Dosimetric research on intensity-modulated arc radiotherapy planning for left breast cancer after breast-preservation surgery.
ABSTRACT Intensity-modulated radiotherapy (IMRT) has played an important role in breast cancer radiotherapy after breast-preservation surgery. Our aim was to study the dosimetric and implementation features/feasibility between IMRT and intensity-modulated arc radiotherapy (Varian RapidArc, Varian, Palo Alto, CA). The forward IMRT plan (f-IMRT), the inverse IMRT, and the RapidArc plan (RA) were generated for 10 patients. Afterward, we compared the target dose distribution of the 3 plans, radiation dose on organs at risk, monitor units, and treatment time. All 3 plans met clinical requirements, with RA performing best in target conformity. In target homogeneity, there was no statistical significance between RA and IMRT, but both of homogeneity were less than f-IMRT's. With regard to the V(5) and V(10) of the left lung, those in RA were higher than in f-IMRT but were lower than in IMRT; for V(20) and V(30), the lowest was observed in RA; and in the V(5) and V(10) of the right lung, as well as the mean dose in normal-side breast and right lung, there was no statistically significance difference between RA and IMRT, and the lowest value was observed in f-IMRT. As for the maximum dose in the normal-side breast, the lowest value was observed in RA. Regarding monitor units (MUs), those in RA were higher than in f-IMRT but were lower than in IMRT. Treatment time of RA was 84.6% and 88.23% shorter than f-IMRT and IMRT, respectively, on average. Compared with f-IMRT and IMRT, RA performed better in target conformity and can reduce high-dose volume in the heart and left lung-which are related to complications-significantly shortening treatment time as well. Compared with IMRT, RA can also significantly reduce low-dose volume and MUs of the afflicted lung.
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ABSTRACT: To investigate the correlation between total monitor units (MU), dosimetric findings, and pre-treatment quality assurance for volumetric modulated arc therapy (VMAT) by RapidArc (RA). Ten patients with breast cancer were considered. Dose prescriptions were: 48 Gy and 40.5 Gy in 15 fractions to, respectively, PTVBoost and PTVWholeBreast. A reference plan was optimized and four more plans using the "MU Objective", a tool for total MU controlling, were prepared imposing ±20 and ±50% total MU for inducing different complexities. Plan objectives were: D95% > 95% for both PTVs, and D2% < 107% for PTVBoost; mean dose < 9.5 Gy and V20 Gy < 10% for ipsilateral lung; V18 Gy < 5% for heart; mean dose <3 Gy for controlateral breast; furthermore V5 Gy, V10 Gy , V20 Gy, and V30 Gy to body were minimized. Plans were evaluated in terms of technical parameters, dosimetric plan objectives findings and pre-treatment quality assurance (QA). Concerning PTVs, there were no significant differences for target coverage (D95%); mean doses for ipsilateral lung and controlateral breast, and V18 Gy for heart decreased with MUs increasing, reaching a plateau with reference plan. Body volume receiving low dose (V5-10 Gy) was minimized for reference plans. All plans had GAI (3 mm, 3%) > 95%. The data suggest that the best plan is the reference one, where the "MU Objective" tool was not used during optimisation. Nevertheless, it is advisable to use the "MU Objective" tool for re-planning when low GAI is found to increase its value. In this case, attention should be paid to OARs dose limits, since their values may be increased.Physica Medica 09/2013; · 1.17 Impact Factor
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ABSTRACT: Radiotherapy increases the morbidity of immediate breast reconstruction. To spare the flapped area without an adverse dose distribution of the target volume and organ at risks, various radiation techniques were assessed. Twelve breasts undergoing skin-sparing mastectomy and immediate transverse rectus abdominis myocutaneous flap reconstruction were evaluated. After a delineation of whole breast, the doughnut-like breast target volume (BTV) including the chest wall and skin and the subtracted central flapped volume (FV) were defined. The opposed wedge tangential radiotherapy (3-dimensional conformal radiotherapy (3-D CRT) ), field-in-field radiotherapy (FiF), inverse intensity-modulated radiotherapy (iIMRT), volumetric modulated arc radiotherapy (VMRT) and the mixture of FiF and iIMRT (HYBRID) were tried. Total 50 Gy was prescribed to the BTV. The paired student t-tests were performed. The V47.5Gy of the BTV was improved in iIMRT and VMRT compared with 3-D CRT and FiF. The mean FV doses in iIMRT and VMRT were 76.7 ± 3.9% and 85.5 ± 4.0%, respectively. However the mean ipsilateral lung doses were aggravated by iIMRT and VMRT. In terms of HYBRID, the V47.5Gy for the BTV was 97.5 ± 0.7%. The mean FV dose was 89.4 ± 2.1%. While the mean FV dose in HYBRID was 13.7 ± 2.1% (P < 0.001) lower than FiF, it was 12.8 ± 1.9% (P < 0.001) higher than iIMRT. The mean ipsilateral lung dose in HYBRID was 2.8 ± 1.9% (P < 0.001) worse than FiF, and 2.6 ± 1.8% (P < 0.001) better than iIMRT. The HYBRID could minimise the adverse dose distribution of lung and reduce 10% of the mean dose to the flapped area. For patients with adverse factors for the failure of breast reconstruction, the HYBRID could be considered.Journal of Medical Imaging and Radiation Oncology 10/2013; 57(5):595-602. · 0.98 Impact Factor
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ABSTRACT: To investigate the effects of using volumetric modulated arc therapy (VMAT) and/or voluntary moderate deep inspiration breath-hold (vmDIBH) in the radiation therapy (RT) of left-sided breast cancer including the regional lymph nodes. For 13 patients, four treatment combinations were compared; 3D-conformal RT (i.e., forward IMRT) in free-breathing 3D-CRT(FB), 3D-CRT(vmDIBH), 2 partial arcs VMAT(FB), and VMAT(vmDIBH). Prescribed dose was 42.56Gy in 16 fractions. For 10 additional patients, 3D-CRT and VMAT in vmDIBH only were also compared. Dose conformity, PTV coverage, ipsilateral and total lung doses were significantly better for VMAT plans compared to 3D-CRT. Mean heart dose (Dmean,heart) reduction in 3D-CRT(vmDIBH) was between 0.9 and 8.6Gy, depending on initial Dmean,heart (in 3D-CRT(FB) plans). VMAT(vmDIBH) reduced the Dmean,heart further when Dmean,heart was still >3.2Gy in 3D-CRT(vmDIBH). Mean contralateral breast dose was higher for VMAT plans (2.7Gy) compared to 3DCRT plans (0.7Gy). VMAT and 3D-CRT(vmDIBH) significantly reduced heart dose for patients treated with locoregional RT of left-sided breast cancer. When Dmean,heart exceeded 3.2Gy in 3D-CRT(vmDIBH) plans, VMAT(vmDIBH) resulted in a cumulative heart dose reduction. VMAT also provided better target coverage and reduced ipsilateral lung dose, at the expense of a small increase in the dose to the contralateral breast.Radiotherapy and Oncology 05/2014; · 4.52 Impact Factor