Volumetric modulated arc planning for lung stereotactic body radiotherapy using conventional and unflattened photon beams: a dosimetric comparison with 3D technique

Zhang, Geoffrey; L, Ku; Dilling, Thomas J.; Stevens, Craig W.; Zhang, Ray R.; Li, Weiqi; Feygelman, Vladimir

doi:10.1186/1748-717x-6-152

Cited by 77 publications

(88 citation statements)

References 27 publications

(29 reference statements)

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“…Yamashita, et al already reported details of treatment from our hospital (20). VMAT has been reported to be a novel rotational technique and an extension of IMRT, and is applicable for SBRT for lung tumors (23,(30)(31)(32)(33)(34). By introducing VMAT, we could reduce the dose delivery time down to 210 sec for a D95 prescription dose of 50 Gy in four fractions (35).…”

Section: Discussionmentioning

confidence: 99%

Flattening filter-free technique in volumetric modulated arc therapy for lung stereotactic body radiotherapy: A clinical comparison with the flattening filter technique

et al. 2018

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Abstract. The present study sought to evaluate the impact of the flattening filter-free (FFF) technique in volumetric modulated arc therapy for lung stereotactic body radiotherapy. Its clinical safety and availability were compared with the flattening filter (FF) method. The cases of 65 patients who underwent lung volumetric modulated arc therapy-stereotactic body radiotherapy (VMAT-SBRT) using FF or FFF techniques were reviewed. A total of 55 Gy/4 fractions (fr) was prescribed for peripheral lesions or 56 Gy/7 fr for central lesions. The total monitor units (MU), treatment time, dose to tumors, dose to organs at risk, tumor control (local control rate, overall survival, progression-free survival) and adverse events between cases treated with FF and cases treated with the FFF technique were compared. A total of 35 patients were treated with conventional FF techniques prior to November 2014 and 30 patients were treated with FFF techniques after this date. It was revealed that the beam-on time was significantly shortened by the FFF technique (P<0.01). Other factors were similar for FFF and FF plans in respect to conformity (P=0.95), homogeneity (P=0.20) and other dosimetric values, including total MU and planning target volume/internal target volume coverage. The median follow-up period was 18 months (range, 2-35). One-year local control rates were 97.1 and 90.0% in the FF group and FFF groups, respectively (P=0.33). Grade 3 pneumonitis was observed in 5.8% of FF patients and 3.4% of FFF patients (P=1.00). No other adverse events ≥grade 3 were observed. The results of the study suggest that VMAT-SBRT using the FFF technique shortens the treatment time for lung SBRT while maintaining a high local control rate with low toxicity.

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Section: Discussionmentioning

confidence: 99%

Flattening filter-free technique in volumetric modulated arc therapy for lung stereotactic body radiotherapy: A clinical comparison with the flattening filter technique

et al. 2018

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“…However, conventional linacs allow caudal arcs to be used to some extent, although the available geometric freedom is less than that of the vero4DRT. We used a conventional linac (the Clinac iX; Varian Medical Systems, Palo Alto, CA) to experimentally explore how much angle could safely be assumed in the context of caudal arcs, In agreement with the literature, (20) the range was maximally 5°. Next, we replanned three representative plans within this range of angle (the plans were termed Plans C).…”

Section: Discussionmentioning

confidence: 73%

Dosimetric advantages of O‐ring design radiotherapy system for skull‐base tumors

Ogura

Mizowaki

Ishida

et al. 2014

J Applied Clin Med Phys

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The purpose of this study was to investigate whether a new O‐ring design radiotherapy delivery system has advantages in radiotherapy planning for skull‐base tumors. Twenty‐five patients with skull‐base tumors were included in this study. Two plans were made using conventional (Plan A) or new (Plan B) techniques. Plan A consisted of four dynamic conformal arcs (DCAs): two were horizontal, and the other two were from cranial directions. Plan B was created by converting horizontal arcs to those from caudal directions making use of the O‐ring design radiotherapy system. The micromultileaf collimators were fitted to cover at least 99% of the planning target volume with prescribed doses, 90% of the dose at the isocenter. The two plans were compared in terms of target homogeneity, conformity, and irradiated volume of normal tissues, using a two‐sided paired t‐test. For evaluation regarding target coverage, the homogeneity indices defined by the International Commission on Radiation Units and Measurements 83 were 0.099±0.010 (mean ± standard deviation) and 0.092±0.010, the conformity indices defined by the Radiation Therapy Oncology Group were 1.720±0.249 and 1.675±0.239, and the Paddick's conformity indices were 0.585±0.078 and 0.602±0.080, in Plans A and B, respectively. For evaluation of irradiated normal tissue, the Paddick's gradient indices were 3.118±0.283 and 2.938±0.263 in Plans A and B, respectively. All of these differences were statistically significant (p‐values <0.05). The mean doses of optic nerves, eyes, brainstem, and hippocampi were also significantly lower in Plan B. The DCA technique from caudal directions using the new O‐ring design radiotherapy system can improve target homogeneity and conformity compared with conventional DCA techniques, and can also decrease the volume of surrounding normal tissues that receives moderate doses.PACS numbers: 87.55.‐x, 87.55.D‐, 87.55.dk

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“…In addition, an IMRT plan is able to reduce the irradiated dose of lung normal tissue compared with a 3D-CRT plan. Zhang et al 18 and Ong et al 19 reported better conformity for tumours and lower doses for risk organ in VMAT compared with those in 3D-CRT. These results indicated the improved value of dosimetric parameters adding intensity modulation to SBRT for earlystage NSCLC.…”

Section: Discussionmentioning

confidence: 99%

“…Some authors have demonstrated the superiority of dosimetric parameters in IMRT plans compared with those in 3D-CRT plans. [18][19][20] Liu et al 20 reported a treatment planning study of ten patients with lung cancer, showing that the CI and HI values in the IMRT plan were significantly superior to those in the 3D-CRT plan. In addition, an IMRT plan is able to reduce the irradiated dose of lung normal tissue compared with a 3D-CRT plan.…”

Section: Discussionmentioning

confidence: 99%

Dosimetric evaluation of compensator intensity modulation-based stereotactic body radiotherapy for Stage I non-small-cell lung cancer

Tajima

Nakayama

Itonaga

et al. 2015

BJR

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Objective: To evaluate the dosimetry of compensator intensity modulation-based stereotactic body radiotherapy (SBRT) [non-coplanar intensity-modulated radiotherapy (ncIMRT)], its use was compared with that of three-dimensional conformation-based SBRT, for patients with Stage I non-small-cell lung cancer (NSCLC). Methods: 21 consecutive patients with Stage I NSCLC were treated with ncIMRT or SBRT at Tokyo Medical University. To compare the two techniques, ncIMRT and SBRT plans for each patient were generated, where the planning target volume (PTV) coverages were adjusted to be equivalent to each other. The prescribed dose was set as 75 Gy in 30 fractions. PTV coverage, conformity index, conformation number (CN) and homogeneity index (HI) were used to compare the two strategies.Results: There was no statistically significant difference between PTV coverage for the 100%, 95% and 90% dose levels in the SBRT plan and those in the ncIMRT plan. The CN values were 0.53 6 0.13 in the SBRT plan and 0.72 6 0.10 in the ncIMRT plan. These values were significantly better than those of the SBRT plan (p , 0.001). The HI in the ncIMRT plan was 1.04 6 0.03%, which was also significantly better than that of SBRT. Conclusion: The ncIMRT plan provided superior conformity and reduced the doses to the lung for patients with Stage I NSCLC. Advances in knowledge: The delivery technique with compensator intensity modulation-based SBRT was evaluated. Concerning target motion, this is thought to be more robust and safer than SBRT for early-stage NSCLC.

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Volumetric modulated arc planning for lung stereotactic body radiotherapy using conventional and unflattened photon beams: a dosimetric comparison with 3D technique

Cited by 77 publications

References 27 publications

Flattening filter-free technique in volumetric modulated arc therapy for lung stereotactic body radiotherapy: A clinical comparison with the flattening filter technique

Flattening filter-free technique in volumetric modulated arc therapy for lung stereotactic body radiotherapy: A clinical comparison with the flattening filter technique

Dosimetric advantages of O‐ring design radiotherapy system for skull‐base tumors

Dosimetric evaluation of compensator intensity modulation-based stereotactic body radiotherapy for Stage I non-small-cell lung cancer

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