Modeling the target dose fall-off in IMRT and VMAT planning techniques for cervical SBRT

Delgado, A. Brito; Cohen, David; Eng, Tony Y.; Stanley, Dennis N.; Shi, Zhicai; Charlton, M. A.; Gutiérrez, Alonso N.

doi:10.1016/j.meddos.2017.07.009

Cited by 5 publications

(8 citation statements)

References 34 publications

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“…This shows that our results are almost consistent with those of Hoffman et al. Some other studies have also concluded a positive correlation between dose gradient and target volume ( 7 , 13 , 14 ), which agrees with our results.…”

Section: Discussionsupporting

confidence: 94%

“…11), finding that the maximum and average analytic GM differences between the two studies were 0.10 and 0.063 cm, respectively. This shows that our results are almost consistent with those of Hoffman et al Some other studies have also concluded a positive correlation between dose gradient and target volume (7,13,14), which agrees with our results.…”

Section: Discussionsupporting

confidence: 94%

“…In order to achieve a therapeutic effect similar to surgery, a highly conformal SBRT treatment plan needs to give the tumor high-dose precise ablation while minimizing organs at risk (OARs) damage, which requires a sharp dose gradient nearly isotropically around the target (1,2,(6)(7)(8). In clinical practice, the targets of different patients are various, and the dose gradient largely depends on the individualized geometric characteristics of the target (7,(9)(10)(11)(12)(13).…”

Section: Introductionmentioning

confidence: 99%

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How Does the Gradient Measure of the Lung SBRT Treatment Plan Depend on the Tumor Volume and Shape?

et al. 2021

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PurposeGradient measure (GM) is a critical index related to normal tissue sparing in radiosurgery. This study aims to describe the dependence of GM on target volume and target shape for lung stereotactic body radiation therapy (SBRT) treatment plans.MethodsA total of 307 peripheral and 119 central lung SBRT treatment plans were enrolled for this study. A least-squares regression was used for data analysis. First, the equations with different functional forms were established to determine the dependence of GM on a univariaty (VP or Sp) and bivariaty (VP and Sp), respectively. Then, the correlation coefficients and p-values of variables for all equations were compared and analyzed to determine the dependence of GM on PTV volume (VP) and sphericity (Sp).ResultsThe power equations had the highest coefficient of determination (R2) in the dependence results of GM on univariate VP. The equations were GM=0.674VP0.178 and GM=0.660VP0.185 for peripheral and central lesions, respectively. On the other hand, the R2 of all functional forms were less than 0.25 when the relationship of GM versus univariate Sp was analyzed. Similarly, the power equation also obtained the highest R2 in bivariaty VP and Sp analysis, whether for central or peripheral. However, the R2 of the bivariate equations were not improved compared with those of univariate equations. Moreover, the p-values of the variable Sp were greater than 0.05.ConclusionsThe GM of the lung SBRT plan is shape-independent and volume-dependent. The dependence of GM on PTV volume for peripheral and central lung cancer can be described by two different power equations. The results of this study can be used as a potential tool to assist dosimetric quality control during the radiosurgery process.

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Section: Discussionsupporting

confidence: 94%

Section: Discussionsupporting

confidence: 94%

Section: Introductionmentioning

confidence: 99%

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How Does the Gradient Measure of the Lung SBRT Treatment Plan Depend on the Tumor Volume and Shape?

et al. 2021

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“…Delgado et al evaluated the target dose fall-off in IMRT and VMAT planning techniques for cervical SBRT through analyzing R 50% and found that VMAT 3-arc 10-MV appears to provide the best dose fall-off than IMRT. 11 However, there have been few research studies comparing the dose fall-off using VMAT and IMRT treatment plans for lung tumors. In the present study, VMAT offered an obvious reduction of R 50% compared to IMRT technique, whereas the values of R 50% using 6-MV were significantly lower than those using 10-MV.…”

Section: Discussionmentioning

confidence: 99%

Treatment plan comparison of volumetric‐modulated arc therapy to intensity‐modulated radiotherapy in lung stereotactic body radiotherapy using either 6‐ or 10‐MV photon energies

Wei

Peng

et al. 2022

J Applied Clin Med Phys

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Purpose The aim of this study was to dosimetrically compare volumetric‐modulated arc therapy (VMAT) with intensity‐modulated radiotherapy (IMRT) techniques using either 6‐ or 10‐MV photon beam energies in lung stereotactic body radiation therapy (SBRT) plans. Methods Thirty patients with primary or metastatic lung tumors eligible for SBRT were randomly selected. VMAT and IMRT treatment plans using either 6‐ or 10‐MV photon energies were generated through automatic SBRT planning software in the RayStation treatment planning system. Results For planning target volume, there was no difference in D95% for all plans, whereas D2% and D50% were significantly increased by 5.22%–5.98% and 2.47%–2.59%, respectively, using VMAT6/10‐MV plans compared to IMRT6/10‐MV plans. When comparing the Dmax of organs at risk (OARs), VMAT6/10‐MV was 18.32%–47.95% lower than IMRT6/10‐MV for almost all OARs. VMAT6/10‐MV obviously decreased Dmean, V5Gy, V10Gy, and V20Gy of whole lung by 9.68%–20.92% than IMRT6/10‐MV. Similar results were found when comparing VMAT6‐MV with IMRT10‐MV or VMAT10‐MV with IMRT6‐MV. The differences in the D2%, heterogeneity index, and conformity index between 6‐ and 10‐MV plans are not statistically significant. Plans using 6‐MV performed 4.68%–8.91% lower levels of Dmax of spinal cord, esophagus, great vessels, and trachea and proximal bronchial tree than those using 10‐MV plans. Similarly, Dmean, V5Gy, V10Gy, and V20Gy of whole lung were also reduced by 2.79%–5.25% using 6‐MV. For dose fall‐off analysis, the D2cm and R50% of VMAT6/10‐MV were lower than those of IMRT6/10‐MV. Dose fall‐off curve based on 10 rings was steeper for VMAT plans than IMRT plans regardless of the energy used. Conclusions For lung SBRT plans, VMAT‐based plans significantly reduced OARs dose and steepened dose fall‐off curves compared to IMRT‐based plans. A 6‐MV energy level was a better choice than 10‐MV for lung SBRT. In addition, the dose differences between different techniques were more obvious than those between different energy levels.

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“…A study found that the difference in the dose fall‐off outside the target between the 6MV IMRT and VMAT SBRT plans of the same patient had little dependence on the geometric characteristics of the target. 33 The reason maybe that SBRT has a smaller target volume and higher dose conformability than conventional radiotherapy, so that the dose is less dependent on the target shape. Moreover, although the anatomical factors may impact the plan results of different patients, it affects little on the relative difference of the results obtained by the same patient using different techniques in this study.…”

Section: Discussionmentioning

confidence: 99%

A novel CRT‐IMRT‐combined (Co‐CRIM) planning technique for peripheral lung stereotactic body radiotherapy in pinnacle treatment planning system

Duan

Wang

Chen

et al. 2021

J Applied Clin Med Phys

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This study attempts to explore a novel peripheral lung stereotactic body radiotherapy (SBRT) planning technique that can balance the pros and cons of three-dimensional conformal radiotherapy (CRT) and intensitymodulated radiation therapy (IMRT) / volumetric modulated arc therapy (VMAT). Methods: Treatment plans were retrospectively designed based on CRT, IMRT, VMAT, and the proposed CRT-IMRT-combined (Co-CRIM) techniques using Pinnacle treatment planning system (TPS) for 20 peripheral lung cancer patients. Co-CRIM used an inverse optimization algorithm available in Pinnacle TPS. To develop a Co-CRIM plan, the number of segments in each field was limited to one, the minimum segment area was set to the internal target volume (ITV), and the minimum monitor units (MU) of the segment was the quotient of fractional dose divided by twice the number of total fields. The performance of Co-CRIM was then compared with other techniques. Results: For conformity index (CI), Co-CRIM performed comparably to IMRT/VMAT but better than CRT. For gradient index (GI), Co-CRIM was similar to IMRT/VMAT or CRT. For heterogeneity index (HI), Co-CRIM was comparable to IMRT/VMAT, higher than CRT. The dosimetric results of spinal cord and lung with Co-CRIM were better than CRT, comparable to IMRT, but inferior to VMAT. The MU resulted from Co-CRIM was lower than IMRT/VMAT but higher than CRT. For plan verification γ passing rate, Co-CRIM was higher than IMRT/VMAT, comparable to CRT. For planning time, Co-CRIM was shorter than CRT or VMAT but similar to IMRT. Conclusions: The proposed Co-CRIM technique on Pinnacle TPS is an effective planning technique for peripheral lung SBRT.

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Modeling the target dose fall-off in IMRT and VMAT planning techniques for cervical SBRT

Cited by 5 publications

References 34 publications

How Does the Gradient Measure of the Lung SBRT Treatment Plan Depend on the Tumor Volume and Shape?

How Does the Gradient Measure of the Lung SBRT Treatment Plan Depend on the Tumor Volume and Shape?

Treatment plan comparison of volumetric‐modulated arc therapy to intensity‐modulated radiotherapy in lung stereotactic body radiotherapy using either 6‐ or 10‐MV photon energies

A novel CRT‐IMRT‐combined (Co‐CRIM) planning technique for peripheral lung stereotactic body radiotherapy in pinnacle treatment planning system

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