QA solutions have been proposed, such as fast sanity checks on the adapted plan, 29 in vivo geometrical accuracy of the delivery using EPID images, 30 or the use of independent calculations fed with linac log files. [31][32][33][34] An MR-only workflow would allow for MRI-based delineation while performing dose calculation on a synthetic computed tomography (CT) derived from that MRI study. The use of log files in combination with an independent dose calculation algorithm using the synthetic CT is an alternative treatment verification method.…”

Section: Introductionmentioning

confidence: 99%

Two‐dimensional EPID dosimetry for an MR‐linac: Proof of concept

et al. 2019

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Purpose At our institute, in vivo patient dose distributions are reconstructed for all treatments delivered using conventional linacs from electronic portal imaging device (EPID) transit images acquired during treatment using a simple back‐projection model. Currently, the clinical implementation of MRI‐guided radiotherapy systems, which aims for online and real‐time adaptation of the treatment plan, is progressing. In our department, the MR‐linac (Unity, Elekta AB, Stockholm, Sweden) is now in clinical use. The aim of this work is to demonstrate the feasibility of two‐dimensional (2D) EPID dosimetric verification for the magnetic resonance (MR)‐linac by comparing back‐projected EPID doses to ionization chamber (IC) array dose distributions. Materials and methods Our conventional back‐projection algorithm was adapted for the MR‐linac. The most important changes involve modeling of the attenuation by and scatter from the cryostat. The commissioning process involved the acquisition of square field EPID measurements using various phantom setups (varying SSD, phantom thickness, and field size). Commissioning models were created for gantry 0°, 90°, and 180° and verified by comparing EPID‐reconstructed 2D dose distributions to measurements made with the OCTAVIUS 1500 IC array (PTW, Freiburg, Germany) for two prostate and one rectum IMRT plans (25 beams total). The average of the γ parameters (y‐mean and y‐pass rate) and the dose difference at a reference point were reported. Due to their construction, the attenuation of couch, bridge, and cryostat shows a much stronger dependence on gantry angle in the MR‐linac compared to conventional linacs. We present a method to correct for these effects. This method is validated by dose reconstruction of the 25 intensity‐modulated radiation therapy beams recorded at a certain gantry angle using the model of another gantry angle, combined with the correction method. Results For dose verification performed at a gantry angle identical to the commissioned model, the average y‐mean and y‐pass rate values (3% global dose, 2 mm, 10% isodose) were 0.37 ± 0.07 and 98.1, 95% CI [98.1 ± 2.4], respectively. The average dose difference at the reference point was −0.5% ± 1.8%. Verification at gantry angles different from the commissioned model (i.e., using the gantry angle dependent correction) reported 0.39 ± 0.08 and 97.6, 95% CI [96.9, 98.3] average y‐mean and y‐pass rate values. The average dose difference at the reference point was −0.1% ± 1.8%. Conclusion The EPID dosimetry back‐projection model was successfully adapted for the MR‐linac at gantry 0°, 90°, and 180°, accounting for the presence of the MRI housing between phantom (or patient) and the EPID. A method to account for the gantry angle dependence was also tested reporting similar results.

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Clinical Experience with Machine Log File Software for Volumetric-Modulated Arc Therapy Techniques

Cited by 17 publications

References 17 publications

Patient‐specific quality assurance using machine log files analysis for stereotactic body radiation therapy (SBRT)

Patient‐specific quality assurance using machine log files analysis for stereotactic body radiation therapy (SBRT)

Treatment plan verification: A review on the comparison of dose distributions

Two‐dimensional EPID dosimetry for an MR‐linac: Proof of concept

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