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This study evaluated the dosimetric accuracy of SunCHECK, a calculation-based IMRT DQA program, when applied to VMAT DQA for the Halcyon LINAC. Virtual VMAT treatment plans were generated utilizing a Delta4 Phantom + diode detector array device to analyze the accuracy of the dose calculation algorithm in SunCHECK. The analysis revealed a strong correlation between the calculated dose in SunCHECK, the planned dose, and the measured delivery dose. The characteristics of dose distribution changes calculated by SunCHECK in the event of MLC errors during VMAT beam delivery were analyzed additionally. After delivering a beam with MLC position errors, the dosimetric error evaluated through log file-based calculations were compared with the error analysis findings obtained from measurements using the Delta4 Phantom + . The dosimetric error calculated based on the log file using SunCHECK showed a similar trend to the dose error calculated through the conventional measurement-based DQA method using a Delta4 Phantom + . The results of this study validate SunCHECK’s accuracy in dose calculation and analysis of dosimetric errors resulting from MLC position errors, thereby confirming its efficacy in VMAT DQA using the Halcyon LINAC.

The Halcyon, closed-bore and O-ring type linear accelerator, is unable to use the specialized device which can reduce respiratory tumor-motion effect such as a gating system, and the internal target volume (ITV)-based IMRT method should be applied to the treatment of moving tumor target. In this study, the tumor-motion effect on the dosimetric accuracy of the ITV-based IMRT using the Halcyon. ITV-based volumetric modulated arc therapy (VMAT) plans using the Halcyon were prepared for ten cases of liver cancer while changing the number of arcs (1-arc, 3-arc, and 5-arc) in the plan. Delivery quality assurance (DQA) plans were created using the Delta4Phantom + diode array to verify the dosimetric accuracy of the VMAT plans. DQA measurements were performed in both the static and the Hexa-Motion mode using the Delta4Hexa-Motion system to evaluate the motion effect on the dosimetric accuracy. In the static mode, the average gamma pass rate (GPR) value was 99.98% for the 3%/3 mm criterion and 99.02% for the 2%/2 mm criterion, which can verify the sufficient dosimetric accuracy of the VMAT plans in this study. The average GPR values calculated with a 3%/3 mm criterion in the Hexa-Motion mode were 68.25%, 69.17%, and 75.52% for the 1-arc, 3-arc, and 5-arc VMAT plans, respectively. When the 2%/2 mm criterion was used, the average GPR values in the Hexa-Motion mode were 50.76%, 50.33%, and 56.21% for the 1-arc, 3-arc, and 5-arc VMAT plans. These significantly lower GPR values show that the dosimetric accuracy in the Halcyon is more affected by tumor motion compared to the conventional linear accelerator. This study verifies that it is advantageous to use a large number of arcs in the ITV-based VMAT plan implemented using the Halcyon to reduce dosimetric error due to tumor motion.

In this study, the effect of Cl activation treatment on performance indicators of CdS/CdTe solar cells was investigated. We improved the performance of CdTe solar cells by applying a novel double treatment method that combines the CdCl2dipping treatment and Freon (difluoro chloromethane) treatment methods that were previously studied. Conventional CdCl2methanol dipping treatment (CdCl2dipping treatment), Freon gas treatment that includes chlorine (Freon treatment), and CdCl2dipping treatment + Freon treatment (double treatment) were performed, and the efficiencies, open circuit voltage (VOC), and short circuit current (JSC) for all three processes were observed. Although the efficiencies of the CdCl2dipping treatment and Freon treatment were similar, there was a trade-off between the VOCand JSCin both processes. The double treatment sample shows an efficiency of 14.3%, which was higher than that of a single-treated sample. To investigate the characteristic change of each part of the solar cell, an equivalent circuit model in which the device was divided into a main junction and a back contact was used. In addition to electrical measurements, secondary ion mass spectroscopy (SIMS) and time of flight (TOF) analysis were performed. Through TOF measurement, drift mobility values for three treatment samples were calculated to be 1.1 cm 2/Vs, 1.8 cm 2/Vs, and 1.9 cm 2/Vs, respectively. With TOF measurement, it was proved that the double treatment had a significant influence on the efficiency of the sample.

The internal target volume (ITV)-based IMRT method can be used to reduce the effect of respiratory tumor motion. In this study, the effect of tumor motion on the dosimetric accuracy during ITV-based IMRT was investigated. ITV-based IMRT plans for a total of ten cases of liver cancer were prepared in TomoTherapy (Tomo) and volumetric modulated arc therapy (VMAT). Delivery quality assurance (DQA) plans were created using Delta4phantom for the verification of dosimetric accuracy of the established Tomo and VMAT plans. DQA measurements were performed in both the static mode and the Hexa-Motion mode by using the Delta4Hexa-Motion system in Tomo and VMAT. In the static mode, the average gamma passing rate (GPR) using a 3% dose difference/3 mm distance-to-agreement criteria was 99.61% in Tomo and 99.35% in VMAT, which confirmed sufficient dosimetric accuracy in both IMRT methods. For the Hexa-Motion measurement, the average GRP result of 90.93% in Tomo was higher than the result of 82.58% obtained in VMAT. In addition, the difference in the GPR results between the static and the Hexa-motion modes in Tomo was 8.68%, which is approximately 8% less than the 16.77% difference in VMAT. This study verifies that the dosimetric error of ITV-based IMRT due to the tumor motion was larger in VMAT than in Tomo. Also, Tomo can be considered to be more suitable than the conventional LINAC-based VMAT method in terms of the dosimetric accuracy of ITV-based IMRT for the treatment of a moving tumor.

The postoperative hypofractionated intensity-modulated radiation therapy (POHIM-RT) trial is a phase II study to evaluate toxicity following hypofractionated intensity modulated radiation therapy (IMRT) for cervical cancer. This study describes the results of a benchmark procedure for RT quality assurance of the POHIM-RT trial. Six participating institutions were provided computed tomography for RT planning and an IMRT plan for a sample and were instructed to delineate volumes, create a treatment plan and quality assurance (QA) plan, and submit the results of all procedures. The inter-institutional agreements on RT volume and plan results were evaluated using the kappa value and dice similarity coefficients. The simultaneous truth and performance level estimation (STAPLE) method was employed to generate a consensus target volume. The treatment volumes, organs-at-risk volumes, and results of the RT plan and QA reported by the institutions were acceptable and adhered well to the protocol. In terms of clinical target volume (CTV) delineation, there were differences between the institutions, particularly in vaginal cuff and paracolpium subsites. Consensus CTV was generated from the collected CTVs with the STAPLE method. The participating institutions showed considerable agreement regarding volume, dose and QA results. To improve CTV agreement in CTV, we provided feedback with images of the consensus target volume and detailed written guidelines for specific subsites that were the most heterogeneous.

Most two-dimensional (2D) detector arrays used for the verification of the intensity-modulated radiotherapy (IMRT) dose distribution comprise diode detectors or ion chamber detectors. These detectors show different sensitivities depending on the angle of incidence of the IMRT beam on the detector. In this study, the effect of the radiation beam’s angle of incidence onto the detector was analyzed in order to find an optimal 2D detector array setup position for delivery quality assurance in breast IMRT. For breast IMRT plans, comprising mostly tangential fields, the dose distribution produced with true composite beams was measured by arranging 2D detector array devices at various angles. The change in dosimetric accuracy was then assessed as a function of the radiation beam’s angle of incidence. A total of 72 dose distributions were measured and analyzed for 12 breast IMRT plans. Both the diode detector array and the ion chamber array showed a higher gamma passing ratio in the sagittal dose distribution measurement, where the beam’s angle of incidence was relatively larger. This study indicates that using a 2D detector array placed at a relatively large angle of incidence offers a more accurate verification of the IMRT dose distribution.

Tumor hypoxia is an important factor for developing resistance to radiation therapy (RT) and presents a bleak prognosis in cancer patients undergoing treatment for RT resistant hepatocellular carcinoma. Here, we present the synthesis of liposome-coated Mn3O4(MGN) nanoparticles (Lipo-MGN) and investigation of their therapeutic potential with RT utilizing a HepG2 cancer model. According to in vitro research, Lipo-MGN effectively produced oxygen in the presence of H2O2and significantly reduced the expression of HIF-1 in human HepG2 cells that were under hypoxic conditions. Lipo-MGN reversed the radio-resistance brought on by hypoxia and increased cell damage. When Lipo-MGN and RT were administered together in a HepG2 xenograft mice model, the tumor growth was delayed more than with RT alone. As determined by MR imaging, liposome-MGN also exhibited T1 contrast enhancement in tumor. According to these findings, Lipo-MGNs may increase the impact of RT by focusing tumor hypoxia. Hypoxic, radioresistant HepG2 cancer may be treated with Lipo-MGN in clinical studies.

Purpose: To investigate disease-free survival (DFS) and prognostic factors following the administration of postoperative (chemo)radiotherapy in patients with early-stage cervical cancers.Methods: The medical records of 1,069 patients from 10 participating institutions were reviewed. Statistically and clinically established factors were considered as candidates for constructing the prediction model. This model was validated, using bootstrapping to correct for optimistic bias.Results: The 5-year DFS rate was 81.1%, with a median follow-up period of 59.6 months. The statistically significant prognostic factors were as follows: pelvic lymph node metastasis, histologic type, parametrial invasion, lymphovascular space invasion, and tumor size. The nomogram for DFS was constructed, and it demonstrated a good discrimination performance, with an internally validated concordance index of 0.72.Conclusions: Our predictive model exhibited accurate predictions and may be useful in designing clinical trials to study if further chemotherapy can reduce the recurrence of disease in high-risk patients.