Investigation of VMAT Algorithms and Dosimetry

Taqaddas, A.

doi:10.1016/j.prro.2013.01.068

Cited by 3 publications

(2 citation statements)

References 35 publications

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“…In the years since the near‐ubiquitous TG‐142 value was established, a new radiotherapy technique has increased in prevalence; volumetric modulated arc therapy (VMAT) is a modern arc‐based therapy characterized by simultaneous variation of three parameters: dose rate, beam aperture shape and gantry rotation speed . VMAT offers the conformality and plan quality of IMRT while offering some improvements; most notably a reduction in monitor units (MU) and a reduced treatment delivery time …”

Section: Introductionmentioning

confidence: 99%

“…11,12 VMAT offers the conformality and plan quality of IMRT while offering some improvements; most notably a reduction in monitor units (MU) and a reduced treatment delivery time. [13][14][15] The rise of VMAT warrants another look at the established annual QA peak isocenter shift tolerance value, as it is reasonable to suspect that an arc-based therapy may differ in sensitivity to isocenter deviation than one consisting of static beams.…”

Section: Introductionmentioning

confidence: 99%

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Evaluation of the Impact of the Linac MLC and Gantry Sag in volumetric modulated arc therapy

et al. 2019

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Purpose Mechanical sag in the radiotherapy linear accelerator gantry and multi‐leaf collimator (MLC) carriage effectively causes systematic deviations in the isocenter with respect to gantry angle. To minimize the impact of this error on treatment, a tolerance value of a 1‐mm mechanical isocenter shift is commonly accepted for intensity‐modulated radiation therapy quality assurance (QA). However, this tolerance value has not been firmly established for volumetric modulated arc therapy (VMAT) treatments. The purpose of this study is therefore to evaluate the impact of gantry and MLC carriage sag on VMAT clinical performance. Methods A published dataset of Elekta and Varian sag measurements served as a starting point for the investigation. Typical sag profiles were chosen and modeled as continuous isocenter deviations in three dimensions. The data were then incorporated into existing Digital Imaging and Communications in Medicine protocol, extended for radiotherapy plans via a “beam‐splitting” algorithm. Three treatment sites were investigated in parallel: head and neck, prostate, and prostate with surrounding lymph nodes. Monte Carlo‐simulated dose distributions were obtained for varying magnifications of the modeled sag. The resulting dose distributions, including that for no error, were compared qualitatively and quantitatively, against multiple metrics. Results The dose‐volume histograms (DVHs) for all plans exhibited a decrease in planning target volume (PTV) dose uniformity with increasing sag magnification, whereas dose to organs at risk exhibited no coherent trend. The prostate plan was shown to be the most vulnerable to mechanical sag across all considered metrics. However, all plans with peak isocenter deviation less than 1 mm were well within typical cutoff points for each metric. Conclusions All avenues of investigation presented substantiate the commonly accepted tolerance value of a 1‐mm peak isocenter shift in annual linac QA.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Evaluation of the Impact of the Linac MLC and Gantry Sag in volumetric modulated arc therapy

et al. 2019

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Comparison of volumetric-modulated arc therapy and intensity-modulated radiation therapy prostate cancer plans accounting for cold spots

Nguyen

Arimura

Asamura

et al. 2019

Radiol Phys Technol

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The dosimetric impact of different photon beam energy on RapidArc radiotherapy planning for cervix carcinoma

Kumar¹,

Yadav²,

Raman³

et al. 2015

J Med Phys

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The main purpose of this study is to know the effect of three different photon energies viz., 6, 10, and 15 mega voltage (MV) on RapidArc (RA) planning for deep-seated cervix tumor and to develop clinically acceptable RA plans with suitable photon energy. RA plans were generated for 6, 10, and 15 MV photon energies for twenty patients reported with cervix carcinoma. RA plans were evaluated in terms of planning target volume (PTV) coverage, dose to organs at risk (OARs), conformity index (CI), homogeneity index (HI), gradient measure, external volume index of dose distribution produced, total number of monitor units (MUs), nontumor integral dose (ID), and low dose volume of normal tissue. A two-sample paired t-test was performed to compare the dosimetric parameters of RA plans. Irrespective of photon energy used for RA planning, plans were dosimetrically similar in terms of PTV coverage, OARs sparing, CI and HI. The numbers of MUs were 13.4 ± 1.4% and 18.2 ± 1.5% higher and IDs were 2.7 ± 0.8% and 3.7 ± 0.9% higher in 6 MV plans in comparison to that in the 10 and 15 MV plans, respectively. V1Gy, V2Gy, V3Gy, and V4Gy were higher in 6 MV plans in comparison to that in 10 and 15 MV plans. Based on this study, 6 MV photon beam is a good choice for RA planning in case of cervix carcinoma, as it does not deliver additional exposure to patients caused by photoneutrons produced in high energy beams.

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Investigation of VMAT Algorithms and Dosimetry

Cited by 3 publications

References 35 publications

Evaluation of the Impact of the Linac MLC and Gantry Sag in volumetric modulated arc therapy

Evaluation of the Impact of the Linac MLC and Gantry Sag in volumetric modulated arc therapy

Comparison of volumetric-modulated arc therapy and intensity-modulated radiation therapy prostate cancer plans accounting for cold spots

The dosimetric impact of different photon beam energy on RapidArc radiotherapy planning for cervix carcinoma

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