Purpose This study aimed to evaluate the clinical impact of hybrid intensity-modulated radiotherapy (IMRT) and hybrid volumetric-modulated arc therapy (VMAT) for early-stage breast cancer, including plan quality and second cancer risk (SCR). Methods Three different plans were designed in full IMRT, hybrid IMRT, and hybrid VMAT for each of eight patients with early-stage breast cancer. Target quality, organs at risk (OARs) sparing, and SCR were compared among the three plans. Results Compared with the hybrid IMRT, full IMRT showed deterioration in terms of D2% of simultaneous integrated boost (SIB), V10 of ipsilateral lung, and excess absolute risk (EAR) to contralateral lung and esophagus. The homogeneity index (HI) of SIB, V5 of ipsilateral lung and combined lung, the Dmax and Dmean of the esophagus, the EAR to contralateral breast and lung, and the EAR to the esophagus with hybrid VMAT dramatically increased by 12.5%, 19.49%, 18.87%, 90.59%, 167.69%, 50.14%, 264.68%, and 160.95%, respectively (p = 0.022; 0.040; 0.044; 0.041; 0.003; 0.020; 0.000; 0.003). The EAR to contralateral breast and contralateral lung by full IMRT was significantly decreased compared with the hybrid VMAT (26.97%, p = 0.033; 50.01%, p = 0.026). Conclusion The results confirmed that hybrid IMRT could achieve better target quality and OARs sparing than full IMRT and hybrid VMAT for early-stage right breast cancer. Hybrid IMRT was the best treatment option, while hybrid VMAT performed the worst among the three plans in terms of SCR to peripheral OARs.

ObjectiveOur study aims to estimate intra-fraction six-dimensional (6D) tumor motion with rotational correction and the related correlations between motions of different degrees of freedom (DoF), as well as quantify sufficient anisotropic clinical target volume (CTV) to planning target volume (PTV) margins during stereotactic body radiotherapy (SBRT) of liver cancer with fiducial tracking technique.MethodsA cohort of 12 patients who were implanted with 3 or 4 golden markers were included in this study, and 495 orthogonal kilovoltage (kV) pairs of images acquired during the first fraction were used to extract the spacial position of each golden marker. Translational and rotational motions of tumor were calculated based on the marker coordinates by using an iterative closest point (ICP) algorithm. Moreover, the Pearson product-moment correlation coefficients (r) were applied to quantify the correlations between motions with different degrees of freedom (DoFs). The population mean displacement (MP¯), systematic error (Σ) and random error (σ) were obtained to calculate PTV margins based on published recipes.ResultsThe mean translational variability of tumors were 0.56, 1.24 and 3.38 mm in the left-right (LR, X), anterior-posterior (AP, Y), and superior-inferior (SI, Z) directions, respectively. The average rotational angles θX , θY and θZ around the three coordinate axes were 0.88, 1.24 and 1.12, respectively. (|r|>0.4) was obtainted between Y -Z , Y - θZ , Z -θZ and θX - θY . The PTV margins calculated based on 13 published recipes in X, Y, and Z directions were 1.08, 2.26 and 5.42 mm, and the 95% confidence interval (CI) of them were (0.88,1.28), (1.99,2.53) and (4.78,6.05), respectively.ConclusionsThe maximum translational motion was in SI direction, and the largest correlation coefficient of Y-Z was obtained. We recommend margins of 2, 3 and 7 mm in LR, AP and SI directions, respectively.

To compare the dosimetric effects of American Association of Physicists in Medicine (AAPM) TG43 dose formalism and AcurosBV ( grid-based Boltzmann solver ,GBBS) formalism on High-dose-rate(HDR) brachytherapy planning for cervical cancer patients irradiated using three different applicators. MethodsA TG43 plan and a AcurosBV plan were generated for each of the 30 patients. twenty patients who had undergone whole pelvic radiotherapy followed by cervical HDR brachytherapy and the remaining 10 patients who underwent total hysterectomy only gave HDR brachytherapy also were enrolled in this study. The patients were divided into three groups according to the types of applicators used: tandem and ovoid (T&O), tandem and ring (T&R), and Cylinder. To compare the dosimetric parameters, the cumulative dosevolume histograms (DVHs) were measured. We also compared the doses at 90% of the volume (D 90% ), the volume receiving 100% and 150% of the prescribed dose (V 100% and V 150% ) for the clinical target volume (CTV-HR) and the doses of point A, the dose receiving 0.1 cc and 2 cc of the volume (D 0.1cc and D 2cc ) for the organs-at-risk (OARs). ResultsIn this study, compared with the AcurosBV plans, TG43 plans predicted higher D 90% , V 100% , and V 150% of CTV-HR, dose of point A and D 0.1cc and D 2cc of OARs in three types of applicators. Except D 2cc of sigmoid in T&R and Cylinder applicators, the D 90% , V 100% , and V 150% of CTV-HR; the Dose of point A and the D 0.1cc and D 2cc of bladder, recutum and small bowel exhibited signi cant discrepancies (P > 0.05). The effects of the three types of applicators on the dose distribution were quite different due to the difference of the materials: The dose difference of CTV-HR and OARs was greatest (around 10%) for T&O applicators but only 1%-5% for T&R and Cylinder applicators. ConclusionsThis study demonstrated that AcurosBV was more accurate in calculating the doses in the air cavity and high-density substance than TG43. In the clinical setting, the AcurosBV exhibited different dosimetric distributions in the cervix plans for HDR brachytherapy, especially in treatment planning when using T&O applicators. The AcurosBV algorithm should be considered when using T&O applicators or some other materials with a much higher or lower density (metal or air) than soft tissue. Howevere, If the density is close to the soft tissue, considering AcurosBV algorithm requires more calculation time, TG43 could still be selected when using applicators in clinical.

Purpose: To compare the dosimetric effects of American Association of Physicists in Medicine (AAPM) TG43 dose formalism and AcurosBV ( grid-based Boltzmann solver ,GBBS) formalism on High-dose-rate(HDR) brachytherapy planning for cervical cancer patients irradiated using three different applicators.Methods: A TG43 plan and a AcurosBV plan were generated for each of the 30 patients. twenty patients who had undergone whole pelvic radiotherapy followed by cervical HDR brachytherapy and the remaining 10 patients who underwent total hysterectomy only gave HDR brachytherapy also were enrolled in this study. The patients were divided into three groups according to the types of applicators used: tandem and ovoid (T&O), tandem and ring (T&R), and Cylinder. To compare the dosimetric parameters, the cumulative dose-volume histograms (DVHs) were measured. We also compared the doses at 90% of the volume (D90%) , the volume receiving 100% and 150% of the prescribed dose (V100% and V150%) for the clinical target volume (CTV-HR) and the doses of point A, the dose receiving 0.1 cc and 2 cc of the volume (D0.1cc and D2cc) for the organs-at-risk (OARs).Results: In this study, compared with the AcurosBV plans, TG43 plans predicted higher D90%, V100%, and V150% of CTV-HR, dose of point A and D0.1cc and D2cc of OARs in three types of applicators. Except D2cc of sigmoid in T&R and Cylinder applicators, the D90%, V100%, and V150% of CTV-HR; the Dose of point A and the D0.1cc and D2cc of bladder, recutum and small bowel exhibited significant discrepancies (P>0.05). The effects of the three types of applicators on the dose distribution were quite different due to the difference of the materials: The dose difference of CTV-HR and OARs was greatest (around 10%) for T&O applicators but only 1%-5% for T&R and Cylinder applicators.Conclusions: This study demonstrated that AcurosBV was more accurate in calculating the doses in the air cavity and high-density substance than TG43. In the clinical setting, the AcurosBV exhibited different dosimetric distributions in the cervix plans for HDR brachytherapy, especially in treatment planning when using T&O applicators. The AcurosBV algorithm should be considered when using T&O applicators or some other materials with a much higher or lower density (metal or air) than soft tissue. Howevere, If the density is close to the soft tissue, considering AcurosBV algorithm requires more calculation time, TG43 could still be selected when using applicators in clinical.