Volumetric Modulated Arc Therapy Technology Research Articles

Comparison of Volumetric Modulated Arc Therapy (VMAT) and Conventional Intensity-Modulated Radiotherapy (IMRT) for Locally Advanced Head and Neck Squamous Cell Carcinoma: A Retrospective Cohort Study.

Purpose This study examines the outcomes of locally advanced head and neck squamous cell carcinoma (HNSCC) following the adoption of conventional intensity-modulated radiotherapy (cIMRT) and volumetric-modulated arc therapy (VMAT) over a decade. The region under study has higher comorbidities associated with increased HNSCC incidence and poorer prognosis. Materials and methods A 10-year retrospective review of electronic medical records included 296 patients with stage III, IVA, and IVB HNSCC (American Joint Committee on Cancer, Seventh edition). Survival outcomes were compared between VMAT and cIMRT using Kaplan-Meier survival curves and adjusted for relevant demographic factors using Cox's proportional hazards model. Analysis was performed using R software(R Foundation, Vienna, Austria). Results The median age of the cohort was 63 years, comprising of 80% males. The oropharynx was the most common primary tumor site. 264 (89%) received 50Gy or higher dose radiation by either cIMRT (22%) or VMAT (67%). At five years, locoregional control (LC) and overall survival (OS) rates were 79.5% and 56.7%, respectively. VMAT showed a significant improvement in five-year OS (63.4% versus 43.8% for cIMRT, p=0.0023)but no significant difference in five-year LC (81% VMAT versus 74.5% cIMRT, p=0.17). Grade 3-4 acute toxicity was observed in 22% of patients. Conclusions VMAT and cIMRT demonstrated excellent LC in locally advanced HNSCCdespite high comorbidity rates. Notably, VMAT was associated with significantly better OS compared to cIMRT. These outcomes surpass historical data, suggesting that VMAT technology may lead to improved patient outcomes. However, larger randomized controlled trials and dosimetric studies are needed to confirm these findings.

Extended Pleurectomy/Decortication for Malignant Pleural Mesothelioma: Humanitas's Experience.

Background: We analysed a series of malignant pleural mesothelioma (MPM) patients who consecutively underwent extended Pleurectomy/Decortication (eP/D) in a centre with a high level of thoracic surgery experience (IRCCS Humanitas Research Hospital) to explore postoperative morbidity and mortality, pattern of recurrence and survival. Methods: A retrospective analysis was performed on MPM patients underwent eP/D in our centre from 2010 to 2021. All patients were identified from our departmental database. Postoperative complications were scored according to Clavien–Dindo criteria. Survival analysis was performed by the Kaplan–Meier methods and Cox multivariable analysis. Results: Eighty-five patients underwent extended pleurectomy decortication (eP/D) during study period. Macroscopical residual disease (R2) was reported in one case. A neoadjuvant chemotherapy regiment was administrated in 88% of the surgical cohort. A complete trimodality treatment including induction with platinum agents and pemetrexed, radical cytoreductive surgery and volumetric modulated arc therapy technology (VMAT) could be administered in 63 patients (74%). Postoperative morbidity rate was 54.11%, major complications (defined as Clavien–Dindo ≥ 3) were reported in 11 patients (12.9%). Thirty-day mortality and 90-day mortality were, respectively, 2.35% and 3.53%. Median disease-free and overall survival were, respectively, 13.7 and 25.5 months. The occurrence of major complications (Clavien–Dindo ≥ 3), operative time, pT3–T4, pathological node involvement (pN+) were prognostic factors associated with worse survival. Conclusions: In our experience, eP/D is a well-tolerated procedure with acceptable mortality and morbidity, allowing for the administration of trimodality regimens in most patients. eP/D offered in a multimodality treatment setting have satisfactory long term oncological results. To obtain best oncological results the goal of surgery should be macroscopic complete resection in carefully selected patients (clinical N0).

Cardiac Dose Control and Optimization Strategy for Left Breast Cancer Radiotherapy With Non-Uniform VMAT Technology.

Purpose: A novel in-house technology “Non-Uniform VMAT (NU-VMAT)” was developed for automated cardiac dose reduction and treatment planning optimization in the left breast radiotherapy. Methods: The NU-VMAT model based on IGM (gantry MLC Movement coefficient index) was established to optimize the volumetric modulated arc therapy (VMAT) MLC movement and modulation intensity in certain gantry angles. The ESAPI embedded in Eclipse® was employed to connect TPS and the optimization program via I/O relevant DICOM RT files. The adjuvant whole-breast radiotherapy of 14 patients with left breast cancer was replanned using our NU-VMAT technology in comparison with VMAT and IMRT technology. Dosimetric parameters including D1%, D99%, and Dmean of PTV, V5, V10, and V20 of ipisilateral lung, V5, D20, D30, and Dmean of heart, monitor units (MUs), and delivery time derived from IMRT, VMAT, and NU-VMAT plans were evaluated for plan quality and delivery efficiency. The quality assurance (QA) was conducted using both point-dose and planar-dose measurements for all treatment plans. Results: The IGM−NU−VMAT curves with plan optimization (range from 50% to 147%) were converged more significantly than IGM-VMAT curves (range from 0% to 297%). The dose distribution requirements of the target and normal tissues could be met using IMRT, VMAT, or NU-VMAT; the lowest Dmean was achieved in NU-VMAT plans (5.38 ± 0.46 Gy vs 5.63 ± 0.61 Gy in IMRT and 7.95 ± 0.52 Gy in VMAT plans). Statistically significant differences were found in terms of delivery time and MU when comparing IMRT with VMAT and NU-VMAT plans (P < .05). In comparison with IMRT plans, the MU and delivery time in NU-VMAT plans dramatically decreased by 69.8% and 28.4%, respectively. Moreover, NU-VMAT plans showed a high gamma passing rate (96.5% ± 1.11) in plane dose verification and minimal dose difference (2.4% ± 0.19) in point absolute dose verification. Conclusion: Our non-uniform VMAT facilitated the treatment strategy optimization for left breast cancer radiotherapy with dosimetric advantage in cardiac dose reduction and delivery efficiency in comparison with the conventional VMAT and IMRT.

Volumetric Modulated Arc Therapy (VMAT): A modern radiotherapy technique - A single institutional experience.

Objective:To evaluate VMAT plans for conformity and homogeneity of radiation dose to the target in order to share our experience as a pioneering institute to use VMAT technology in Pakistan.Methods:Since December 2014 to January 2018, 530 patients of various anatomical sites were treated by VMAT technique at Neurospinal Cancer Care Institute (NCCI) Karachi Pakistan. ERGO++ planning system (Version 1.7.2) was used to develop VMAT plans with single or multiple arcs by the rotation of couch and gantry. The plans were evaluated by calculating Conformity Index (CI) and Homogeneity Index (HI) and critical organ (OARs) doses of individual tumor sites.Results:The average CI of various sites was 1.4 (range: 1.0–2.0) and average HI of various sites was 1.20 (range: 1.07–1.374), respective critical organ doses were adequately achieved.Conclusions:VMAT treatment planning technique showed good conformal and homogeneous target coverage with sparing of organs at risk and reduced treatment delivery time. With these features, safety of VMAT technique may allow its routine clinical use, though it is still under investigation in many areas.

Analyzation of the local confidence limits for IMRT and VMAT based on AAPM TG119 report

The aim of this study was to generate a local confidence limit (CL) for intensity-modulated radiation therapy (IMRT) and volumetric-modulated arc therapy (VMAT) techniques for Clinac IX linear accelerator using the American Association of Physicists in Medicine (AAPM) Task Group (TG119) protocol. The results were compared with the published studies to test the capability and quality of the VMAT technique in our clinic. We used TG119 cases to create plans for IMRT and VMAT in Eclipse Treatment Planning System for Clinac IX using 6 MV and 10 MV photons. Two preliminary and 5 clinical test cases were created based on the dose prescriptions and planning objectives provided by TG119. Verification plans were created in a planning slab phantom, 2D matrix dosimetry system (MatriXX) with multicube phantom and a volumetric phantom (Delta4). Radiation absorption doses to high-dose points in the planning target volume region and low-dose points in avoidance structures were measured with a 0.125 cc semiflex thimble ionization chamber (PTW). The measured and planned doses were normalized with respect to their prescription doses and intercompared with each other. The gamma analysis was carried out for MatriXX and Delta4 adopting the acceptance criteria of 3% dose difference and 3 mm distance to agreement with 10% threshold dose, respectively. The local CLs with the bench mark set by TG119 were obtained for point, composite planar and field-by-field measurements for IMRT and VMAT with different energies. In this study, the CLs for the high-dose regions of IMRT with 6 MV and 10 MV were 0.025 and 0.014, respectively. For VMAT, they were 0.032 and 0.018. The counterpart CL was 0.045 in TG119. And in organs at risk region, the CLs of IMRT with 6 MV and 10 MV beam were 0.022 and 0.019, respectively, with the counterpart CL indicated by TG119 was 0.047. For VMAT with 6 MV and 10 MV photon beams, the CLs were measured 0.030 and 0.027 with Delta4, respectively. The CLs of the maximum gamma passing for all values were 2.0 in 6 MV VMAT plan, which however recommended in TG119 was 12.4. The data presented here showed all the CLs in our clinic meet the criteria of TG119 report well. All these local CLs reached the goals mentioned in AAPM TG119, which indicated that the local clinic had commissioned IMRT and VMAT techniques with adequate accuracy. Prior to the clinical application practice, it is essential to verify with the TG119 test cases for IMRT and VMAT, which allows us to better understand the basic capability of VMAT technology.

Effect of translational couch shifts in volumetric modulated arc therapy (VMAT) plans and predicting its impact on daily dose delivery

AbstractAimTo evaluate the impact of couch translational shifts on dose–volume histogram (DVH) and radiobiological parameters [tumour control probability (TCP), equivalent uniform dose (EUD) and normal tissue complication probability (NTCP)] of volumetric modulated arc therapy (VMAT) plans and to develop a simple and swift method to predict the same online, on a daily basis.MethodsIn total, ten prostate patients treated with VMAT technology were selected for this study. The plans were generated using Eclipse TPS and delivered using Clinac ix LINAC equipped with a Millennium 120 multileaf collimator. In order to find the effect of systematic translational couch shifts on the DVH and radiobiological parameters, errors were introduced in the clinically accepted base plan with an increment of 1 mm and up to 5 mm from the iso-centre in both positive and negative directions of each of the three axis, x [right–left (R-L)], y [superior–inferior (S-I)] and z [anterior–posterior (A-P)]. The percentages of difference in these parameters (∆D, ∆TCP, ∆EUD and ∆NTCP) were analyzed between the base plan and the error introduced plans. DVHs of the base plan and the error plans were imported into the MATLAB software (R2013a) and an in-house MATLAB code was generated to find the best curve fitted polynomial functions for each point on the DVH, there by generating predicted DVH for planning target volume (PTV), clinical target volume (CTV) and organs at risks (OARs). Functions f(x, vj), f(y, vj) and f(z, vj) were found to represent the variation in the dose when there are couch translation shifts in R-L, S-I and A-P directions, respectively. The validation of this method was done by introducing daily couch shifts and comparing the treatment planning system (TPS) generated DVHs and radiobiological parameters with MATLAB code predicted parameters.ResultsIt was noted that the variations in the dose to the CTV, due to both systematic and random shifts, were very small. For CTV and PTV, the maximum variations in both DVH and radiobiological parameters were observed in the S-I direction than in the A-P or R-L directions. ∆V70 Gy and ∆V60 Gy of the bladder varied more due to S-I shift whereas, ∆V40 Gy, ∆EUD and ∆NTCP varied due to A-P shifts. All the parameters in rectum were most affected by the A-P shifts than the shifts in other two directions. The maximum percentage of deviation between the TPS calculated and MATLAB predicted DVHs of plans were calculated for targets and OARs and were found to be less than 0·5%.ConclusionThe variations in the parameters depend upon the direction and magnitude of the shift. The DVH curves generated by the TPS and predicted by the MATLAB showed good correlation.

Comparative of radiation technology of IMRT, VMAT and HT applied to lung cancer stereotactic body radiotherapy

The radiation techniques for lung cancer stereotactic body radiotherapy (SBRT) include intensity modulated radiation therapy (IMRT), volumetric modulated arc therapy (VMAT) and helical tomotherapy (HT). Concerning the target conformity and dosimetric homogeneity index, HT and VMAT technologies are superior to IMRT. On the contrary, HT and VMAT technology can increase low dose area irradiated of lung. Comparing to other two technologies, VMAT can obviously shorten the treatment time. At present, there is no consensus how to choose individually optimized radiotherapy technology for different location and stages lung tumors. Key words: Lung tumors; Radiotherapy; Stereotactic body radiotherapy

Dosimetric comparison of head and neck cancer patients planned with multivendor volumetric modulated arc therapy technology.

Purpose of this study is to dosimetrically compare head and neck (H and N) cancer patients planned with multivendor volumetric modulated arc therapy (VMAT) technology. VMAT treatment planning can be done using biological (treatment planning system [TPSB]: Monaco) or physical (TPSP: Eclipse)-based cost function optimization techniques. Planning and dosimetric comparisons were done in both techniques for H and N cases. Twenty H and N patients were retrospectively selected for this study. VMAT plans were generated using TPSP (V11.0) and TPSB (V3.0) TPS. A total dose of 66 Gy (planning target volume 1 [PTV1]) and 60 Gy (PTV2) were prescribed to primary and nodal target volumes. Clinical planning objectives were achieved by both the optimization techniques. Dosimetric parameters were calculated for PTVs, and quantitative analyses were performed for critical organs. Monitor units were compared between two TPSs, and gamma analysis was performed between I'matriXX measured and TPS calculated. Clinically, acceptable VMAT plans showed comparable dose distributions between TPSB and TPSP optimization techniques. Comparison of mean dose, homogeneity index, and conformity index for PTV1 showed no statistical difference (P - 0.922, 0.096, and 0.097); however, in PTV2 statistically significant difference was observed (P - 0.024, 0.008, and 0.002) between TPSB and TPSP. TPSB optimization showed statistically significant superiority for spinal cord and brainstem (D1% P - 0.0078, 0.00002) whereas improved parotid sparing was observed in TPSP optimization (mean dose P - 0.00205). Gamma analysis illustrated that both systems could produce clinically deliverable plans. VMAT plans by TPSP and TPSB offered clinically acceptable dose distributions. TPSB-based optimization showed enhanced sparing of serial organs whereas TPSP-based optimization showed superior sparing of parallel organs.

Neurovascular bundle-sparing radiotherapy for prostate cancer using MRI-CT registration: A dosimetric feasibility study.

128 Background: Sexual dysfunction after radiotherapy for prostate cancer remains an important late adverse toxicity. The neurovascular bundles (NVB) that lie postero-laterally to the prostate are typically spared during prostatectomy, but in traditional radiotherapy planning they are not contoured as an organ-at-risk with dose constraints. Our goal was to determine the feasibility in sparing the NVB while still delivering adequate dose to the prostate. Methods: Twelve consecutive patients with intermediate- or high-risk prostate cancer (with no gross disease within 2mm of either NVB) who were treated with external beam radiotherapy, with the same primary PTV margins, to a dose of 79.2 Gy were evaluated. Pelvic MRI and simulation CT scans were registered using dedicated software to allow for bilateral NVB target delineation on T2-weighted MRI. A volumetric modulated arc therapy (VMAT) plan was generated using the NVB bilaterally with 2mm margin as an organ to spare (with goal of reducing V70Gy by 30%) and compared to the patient’s delivered plan. Dose-volume histogram (DVH) endpoints for NVB, rectum, bladder, and PTV79.2 were compared between the two plans using a 2-tailed paired t-test. Results: The V70 for the NVB was significantly lower on the NVB sparing plan (p &lt;0.01), while rectum and bladder endpoints were similar. Target V100% was lower (but still &gt; 95%), and V105 was higher for the NVB Sparing plans (p &lt;0.01). The table summarizes the DVH comparisons between the two plans. Conclusions: “NVB-sparing” radiotherapy is dosimetrically feasible using VMAT technology; target coverage is acceptable without increased dose to other normal structures, but with higher target dose inhomogeneity. The clinical impact of “NVH-sparing” radiotherapy is currently under study at our institution. [Table: see text]

Neurovascular bundle–sparing radiotherapy for prostate cancer using MRI-CT registration: A dosimetric feasibility study

PurposeSexual dysfunction after radiotherapy for prostate cancer remains an important late adverse toxicity. The neurovascular bundles (NVB) that lie posterolaterally to the prostate are typically spared during prostatectomy, but in traditional radiotherapy planning they are not contoured as an organ-at-risk with dose constraints. Our goal was to determine the dosimetric feasibility of “NVB-sparing” prostate radiotherapy while still delivering adequate dose to the prostate. MethodsTwenty-five consecutive patients with prostate cancer (with no extraprostatic disease on pelvic magnetic resonance imaging [MRI]) who that were treated with external beam radiotherapy, with the same primary planning target volume margins, to a dose of 79.2 Gy were evaluated. Pelvic MRI and simulation computed tomography scans were registered using dedicated software to allow for bilateral NVB target delineation on T2-weighted MRI. A volumetric modulated arc therapy plan was generated using the NVB bilaterally with 2 mm margin as an organ to spare and compared to the patient’s previously delivered plan. Dose-volume histogram endpoints for NVB, rectum, bladder, and planning target volume 79.2 were compared between the 2 plans using a 2-tailed paired t-test. ResultsThe V70 for the NVB was significantly lower on the NVB-sparing plan (p <0.01), while rectum and bladder endpoints were similar. Target V100% was similar but V105% was higher for the NVB-sparing plans (p <0.01). Conclusions“NVB-sparing” radiotherapy is dosimetrically feasible using CT-MRI registration, and for volumetric modulated arc therapy technology — target coverage is acceptable without increased dose to other normal structures, but with higher target dose inhomogeneity. The clinical impact of “NVB-sparing” radiotherapy is currently under study at our institution.

Clinical utility of RapidArc™ radiotherapy technology.

RapidArc™ is a radiation technique that delivers highly conformal dose distributions through the complete rotation (360°) and speed variation of the linear accelerator gantry. This technique, called volumetric modulated arc therapy (VMAT), compared with conventional radiotherapy techniques, can achieve high-target volume coverage and sparing damage to normal tissues. RapidArc delivers precise dose distribution and conformity similar to or greater than intensity-modulated radiation therapy in a short time, generally a few minutes, to which image-guided radiation therapy is added. RapidArc has become a currently used technology in many centers, which use RapidArc technology to treat a large number of patients. Large and small hospitals use it to treat the most challenging cases, but more and more frequently for the most common cancers. The clinical use of RapidArc and VMAT technology is constantly growing. At present, a limited number of clinical data are published, mostly concerning planning and feasibility studies. Clinical outcome data are increasing for a few tumor sites, even if only a little. The purpose of this work is to discuss the current status of VMAT techniques in clinical use through a review of the published data of planning systems and clinical outcomes in several tumor sites. The study consisted of a systematic review based on analysis of manuscripts retrieved from the PubMed, BioMed Central, and Scopus databases by searching for the keywords “RapidArc”, “Volumetric modulated arc radiotherapy”, and “Intensity-modulated radiotherapy”.

Quality control of linac in daily volumetric-modulated arc therapy

Objective To verify the daily delivery accuracy of volumetric-modulated arc therapy(VMAT) and achieve the process quality control (PQC) of linac using statistical process control (SPC)technology. Methods The log files of all treatments were taken out from the linac system. An in-house software which created by Matlab 7.14 was used to analyze the daily parameters accuracy and the mechanism and dose delivery accuracy of the linac for each VMAT, and an daily evaluation report was automatically created for the linac. The stability of the linac and the deviation of the delivery accuracy for various cancer sites were also analyzed. To achieve the process quality control of linac using SPC technology, the control limit of each parameter was calculated by Johnson alternation and the single value control charts were drawn. Results 76 patients mainly with nasopharyngeal carcinoma, cervical carcinoma, rectal cancer and laryngeal cancer, got the treatment daily with VMAT technology, and a total of 2 446 arcs were delivered by the linac in continuous 16 days. The gantry angle error, y and x collimator position error, MLC leaf position error and dose delivery error were 0.49°, 0.09 mm, 0.38 mm, 0.31 mm, 0.05 MU, respectively. Compare to the nasopharynx, uteri, rectal and larynx cancer, it can be seen that the variation factors of dose delivery and gantry angle errors for various cancer sites were higher, which was 8.10%and 4.54%, respectively. Through the process quality control of the linac, it was found that all the parameters were in control. While some abnormal points arose (the error was greater than UCL) , and the ratio of the gantry angle which was out of control (0.45%) was the highest in all parameters. Conclusions linac delivery accuracy could be monitored and verified during the whole VMAT treatment for each patient, and the daily running condition of linac could be monitored. Through the introduction of SPC technology and the control charts, the process quality control of linac in VMAT could be achieved. It is a financial and valid method for the daily quality assurance of linac. Key words: Volumetric-modulated arc therapy; linac; Statistical process control; Process quality control; Position accuracy

Dosimetric comparison of 3D conformal, IMRT, and V-MAT techniques for accelerated partial-breast irradiation (APBI)

The purpose is to dosimetrically compare the following 3 delivery techniques: 3-dimensional conformal radiation therapy (3D-CRT), intensity-modulated arc therapy (IMRT), and volumetric-modulated arc therapy (V-MAT) in the treatment of accelerated partial-breast irradiation (APBI). Overall, 16 patients with T1/2N0 breast cancer were treated with 3D-CRT (multiple, noncoplanar photon fields) on the RTOG 0413 partial-breast trial. These cases were subsequently replanned using static gantry IMRT and V-MAT technology to understand dosimetric differences among these 3 techniques. Several dosimetric parameters were used in plan quality evaluation, including dose conformity index (CI) and dose-volume histogram analysis of normal tissue coverage. Quality assurance studies including gamma analysis were performed to compare the measured and calculated dose distributions. The IMRT and V-MAT plans gave more conformal target dose distributions than the 3D-CRT plans (p < 0.05 in CI). The volume of ipsilateral breast receiving 5 and 10Gy was significantly less using the V-MAT technique than with either 3D-CRT or IMRT (p < 0.05). The maximum lung dose and the ipsilateral lung volume receiving 10 (V10) or 20Gy (V20) were significantly less with both V-MAT and IMRT (p < 0.05). The IMRT technique was superior to 3D-CRT and V-MAT of low dose distributions in ipsilateral lung (p < 0.05 in V5 and D5). The total mean monitor units (MUs) for V-MAT (621.0 ± 111.9) were 12.2% less than those for 3D-CRT (707.3 ± 130.9) and 46.5% less than those for IMRT (1161.4 ± 315.6) (p < 0.05). The average machine delivery time was 1.5 ± 0.2 minutes for the V-MAT plans, 7.0 ± 1.6 minutes for the 3D-CRT plans, and 11.5 ± 1.9 minutes for the IMRT plans, demonstrating much less delivery time for V-MAT. Based on this preliminary study, V-MAT and IMRT techniques offer improved dose conformity as compared with 3D-CRT techniques without increasing dose to the ipsilateral lung. In terms of MU and delivery time, V-MAT is significantly more efficient for APBI than for conventional 3D-CRT and static-beam IMRT.

SU‐E‐T‐622: Feasibility of Partial Volumetric Modulated Arc Therapy for Boost Treatment of Breast Cancer

Purpose: To evaluate the possible dosimetric advantage of volumetric modulated arc therapy (VMAT) over conventional 3D conformal therapy for left breast tumor bed boost treatment. Methods: Ten patients were retrospectively planned with VMAT technology for treatment of left breast after lumpectomy. 6 patients were simulated under deep inspiration breath hold, 4 patients were free breath. In each plan, a partial ARC of 200° to 220° was used. All VMAT plans were normalized to deliver 100% of the 16Gy in 8 fractions prescription dose to 95% of PTV volume. The plans were evaluated by calculation of heart maximum dose (Dmax_heart), percentage of lung volume receiving 10% of prescribed dose (V10_lung), percentage of ipsilateral breast receiving 50% of prescribed dose (V50_breast), maximum dose (Dmax), and the location of hot spot. These dosimetric parameters were compared with those for clinical plans using conventional 3D conformal technique. Results: For these ten patients (mean breast volume 1198 cc, mean boost PTV 161 cc), the mean dosimetric parameters for ARC plans/3D plans were 8.8%/28.5% of prescription dose for Dmax_heart, 5.4%/17.7% of total lung volume for V10_lung, 35.8%/40.0% of ipsilateral breast volume for V50_breast, 111.2%/111.6% of prescription dose for Dmax. Hot spots were located inside PTV in all 10 cases for ARC plans, but only in 6 out of 10 cases for 3D conformal plans. Conclusion: Initial results suggest that partial arc VMAT plans have dosimetric advantages for breast boost treatment. The plan quality was superior to conventional 3D conformal plans. In addition, with a template of standardized ARC beam arrangement and dose constraints for optimization, treatment planning and delivery for breast tumor bed boost can be more efficient.

Assessing the Feasibility of using Volumetric Modulated Arc Therapy Technology to Increase the Throughput and Quality of Radiotherapy in Developing Countries

Assessing the Feasibility of using Volumetric Modulated Arc Therapy Technology to Increase the Throughput and Quality of Radiotherapy in Developing Countries

Impact of Volumetric Modulated Arc Therapy Technique on Treatment With Partial Breast Irradiation

To investigate the technical feasibility of volumetric modulated arc therapy (V-MAT) in the delivery of partial breast irradiation (PBI). V-MAT and the standard, three-dimensional conformal radiotherapy (3D-CRT), were compared retrospectively in 8 patients previously treated with PBI. These patients' plans were replanned with a single partial arc using V-MAT that included partial blocking to minimize normal tissue dose. Dosimetric parameters were calculated to evaluate plan quality. Quality assurance studies included verifying both the point and the multiple planar doses. Total monitor units and delivery time were also evaluated, and collision clearance was analyzed. Volumes of ipsilateral lung irradiated to 10 Gy (V10) and 20 Gy (V20) by V-MAT were significantly less than those of 3D-CRT (p = 0.03 for V10 and p = 0.025 for V20). The volume of ipsilateral breast irradiated to 5 Gy was significantly less by using V-MAT than with 3D-CRT (p = 0.02), with a ratio of integrated dose of <1.00. The total mean monitor units (489 +/- 38) for V-MAT were significantly less than those for 3D-CRT (634 +/- 123) (p = 0.017), with a 23% reduction. The average machine delivery time was 1.21 +/- 0.10 min for the V-MAT plans and 6.28 +/- 1.40 min for the 3D-CRT plans, resulting in a reduction factor of 80.1%. The conformity indexes were 1.3 in the V-MAT plans and 1.5 in the 3D-CRT plans (p = 0.102). V-MAT technology is feasible for PBI patients. Compared to a conventional 3D-CRT technique, it is more efficient, offers equivalent or better dose conformity, delivers lower doses to the ipsilateral lung and breast, and may potentially reduce intrafractional motion.

Sci-Thurs PM: Planning-12: Efficient Treatment Delivery of Lung Stereotactic Body Radiation Therapy (SBRT) Using Volumetric Modulated Arc Therapy (VMAT)

This study investigates the potential of VMAT technology for treatment planning of non-small lung (NSLC) cancer. VMAT plans were generated for patients previously treated with SBRT for NSLC. When comparing the 3d-conformal clinical plans and VMAT plans using two arcs, the later showed improved conformality: the 30Gy volume was reduced by 12% and the maximum dose at 2cm from the PTV decreased on average by 18%. For the NSCL treatments, a five-fold reduction in treatment delivery times using VMAT is also predicted.