Intensity modulation with photons for benign intracranial tumours: A planning comparison of volumetric single arc, helical arc and fixed gantry techniques

Fogliata, Antonella; Clivio, Alessandro; Nicolini, G.; Vanetti, Eugenio; Cozzi, Luca

doi:10.1016/j.radonc.2008.07.021

Cited by 177 publications

(148 citation statements)

References 24 publications

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“…For studies on RapidArc, Cozzi et al ( 9 ) and Fogliata et al ( 10 ) reported that the performance provided by the RapidArc to be consistent at least with similar target coverage, as well as sparing OARs in cervix uteri cancer and small benign brain tumors. ( 8 , 11 , 59 ) Doornaert et al ( 20 ) showed that RapidArc achieved excellent target coverage and OARs sparing, with delivery completed in less than 3 min for HN cancer.…”

Section: Discussionmentioning

confidence: 99%

Comparative analysis of SmartArc‐based dual arc volumetric‐modulated arc radiotherapy (VMAT) versus intensity‐modulated radiotherapy (IMRT) for nasopharyngeal carcinoma

Lee

Chao

Ting

et al. 2011

J Applied Clin Med Phys

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The purpose of this study was to evaluate and quantify the planning performance of SmartArc‐based volumetric‐modulated arc radiotherapy (VMAT) versus fixed‐beam intensity‐modulated radiotherapy (IMRT) for nasopharyngeal carcinoma (NPC) using a sequential mode treatment plan. The plan quality and performance of dual arc‐VMAT (DA‐VMAT) using the Pinnacle3 Smart‐Arc system (clinical version 9.0; Philips, Fitchburg, WI, USA) were evaluated and compared with those of seven‐field (7F)‐IMRT in 18 consecutive NPC patients. Analysis parameters included the conformity index (CI) and homogeneity index (HI) for the planning target volume (PTV), maximum and mean dose, normal tissue complication probability (NTCP) for the specified organs at risk (OARs), and comprehensive quality index (CQI) for an overall evaluation in the 11 OARs. Treatment delivery time, monitor units per fraction (MU/fr), and gamma (Γ3mm,3%) evaluations were also analyzed. DA‐VMAT achieved similar target coverage and slightly better homogeneity than conventional 7F‐IMRT with a similar CI and HI. NTCP values were only significantly lower in the left parotid gland (for xerostomia) for DA‐VMAT plans. The mean value of CQI at 0.98±0.02 indicated a 2% benefit in sparing OARs by DA‐VMAT. The MU/fr used and average delivery times appeared to show improved efficiencies in DA‐VMAT. Each technique demonstrated high accuracy in dose delivery in terms of a high‐quality assurance (QA) passing rate (>98%) of the (Γ3mm,3%) criterion. The major difference between DA‐VMAT and 7F‐IMRT using a sequential mode for treating NPC cases appears to be improved efficiency, resulting in a faster delivery time and the use of fewer MU/fr.PACS number: 87.53.Tf, 87.55.x, 87.55.D, 87.55.dk

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Section: Discussionmentioning

confidence: 99%

Comparative analysis of SmartArc‐based dual arc volumetric‐modulated arc radiotherapy (VMAT) versus intensity‐modulated radiotherapy (IMRT) for nasopharyngeal carcinoma

Lee

Chao

Ting

et al. 2011

J Applied Clin Med Phys

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“…Further, a radiotherapy technique termed volumetric‐modulated arc therapy (VMAT) has been newly developed (2) . Some studies 3 , 4 have compared VMAT with IMRT in relation to target coverage, healthy tissue sparing, and treatment time. RapidArc (Varian Medical Systems, Palo Alto, CA) is a technology commercialized as a derivative of VMAT treatment planning and delivery.…”

Section: Introductionmentioning

confidence: 99%

Angular dependence correction of MatriXX and its application to composite dose verification

Shimohigashi

Araki

Tominaga

et al. 2012

J Applied Clin Med Phys

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We measured the angular dependence of central and off‐axis detectors in a 2D ionization chamber array, MatriXX, and applied correction factors (CFs) to improve the accuracy of composite dose verification of IMRT and VMAT. The MatriXX doses were measured with a 10° step for gantry angles (θ) of 0°–180°, and a 1° step for lateral angles of 90°–110° in a phantom, with a 30×10 cm2 field for 6 MV and 10 MV photons. The MatriXX doses were also calculated under the same conditions by the Monte Carlo (MC) algorithm. The CFs for the angular dependence of MatriXX were obtained as a function of θ from the ratios of MatriXX‐measured doses to MC‐calculated doses, and normalized at θ=0°. The corrected MatriXX were validated with different fields, various simple plans, and clinical treatment plans. The dose distributions were compared with those of MC calculations and film. The absolute doses were also compared with ionization chamber and MC‐calculated doses. The angular dependence of MatriXX showed over‐responses of up to 6% and 4% at θ=90° and under‐responses of up to 15% and 11% at 92°, and 8% and 5% at 180° for 6 MV and 10 MV photons, respectively. At 92°, the CFs for the off‐axis detectors were larger by up to 7% and 6% than those for the central detectors for 6 MV and 10 MV photons, respectively, and were within 2.5% at other gantry angles. For simple plans, MatriXX doses with angular correction were within 2% of those measured with the ionization chamber at the central axis and off‐axis. For clinical treatment plans, MatriXX with angular correction agreed well with dose distributions calculated by the treatment planning system (TPS) for gamma evaluation at 3% and 3 mm. The angular dependence corrections of MatriXX were useful in improving the measurement accuracy of composite dose verification of IMRT and VMAT.PACS number: 87.55.Qr, 87.56.Fc

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“…These delivery times are considerably less than usually 7 field ss-IMRT delivery times. This is because with VMAT the entire volume can be treated at one time which in turn means treatment times are not target size dependent as long as the whole target can be covered in a single field [9], [40]. Thus VMAT can allow more efficient treatment delivery that can lead to reduced patient discomfort, reduced intra-fractional motion and increased time for image guided radiotherapy.…”

Section: Discussionmentioning

confidence: 99%

Investigation of VMAT Algorithms and Dosimetry

Taqaddas

2013

Practical Radiation Oncology

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Abstract-Purpose: Planning and dosimetry of different VMAT algorithms (SmartArc, Ergo++, Autobeam) is compared with IMRT for Head and Neck Cancer patients. Modelling was performed to rule out the causes of discrepancies between planned and delivered dose.Methods: Five HNC patients previously treated with IMRT were re-planned with SmartArc (SA), Ergo++ and Autobeam. Plans were compared with each other and against IMRT and evaluated using DVHs for PTVs and OARs, delivery time, monitor units (MU) and dosimetric accuracy. Modelling of control point (CP) spacing, Leafend Separation and MLC/Aperture shape was performed to rule out causes of discrepancies between planned and delivered doses. Additionally estimated arc delivery times, overall plan generation times and effect of CP spacing and number of arcs on plan generation times were recorded.Results: Single arc SmartArc plans (SA4d) were generally better than IMRT and double arc plans (SA2Arcs) in terms of homogeneity and target coverage. Double arc plans seemed to have a positive role in achieving improved Conformity Index (CI) and better sparing of some Organs at Risk (OARs) compared to Step and Shoot IMRT (ss-IMRT) and SA4d. Overall Ergo++ plans achieved best CI for both PTVs. Dosimetric validation of all VMAT plans without modelling was found to be lower than ss-IMRT. Total MUs required for delivery were on average 19%, 30%, 10.6% and 6.5% lower than ss-IMRT for SA4d, SA2d (Single arc with 2 0 Gantry Spacing), SA2Arcs and Autobeam plans respectively. Autobeam was most efficient in terms of actual treatment delivery times whereas Ergo++ plans took longest to deliver.Conclusion: Overall SA single arc plans on average achieved best target coverage and homogeneity for both PTVs. SA2Arc plans showed improved CI and some OARs sparing. Very good dosimetric results were achieved with modelling. Ergo++ plans achieved best CI. Autobeam resulted in fastest treatment delivery times.

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Intensity modulation with photons for benign intracranial tumours: A planning comparison of volumetric single arc, helical arc and fixed gantry techniques

Cited by 177 publications

References 24 publications

Comparative analysis of SmartArc‐based dual arc volumetric‐modulated arc radiotherapy (VMAT) versus intensity‐modulated radiotherapy (IMRT) for nasopharyngeal carcinoma

Comparative analysis of SmartArc‐based dual arc volumetric‐modulated arc radiotherapy (VMAT) versus intensity‐modulated radiotherapy (IMRT) for nasopharyngeal carcinoma

Angular dependence correction of MatriXX and its application to composite dose verification

Investigation of VMAT Algorithms and Dosimetry

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