Predictive factors for severe radiation-induced lung injury in patients with lung cancer and coexisting interstitial lung disease

BACKGROUND AND PURPOSE

This study aimed to investigate the predictive factors of severe radiation-induced lung injury (RILI) in patients with lung cancer and coexisting interstitial lung disease (ILD) undergoing conventionally fractionated thoracic radiotherapy.

MATERIALS AND METHODS

The study includes consecutive patients treated with thoracic radiotherapy for lung cancer at two tertiary centers between 2010 and 2021. RILI severity was graded using the National Cancer Institute Common Terminology Criteria version 5.0, with severe RILI defined as toxicity grade ≥4, and symptomatic RILI as grade ≥2. The absolute neutrophil count (ANC), absolute lymphocyte count (ALC), and C-reactive protein were collected within 4 weeks before starting radiotherapy. Neutrophil-lymphocyte ratios (NLR) were calculated as ANC/ALC. The median follow-up was 9 (range, 6-114) months.

RESULTS

Among 54 patients, 22 (40.7 %) had severe RILI. On multivariate logistic regression analysis, high pretreatment ANC (p = 0.030, OR = 4.313), pretreatment NLR (p = 0.007, OR = 5.784), and ILD severity (p = 0.027, OR = 2.416) were significant predictors of severe RILI. Dosimetric factors were not associated with severe RP. Overall survival was significantly worse for patients with severe RILI than those without, with 1-year cumulative overall survival rates of 7.4 % and 62.8 %, respectively.

CONCLUSION

Pretreatment blood NLR, ANC, and ILD severity were associated with severe RILI. Overall survival was dismal for patients with severe RILI.

Postoperative Scar Management Using Laser Therapy for Breast Reconstruction With Latissimus Dorsi Flap

BACKGROUND

Postoperative scar formation is inevitable, and a gold standard management has not been established to date. Due to the fact long and large scar formation occurs in reconstructive surgery, this study analyzed the relationship between various factors in patients who received breast reconstruction using latissimus dorsi (LD) flap to investigate appropriate and effective management approaches.

PATIENTS AND METHODS

Twenty-seven patients who underwent breast reconstruction between June 2014 and January 2015 received laser therapy on their LD donor site at the Kyungpook National University Chilgok Hospital. Scar evaluation was performed on both the surgical scar and intact skin on the contralateral side. Scar evaluation was conducted at five specific points, 2 cm from the midpoint of the scar on each side. Laser treatment was performed at 4-week intervals, and patients were then followed-up for 6 months. To assess scars, gross images were taken using the same settings. In addition, spectrophotometry was used for color assessment, durometer for texture and pressure evaluation, and Vernier calipers and height gauges for a more precise and objective approach.

RESULTS

The mean age of the participants was 45.7 years, and the mean body mass index was 22.1 kg/m2 The operator-evaluated scar scale scores were 107.2 and 97.3 in the experimental and control groups, respectively. In the patient-rated questionnaire, the scores were 62.3 and 59.4 in the experimental and control groups, respectively.

CONCLUSION

When analyzing early-stage postoperative scars based on various factors, laser therapy is considered a very useful scar management approach. Additionally, when performing reconstructive surgery, tension force is regarded as a significant factor to take into account since it affects scar widening.

Deep-Learning Model Prediction of Radiation Pneumonitis Using Pretreatment Chest Computed Tomography and Clinical Factors

Objectives: This study aimed to build a comprehensive deep-learning model for the prediction of radiation pneumonitis using chest computed tomography (CT), clinical, dosimetric, and laboratory data. Introduction: Radiation therapy is an effective tool for treating patients with lung cancer. Despite its effectiveness, the risk of radiation pneumonitis limits its application. Although several studies have demonstrated models to predict radiation pneumonitis, no reliable model has been developed yet. Herein, we developed prediction models using pretreatment chest CT and various clinical data to assess the likelihood of radiation pneumonitis in lung cancer patients. Methods: This retrospective study analyzed 3-dimensional (3D) lung volume data from chest CT scans and 27 features including dosimetric, clinical, and laboratory data from 548 patients who were treated at our institution between 2010 and 2021. We developed a neural network, named MergeNet, which processes lung 3D CT, clinical, dosimetric, and laboratory data. The MergeNet integrates a convolutional neural network with subsequent fully connected layers. A support vector machine (SVM) and light gradient boosting machine (LGBM) model were also implemented for comparison. For comparison, the convolution-only neural network was implemented as well. Three-dimensional Resnet-10 network and 4-fold cross-validation were used. Results: Classification performance was quantified by using the area under the receiver operative characteristic curve (AUC) metrics. MergeNet showed the AUC of 0.689. SVM, LGBM, and convolution-only networks showed AUCs of 0.525, 0.541, and 0.550, respectively. Application of DeLong test to pairs of receiver operating characteristic curves respectively yielded P values of .001 for the MergeNet-SVM pair and 0.001 for the MergeNet-LGBM pair. Conclusion: The MergeNet model, which incorporates chest CT, clinical, dosimetric, and laboratory data, demonstrated superior performance compared to other models. However, since its prediction performance has not yet reached an efficient level for clinical application, further research is required. Contribution: This study showed that MergeNet may be an effective means to predict radiation pneumonitis. Various predictive factors can be used together for the radiation pneumonitis prediction task via the MergeNet.

Free Vertical Latissimus Dorsi Flap for Tongue Reconstruction After Total Glossectomy

BACKGROUND/AIM

The tongue is an important anatomical structure, playing an significant role in natural speech, swallowing, and sense of taste. Immediate reconstruction using autologous tissue must be performed following glossectomy for tongue cancer to improve patient quality of life. This study aimed to demonstrate the usefulness of a surgical technique using the free vertical latissimus dorsi flap (FvLDF) for tongue reconstructions using autologous tissue.

PATIENTS AND METHODS

Among patients who underwent total glossectomy for tongue cancer from November 2014 to February 2023, we selected 10 patients who underwent immediate tongue reconstruction with a radial free forearm flap (RFFF) or free anterolateral thigh flap and four patients who underwent FvLDF. The patients were compared regarding postoperative function (width of oropharyngeal space in computed tomography, language-speech evaluation), aesthetic results, and features.

RESULTS

All four patients who underwent FvLDF showed successful flap survival, with no severe complications. Because vertical incision was made during flap harvest with primary closure possible with the mid-axillary line, donor morbidity was significantly lower in patients who underwent reconstruction with FvLDF than in those who underwent reconstruction with RFFF, and good aesthetic results were obtained. In comparing the oropharyngeal space of patients on neck CT preoperatively and postoperatively, the width increase rate of patients who underwent reconstruction with FvLDF was significantly smaller. FvLDF patients demonstrated good speech and swallowing functions.

CONCLUSION

Considering the advantages of reconstruction with FvLDF in terms of features and aesthetic results, this surgical technique may be a reliable alternative technique for tongue defects after glossectomy.

The role of a photographic atlas in reducing unanticipated healthcare utilization following circumcision

INTRODUCTION

Circumcision is a common procedure that can evoke caregiver anxiety in the postoperative period due to unfamiliarity with the healing process. To mitigate unnecessary healthcare utilization such as phone calls and unanticipated clinic or emergency department (ED) visits, photographic atlases have been developed to better prepare caregivers for the recovery process. The objective of our study is to further investigate the efficacy of a photographic atlas in its ability to decrease postoperative healthcare utilization using an increased sample size and extended study period compared to previous studies.

MATERIALS AND METHODS

In this study, we compared a prospective intervention cohort of patients undergoing circumcision at our institution who received a photographic atlas during postoperative teaching to a retrospective cohort of patients who had not received it. Our primary outcome was unanticipated healthcare utilization, defined as postoperative telephone calls and unanticipated presentations to the urology clinic or ED.

RESULTS

The retrospective no-atlas cohort included 105 patients, and the prospective intervention atlas cohort included 80 patients. Both groups were similar with respect to age (p = 0.47) and other demographics. There was no statistically significant difference in healthcare utilization between the no-atlas and atlas cohort. Specifically, we identified no difference in the number of phone calls to clinic staff (12 [11.4%] vs. 11 [13.8%], p = 0.64) or unanticipated postoperative clinic or ED visits (2 [1.9%] vs. 4 [5.0%], p = 0.41).

DISCUSSION

The use of a photographic atlas as part of caregiver support for circumcision patients did not demonstrate a statistically significant reduction in either postoperative phone calls or clinic/ED visits. The decrease in absolute number of caregiver phone calls was minimal (12-11), with a small increase in follow-up presentations (2-4). The lack of significant change may be due to the already infrequent occurrence of these events following circumcision, as demonstrated by the no-atlas cohort. Other potential advantages of the atlas, such as improved caregiver confidence and satisfaction, may have been present, but were not measured in this study.

CONCLUSIONS

Adding to the mixed results of previous studies, these findings do not support that photographic atlases decrease unanticipated healthcare utilization in children undergoing a circumcision. However, utilization was found to be low. Additionally, further studies are needed to determine other significant benefits of this form of education, such as improved caregiver confidence and satisfaction.

Comparison between 1-week and 2-week palliative radiotherapy courses for superior vena cava syndrome

PURPOSE

The aim of this study was to evaluate the effectiveness of palliative radiation therapy (RT) for superior vena cava (SVC) syndrome from lung cancer and to compare the 2-week and 1-week schedules.

MATERIALS AND METHODS

A retrospective study was conducted on lung cancer patients with palliative RT for SVC syndrome. Patients received 30 Gy in 10 fractions (2-week group) or 20 Gy in 5 fractions (1-week group) between July 2012 and June 2022. Treatment outcomes were evaluated at 1 to 2 months after RT. The tumor response and recanalization were evaluated based on the computed tomography (CT).

RESULTS

Of the 39 patients, 24 received a 2-week course RT and 15 received a 1-week course of RT. The most common SVC-associated symptoms were edema (51.3%) and dyspnea (43.6%). There were no significant differences in performance status, histology, and grade of SVC. Symptom relief in symptomatic patients was comparable (85.7% in the 2-week group vs. 91.6% in the 1-week group; p = 0.581). There were no significant differences between the 2-week and 1-week groups in recanalization rates (62.5% vs. 60.0%; p = 0.876), tumor responses (75% vs. 60.0%; p = 0.876), and 6-month overall survival rates (29.2% vs. 36.4%; p = 0.726). In each of the two groups, one patient was consulted for re-irradiation. The median survival were 3.7 months for the 2-week group and 4.4 months for the 1-week group.

CONCLUSION

In patients with SVC syndrome, the palliative effect of a 1-week course was equivalent to that of a 2-week course. Given the poor prognosis, a 1-week course may be an option.

Korean Real-World Data on Patients With Unresectable Stage III NSCLC Treated With Durvalumab After Chemoradiotherapy: PACIFIC-KR

INTRODUCTION

This study aimed to investigate real-world evidence for efficacy and safety of durvalumab consolidation (DC) after chemoradiotherapy (CRT) in patients with unresectable stage III NSCLC.

METHODS

Patients with stage III NSCLC who started DC after CRT between September 2018 and December 2020 and were treated at five tertiary hospitals in the Republic of Korea were included. The primary end point was real-world progression-free survival (rwPFS). Secondary end points were overall survival, objective response rate, and adverse events including radiation pneumonitis (RP) and immune-related adverse events (irAEs).

RESULTS

A total of 157 patients were enrolled. At the median follow-up of 19.1 months, median rwPFS of DC was 25.9 months (95% confidence interval: 16.5-35.4) and the 1-, 2-, and 3-year rwPFS rates were 59.4%, 51.8%, and 43.5%, respectively. The median overall survival was not mature, and objective response rate of DC was 51.0%. High programmed death-ligand 1 expression (≥50%) and development of RP requiring steroid treatment were significantly associated with longer (p = 0.043) and shorter rwPFS (p = 0.036), respectively. RP, RP requiring steroid treatment, and irAEs developed in 57 (36.3%), 42 (26.8%), and 53 (33.8%) patients, respectively. Among peripheral blood cell counts at the initiation of DC, a high derived monocyte-to-lymphocyte ratio was the most significant risk factor for the development of RP requiring steroid treatment (OR 44.76, 95% CI: 8.89-225.43, p < 0.001) and irAEs (OR 2.85, 95% CI: 1.27-6.41, p = 0.011).

CONCLUSIONS

Compared with the outcome of the PACIFIC trial, these real-world data revealed favorable survival benefits of DC after CRT in patients with unresectable stage III NSCLC. Blood-based biomarkers could predict higher-grade RP and irAEs before the initiation of DC.

Artificial Intelligence Literacy: Developing a Multi-institutional Infrastructure for AI Education

RATIONALE AND OBJECTIVES

To evaluate the effectiveness of an artificial intelligence (AI) in radiology literacy course on participants from nine radiology residency programs in the Southeast and Mid-Atlantic United States.

MATERIALS AND METHODS

A week-long AI in radiology course was developed and included participants from nine radiology residency programs in the Southeast and Mid-Atlantic United States. Ten 30 minutes lectures utilizing a remote learning format covered basic AI terms and methods, clinical applications of AI in radiology by four different subspecialties, and special topics lectures on the economics of AI, ethics of AI, algorithm bias, and medicolegal implications of AI in medicine. A proctored hands-on clinical AI session allowed participants to directly use an FDA cleared AI-assisted viewer and reporting system for advanced cancer. Pre- and post-course electronic surveys were distributed to assess participants' knowledge of AI terminology and applications and interest in AI education.

RESULTS

There were an average of 75 participants each day of the course (range: 50-120). Nearly all participants reported a lack of sufficient exposure to AI in their radiology training (96.7%, 90/93). Mean participant score on the pre-course AI knowledge evaluation was 8.3/15, with a statistically significant increase to 10.1/15 on the post-course evaluation (p= 0.04). A majority of participants reported an interest in continued AI in radiology education in the future (78.6%, 22/28).

CONCLUSION

A multi-institutional AI in radiology literacy course successfully improved AI education of participants, with the majority of participants reporting a continued interest in AI in radiology education in the future.

Abstract WMP43: Health Care Disparities In Reperfusion Therapy For Patients With Acute Ischemic Stroke Across Hospitals

Background: Medical care disparities are wide, and stroke in no exception. Reperfusion therapy is the standard treatment for acute ischemic stroke, but its use may vary across hospitals.

Methods: Data from 75,870 patients admitted to 247 acute stroke hospitals nationwide were obtained through the 2013-2018 acute stroke quality evaluation program conducted by the Health Insurance Review and Assessment Service. The primary outcome was the hospital reperfusion therapy rate (RTR), defined as the proportion of intravenous tissue plasminogen activator (IVT) and/or endovascular thrombectomy (EVT) cases in patients potentially eligible for reperfusion therapy (onset-to-arrival time ≤ 6 hours and initial NIHSS score ≥ 4). Hospital RTRs, adjusted for age, sex, onset-to-arrival time, and initial stroke severity, were analyzed with hospital characteristics.

Results: During the study period, 10,513 stroke patients were potentially eligible for reperfusion treatment and were admitted to 247 acute care hospitals. The RTR of the study population was 52.9%. The mean hospital RTR was 34.8% [median (IQR) 37.5% (9.8 - 56.2)]. A higher number of beds and average monthly stroke admissions were associated with a higher hospital RTR. Multivariable analysis revealed the average stroke admission per month, presence of stroke unit, the average IVT per month, and the average EVT per month were the independent determinants for hospital RTR. Hospital RTR was inversely correlated with 1-year mortality regardless of hospital stroke volume.

Conclusions: RTRs vary widely across hospitals. The higher the hospital stroke volume, the higher the hospital RTRs. High hospital RTRs correlates with low 1-year mortality regardless of hospital stroke volume.

Abstract WP40: Development Of The System For National Statistics Of Stroke And Acute Myocardial Infarction Using Claims-based Algorithms In Korea

Background: The epidemiology of stroke and acute myocardial infarction (AMI) in Korea is limited by inaccurate methods for estimating incidence. Therefore, this study aimed to build the system for national statistics of stroke and AMI in Korea using claims-based identification algorithms.

Methods: We identified stroke and AMI using the claims-based algorithms based on the 2018 National Health Insurance Service (NHIS) data. The identification algorithms were validated using investigation of medical records of the sampled cases including the patient groups and the control groups based on a 2-stage stratified sampling method. The sampled cases were divided into 6 strata according to regions (capital and non-capital) and types of centers (tertiary hospitals, general hospitals, and hospitals). Based on the medical records results, we calculated sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV), and weighted PPV and weighted NPV were calculated by applying strata-specific sampling rates. The incidence rate of stroke and AMI is the number of new cases of stroke and AMI, including recurrent events, which was calculated by applying the algorithms using weighted PPV and NPV to the claims data.

Results: In total, 2,200 cases (1,086 cases in stroke [578 patients and 508 controls] and 1,114 cases in AMI [520 patients and 594 controls]) were sampled after applying algorithms for review of hospital records. In hospital record reviews, the stroke algorithm had 95.2% sensitivity, 99.6% specificity, 89.3% PPV, and 99.8% NPV, and AMI algorithms showed 97.7% sensitivity, 99.9% specificity, 90.0% PPV, and 99.9% NPV. We identified 94,994 stroke and 33,834 AMI cases including recurrent events using validated identification algorithms in 2018. The age- and sex-standardized incidence rate of stroke was 175.7 cases per 100,000 person-years and the incidence rate of AMI was 49.3 cases per 100,000 person-years in 2018.

Conclusion: We developed the national statistical system to estimate the incidence of stroke and AMI using validated claims-based algorithms in Korea. By using this system, we expect that it will be possible to conduct nationwide epidemiological research and improve acute cardiovascular care in Korea.

Abstract WP207: Treatments Advanced, But Outcomes Stagnated In Young Adults With Acute Ischemic Stroke In Korea Between 2008 And 2019

Background: Outcome improvement in young stroke patients is of great interest given their long life expectancy and substantial societal burden. We aimed to investigate whether the treatment advancement has been made and translated into outcome improvement in young patients with acute ischemic stroke (AIS).

Methods: From a prospective multicenter stroke registry in South Korea, young AIS patients (aged 18-50) hospitalized between 2008 and 2019 were identified. The study period was divided into 4 epochs. The secular trends of patient characteristics, treatments, and outcomes adjusted for potential confounders were analyzed.

Results: This study included 7,050 young AIS patients (mean age 43.1; men 71.9%) from 70,567 enrolled during the period. The mean age decreased from 43.6 years in 2008-2010 to 42.9 years in 2017-19 (P trend =.009). Obesity increased (40.1% to 49.0%), but current smoking decreased (53.1% to 42.8%). Other vascular risk factors and sex proportions did not change (P trend ’s > 0.5). Onset-to-arrival time and door-to-puncture time for mechanical thrombectomy did not change (P trend ’s > 0.5), but door-to-needle time for intravenous thrombolysis improved (P trend <.001). Acute and secondary stroke prevention treatments including intravenous thrombolysis (9.5% to 13.8%), mechanical thrombectomy (3.2% to 9.2%), dual antiplatelet therapy for minor stroke (26.6% to 48.0%), direct oral anticoagulant for atrial fibrillation (0.0% to 56.2%) and statins (71.5% to 91.2%) improved significantly (P trend ’s <.01). For stroke outcomes, for which data were available since 2011, the proportions of 3-month modified Rankin Scale 0-1 (68.3% to 69.1%) and 0-2 (87.6% to 86.2%), one-year mortality (2.5% to 2.4%), and one-year stroke recurrence (4.4% to 5.3%) did not improve (adjusted P trend ’s > 0.2).

Conclusions: This study shows that the treatment improvements did not lead to outcome improvements in young AIS patients. The findings indicate that we should not be complacent with the current advances.

Abstract WP98: Utilization Of Perfusion Imaging For Acute Ischemic Stroke: Secular Trends And Effects On Outcomes Of Endovascular Treatment

Introduction: Perfusion imaging (PI) could guide decision-making for endovascular treatment (EVT) of acute ischemic stroke (AIS). However, PI was underused even in the US before the pivotal EVT trials proved its usefulness in 2018. This study aimed to describe the secular trends of PI utilization and investigate the effectiveness of PI-based EVT in real-world practice.

Methods: Using a prospective multicenter (n=17) stroke registry in South Korea, we identified patients with AIS who presented within 24 hours from onset between 2011 and 2021. The study period was divided into 3 epochs: 2011-2014, 2015-2017, and 2018-2021. The study population was divided into the early (arrival within 6 hours) and late window (6-24 hours) groups.

Results: A total of 51,650 patients (15,654 patients in 2011-2014, 14,432 patients in 2015-2017, and 21,564 patients in 2018-2021) were analyzed. Utilization of PI decreased in the overall population and early window group ( P trend <0.001); 43.3% and 54.1% in 2011-2014, 40.1% and 44.1% in 2015-2017, and 38.4% and 40.2% in 2018-2021, respectively; but increased in the late window group ( P trend <0.001); 31.3% in 2011-2014, 35.7% in 2015-2017, and 36.5% in 2018-2021. Of 10,872 patients with anterior large-vessel occlusion (aLVO), the EVT rate was not different between patients with and without PI (48.7% vs. 46.6%, P =0.08) in the early window but higher in those with PI than without PI in the late window (29.8% vs. 18.7%, P <0.001). The EVT outcome (3-month mRS 0-2) was not different between patients with and without PI in the early window (44.1% vs. 41.8%, P =0.21) and late window (38.4% vs. 39.2%, P =0.81). Propensity score analysis and instrumental variable analysis with PI rate per center as an instrument will be performed to adjust imbalances between patients with and without PI.

Conclusion: Between 2011 and 2021 in South Korea, PI utilization has decreased in patients arriving within 6 hours from onset but has increased in those arriving between 6 and 24 hours. Among patients with aLVO, PI likely increased the EVT rate in the late window but did not in the early window. PI utilization did not seem to affect the EVT outcomes, but in-depth analysis is required.

Abstract 44: Impact Of Novel Oral Anticoagulant Use On Secular Trend Of Vascular Events Or Death After Atrial Fibrillation-related Acute Ischemic Stroke

Introduction: Now novel oral anticoagulants (NOAC) are strongly recommended for secondary stroke prevention in patients with atrial fibrillation (AF). However, it remains unclear to what extent the introduction of NOACs improved clinical outcomes in real-world practice.

Methods: Using a nationwide prospective multi-center stroke registry database, we identified consecutive AIS patients with AF enrolled between Jan 2011 and Dec 2019, and analyzed one-year clinical events and NOAC prescription at discharge. The primary outcome was the composite of stroke, myocardial infarction, and all-cause death. To assess the mediation effect of NOAC on the outcomes, we performed natural effect models according to the calendar year. The exposure-mediator analysis, exposure-outcome analysis, and mediator-outcome analysis were performed using multivariate regression analysis according to the characteristics of the variables.

Results: We analyzed 12,500 patients (mean age, 74.4 years; 51.3% male; median NIHSS at presentation, 8). From 2011 to 2019, the cumulative one-year incidence of the primary composite outcome (28.3% to 22.1%), all-cause mortality (23.8% to 17.9%), and stroke recurrence (8.3% to 5.1%) significantly decreased, while the NOAC prescription rate at discharge increased (0% to 75.6%). One-year increase in the calendar year was independently associated with a delayed occurrence of primary composite outcomes (Step 1: adjusted Time Ratio (aTR), 1.10; 95% confidence interval, 1.07-1.14) and with an increased NOAC prescription rate (Step 2: adjusted odds ratio, 2.20; 2.14-2.27). Increase in the NOAC prescription rate was significantly associated with the delayed occurrence of primary composite outcome (Step 3: aTR, 3.80; 3.15-4.58). However, after controlling for the NOAC prescription rate (mediator), the calendar year was no longer associated with the primary composite outcomes. (Step 4: aTR, 0.78; 95% CI 0.60-1.03). Thus, our results indicate full mediation of NOAC prescription in the association between the calendar year and primary composite outcomes.

Conclusion: The reduced risk of major vascular events or death over time in AIS patients with AF was fully mediated by the increase in NOAC use.

Dummy run quality assurance study in the Korean Radiation Oncology Group 19 − 09 multi-institutional prospective cohort study of breast cancer

Background

The Korean Radiation Oncology Group (KROG) 19 − 09 prospective cohort study aims to determine the effect of regional nodal irradiation on regional recurrence rates in ypN0 breast cancer patients. Dosimetric variations between radiotherapy (RT) plans of participating institutions may affect the clinical outcome of the study. We performed this study to assess inter-institutional dosimetric variations by dummy run.

Methods

Twelve participating institutions created RT plans for four clinical scenarios using computed tomography images of two dummy cases. Based on a reference structure set, we analyzed dose-volume histograms after collecting the RT plans.

Results

We found variations in dose distribution between institutions, especially in the regional nodal areas. Whole breast and regional nodal irradiation (WBI + RNI) plans had lower inter-institutional agreement and similarity for 95% isodose lines than WBI plans. Fleiss’s kappa values, which were used to measure inter-institutional agreement for the 95% isodose lines, were 0.830 and 0.767 for the large and medium breast WBI plans, respectively, and 0.731 and 0.679 for the large and medium breast WBI + RNI plans, respectively. There were outliers in minimum dose delivered to 95% of the structure (D95%) of axillary level 1 among WBI plans and in D95% of the interpectoral region and axillary level 4 among WBI + RNI plans.

Conclusion

We found inter-institutional and inter-case variations in radiation dose delivered to target volumes and organs at risk. As KROG 19 − 09 is a prospective cohort study, we accepted the dosimetric variation among the different institutions. Actual patient RT plan data should be collected to achieve reliable KROG 19 − 09 study results.

Incidence of hypothyroidism after treatment for breast cancer: A Korean population-based study

This Korean population-based study aimed to describe the patterns of hypothyroidism after adjuvant radiation therapy (RT) in patients with breast cancer. The Korean Health Insurance Review and Assessment Service database was searched for patients with invasive breast carcinomas. We calculated the cumulative incidence and incidence rates per 1,000 person-years of subsequent hypothyroidism and compared them using the log-rank test and the Cox proportional hazards model. Between 2007 and 2018, 117,135 women diagnosed with breast cancer with a median follow-up time of 4.6 years were identified. The 8-year incidence of hypothyroidism was 9.3% in patients treated with radiation and 8.6% in those treated without radiation (p = 0.002). The incidence rates per 1,000 person-years in the corresponding treatment groups were 6.2 and 5.7 cases, respectively. The hazard ratio (HR) in patients receiving RT was 1.081 (95% confidence interval [CI], 1.013–1.134; p = 0.002). After mastectomy, RT showed a trend toward a higher risk of hypothyroidism (HR = 1.248; 95% CI, 0.977–1.595; p = 0.076). Our study provides one of the largest population-based data analyses regarding the risk of hypothyroidism among Korean patients with breast cancer. The adjusted risk for patients treated with RT exceeded that for patients with breast cancer treated without RT. The effect was evident immediately after treatment and lasted up to approximately 9 years.

Influence of respiratory movement during post mastectomy radiotherapy on targets and heart for breast cancer

BACKGROUND/AIM

This study aimed to compare the dosimetric consequences of respiratory movement in volumetric-modulated arc therapy (VMAT) and three-dimensional conformal radiation therapy (3D-CRT) during postmastectomy radiation therapy, including internal mammary nodes (IMNs).

MATERIALS AND METHODS

Respiratory motion was implemented to a phantom using a dynamic device. The plans were delivered during cranial-caudal and ventral-dorsal movement in 5-mm (R05) and 10-mm (R10) amplitudes.

RESULTS

At the IMN, the dose errors were -2.8% (R05) and -6.2% (R10) for 3D-CRT and -4.9% (R05) and -8.5% (R10) for VMAT. The dose errors in chest wall were -.5% (R05) and -6.0% (R10) for 3D-CRT and -1.9% (R05) and -5.3% (R10) for VMAT. The left anterior descending doses showed significantly small absolute values. The gamma pass rates of VMAT were higher than those of 3D-CRT.

CONCLUSIONS

The benefit of VMAT technique in dose distribution was maintained, except in occasional instances of large breathing motion.

Abstract WMP102: Prevalence Of Genetic Mutations In 15 Mendelian Stroke Genes In Young Stroke Patients

Introduction: Although the heritability of stroke might be higher in young-age stroke population, it is even uncertain how many of them has monogenic causes of stroke. We aimed to estimate the prevalence and clinical characteristics of 15 monogenic disorders associated with stroke in a large, unselected young-age stroke population

Methods: From a prospective, nationwide, multicenter, acute stroke registry of consecutive patients admitted to 15 academic or regional stroke centers in Korea, we enrolled all patients aged 55 years or younger except those who refuse to participate in this study. We performed genetic analysis using a customized targeted next-generation sequencing panel ( GLA, NOTCH3, HTRA1, RNF213, ACVRL1, ENG, CBS, TREX1, ABCC6, COL4A1, FBN1, NF1, COL3A1, MT-TL1, and APP ) to find clinically relevant genetic variants, and reviewed clinical information of the patients.

Results: Genetic analysis was performed in 1,033 patients (male 70.7%, mean age 45.8±7.9). Twenty-eight clinically relevant genetic variants were identified in 131 (12.7%) patients, and were found most frequently in RNF213 (59, 5.7%) followed by ABCC6 (53, 5.1%) and NOTCH3 (15, 1.5%). Genetic variants were more commonly observed in younger group than older group (17.1% vs. 9.3%, p=0.021), but were not different according to vascular risk factor burden. Patients with premature (<60y) family history of stroke had genetic variants more frequently than those with family history at ≥60y (23.7% vs. 11.4%, p=0.047). Typical neuroimaging abnormalities were observed in only 25% of patients with RNF213 variants and 27% of those with NOTCH3 variants. Variants of uncertain significance were found in 15.4%.

Conclusion: Clinically relevant genetic variants were not uncommon than expected. We might have opportunities to improve our daily practice by genetic counseling patients and their families to reduce the future stroke.

Abstract TP180: Secular Trends For Demographics, Characteristics, Management, And Clinical Outcome Of Young Adults With Acute Ischemic Stroke

Background: The incidence of stroke in young adults is increasing with the growing prevalence of stroke risk factors among young adults over the last decades. However, studies on secular trends in the young-age stroke population are scarce.

Methods: We extracted data of acute ischemic stroke (AIS) patients aged 18-50 (n=7053; age, 43±6; male, 72%) from the multicenter stroke registry in South Korea. Demographics, risk factors, stroke characteristics, management, and clinical outcomes in young adults with AIS were summarized according to calendar year (2008-2019). Trends analysis was conducted using a linear regression model for continuous variables and the Mann-Kendall trend test for categorical variables.

Results: There was no significant change between 2008 and 2019 in the proportions of young adults among female patients (7.1% to 7.0%, p=0.44). However, the proportions of young adults within male patients tended to decrease (12.4% to 10.7%; p=0.001) The prevalence, and awareness of risk factors were unchanged during the study period. Regarding stroke subtypes, there was a significant increase in other determined etiology (8% to 20%; p<0.001) and a tendency to decrease in large artery atherosclerosis (26% in 2008; 34% in 2009 to 26% in 2019; p=0.28). The endovascular thrombectomy (EVT) rate increased (2% to 8%; p<0.001), but the intravenous thrombolysis rate (8.8% to 10.6%) and door-to-needle time (38 to 36 min) did not change. Use of dual antiplatelet (DAPT; 29% to 55%; p=<0.001) increased and direct oral anticoagulants (DOACs) in patients with atrial fibrillation tended to increase (11.7% in 2013 to 44.8% in 2019; p=0.07; DOAC began to be used in 2013 in Korea). However, the use of anticoagulants among young adult patients having atrial fibrillation tended to decrease (80% to 66%; p=0.054). Clinical outcomes, including a 3-month modified ranking scale 0-2 (84.6% to 85.2%), 1-year mortality (2.8% to 2.4%), and stroke recurrence rate (4.5 to 5.6%), did not improve during the study period.

Conclusions: Among young adults with ischemic stroke, the EVT rate and use of DAPT or DOACs increased. Still, awareness of risk factors, door-to-needle time, and anticoagulation for atrial fibrillation required more attention to improve clinical outcomes.

Abstract WP184: The Risk Of Stroke Recurrence According To Neuroimaging Parameters In Patients With Acute Ischemic Stroke And Atrial Fibrillation

Purpose: The usefulness of the existing risk stratification tools for atrial fibrillation (AF) is limited in predicting stroke recurrence in patients with acute ischemic stroke (AIS). Neuroimaging parameters obtained from diagnostic work-up of AIS could offer more elaborate prediction.

Methods: A multicenter prospective cohort of AIS patients with AF recruited from 14 university hospitals or regional stroke centers were followed up for recurrent ischemic stroke (RIS) and a composite of all stroke and TIA. Neuroimaging features were derived from acute and chronic infarction patterns, and SVD markers such as lacunes, CMBs, and WMH. Cumulative incidences according to each neuroimaging parameter were estimated and compared using the Kaplan-Meier method with log-rank test and multivariable cause-specific hazard models with death as a competing risk.

Results: A total of 2,270 patients were followed up for 431 days (IQR, 365-735), during which 111 RISs and 130 composite outcomes occurred. In unadjusted analysis, lesion multiplicity among acute infarction patterns, the presence of chronic non-lacunar infarction, and the presence of lacunes among SVD markers increased the risk of RIS significantly (Table). Other neuroimaging features such as territory multiplicity and location, confluency, topography, and size of acute lesions, lesion multiplicity, territory multiplicity, confluency, topography, and size of chronic infarction, number of lacunes, presence of CMBs, and WMH did not affect the incidence of RIS. The adjusted hazard ratios of lesion multiplicity of acute infarction, chronic infarction and lacunes were 1.45 (95% CI, 0.99-2.11), 1.57 (1.06-2.34) and 1.97 (1.30-2.98) for RIS, respectively. Similar findings were obtained for the composite outcome.

Conclusions: Several neuroimaging markers were associated with recurrent ischemic stroke in AIS with AF. This could pave the way to a new stratification scheme for AF including neuroimaging parameters.

Abstract WP186: Long-term Incidence Of Gastrointestinal Bleeding After Ischemic Stroke

Background: Incidence of gastrointestinal (GI) bleeding after acute ischemic stroke (AIS) was reported as 1.5% during hospitalization, one-thirds of which required blood transfusion. However, it is not known about the long-term incidence and the incidence rates by period after AIS.

Methods: AIS patients who were admitted to the 14 participating hospitals between 2011 and 2013 were identified using a nationwide multicenter prospective stroke registry database. GI bleeding was captured with related diagnosis codes by International Classification of Diseases-10th Revision through the linkage between the registry database and the claims data. Bleeding requiring at least 2 packs of blood transfusion was defined as major GI bleeding. Incidence rates were calculated for each period as follow; 0-30 days, 31-90 days, 91-180 days, 181-365 days, 1-2 years, 2-3years, after 3 years.

Results: Of 10,818 AIS patients, 59.0% were male and mean age was 67.5 ± 12.9 years. The median follow-up duration was 3.1 (interquartile range 2.3 to 4.0) years. During 31,208 person-years, 947 patients (8.8%) had 1,224 episodes of major GI bleeding. Annual incidence rate was 3.92 per 100 person-years. The incidence rates by periods were the highest at 19.21 per 100 person-years in the first month of AIS, gradually decreased to 9.02 in one to three months, 6.18 in three to six months, and 3.48 in six to twelve months. After three years, it remained at about 2.62 events per 100 person-years. During the observation period, only one major GI bleeding occurred without recurrence in about 80% of patients, about 13% recurred twice, and about 6% of patients had three or more recurrences. In the multivariable recurrent event analysis, anemia at admission, lower eGFR below 60, and mRS at 3 months ≥4 were independently associated with higher risk of major GI bleeding during the most of the observation period above 3 years.

Conclusions: Major GI bleeding, requiring transfusion, seems to occur frequently after AIS, and the risk was gradually decreased after stroke. The efforts are needed to prevent it, especially in stroke patients with anemia and decreased renal function.

Multi-criteria optimization for planning volumetric-modulated arc therapy for prostate cancer

We aimed to compare the volumetric-modulated arc therapy (VMAT) plans with or without multi-criteria optimization (MCO) on commercial treatment-planning systems (Eclipse, Varian Medical System, Palo Alto, CA, USA) for patients with prostate cancer. We selected 25 plans of patients with prostate cancer who were previously treated on the basis of a VMAT plan. All plans were imported into the Eclipse Treatment Planning System version 15.6, and re-calculation and re-optimization were performed. The MCO plan was then generated. The dosimetric quality of the plans was evaluated using dosimetric parameters and dose indices that account for target coverage and sparing of the organs at risk (OARs). We defined the rectum, bladder, and bilateral femoral heads. The VMAT-MCO plan offers an improvement of gross treatment volume coverage with increased minimal dose and reduced maximal dose. In the planning treatment volume, the Dmean and better gradient, homogeneity, and conformity indexes improved despite the increasing hot and cold spots. When implemented through the MCO plan, a steeper fall off the adjacent OARs in the overlap area was achieved to obtain lower dose parameters. MCO generated better sparing of the rectum and bladder through a tradeoff of the increasing dose to the bilateral femoral heads within the tolerable dose constraints. Compared with re-optimization and re-calculation, respectively, significant dose reductions were observed in the bladder (241 cGy and 254 cGy; p<0.001) and rectum (474 cGy and 604 cGy, p<0.001) with the MCO. Planning evaluation and dosimetric measurements showed that the VMAT-MCO plan using visualized navigation can provide sparing of OAR doses without compromising the target coverage in the same OAR dose constraints.

Aesthetic outcomes and complications following post-mastectomy radiation therapy in patients undergoing immediate extended latissimus dorsi flap reconstruction and implant insertion

Background

Complications of radiotherapy after implant-based reconstruction include capsular contracture development, seroma formation, and reoperation for implant removal or replacement. However, there is a lack of studies regarding aesthetic outcomes and complication rates following radiation therapy among patients undergoing latissimus dorsi (LD) flap-based reconstruction with implant insertion for volume shortage. The present study aimed to evaluate clinical and aesthetic outcomes of post-mastectomy radiation therapy (PMRT) among patients receiving both LD flap reconstruction and implant insertion.

Methods

This study comprised 66 patients who underwent mastectomy and breast reconstruction between March 2014 and July 2019. Patient demographics and outcomes were compared among patients who did and did not receive PMRT. Aesthetic outcomes were compared using gross photographs. The incidence of complications, including seroma formation, flap necrosis, nipple-areola complex necrosis, hematoma development, and capsular contractures, was compared between groups.

Results

No differences in aesthetic outcomes using gross photos during outpatient follow-up were observed between the radiation and control groups. No significant difference in the frequency of complications was observed between groups.

Conclusions

The use of implants and LD reconstruction are inevitable in a proportion of patients due to a lack of LD flap volume. For these patients, PMRT could be safe treatment option if the necessary precautions are implemented.

Pattern of local recurrence after mastectomy and reconstruction in breast cancer patients: a systematic review

Background

This study aimed to describe the locations of local recurrences based on the mastectomy and reconstruction type in breast cancer patients.

Methods

In November 2020, a systematic literature review was performed through MEDLINE/PubMed and the Cochrane Centre Register of Controlled Trials. Publications that included skin-sparing or nipple-sparing mastectomy followed by breast reconstruction and described the location of local recurrences were analyzed. Exclusion criteria included salvage or prophylactic mastectomy, unclear distinction between local and regional recurrences, rare tumor types.

Results

From 19 publications, 272 local recurrences lesions were reported in a total of 4,787 patients. After autologous reconstruction (n=2,465), local recurrences were located in the skin in 45 (1.8%) patients, in the chest wall in 18 (0.7%), and in the nipple-areolar complex in 9 (0.4%). After implant reconstruction (n=1,917), local recurrences sites included the skin in 91 (4.7%) patients, chest wall in 8 (0.4%), and nipple-areolar complex in 8 (0.4%). Of the 70 lesions with reported in-breast location, 57 (81.4%) relapsed in the original tumor location.

Discussion

Although meta-analysis was not conducted, present analysis demonstrated that most local recurrences after skin-sparing or nipple-sparing mastectomy occurred within the skin or subcutaneous tissues. It was found that the original tumor location was the most frequent site of relapse. Therefore, special attention should be paid to the original tumor overlying the skin while planning postmastectomy radiation therapy.

Abstract P97: Changes in Stroke Patient’s Health-Seeking Behavior by Covid-19 Epidemic Regions: Data From Korean Stroke Registry

Background and purpose: With the wide spread of coronavirus disease 2019 (COVID-19) around the world, not only patients with COVID-19, but also patients with other disease such as stroke have undergone many changes in their health-seeking behavior. Between late February and March 2020, COVID-19 was epidemic in the community of Daegu city and Gyeongsangbuk-do region (D-G region) in Korea. We aimed to clarify the changes in the health-seeking behaviors of stroke patients and stroke care services by region in Korea through analysis of data from Korean Stroke Registry (KSR).

Methods: We retrospectively reviewed the data with acute stroke and transient ischemic attack (TIA) patients between 2019 and 2020. We compared the stroke onset to hospital arrival (onset-to-door) time of these patients in the D-G region and other regions in Korea during the epidemic period in 2020 (post-COVID-19: February 18-March 31, 2020) and the same period in 2019 (Pre-COVID-19). In addition, we investigated the in-hospital stroke pathways with the patients.

Results: 1,792 patients in pre-COVID-19 and 1,555 patients in post-COVID-19 who visited KSR-registered hospitals were analyzed. Compared to pre-COVID-19, the number of patients registered in KSR decreased in most regions in post-COVID-19. In the D-G region, the number of registered patients decreased by two thirds, and the proportion of patients with TIA decreased significantly. (9.97% to 2.91%). Unlike other regions, the median onset-to-door time increased significantly in the D-G region (361 versus 526.5 minutes, p=0.0084). The proportion of patients with onset-to-door time within 3 hours also decreased significantly (36.45% versus 28.16%, p=0.0485). Patients in their 60s and 70s and mild symptoms (NIHSS score 0 to 3) came to the hospital later. As a result, the patients who underwent thrombectomy also decreased, but the treatment time did not differ between the two periods.

Conclusion: During the epidemic of COVID-19, the patients residing in the epicenter showed distinct changes in health-seeking behavior. Appropriate public education about stroke is needed during the COVID-19 pandemic.

Relationship between internal accuracy and load-bearing capacity of minimally invasive lithium disilicate occlusal veneers

PURPOSE

To test whether internal accuracy affects the load-bearing capacity of 0.5-mm-thick occlusal veneers made out of milled or heat-pressed lithium disilicate (LS2).

MATERIALS AND METHODS

Extracted human molars (N = 80) were divided into four groups (n = 20 each) depending on the bonding substrate (enamel [E] or dentin [D]) and the fabrication method (milling [CAD] or heat pressing [PRE]) for the occlusal LS2 veneers: (1) E-CAD, (2) D-CAD, (3) E-PRE, or (4) D-PRE. After restoration fabrication, the abutment teeth and the corresponding restorations were scanned and superimposed in order to measure the marginal and internal accuracy. After adhesive cementation, the specimens were thermomechanically aged and thereafter loaded until fracture. The load-bearing capacities (F_max) were measured. F_max and the marginal and internal accuracy between the groups were compared using Kruskal-Wallis test (P < .05) and pairwise group comparisons. In addition, the relationship between F_max and the internal accuracy was analyzed using Spearman rank correlation.

RESULTS

Median F_max values (and first and third quartiles) per group were as follows: 1,495 N (Q1: 932; Q3: 2'318) for E-CAD; 1,575 N (Q1: 1,314; Q3: 1,668) for E-PRE; 1,856 N (Q1: 1,555; Q3: 2,013) for D-CAD; and 1,877 N (Q1: 1,566; Q3: 2,131) for D-PRE. No statistical difference was found between the groups (P = .0981). Overall, the internal accuracy in the areas of the cusp (P < .0007) and fossa (P < .0001) showed significant differences. While no significant differences were detected in the marginal area (P = .3518), a significant correlation with a negative linear relationship was found between the 3D internal accuracy and the F_max values (P = .0007).

CONCLUSION

An increase in the internal accuracy raised the load-bearing capacity of minimally invasive LS2 occlusal veneers. In general, the restorations bonded to dentin in the occlusal regions showed a better accuracy compared to those bonded to enamel.

Prognostic significance of genetic variants in GLUT1 in stage III non-small cell lung cancer treated with radiotherapy

Background

To examine the impact of polymorphisms of glucose transporter 1 (GLUT1) gene on the prognosis of patients with stage III non‐small cell lung cancer (NSCLC) who received radiotherapy.

Methods

Five single nucleotide polymorphisms (SNPs) (rs4658C>G, rs1385129G>A, rs3820589A>T, rs3806401A>C and rs3806400C>T) in GLUT1 gene were evaluated in 90 patients with pathologically confirmed stage III NSCLC. A total of 21 patients were treated with radiotherapy alone, 25 with sequential chemoradiotherapy, and 44 with concurrent chemoradiotherapy. The association of the genetic variations of five SNPs with overall survival (OS) and progression‐free survival (PFS) was analyzed.

Results

Two SNPs (rs1385129 and rs3806401) were significant risk factors for OS. Three SNPs (rs1385129, rs3820589 and rs3806401) were in linkage disequilibrium. In Cox proportional hazard models, GAA haplotype was a good prognostic factor for OS (hazard ratio [HR] = 0.57, 95% confidence interval [CI]: 0.39–0.81, p = 0.002) and PFS (HR = 0.68, 95% CI: 0.47–0.99, p = 0.043), compared to variant haplotypes. The GAA/GAA diplotype was observed in 46.7% of patients; these patients showed significantly better OS (HR = 0.38, 95% CI: 0.22–0.65, p < 0.001) and PFS (HR = 0.51, 95% CI: 0.31–0.85, p = 0.009) compared to those with other diplotypes.

Conclusions

These results suggest that polymorphisms of GLUT1 gene could be used as a prognostic marker for patients with stage III NSCLC treated with radiotherapy.

Clinical outcomes of stereotactic body radiation therapy for small hepatocellular carcinoma

BACKGROUND AND AIM

The purpose of this study was to investigate the long-term oncologic outcomes after stereotactic body radiation therapy (SBRT) for small hepatocellular carcinoma (HCC).

METHODS

A total of 290 patients with HCC were registered between March 2007 and July 2013. A dose of 10-15 Gy per fraction was given over three to four consecutive days, resulting in a total dose of 30-60 Gy. Overall and recurrence-free survivals were estimated from the date of the start of SBRT to the date of death, the last follow-up examination, or to the date of tumor recurrence.

RESULTS

The median follow-up period of all patients was 38.2 months, and the median tumor size was 1.7 cm. Overall survival (OS) rate at 5 years was 44.9%. Multivariate analyses revealed that age, Child-Pugh class, tumor size, and albumin levels were significant factors for OS. The 5-year local control rate was 91.3%. In multivariate analysis, tumor size and albumin were significantly associated with local tumor control. However, there was a negative correlation between total dose and tumor size in Pearson's correlation analysis (r = -0.111, P = 0.046).

CONCLUSIONS

Stereotactic body radiation therapy was an excellent ablative treatment option for patients with small HCC. Tumor size was a significant factor for local tumor control after SBRT, although the total dose was negatively correlated with tumor size. Considering the low OS rates and the high local tumor control rates, the combined SBRT and systemic therapies may be beneficial for improving survival outcomes.

Radiotherapy for mandibular metastases from hepatocellular carcinoma: a single institutional experience

Purpose

A mandibular metastasis is uncommon in patients with hepatocellular carcinoma (HCC). We report the clinical features of this rare lesion and evaluate the effectiveness of radiotherapy in affected patients.

Materials and Methods

We retrospectively reviewed our institutional medical records for HCC patients who received radiotherapy for bone metastasis, and included cases of mandible metastasis. The clinical features of these cases, and the characteristics and outcomes of the treatments were assessed.

Results

A total of 1,498 patients with a bone metastasis from HCC were treated with radiotherapy between July 1998 and April 2012 at our institution. We identified 9 patients (0.6%) in this cohort that received radiotherapy for a mandibular metastasis. The condyle was the most common location of mandibular metastasis. The median radiation dose was 40 Gy (range, 27.5 to 60 Gy), with a daily dose of 2–3 Gy. All of these 9 patients died during a median follow-up of 9 months (range, 1 to 19 months). Symptom relief was achieved in 7 of 8 patients who completed radiotherapy. Tumor size reduction was observed in 2 of 4 patients who underwent radiologic evaluation after radiotherapy.

conclusions

Metastasis to the mandible from HCC has a poor prognosis. Radiotherapy can be an effective local treatment option for symptomatic relief in these cases.

Current status of stereotactic body radiotherapy for the treatment of hepatocellular carcinoma

Stereotactic body radiotherapy (SBRT) is an advanced form of radiotherapy (RT) with a growing interest on its application in the treatment of hepatocellular carcinoma (HCC). It can deliver ablative radiation doses to tumors in a few fractions without excessive doses to normal tissues, with the help of advanced modern RT and imaging technologies. Currently, SBRT is recommended as an alternative to curative treatments, such as surgery and radiofrequency ablation. This review discusses the current status of SBRT to aid in the decision making on how it is incorporated into the HCC management.

Stereotactic body radiation therapy for locally advanced pancreatic cancer

PURPOSE

Stereotactic body radiation therapy (SBRT) is a promising treatment modality for locally advanced pancreatic cancer (LAPC). We evaluated the clinical outcomes of SBRT in patients with LAPC.

PATIENTS AND METHODS

We retrospectively analyzed the medical records of patients with LAPC who underwent SBRT at our institution between April 2011 and July 2016. Fiducial markers were implanted using endoscopic ultrasound guidance one week prior to 4-dimensional computed tomography (CT) simulation and daily cone beam CT was used for image guidance. Patients received volumetric modulated arc therapy or intensity modulated radiotherapy using respiratory gating technique. A median dose of 28 Gy (range, 24-36 Gy) was given over four consecutive fractions delivered within one week. Survival outcomes including freedom from local disease progression (FFLP), progression-free survival (PFS), and overall survival (OS) were analyzed. Acute and late toxicities related to SBRT were assessed.

RESULTS

A total of 95 patients with LAPC were analyzed, 52 of which (54.7%) had pancreatic head cancers. Most (94.7%) had received gemcitabine-based chemotherapy. The 1-year FFLP rate was 80.1%. Median OS and PFS were 16.7 months and 10.2 months, respectively; the 1-year OS and PFS rates were 67.4% and 42.9%, respectively. Among 79 patients who experienced failure, the sites of first failures were isolated local progressions in 12 patients (15.2%), distant metastasis in 55 patients (69.6%), and both in 12 patients (15.2%). Seven patients (7.4%) were able to undergo surgical resection after SBRT and four had margin-negative resections. Three patients (3.2%) had grade 3 nausea/vomiting during SBRT, and late grade 3 toxicity was observed in another three patients.

CONCLUSIONS

LAPC patients who received chemotherapy and SBRT had favorable FFLP and OS with minimal treatment-related toxicity. The most common pattern of failure was distant metastasis, which warrants further studies on the optimal scheme of chemotherapy and SBRT.

Abstract 91: Physicians’ Attitudes Toward Elevated Blood Pressure and Recurrent Events After Acute Ischemic Stroke

Background: Strict blood pressure (BP) control among acute ischemic stroke (AIS) survivors would improve prognosis and decrease recurrent vascular events, which, however, has not been investigated in detail.

Methods: AIS survivors at discharge who was admitted between 2010 and 2011 were included in the analysis dataset. Baseline characteristics were gathered through a multicenter prospective stroke registry (CRCS-K). BP measurements, clinic visit and prescription of BP-lowering medications after discharge were collected through medical records until 1 year (± 2 months of grace period). Recurrent vascular events until 1 year after stroke including stroke, myocardial infarction and death were gathered through a structured telephone interview by trained research registrars or medical records review. Individual treatment intensification (TI) scores were calculated by the following equation; (observed medication change - predicted medication change by a standard guideline) / number of clinic visit. TI scores were categorized into quintile groups and their associations with recurrent events were assessed by Cox proportional hazard models.

Results: Of the 3482 AIS survivors, 2675 (77%) were diagnosed of hypertension and 1977 (57%) had BP-lowering medication prescription at discharge. Median NIHSS score at admission was 3 [1 - 6] points and 1573 (45.3%) had mRS score 0f 0 - 1 at discharge. TI score over 1-year after discharge was mean - 0.24 ± 0.30 and median - 0.15 [- 0.42, 0]. Compared to Q3 (third quintile; group TI score, - 0.15 ± 0.05), Q5 (group TI score, 0.04 ± 0.08) had higher proportion of cardioembolic stroke (32% vs 20%) and higher median NIHSS score (4 vs 3). Extreme groups of TI scores, Q1 or Q5, showed increased hazard for having mortality or composite events (see Table).

Conclusions: Physicians’ attitudes toward elevated BP, represented by the TI score, was significantly associated with long-term vascular outcomes.

Long-term outcomes of the 2-week schedule of hypofractionated radiotherapy for recurrent hepatocellular carcinoma

Background

The 2-week schedule of hypofractionated radiotherapy as a salvage treatment for hepatocellular carcinoma (HCC) has previously exhibited promising results; this study aimed to assess its long-term clinical outcomes in patients with recurrent HCC ineligible for curative treatments.

Methods

We retrospectively enrolled 77 patients (84 lesions) with HCC who were treated with hypofractionated radiotherapy between December 2008 and July 2013. Primary inclusion criteria were HCC unsuitable for curative treatments and HCC located within 2 cm of a critical normal organ. We administered 3.5–5 Gy/fraction for 2 weeks, resulting in a total dose of 35–50 Gy.

Results

The median follow-up period was 33.6 (range, 4.8–78.3) months. The 3- and 5-year overall survival rates were 52.3% and 40.9%, respectively, and local control rates were 79.5% and 72.6% in all treated lesions, respectively. The 5-year local control rate was better in the higher radiation dose group than in the lower radiation dose group (50 Gy: 79.7% vs. < 50 Gy: 66.1%); however, the difference was not statistically significant (P = 0.493). We observed grade ≥ 3 hepatic toxicity in 2 (2.6%) patients and grade 3 gastrointestinal bleeding in 1 (1.3%) patient. However, grade ≥ 4 toxicity was not observed after hypofractionated radiotherapy.

Conclusions

The 2-week schedule of hypofractionated radiotherapy for recurrent HCC exhibited good local control and acceptable treatment-related toxicity during the long-term follow-up period. Thus, this fractionation schedule can be a potential salvage treatment option for recurrent HCC, particularly for tumors located close to a radiosensitive gastrointestinal organ.

Electronic supplementary material

The online version of this article (10.1186/s12885-018-4953-x) contains supplementary material, which is available to authorized users.

Incidence of psoriasiform diseases secondary to tumour necrosis factor antagonists in patients with inflammatory bowel disease: a nationwide population-based cohort study

BACKGROUND

There are increasing reports of paradoxical psoriasiform diseases secondary to anti-tumour necrosis factor (TNF) agents.

AIMS

To determine the risks of paradoxical psoriasiform diseases secondary to anti-TNF agents in patients with inflammatory bowel disease (IBD).

METHODS

A nationwide population study was performed using the Korea National Health Insurance Claim Data. A total of 50 502 patients with IBD were identified between 2007 and 2016. We compared 5428 patients who were treated with any anti-TNF agent for more than 6 months (anti-TNF group) and 10 856 matched controls who had never taken anti-TNF agents (control group).

RESULTS

Incidence of psoriasis was significantly higher in the anti-TNF group (36.8 per 10 000 person-years) compared to the control group (14.5 per 10 000 person-years) (hazard ratio [HR] 2.357, 95% confidence interval [CI] 1.668-3.331). Palmoplantar pustulosis (HR 9.355, 95% CI 2.754-31.780) and psoriatic arthritis (HR 2.926, 95% CI 1.640-5.218) also showed higher risks in the anti-TNF group. In subgroup analyses, HRs for psoriasis by IBD subtype were 2.549 (95% CI 1.658-3.920) in Crohn's disease and 2.105 (95% CI 1.155-3.836) in ulcerative colitis. Interestingly, men and younger (10-39 years) patients have significantly higher risks of palmoplantar pustulosis (HR 19.682 [95% CI 3.867-100.169] and HR 14.318 [95% CI 2.915-70.315], respectively), whereas women and older (≥40 years) patients showed similar rates between the two groups.

CONCLUSIONS

The risks of psoriasiform diseases are increased by anti-TNF agents in patients with IBD. Among psoriasiform diseases, the risk of palmoplantar pustulosis shows the biggest increase particularly in male and younger patients.

Detection and classification of the breast abnormalities in digital mammograms via regional Convolutional Neural Network

Automatic detection and classification of the masses in mammograms are still a big challenge and play a crucial role to assist radiologists for accurate diagnosis. In this paper, we propose a novel computer-aided diagnose (CAD) system based on one of the regional deep learning techniques: a ROI-based Convolutional Neural Network (CNN) which is called You Only Look Once (YOLO). Our proposed YOLO-based CAD system contains four main stages: mammograms preprocessing, feature extraction utilizing multi convolutional deep layers, mass detection with confidence model, and finally mass classification using fully connected neural network (FC-NN). A set of training mammograms with the information of ROI masses and their types are used to train YOLO. The trained YOLO-based CAD system detects the masses and classifies their types into benign or malignant. Our results show that the proposed YOLO-based CAD system detects the mass location with an overall accuracy of 96.33%. The system also distinguishes between benign and malignant lesions with an overall accuracy of 85.52%. Our proposed system seems to be feasible as a CAD system capable of detection and classification at the same time. It also overcomes some challenging breast cancer cases such as the mass existing in the pectoral muscles or dense regions.

Effective ion charge (Zeff) measurements and impurity behavior in KSTAR

A visible bremsstrahlung detector array diagnostic system has been developed on the Korea Superconducting Tokamak Advanced Research (KSTAR) to view the whole minor radius in a narrow region of the continuum free of spectral lines. The interference filters coupled with photomultiplier tubes have been employed to determine the effective charge Z_eff by using visible bremsstrahlung data during neutral beam injection in the KSTAR plasma. The Z_eff profiles are typically flat for L-mode plasmas and evolve to hollow profiles during the H mode in the KSTAR. A comparison of the visible bremsstrahlung emission based on the calculated Z_eff profiles is consistent with measured values of Z_eff from a visible spectrometer in the core plasma. The electron temperature is measured by X-ray imaging crystal spectrometry, and electron density needed for the analysis is taken by the assumption of parabolic profiles of these parameters. The line of sight averaged local bremsstrahlung emissivity is determined with low uncertainty, and the radial emissivity is obtained by using the Abel inversion technique. In addition, a dependence of effective charge Z_eff on the line-averaged electron density is evaluated, and Z_eff is also determined to observe the effect of boronization.

Development of a semi-continuous two-stage simultaneous saccharification and fermentation process for enhanced 2,3-butanediol production by Klebsiella oxytoca

Klebsiella oxytoca naturally produces a large amount of 2,3-butanediol (2,3-BD), a promising chemical with wide industrial applications, along with various by-products. Previously, we have developed a metabolically engineered K. oxytoca ΔldhA ΔpflB strain to reduce the formation of by-products. To improve 2,3-BD productivity and examine the stability of K. oxytoca ΔldhA ΔpflB strain for industrial application, a semi-continuous two-stage simultaneous saccharification and fermentation (STSSF) process was developed. The STSSF with the K. oxytoca ΔldhA ΔpflB mutant using cassava as a carbon source could produce 108 ± 3·73 g_(2,3-BD)  l^-1 with a yield of 0·45 g_(2,3-BD)  g_(glucose)^-1 and a productivity of 3·00 g_(2,3-BD) l^-1  h^-1 . No apparent changes in the final titre, yield and productivity of 2,3-BD were observed for up to 20 cycles of STSSF. Also, microbial contamination and spontaneous mutation of the host strain with potential detrimental effects on fermentation efficiency did not occur during the whole fermentation period. These results strongly underpin that the K. oxytoca ΔldhA ΔpflB mutant is stable and that the STSSF process is commercially exploitable.

SIGNIFICANCE AND IMPACT OF THE STUDY

There is growing interest in the production of 2,3-butanediol (2,3-BD) from renewable resources by microbial fermentation because of its wide applications to specialty and commodity chemical industries. Klebsiella oxytoca usually produces 2,3-BD as a major end product during the fermentation of carbohydrates. This is the first study to provide a high-efficiency simultaneous saccharification and 2,3-BD fermentation process. Also, this study proves the stability of a metabolically engineered 2,3-BD overproducing K. oxytoca strain for industrial application.

Incidence and Dose-volume Analysis of Acute Bladder Toxicity following Pelvic Radiotherapy

Aims and Background

The authors performed this prospective study to evaluate the incidence of acute bladder toxicity following pelvic radiation therapy and to determine any dosimetric predictors for the toxicity.

Methods and Study Design

Acute bladder toxicity was evaluated weekly by physicians using the Common Terminology Criteria for Adverse Events (CTCAE version 4.0). At the same time, the International Prostate Symptom Score (IPSS) and Overactive Bladder Symptom Score (OABSS) were also assessed by each patient during radiation therapy. We contoured the bladder wall, solid bladder and trigone on the planning computed tomography and analyzed dose-volume histograms to determine which of these could be the most suitable dosimetric predictor.

Results

Of 92 eligible patients, 27 (29%) demonstrated CTCAE grade 2 acute bladder toxicity, with nocturia as the most frequently observed symptom. IPSS demonstrated better agreement with CTCAE than OABSS. In receiver-operating characteristic curve analysis, the largest area under the curve was observed for V20 of both the bladder wall and the bladder.

Conclusions

Acute bladder toxicity during pelvic radiation therapy is not a trivial complication and should be actively investigated. Dose-volume relationships demonstrate that both bladder wall V20 and bladder solid V20 are useful surrogates for identifying patients at high risk of toxicity. The roles of IPSS and OABSS need to be validated in a larger study.

Comparison of the Analgesic Effect of an Ice Cube versus 4% Lidocaine Cream in Intradermal Antibiotic Skin Testing

Objective

This study was performed to compare the analgesic effect of an ice cube with that of 4% lidocaine cream (L.M.X.4®) for intradermal skin testing.

Methods

In this prospective randomised study, healthy adult volunteers were divided into ice cube and lidocaine analgesic pretreatment groups. Randomisation was performed using a randomisation table in blocks of four. Intradermal skin testing was performed after applying ice in the ice cube group and 5 mg of lidocaine cream in the lidocaine group. After the intradermal skin test, the pain intensity was investigated using the visual analog scale (VAS) on questionnaires. We calculated that a minimum of 24 subjects were required for statistical power of 80% at a significance level of 0.05 (two-sided). The groups' VAS scores were compared using the Mann-Whitney U-test.

Results

The study population consisted of 35 volunteers: 17 in the ice cube group and 18 in the lidocaine group. There were no differences in demographic characteristics between the two groups. The median VAS score was 20 (interquartile range: 0-35) in the ice cube group and 70 (interquartile range: 50-80) in the lidocaine group (p<0.001).

Conclusions

The results suggested the utility of an ice cube as analgesic pretreatment for intradermal skin testing in the emergency department.

First insights into the function of the sawshark rostrum through examination of rostral tooth microwear

Potential roles of the rostrum of sawsharks (Pristiophoridae), including predation and self-defence, were assessed through a variety of inferential methods. Comparison of microwear on the surface of the rostral teeth of sawsharks and sawfishes (Pristidae) show that microwear patterns are alike and suggest that the elongate rostra in these two elasmobranch families are used for a similar purpose (predation). Raman spectroscopy indicates that the rostral teeth of both sawsharks and sawfishes are composed of hydroxyapatite, but differ in their collagen content. Sawfishes possess collagen throughout their rostral teeth whereas collagen is present only in the centre of the rostral teeth of sawsharks, which may relate to differences in ecological use. The ratio of rostrum length to total length in the common sawshark Pristiophorus cirratus was found to be similar to the largetooth sawfish Pristis pristis but not the knifetooth sawfish Anoxypristis cuspidata. Analysis of the stomach contents of P. cirratus indicates that the diet consists of demersal fishes and crustaceans, with shrimp from the family Pandalidae being the most important dietary component. No prey item showed evidence of wounds inflicted by the rostral teeth. In light of the similarities in microwear patterns, rostral tooth chemistry and diet with sawfishes, it is hypothesised that sawsharks use their rostrum in a similar manner for predation (sensing and capturing prey) and possibly for self-defence.

Non-local means filter denoising for DEXA images

Dual high and low energy images of Dual Energy X-ray Absorptiometry (DEXA) suffer from noises due to the use of weak amount of X-rays. Denoising these DEXA images could be a key process to enhance and improve a Bone Mineral Density (BMD) map which is derived from a pair of high and low energy images. This could further improve the accuracy of diagnosis of bone fractures, osteoporosis, and etc. In this paper, we present a denoising technique for dual high and low energy images of DEXA via non-local means filter (NLMF). The noise of dual DEXA images is modeled based on both source and detector noises of a DEXA system. Then, the parameters of the proposed NLMF are optimized for denoising utilizing the experimental data from uniform phantoms. The optimized NLMF is tested and verified with the DEXA images of the uniform phantoms and real human spine. The quantitative evaluation shows the improvement of Signal-to-Noise Ratio (SNR) for the high and low phantom images on the order of 30.36% and 27.02% and for the high and low real spine images on the order of 22.28% and 33.43%, respectively. Our work suggests that denoising via NLMF could be a key preprocessing process for clinical DEXA imaging.

Do laryngoscopic findings reflect the characteristics of reflux in patients with laryngopharyngeal reflux?

OBJECTIVE

To analyse the association between 24-hour multichannel intraluminal impedance-pH (24-h MII-pH) parameters and each item of the reflux finding score (RFS) to determine whether the laryngoscopic findings of the RFS could reflect the characteristics of reflux in patients with laryngopharyngeal reflux (LPR).

STUDY DESIGN

Prospective cohort study.

SETTINGS

Tertiary care referral medical centre.

PARTICIPANTS

Patients complaining of LPR symptoms were evaluated via a 24-hour MII-pH. Among them, 99 patients whose LPR was confirmed via 24-hour MII-pH were enrolled in this study.

MAIN OUTCOME MEASURES

Correlations between RFS ratings and 24-hour MII-pH parameters were evaluated and compared between patients with or without each laryngoscopic finding used in the RFS.

RESULTS

Subglottic oedema had a statistically significant positive correlation with number of non-acid LPR and non-acid full column reflux events. Ventricular obliteration and posterior commissure hypertrophy showed a significant correlation with non-acid exposure time and total reflux exposure time. We also found a significant correlation between granuloma/granulation score and number of acid LPR events. The numbers of non-acid LPR and full column reflux events in patients with subglottic oedema were significantly higher than those without subglottic oedema.

CONCLUSION

Among the laryngoscopic findings used in the RFS, subglottic oedema is specific for non-acid reflux episodes, and granuloma/granulation is specific for acid reflux episodes.

Deformation mechanisms to ameliorate the mechanical properties of novel TRIP/TWIP Co-Cr-Mo-(Cu) ultrafine eutectic alloys

In the present study, the microstructural evolution and the modulation of the mechanical properties have been investigated for a Co-Cr-Mo (CCM) ternary eutectic alloy by addition of a small amount of copper (0.5 and 1 at.%). The microstructural observations reveal a distinct dissimilarity in the eutectic structure such as a broken lamellar structure and a well-aligned lamellar structure and an increasing volume fraction of Co lamellae as increasing amount of copper addition. This microstructural evolution leads to improved plasticity from 1% to 10% without the typical tradeoff between the overall strength and compressive plasticity. Moreover, investigation of the fractured samples indicates that the CCMCu alloy exhibits higher plastic deformability and combinatorial mechanisms for improved plastic behavior. The improved plasticity of CCMCu alloys originates from several deformation mechanisms; i) slip, ii) deformation twinning, iii) strain-induced transformation and iv) shear banding. These results reveal that the mechanical properties of eutectic alloys in the Co-Cr-Mo system can be ameliorated by micro-alloying such as Cu addition.

Ten-Year Experience With Bowel Transplantation at Seoul St. Mary's Hospital

A retrospective review of intestinal transplantation (ITx) at Seoul St. Mary's Hospital was made by collecting clinical data over the past 10 years. Fifteen consecutive cases from 2004 were analyzed. Five children and 10 adults (6 months to 69 years of age) were included. Primary diseases in adults included 4 mesenteric vessel thromboses, 2 strangulations, and 1 each of visceral myopathy, malignant gastrointestinal stromal tumor (GIST), mesenteric lymphangiectasis, and injury. Pediatric cases involved 2 Hirschsprung disease, 2 visceral myopathy, and 1 necrotizing enterocolitis. Three of 7 stomas were closed using a serial transverse enteroplasty procedure before transplantation. The ITx were performed using 3 living-donor Itx, 12 deceased-donor ITx, 14 isolated Itx, and 1 modified multivisceral transplantation. Daclizumab, basiliximab, alemtusumab, or basiliximab with rabbit antithymocyte globulin (rATG) was used for the induction; tacrolimus monotherapy was used as the basic maintenance immunosuppressant; and m-TOR inhibitor was used for renal dysfunction patients. Seven cases of acute cellular rejection were treated with rATG. Three cases of antibody-mediated rejection were treated with rituximab alone or with rituximab and bortezomib combination. There were 4 cases of early mortality within 6 months after Itx. Causes of death were declamping shock, cardiac tamponade with acute cellular rejection, dysmotility, and sepsis. Surgical complications consisted of 1 feeding jejunostomy displacement, and a minor leakage at a colo-colostomy site. One-year survival of the patient and graft was 73.33% (Kaplan-Meier survival curve). Although the total number of ITx is small, its social impact has been remarkable in changing the related laws and reimbursement policy in Korea.

Effect of metronidazole use on tacrolimus concentrations in transplant patients treated for Clostridium difficile

BACKGROUND

Two case reports suggest that metronidazole treatment for Clostridium difficile infections (CDI) increases tacrolimus (TAC) trough levels. The primary objective of this study was to determine the clinical significance of this potential interaction in transplant patients receiving CDI treatment. Currently, no robust literature exists to estimate a magnitude of pharmacokinetic interaction between metronidazole and TAC.

METHODS

In this retrospective study, the effects of CDI and metronidazole treatment on TAC levels in 52 adult solid organ transplant patients were investigated. The primary outcome was to determine the difference in dose-normalized TAC levels between baseline and symptom resolution in patients treated with metronidazole or vancomycin. The secondary outcome was to determine the difference in dose-normalized TAC levels at baseline and CDI diagnosis.

RESULTS

The average change in log-transformed dose-normalized TAC levels from baseline to symptom resolution was 0.99 for metronidazole (n = 35) and 1.04 for vancomycin (n = 17) treatment. The mean difference between the groups was 0.96 (95% confidence interval: 0.74-1.24). No significant difference was found between dose-normalized TAC levels at CDI diagnosis and baseline (P = 0.37).

CONCLUSION

CDI treatment with metronidazole was not associated with a >30% increase in TAC levels compared with vancomycin. Both treatment groups required TAC dose adjustments to maintain goal TAC levels and those treated with metronidazole did not require a significantly greater dose adjustment.

Effect of microbial inoculant or molasses on fermentative quality and aerobic stability of sawdust-based spent mushroom substrate

In the first experiment, the effect of two novel Lactobacillus plantarum strains was studied on the fermentation of spent mushroom substrate (SMS) through 10d of ensiling. Based on lactic acid production and lactic acid bacteria population, L. plantarum KU5 was identified as the best strain for fermentation with a 5-L bag silo. Spent mushroom substrate was ensiled with 0.5% (v/w) L. plantarum KU5 without or with 5% molasses. Silages treated with microbial inoculant and molasses had the lowest pH and the highest fermentative odors. In a second set of experiments similar to the above 5-L silo study, the simultaneous application of L. plantarum KU5 inoculant and molasses to 80-L silos improved fermentability and aerobic stability of SMS silages. For similar treatment using ton-bag silos, aerobic stability decreased and NH3-N content increased dramatically. In conclusion, sawdust-based SMS for animal use was successfully ensiled with L. plantarum KU5 inoculant and molasses.

Who may benefit from robotic gastrectomy?: A subgroup analysis of multicenter prospective comparative study data on robotic versus laparoscopic gastrectomy

AIMS

Robotic gastrectomy for gastric cancer has been proven to be a feasible and safe minimally invasive procedure. However, our previous multicenter prospective study indicated that robotic gastrectomy is not superior to laparoscopic gastrectomy. This study aimed to identify which subgroups of patients would benefit from robotic gastrectomy rather than from conventional laparoscopic gastrectomy.

METHODS

A prospective multicenter comparative study comparing laparoscopic and robotic gastrectomy was previously conducted. We divided the patients into subgroups according to obesity, type of gastrectomy performed, and extent of lymph node dissection. Surgical outcomes were compared between the robotic and laparoscopic groups in each subgroup.

RESULTS

A total of 434 patients were enrolled into the robotic (n = 223) and laparoscopic (n = 211) surgery groups. According to obesity and gastrectomy type, there was no difference in the estimated blood loss (EBL), number of retrieved lymph nodes, complication rate, open conversion rate, and the length of hospital stay between the robotic and laparoscopic groups. According to the extent of lymph node dissection, the robotic group showed a significantly lower EBL than did the laparoscopic group after D2 dissection (P = 0.021), while there was no difference in EBL in patients that did not undergo D2 dissection (P = 0.365).

CONCLUSION

Patients with gastric cancer undergoing D2 lymph node dissection can benefit from less blood loss when a robotic surgery system is used.

Evaluation of a commercial orthopaedic metal artefact reduction tool in radiation therapy of patients with head and neck cancer

OBJECTIVE

To assess the image quality and dosimetric effects of the Philips orthopaedic metal artefact reduction (OMAR) (Philips Healthcare System, Cleveland, OH) function for reducing metal artefacts on CT images of head and neck (H&N) patients.

METHODS

11 patients and a custom-built phantom with metal bead inserts (alumina, titanium, zirconia and chrome) were scanned. The image was reconstructed in two ways: with and without OMAR (OMAR and non-OMAR image). The mean and standard deviation values of CT Hounsfield unit (HU) for selected regions of interest of each case were investigated for both images. Volumetric modulated arc therapy plans were generated for all cases. Gamma analysis of each dose distribution pair in the patient (1%/1 mm criteria) and phantom (2%/2 mm and 3%/3 mm criteria) images was performed. The film measurements in phantom for two metal beads were conducted for evaluating the calculated dose on both OMAR and non-OMAR images.

RESULTS

In the OMAR images, noise values were generally reduced, and the mean HU became closer to the reference value (measured from patients without metal implants) in both patient and phantom cases. Although dosimetric difference was insignificant for the eight closed-mouth patients (γ = 99.4 ± 0.5%), there was a large discrepancy in dosimetric calculation between OMAR and non-OMAR images for the three opened-mouth patients (γ = 91.1%, 94.8% and 96.6%). Moreover, the calculated dose on the OMAR image is closer to the real delivered dose on a radiochromic film than was the dose from the non-OMAR image.

CONCLUSION

The OMAR algorithm increases the accuracy of CT HU and reduces the noise such that the entire radiation treatment planning process can be improved, especially for contouring and segmentation.

ADVANCES IN KNOWLEDGE

OMAR reconstruction is appropriate for the radiotherapy planning process of H&N patients, particularly of patients who use a bite block.

The effect of MLC speed and acceleration on the plan delivery accuracy of VMAT

OBJECTIVE

To determine a new metric utilizing multileaf collimator (MLC) speeds and accelerations to predict plan delivery accuracy of volumetric modulated arc therapy (VMAT).

METHODS

To verify VMAT delivery accuracy, gamma evaluations, analysis of mechanical parameter difference between plans and log files, and analysis of changes in dose-volumetric parameters between plans and plans reconstructed with log files were performed with 40 VMAT plans. The average proportion of leaf speeds ranging from l to h cm s(-1) (Sl-h and l-h = 0-0.4, 0.4-0.8, 0.8-1.2, 1.2-1.6 and 1.6-2.0), mean and standard deviation of MLC speeds were calculated for each VMAT plan. The same was carried out for accelerations in centimetre per second squared (Al-h and l-h = 0-4, 4-8, 8-12, 12-16 and 16-20). The correlations of those indicators to plan delivery accuracy were analysed with Spearman's correlation coefficient (rs).

RESULTS

The S1.2-1.6 and mean acceleration of MLCs showed generally higher correlations to plan delivery accuracy than did others. The highest rs values were observed between S1.2-1.6 and global 1%/2 mm (rs = -0.698 with p < 0.001) as well as mean acceleration and global 1%/2 mm (rs = -0.650 with p < 0.001). As the proportion of MLC speeds and accelerations >0.4 and 4 cm s(-2) increased, the plan delivery accuracy of VMAT decreased.

CONCLUSION

The variations in MLC speeds and accelerations showed considerable correlations to VMAT delivery accuracy.

ADVANCES IN KNOWLEDGE

As the MLC speeds and accelerations increased, VMAT delivery accuracy reduced.

Effect of By-product Feed-based Silage Feeding on the Performance, Blood Metabolites, and Carcass Characteristics of Hanwoo Steers (a Field Study)

This study was conducted to determine the effects of feeding by-product feed (BF)-based silage on the performance, blood metabolite parameters, and carcass characteristics of Hanwoo steers. The BF-based silage was composed of 50% spent mushroom substrate, 21% recycled poultry bedding, 15% cut ryegrass straw, 10.8% rice bran, 2% molasses, 0.6% bentonite, and 0.6% microbial additive (on a wet basis), and ensiled for over 5 d. Fifteen steers were allocated to three diets during the growing and fattening periods (3.1 and 9.8 months, respectively): a control diet (concentrate mix and free access to rice straw), a 50% BF-based silage diet (control diet+50% of maximum BF-based silage intake), and a 100% BF-based silage diet (the same amount of concentrate mix and ad libitum BF-based silage). The BF-based silage was fed during the growing and fattening periods, and was replaced with larger particles of rice straw during the finishing period. After 19.6 months of the whole period all the steers were slaughtered. Compared with feeding rice straw, feeding BF-based silage tended (p = 0.10) to increase the average daily gain (27%) and feed efficiency (18%) of the growing steers, caused by increased voluntary feed intake. Feeding BF-based silage had little effect on serum constituents, electrolytes, enzymes, or the blood cell profiles of fattening steers, except for low serum Ca and high blood urea concentrations (p<0.05). Feeding BF-based silage did not affect cold carcass weight, yield traits such as back fat thickness, longissimus muscle area, yield index or yield grade, or quality traits such as meat color, fat color, texture, maturity, marbling score, or quality grade. However, it improved good quality grade (1⁺ and 1⁺⁺) appearance rates (60% for the control group vs 100% for the BF-based silage-fed groups). In conclusion, cheap BF-based silage could be successfully used as a good quality roughage source for beef cattle.