Purpose. To compare five techniques for the postmastectomy radiotherapy (PMRT) with simultaneous integrated boost (SIB). Materials and Methods. Twenty patients with left-sided breast cancer were retrospectively selected. Five treatment plans were created for each patient: TomoDirect (TD), unblocked helical TomoTherapy (unb-HT), blocked HT (b-HT), hybrid intensity-modulated radiotherapy (hy-IMRT), and fixed-field IMRT (ff-IMRT). A dose of 50.4 Gy in 28 fractions to PTVtotal and 60.2 Gy in 28 fractions to PTVboost were prescribed. The dosimetric parameters for targets and organs at risk (OARs), the normal tissue complication probability (NTCP), the second cancer complication probability (SCCP) for OARs, and the treatment efficiency were assessed and compared. Results. TD plans and hy-IMRT plans had similar good dose coverage and homogeneity for both PTVboost and PTVtotal and superior dose sparing for the lungs and heart. The ff-IMRT plans had similar dosimetric results for the target volumes compared with the TD and hy-IMRT plans, but gave a relatively higher NTCP and SCCP for the lungs. The unb-HT plans exhibited the highest OAR mean dose, highest NTCP for the lungs (0.97±1.25‰) and heart (4.58±3.62%), and highest SCCP for the lungs (3.57±0.05%) and contralateral breast (2.75±0.29%) among all techniques. The b-HT plans significantly outperformed unb-HT plans with respect to the sparing of the lungs and heart. This technique also showed the best conformity index (0.73±0.08) for PTVboost and the optimal NTCP for the lungs (0.03±0.03‰) and heart (0.61±0.73%). Concerning the delivery efficiency, the hy-IMRT and ff-IMRT achieved much higher delivery efficiency compared with TomoTherapy plans. Conclusion. Of the five techniques studied, TD and hy-IMRT are considered the preferable options for PMRT with SIB for left-sided breast cancer treatment and can be routinely applied in clinical practice.

To compare the dosimetric influence of applicator displacement on two-dimensional brachytherapy (2D-BT) and three-dimensional brachytherapy (3D-BT) for cervical cancer. Nineteen patients who received computed tomography-guided tandem-and-ovoid (T&O) brachytherapy were retrospectively selected. Both 2D (point-based) and 3D (volume-based) plans with and without virtual applicator displacement in the 3 axes were created for each patient. Dose changes at point A, D90 of the high-risk clinical target volume (HR-CTV) and intermediate-risk CTV (IR-CTV), and the D0.1cc, D1cc, D2cc, and D5cc of organs-at-risk (OARs) caused by applicator displacement were evaluated. Both 2D-BT and 3D-BT plans were sensitive to T&O applicator displacement. The D90 of the CTV and the dose at point A were very sensitive to applicator displacement in the right–left direction ( X-axis). An applicator shift of >2 mm in the X-axis resulted in a change of >5% in the dose at point A and D90 of HR-CTV and IR-CTV. In addition, the doses to the OARs were mostly affected by applicator displacement in the anterior–posterior direction ( Z-axis). A displacement of <1.5 mm in the Z-axis was required to avoid a dose change of >10% for OARs. For both 2D-BT and 3D-BT plans, T&O displacement greater than  ± 2 mm in the X-axis or T&O applicator displacement  ± 1.5 mm in the Z-axis resulted in significant dose changes to the tumor and OARs. In comparison with 3D-BT plans, 2D-BT plans delivered a higher dose to the tumor, and the OARs received more undesirable doses when applicator displacement occurred. The influence of applicator displacement on the doses to the tumor and OARs differed between 2D-BT and 3D-BT. Physicians should take individual patient differences into account when selecting a brachytherapy plan to mitigate the influence of applicator displacement.

Purpose: To evaluate the performance of Delta4DVH Anatomy in patient-specific intensity-modulated radiotherapy quality assurance. Materials and Methods: Dose comparisons were performed between Anatomy doses calculated with treatment plan dose measured modification and pencil beam algorithms, treatment planning system doses, film doses, and ion chamber measured doses in homogeneous and inhomogeneous geometries. The sensitivity of Anatomy doses to machine errors and output calibration errors was also investigated. Results: For a Volumetric Modulated Arc Therapy (VMAT) plan evaluated on the Delta4 geometry, the conventional gamma passing rate was 99.6%. For a water-equivalent slab geometry, good agreements were found between dose profiles in film, treatment planning system, and Anatomy treatment plan dose measured modification and pencil beam calculations. Gamma passing rate for Anatomy treatment plan dose measured modification and pencil beam doses versus treatment planning system doses was 100%. However, gamma passing rate dropped to 97.2% and 96% for treatment plan dose measured modification and pencil beam calculations in inhomogeneous head & neck phantom, respectively. For the 10 patients’ quality assurance plans, good agreements were found between ion chamber measured doses and the planned ones (deviation: 0.09% ± 1.17%). The averaged gamma passing rate for conventional and Anatomy treatment plan dose measured modification and pencil beam gamma analyses in Delta4 geometry was 99.6% ± 0.89%, 98.54% ± 1.60%, and 98.95% ± 1.27%, respectively, higher than averaged gamma passing rate of 97.75% ± 1.23% and 93.04% ± 2.69% for treatment plan dose measured modification and pencil beam in patients’ geometries, respectively. Anatomy treatment plan dose measured modification dose profiles agreed well with those in treatment planning system for both Delta4 and patients’ geometries, while pencil beam doses demonstrated substantial disagreement in patients’ geometries when compared to treatment planning system doses. Both treatment planning system doses are sensitive to multileaf collimator and monitor unit (MU) errors for high and medium dose metrics but not sensitive to the gantry and collimator rotation error smaller than 3°. Conclusions: The new Delta4DVH Anatomy with treatment plan dose measured modification algorithm is a useful tool for the anatomy-based patient-specific quality assurance. Cautions should be taken when using pencil beam algorithm due to its limitations in handling heterogeneity and in high-dose gradient regions.

Purpose To investigate the appropriate timing of adaptive radiotherapy (ART) for high-grade glioma. Methods Ten patients with high-grade gliomas were selected and underwent CT/MRI (CT 1 /MRI 1 , CT 2 /MRI 2 , CT 3 /MRI 3 , and CT 4 /MRI 4 ) scans before RT and during 10-, 20- and 30-fraction RT, and the corresponding RT plans (plan 1 , plan 2 , plan 3 and plan 4 ) were made. The dose of the initial plan (plan 1 ) was projected to CT2 and CT3 using the image registration technique to obtain the projection plans (plan 1–2 and plan 1–3 ) and by superimposing the doses to obtain the ART plans (plan 10+20 and plan 20+10 ), respectively. The dosimetric differences in the target volume and organs at risk (OARs) were compared between the projection and adaptive plans. The tumor control probability (TCP) for the planning target volume (PTV) and normal tissue complication probability (NTCP) for the OARs were compared between the two adaptive plans. Results Compared with the projection plan, the D 2 to the PTV of ART decreased, the conformity index (CI) to the PTV increased, and the D 2 /D mean to the brainstem, optic chiasm and pituitary, as well as the V 20 , V 30 , V 40 and V 50 to the normal brain decreased. The D 2 to the pituitary and optic chiasm as well as the V 20 , V 30 , V 40 and V 50 to the normal brain in plan 10+20 were lower than those in plan 20+10 , while the CI to the PTV was higher than that in plan 20+10 . The TCP of the PTV in plan 10+20 was higher than that in plan 20+10 . Conclusion ART can improve the precision of target volume irradiation and reduce the irradiation dose to the OARs in high-grade glioma. The time point after 10 fractions of RT is appropriate for ART.