Evaluation of Fused Deposition Modeling Materials for 3D-Printed Container of Dosimetric Polymer Gel

Accurate dosimetric verification is becoming increasingly important in radiotherapy. Although polymer gel dosimetry may be useful for verifying complex 3D dose distributions, it has limitations for clinical application due to its strong reactivity with oxygen and other contaminants. Therefore, it is important that the material of the gel storage container blocks reaction with external contaminants. In this study, we tested the effect of air and the chemical permeability of various polymer-based 3D printing materials that can be used as gel containers. A methacrylic acid, gelatin, and tetrakis (hydroxymethyl) phosphonium chloride gel was used. Five types of printing materials that can be applied to the fused deposition modeling (FDM)-type 3D printer were compared: acrylonitrile butadiene styrene (ABS), co-polyester (CPE), polycarbonate (PC), polylactic acid (PLA), and polypropylene (PP) (reference: glass vial). The map of R2 (1/T2) relaxation rates for each material, obtained from magnetic resonance imaging scans, was analyzed. Additionally, response histograms and dose calibration curves from the R2 map were evaluated. The R2 distribution showed that CPE had sharper boundaries than the other materials, and the profile gradient of CPE was also closest to the reference vial. Histograms and dose calibration showed that CPE provided the most homogeneous and the highest relative response of 83.5%, with 8.6% root mean square error, compared with the reference vial. These results indicate that CPE is a reasonable material for the FDM-type 3D printing gel container.

Deep learning proton beam range estimation model for quality assurance based on two-dimensional scintillated light distributions in simulations

BACKGROUND

Many studies have utilized optical camera systems with volumetric scintillators for quality assurances (QA) to estimate the proton beam range. However, previous analytically driven range estimation methods have the difficulty to derive the dose distributions from the scintillation images with quenching and optical effects.

PURPOSE

In this study, a deep learning method utilized to QA was used to predict the beam range and spread-out Bragg peak (SOBP) for two-dimensional (2D) map conversion from the scintillation light distribution (LD) into the dose distribution in a water phantom.

METHODS

The 2D residual U-net modeling for deep learning was used to predict the 2D water dose map from a 2D scintillation LD map. Monte Carlo simulations for dataset preparation were performed with varying monoenergetic proton beam energies, field sizes, and beam axis shifts. The LD was reconstructed using photons backpropagated from the aperture as a virtual lens. The SOBP samples were constructed based on monoenergetic dose distributions. The training set, including the validation set, consisted of 8659 image pairs of LD and water dose maps. After training, dose map prediction was performed using a 300 image pair test set generated under random conditions. The pairs of simulated and predicted dose maps were analyzed by Bragg peak fitting and gamma index maps to evaluate the model prediction.

RESULT

The estimated beam range and SOBP width resolutions were 0.02 and 0.19 mm respectively for varying beam conditions, and the beam range and SOBP width deviations from the reference simulation result were less than 0.1 and 0.8 mm respectively. The simulated and predicted distributions showed good agreement in the gamma analysis, except for rare cases with failed gamma indices in the proximal and field-marginal regions.

CONCLUSION

The deep learning conversion method using scintillation LDs in an optical camera system with a scintillator is feasible for estimating proton beam range and SOBP width with high accuracy.

Phase I dose escalation and expansion study of golidocitinib, a highly selective JAK1 inhibitor, in relapsed or refractory peripheral T-cell lymphomas

BACKGROUND

Relapsed or refractory peripheral T-cell lymphomas (r/r PTCLs) are a group of rare and aggressive diseases that lack effective therapies. Constitutive activation of the Janus kinase (JAK)/signal transducer and activator of transcription (STAT) pathway is reported to be associated with PTCLs. Golidocitinib is an oral, potent JAK1 selective inhibitor evaluated in a phase I/II multinational study in patients with r/r PTCLs.

PATIENTS AND METHODS

Patients with r/r PTCLs were eligible. The primary objectives were to assess safety and tolerability of golidocitinib and to define its recommended phase II dose (RP2D). The secondary objectives were to evaluate its antitumor activity and pharmacokinetics (PK).

RESULTS

A total of 51 patients were enrolled and received golidocitinib treatment at 150 or 250 mg once daily (QD). The median prior lines of therapies were 2 (range: 1-8). Golidocitinib was tolerated at both doses tested, while a higher incidence of serious adverse events and dose modifications at 250 mg were observed. The most common grade ≥3 drug-related treatment-emergent adverse events were neutropenia (27.5%) and thrombocytopenia (11.8%). An objective response rate of 39.2% and a complete response rate of 21.6% were observed. With median follow-up time of 14.7 and 15.9 months, the median duration of response (DoR) and progression-free survival were 8.0 and 3.3 months, respectively. Based on these data, 150 mg QD was defined as the RP2D. Golidocitinib demonstrated a favorable PK profile as an oral agent. Biomarker analysis suggested a potential correlation between JAK/STAT pathway aberrations and clinical activity of golidocitinib.

CONCLUSIONS

In this phase I study, golidocitinib demonstrated an acceptable safety profile and encouraging antitumor efficacy in heavily pretreated patients with r/r PTCLs. These results support the initiation of the multinational pivotal study in patients with r/r PTCLs.

Novel Functional Radiomics for Prediction of Cardiac PET Avidity in Lung Cancer Radiotherapy

PURPOSE/OBJECTIVE(S)

Traditional methods of evaluating cardiotoxicity focus solely on radiation doses to the heart and do not incorporate functional imaging information. Functional imaging has great potential to improve the ability to provide early prediction for cardiotoxicity for lung cancer patients undergoing radiotherapy. FDG-based PET/CT imaging is routinely obtained as part of standard staging work up for lung cancer patients. Although FDG PET/CT scans are typically used to evaluate the tumor, imaging guidelines note that FDG PET/CT scans are an FDA-approved method to image for cardiac inflammation, and studies have noted that the PET cardiac signal can be predictive of clinical outcomes. The purpose of this work was to develop a radiomics model to predict clinical cardiac assessment of standard of care FDG PET/CT scans.

MATERIALS/METHODS

The study included 100 consecutive lung cancer patients treated with radiotherapy who underwent standard pre-treatment FDG-PET/CT staging scans. A clinician reviewed the PET/CT scans per clinical cardiac assessment guidelines and classified the cardiac uptake as: 0 = uniform diffuse, 1 = absent, 2 = heterogeneous, with event rates of 20%, 44%, and 35%, respectively. The heart was delineated and 200 novel functional radiomics features were selected to classify cardiac FDG uptake patterns. We divided the data into an 80% training set and a 20% test set to train and evaluate the classification models. Feature reduction was carried out using the Wilcoxon test (with Bonferroni adjusted p<0.05), hierarchical clustering, and Recursive Feature Elimination. Two automatic machine learning (AutoML) frameworks were used to determine classification models: a Random Forest Classifier (Tree-based Pipeline Optimization Tool, TPOT) and Linear Discriminant Analysis (AutoSklearn). 10-fold cross validation was carried out for training and the accuracy of the ability of the models to predict for clinical cardiac assessment is reported.

RESULTS

Fifty-one independent radiomics features were reduced to 3 clinically pertinent features (PET 2D Skewness, PET Grey Level Co-occurrence Matrix Correlation, and PET Median) using feature reduction techniques. The model selected by TPOT showed 89.8% predictive accuracy in the cross validation of the training set and 85% predictive accuracy on the test set. The model selected by AutoSklearn showed 89.7% predictive accuracy in the cross validation of the training set and 80% predictive accuracy on the test set.

CONCLUSION

The novelty of this work is that it is the first study to develop and evaluate functional cardiac radiomic features from standard of care FDG PET/CT scans with the data showing good predictive accuracy with clinical imaging evaluation. If validated, the current work provides automated methods to provide functional cardiac information using standard of care imaging that can be used as an imaging biomarker for early clinical toxicity prediction for lung cancer patients.

A study of quantitative indicators for slice sorting in cine-mode 4DCT

The uncertainties of four-dimensional computed tomography (4DCT), also called as residual motion artefacts (RMA), induced from irregular respiratory patterns can degrade the quality of overall radiotherapy. This study aims to quantify and reduce those uncertainties. A comparative study on quantitative indicators for RMA was performed, and based on this, we proposed a new 4DCT sorting method that is applicable without disrupting the current clinical workflow. In addition to the default phase sorting strategy, both additional amplitude information from external surrogates and the quantitative metric for RMA, investigated in this study, were introduced. The comparison of quantitative indicators and the performance of the proposed sorting method were evaluated via 10 cases of breath-hold (BH) CT and 30 cases of 4DCT. It was confirmed that N-RMSD (normalised root-mean-square-deviation) was best matched to the visual standards of our institute’s regime, manual sorting method, and could accurately represent RMA. The performance of the proposed method to reduce 4DCT uncertainties was improved by about 18.8% in the averaged value of N-RMSD compared to the default phase sorting method. To the best of our knowledge, this is the first study that evaluates RMA indicators using both BHCT and 4DCT with visual-criteria-based manual sorting and proposes an improved 4DCT sorting strategy based on them.

Endoscopic variceal obturation and retrograde transvenous obliteration for acute gastric cardiofundal variceal bleeding in liver cirrhosis

BACKGROUND/AIMS

We retrospectively compared the effect of endoscopic variceal obturation (EVO) and retrograde transvenous obliteration (RTO) in acute cardiofundal variceal bleeding.

METHODS

Patients with acute cardiofundal variceal bleeding treated with EVO or RTO at two hospitals were included.

RESULTS

Ninety patients treated with EVO and 86 treated with RTO were analyzed. The mean model for end-stage liver disease score was significantly higher in EVO group than in RTO group (13.5 vs. 11.7, P = 0.016). The bleeding control rates were high (97.8% vs. 96.5%), and the treatment-related complication rates were low in both EVO and RTO groups (2.2% vs. 3.5%). During the median follow-up of 18.0 months, gastric variceal (GV) and esophageal variceal rebleeding occurred in 34 (19.3%) and 7 (4.0%) patients, respectively. The all-variceal rebleeding rates were comparable between EVO and RTO groups (32.4% vs. 20.8% at 2-year, P = 0.150), while the GV rebleeding rate was significantly higher in EVO group than in RTO group (32.4% vs. 12.8% at 2-year, P = 0.003). On propensity score-matched analysis (71 patients in EVO vs. 71 patients in RTO group), both all-variceal and GV rebleeding rates were significantly higher in EVO group than in RTO group (all P < 0.05). In Cox regression analysis, EVO (vs. RTO) was the only significant predictor of higher GV rebleeding risk (hazard ratio 3.132, P = 0.005). The mortality rates were similar between two groups (P = 0.597).

CONCLUSIONS

Both EVO and RTO effectively controlled acute cardiofundal variceal bleeding. RTO was superior to EVO in preventing all-variceal and GV rebleeding after treatment, with similar survival outcomes.

Feasibility of automated planning for whole-brain radiation therapy using deep learning

PURPOSE

The purpose of this study was to develop automated planning for whole-brain radiation therapy (WBRT) using a U-net-based deep-learning model for predicting the multileaf collimator (MLC) shape bypassing the contouring processes.

METHODS

A dataset of 55 cases, including 40 training sets, five validation sets, and 10 test sets, was used to predict the static MLC shape. The digitally reconstructed radiograph (DRR) reconstructed from planning CT images as an input layer and the MLC shape as an output layer are connected one-to-one via the U-net modeling. The Dice similarity coefficient (DSC) was used as the loss function in the training and ninefold cross-validation. Dose-volume-histogram (DVH) curves were constructed for assessing the automatic MLC shaping performance. Deep-learning (DL) and manually optimized (MO) approaches were compared based on the DVH curves and dose distributions.

RESULTS

The ninefold cross-validation ensemble test results were consistent with DSC values of 94.6 ± 0.4 and 94.7 ± 0.9 in training and validation learnings, respectively. The dose coverages of 95% target volume were (98.0 ± 0.7)% and (98.3 ± 0.8)%, and the maximum doses for the lens as critical organ-at-risk were 2.9 Gy and 3.9 Gy for DL and MO, respectively. The DL technique shows the consistent results in terms of the DVH parameter except for MLC shaping prediction for dose saving of small organs such as lens.

CONCLUSIONS

Comparable with the MO plan result, the WBRT plan quality obtained using the DL approach is clinically acceptable. Moreover, the DL approach enables WBRT auto-planning without the time-consuming manual MLC shaping and target contouring.

Hybridisation of perovskite nanocrystals with organic molecules for highly efficient liquid scintillators

Compared with solid scintillators, liquid scintillators have limited capability in dosimetry and radiography due to their relatively low light yields. Here, we report a new generation of highly efficient and low-cost liquid scintillators constructed by surface hybridisation of colloidal metal halide perovskite CsPbA3 (A: Cl, Br, I) nanocrystals (NCs) with organic molecules (2,5-diphenyloxazole). The hybrid liquid scintillators, compared to state-of-the-art CsI and Gd2O2S, demonstrate markedly highly competitive radioluminescence quantum yields under X-ray irradiation typically employed in diagnosis and treatment. Experimental and theoretical analyses suggest that the enhanced quantum yield is associated with X-ray photon-induced charge transfer from the organic molecules to the NCs. High-resolution X-ray imaging is demonstrated using a hybrid CsPbBr3 NC-based liquid scintillator. The novel X-ray scintillation mechanism in our hybrid scintillators could be extended to enhance the quantum yield of various types of scintillators, enabling low-dose radiation detection in various fields, including fundamental science and imaging.

Clinical implementation of a wide-field electron arc technique with a scatterer for widespread Kaposi's sarcoma in the distal extremities

A novel wide-field electron arc technique with a scatterer is implemented for widespread Kaposi's sarcoma (KS) in the distal extremities. Monte Carlo beam modeling for electron arc beams was established to achieve <2% deviation from the measurements, and used for dose calculation. MC-based electron arc plan was performed using CT images of a foot and leg mimicking phantom and compared with in-vivo measurement data. We enrolled one patient with recurrent KS on the lower extremities who had been treated with photon radiation therapy. The 4- and 6-MeV electron arc plans were created, and then compared to two photon plans: two opposite photon beam and volumetric modulated arc with bolus. Compared to the two photon techniques, the electron arc plans resulted in superior dose saving to normal organs beneath the skin region, although it shows inferior coverage and homogeneity for PTV. The electron arc treatment technique with scatterer was successfully implemented for the treatment of widespread KS in the distal extremities with lower radiation exposure to the normal organs beyond the skin lesions, which could be a treatment option for recurrent skin cancer in the extremities.

Abdominal multi-organ auto-segmentation using 3D-patch-based deep convolutional neural network

Segmentation of normal organs is a critical and time-consuming process in radiotherapy. Auto-segmentation of abdominal organs has been made possible by the advent of the convolutional neural network. We utilized the U-Net, a 3D-patch-based convolutional neural network, and added graph-cut algorithm-based post-processing. The inputs were 3D-patch-based CT images consisting of 64 × 64 × 64 voxels designed to produce 3D multi-label semantic images representing the liver, stomach, duodenum, and right/left kidneys. The datasets for training, validating, and testing consisted of 80, 20, and 20 CT simulation scans, respectively. For accuracy assessment, the predicted structures were compared with those produced from the atlas-based method and inter-observer segmentation using the Dice similarity coefficient, Hausdorff distance, and mean surface distance. The efficiency was quantified by measuring the time elapsed for segmentation with or without automation using the U-Net. The U-Net-based auto-segmentation outperformed the atlas-based auto-segmentation in all abdominal structures, and showed comparable results to the inter-observer segmentations especially for liver and kidney. The average segmentation time without automation was 22.6 minutes, which was reduced to 7.1 minutes with automation using the U-Net. Our proposed auto-segmentation framework using the 3D-patch-based U-Net for abdominal multi-organs demonstrated potential clinical usefulness in terms of accuracy and time-efficiency.

Automated Field-In-Field (FIF) Plan Framework Combining Scripting Application Programming Interface and User-Executed Program for Breast Forward IMRT

Purpose:

To develop an one-click option on treatment planning system that enables for the automated breast FIF planning by combining the Eclipse Scripting application programming interfaces and user-executed programming in Windows.

Methods:

Scripting application programming interfaces were designed to promote automation in clinical workflow associated with radiation oncology. However, scripting cannot provide all functions that users want to perform. Thus, a new framework proposes to integrate the benefits of the scripting application and user-executed programming for the automated field-in-field technique. We adopted the Eclipse Scripting applications, which provide an interface between treatment planning system server and client and enable for running the executed program to create dose clouds and adjust the planning parameters such as multi-leaf collimator placements and monitor unit values. Importantly, all tasks are designed to perform with one-click option on treatment planning system, including the automated pushback of the proposed plan to the treatment planning system.

Results:

The plans produced from the proposed framework were validated against the manual field-in-field plans with 40 retrospective breast patient cases in planning efficiency and plan quality. The elapsed time for running the framework was less than 1 minute, which significantly reduced the manual multi-leaf collimator/monitor unit adjustment time. It decreased the total planning time by more than 50%, relative to the manual field-in-field planning. In dosimetric aspects, the mean and maximum dose of the heart, lung, and whole breast did not exceed 1% deviation from the manual plans in most patient cases, while maintaining the target dose coverage and homogeneity index inside the target volume. From numerical analysis, the automated plans were demonstrated to be sufficiently close to the manual plans.

Conclusion:

The combination of scripting applications and user-executed programming for automated breast field-in-field planning accomplished a significant enhancement in planning efficiency without degrading the plan quality, relative to the manual field-in-field procedure.

An additional tilted-scan-based CT metal-artifact-reduction method for radiation therapy planning

Purpose

As computed tomography (CT) imaging is the most commonly used modality for treatment planning in radiation therapy, metal artifacts in the planning CT images may complicate the target delineation and reduce the dose calculation accuracy. Although current CT scanners do provide certain correction steps, it is a common understanding that there is not a universal solution yet to the metal artifact reduction (MAR) in general. Particularly noting the importance of MAR for radiation treatment planning, we propose a novel MAR method in this work that recruits an additional tilted CT scan and synthesizes nearly metal‐artifact‐free CT images.

Methods

The proposed method is based on the facts that the most pronounced metal artifacts in CT images show up along the x‐ray beam direction traversing multiple metallic objects and that a tilted CT scan can provide complementary information free of such metal artifacts in the earlier scan. Although the tilted CT scan would contain its own metal artifacts in the images, the artifacts may manifest in a different fashion leaving a chance to concatenate the two CT images with the metal artifacts much suppressed. We developed an image processing technique that uses the structural similarity (SSIM) for suppressing the metal artifacts. On top of the additional scan, we proposed to use an existing MAR method for each scan if necessary to further suppress the metal artifacts.

Results

The proposed method was validated by a simulation study using the pelvic region of an XCAT numerical phantom and also by an experimental study using the head part of the Rando phantom. The proposed method was found to effectively reduce the metal artifacts. Quantitative analyses revealed that the proposed method reduced the mean absolute percentages of the error by up to 86% and 89% in the simulation and experimental studies, respectively.

Conclusions

It was confirmed that the proposed method, using complementary information acquired from an additional tilted CT scan, can provide nearly metal‐artifact‐free images for the treatment planning.

Dosimetric analysis of stereotactic rotational versus static intensity-modulated radiation therapy for pancreatic cancer

PURPOSE

Stereotactic body radiation therapy is a promising treatment modality for locally advanced pancreatic cancer. To determine the optimal radiation treatment, we compared the plan characteristics of volumetric-modulated arc therapy and intensity-modulated radiation therapy when administered with stereotactic body radiation therapy to treat pancreatic cancer.

PATIENTS AND METHODS

Fifteen patients with locally advanced pancreatic cancer were treated by stereotactic body radiation therapy at a dose of 24-32Gy in four fractions with marker-guided gated volumetric-modulated arc therapy. Four dimensional-computed tomography scans were used to assess the target and surrounding normal organs. The same images, contours, and dose constraints were used for dual-arc volumetric-modulated arc therapy and 9-field intensity-modulated radiation therapy planning. Plans were compared using dosimetric parameters and treatment performance.

RESULTS

Volumetric-modulated arc therapy required significantly lower monitor units (1726 vs. 4188; P<0.001) and shorter treatment delivery time in comparison with intensity-modulated radiation therapy (22.5min vs. 52.4min; P<0.001). Regarding target volume coverage, both modalities demonstrated comparable results (V_95%, 99.3% vs. 99.4%; P=0.796). Both modalities satisfied the dosimetric determinants for duodenal toxicity and the maximum and mean doses administered to normal organ were also statistically similar.

CONCLUSION

In comparison with 9-field intensity-modulated radiation therapy, volumetric-modulated arc therapy significantly reduces the number of monitoring units and treatment delivery times while administering similar dosimetric quality. Based on these results, volumetric-modulated arc therapy might be an appropriate treatment for locally advanced pancreatic cancer when combined with stereotactic body radiation therapy.

Targeting Accuracy of Image-Guided Stereotactic Body Radiation Therapy for Hepatocellular Carcinoma in Real-Life Clinical Practice: In Vivo Assessment Using Hepatic Parenchymal Changes on Gd-EOB-DTPA-Enhanced Magnetic Resonance Images

PURPOSE

Stereotactic body radiation therapy (SBRT) for hepatocellular carcinoma (HCC) has emerged as an alternative treatment option when curative treatment modalities cannot be applied. Although excellent local tumor control has been achieved with SBRT, the targeting accuracy in real-life practice remains poorly understood. We proposed an in vivo assessment of targeting accuracy using hepatic parenchymal changes observed on gadolinium ethoxybenzyl diethylenetriaminepentaacetic acid (Gd-EOB-DTPA)-enhanced magnetic resonance (MR) images and applied this method to investigate the "real-life" targeting accuracy of image-guided SBRT.

METHODS AND MATERIALS

We selected 29 patients with available follow-up MR images acquired 2 to 4 months after completion of SBRT. All patients were administered 45 Gy in 3 fractions. The treated HCC and the region of hepatic parenchymal changes in the hepatobiliary phase of MR images were delineated. We evaluated the discrepancies between the center of the HCC and that of the parenchymal change area (intercenter discrepancy [ICD]). We also analyzed the difference in ICDs between those who underwent SBRT with intrahepatic marker guidance and those with diaphragm guidance.

RESULTS

The median ICD in the 3-dimensional direction was 6.81 mm (interquartile range [IQR], 4.27-9.61 mm). Those for the craniocaudal, left-right, and anteroposterior components were 2.70 mm (IQR, 1.83-4.06 mm), 1.63 mm (IQR, 0.76-3.49), and 4.12 mm (IQR, 1.20-6.96 mm), respectively. The median ICD for patients who underwent treatment with intrahepatic marker guidance and those with diaphragm guidance was 7.53 mm (IQR, 6.63-10.86 mm) and 5.60 mm (IQR, 4.28-8.18 mm), respectively. There was no significant difference in ICD between those who underwent treatment with intrahepatic marker guidance and those with diaphragm guidance (P = .296).

CONCLUSIONS

The hepatic parenchymal changes observed on Gd-EOB-DTPA-enhanced MR images can be used to assess the targeting accuracy after SBRT for HCC.

Stereotactic body radiation therapy using a respiratory-gated volumetric-modulated arc therapy technique for small hepatocellular carcinoma

Background

Volumetric-modulated arc therapy (VMAT) is a highly sophisticated linear accelerator-based treatment method, and allows dose rate-changing intensity modulation with gantry rotation. We report our clinical experiences with stereotactic body radiation therapy (SBRT) using a respiratory-gated VMAT technique for patients with hepatocellular carcinoma (HCC) when established curative treatments cannot be applied.

Methods

A total of 119 patients (139 lesions) with HCC who were treated with SBRT were registered between March 2012 and July 2013 at our institution. A dose of 10–15 Gy per fraction was applied over 3–4 consecutive days, resulting in a total dose of 30–60 Gy.

Results

The median follow-up period was 25.8 months (range, 3.2–36.8 months). The overall 3-year survival rate was 83.8%. The local control rate at 3 years was 97.0% in all treated lesions. Multivariate analysis revealed that the Child-Pugh class before SBRT had significant effects on overall survival (Child-Pugh A: hazard ratio = 0.463; 95% CI, 0.262–0.817; p = 0.008).

Conclusions

SBRT using a respiratory-gated VMAT technique was an excellent ablative treatment modality for patients with HCC. SBRT is a good alternative treatment for patients with small HCCs that are unsuitable for surgical resection or local ablative therapy.

Electronic supplementary material

The online version of this article (10.1186/s12885-018-4340-7) contains supplementary material, which is available to authorized users.

High-dose radiotherapy is associated with better local control of bone metastasis from hepatocellular carcinoma

We evaluated the pain and radiologic response, time to progression, and dose-response relationship after palliative radiotherapy for bone metastasis from hepatocellular carcinoma. We retrospectively reviewed the medical records of 91 patients between January 2004 and August 2012. The reviewed medical records included data on changes in pain, local tumor progression, and radiologic response evaluated via follow-up images. The radiologic response was assessed based on the Response Evaluation Criteria In Solid Tumors. The pain response was defined according to the International Bone Metastases Consensus Working Party palliative radiotherapy endpoints. Median radiation dose was 40 Gy (range, 20-66 Gy), with various fraction sizes (range, 2.0-6.0 Gy). Pain response rate was 81.4%. During the follow-up periods, radiologic local tumor progression was found in 42 patients (46.2%). The median time to progression was 14.1 months. When the patients were divided into two groups according to their radiation dose (< 55 Gy10 vs. ≥ 55 Gy10), the pain response rates of the high- and low-dose groups did not differ significantly (p = 0.728). However, the radiologic response rate and the time to progression showed significant differences between the two groups (p = 0.009 and p = 0.018, respectively). With dose escalation, higher radiologic response rates and a longer time to progression were achieved in patients with mass-forming bone metastases from hepatocellular carcinoma.

Dataset on electro-optically tunable smart-supercapacitors based on oxygen-excess nanograin tungsten oxide thin film

The dataset presented here is related to the research article entitled "Highly Efficient Electro-optically Tunable Smart-supercapacitors Using an Oxygen-excess Nanograin Tungsten Oxide Thin Film" (Akbar et al., 2017) [9] where we have presented a nanograin WO₃ film as a bifunctional electrode for smart supercapacitor devices. In this article we provide additional information concerning nanograin tungsten oxide thin films such as atomic force microscopy, Raman spectroscopy, and X-ray diffraction spectroscopy. Moreover, their electrochemical properties such as cyclic voltammetry, electrochemical supercapacitor properties, and electrochromic properties including coloration efficiency, optical modulation and electrochemical impedance spectroscopy are presented.

Dataset on electro-optically tunable smart-supercapacitors based on oxygen-excess nanograin tungsten oxide thin film

The dataset presented here is related to the research article entitled “Highly Efficient Electro-optically Tunable Smart-supercapacitors Using an Oxygen-excess Nanograin Tungsten Oxide Thin Film” (Akbar et al., 2017) [9] where we have presented a nanograin WO₃ film as a bifunctional electrode for smart supercapacitor devices. In this article we provide additional information concerning nanograin tungsten oxide thin films such as atomic force microscopy, Raman spectroscopy, and X-ray diffraction spectroscopy. Moreover, their electrochemical properties such as cyclic voltammetry, electrochemical supercapacitor properties, and electrochromic properties including coloration efficiency, optical modulation and electrochemical impedance spectroscopy are presented.

Positive Rates of Preliminary Crossmatches Among Transplantation Candidates Waitlisted for Different Organs in the Korean Network for Organ Sharing

OBJECTIVE

For deceased-donor organ transplantations, negative T cell crossmatches (XMs) are mandatory for kidney and pancreas allocation in the Korean Network for Organ Sharing (KONOS) organ allocation system. Submission and periodic renewal of serum to the KONOS is required for all transplantation candidates of kidney or pancreas and these sera are distributed to 23 laboratories for preliminary XMs. We have investigated how sensitization status varies among transplantation candidates waitlisted for different organs.

METHODS

Positive rates of T cell XMs performed during recent 1-year period (from March 2014 to February 2015) in the Korea Organ Donation Agency laboratory have been analyzed according to different organs. For 163 cases of deceased donors, 3605 recipients (22.1 recipients per one donor) were crossmatched using both of National Institutes of Health and antihuman globulin complement-dependent cytotoxicity (CDC) methods and flow cytometry method.

RESULTS

T cell XM positive rates varied among transplantation candidates for different organs. The positive rate was high for kidney (485/3,145, 15.4%), and low for pancreas or kidney/pancreas (7/200, 3.5%), lung (0/41, 0%), and heart (11/221, 5.0%). Among XM-positive individuals, nearly two-thirds of the kidney transplantation candidates showed strong sensitization status with CDC+/flow+ results (64.5%), whereas pancreas or kidney/pancreas transplantation candidates more commonly showed weaker sensitization status with CDC-/flow+ results (85.7%).

CONCLUSION

Kidney transplantation candidates show a much higher positive rate and stronger sensitization status than candidates for other organs. The results of this study would be useful for determining the number of candidates to be crossmatched for different organs.

Gated Volumetric-Modulated Arc Therapy vs. Tumor-Tracking CyberKnife Radiotherapy as Stereotactic Body Radiotherapy for Hepatocellular Carcinoma: A Dosimetric Comparison Study Focused on the Impact of Respiratory Motion Managements

Purpose

To assess the potential dosimetric benefits associated with the CyberKnife (CK) tumor tracking capability, wherein an extra margin for respiratory tumor motion is not required, when compared to respiratory-gated volumetric-modulated arc therapy (VMAT) for hepatocellular carcinoma (HCC).

Methods

Twenty-nine HCC patients previously treated with double-arc VMAT were enrolled. In each VMAT plan, the individual internal target volume (ITV) margin around the tumor was determined by measuring its motion over 30–70% of respiratory phases using four-dimensional computed tomography, followed by a 5-mm isotropic margin for the planning target volume (PTV). For each VMAT plan, two CK plans were generated using the original (CK_original, ITV included) and modified PTVs (CK_modified, ITV excluded) for comparison. In each case, the CK_original and CK_modified plans were compared to the original VMAT plan in terms of the dosimetric parameters including the conformity index (CI), PTV coverage (CO), organs at risk (OAR) doses, and normal liver tissue sparing.

Results

The original PTVs with median 24 cc (range, 9–65 cc) were significantly reduced to median 12 cc (range, 5–41 cc) in the CK_modified plans. Statistically significant differences in plan qualities were observed between the VMAT and the CK plans: mean CI, 1.05 in VMAT vs. 1.17 in both CK plans (p < 0.001); and mean CO, 93.0% in VMAT vs. 96.6% in CK_original and 96.9% in CK_modified (p < 0.001). The average volume of normal liver tissue receiving > 15 Gy was significantly decreased in the CK_modified plan, as compared to that in the VMAT and CK_original plans, by 1.75- and 1.61-fold, respectively.

Conclusions

The tumor tracking capability of the CK system can significantly decrease the volume of normal liver tissue receiving > 15 Gy, while maintaining high precision in target localization, conformity, tumor coverage, and dose sparing of the OAR. Therefore, it can be a valuable SBRT option, particularly for HCC patients with poor liver function.

Analysis of prostate bed motion using an endorectal balloon and cone beam computed tomography during postprostatectomy radiotherapy

Background

The authors conducted this prospective study to analyze the amount of interfractional prostate bed motion (PBM) and quantify its components with the use of an endorectal balloon (ERB).

Methods

A total of 1,348 cone beam computed tomography images from 46 patients who underwent postprostatectomy radiotherapy were analyzed. For the pilot image, electronic portal imaging, guided by skin marks was performed to ensure proper positioning and inflation of the ERB. Then, for bone matching, manual or automatic registration of the planning and each cone beam computed tomography was performed, based on the bony anatomy of the pelvis. Shifts (bony misalignment [BM]) in three directions were recorded at each treatment session. For prostate bed matching, manual matching was conducted based on the anterior rectal wall and the shift (PBM) was recorded. Total setup error was defined as the shift from the skin mark to the prostate bed matching, based on anterior rectal wall stretched by the ERB. PBM was defined as the difference between the total setup error and BM.

Results

Systematic errors for the total setup error were 1.0, 1.3, and 1.0 mm in the right–left, anterior–posterior, and superior–inferior directions, with random errors of 1.9, 2.4, and 1.9 mm, respectively. Systematic errors were 1.6, 1.6, and 0.3 mm for BM and 0.8, 1.1, and 0.9 mm for PBM, with random errors of 2.4, 2.5, and 1.1 mm for BM and 1.8, 2.2, and 1.9 mm for PBM.

Conclusion

The BM was the main component of the total setup error, suggesting that interfractional PBM was well controlled by the ERB device. Planning target volume margins of <5 mm were needed to include 95% of the interfractional variations when using an ERB.