Observation of New Baryons in the Ξ_{b}^{-}π^{+}π^{-} and Ξ_{b}^{0}π^{+}π^{-} Systems

The first observation and study of two new baryonic structures in the final state Ξ_{b}^{0}π^{+}π^{-} and the confirmation of the Ξ_{b}(6100)^{-} state in the Ξ_{b}^{-}π^{+}π^{-} decay mode are reported using proton-proton collision data collected by the LHCb experiment, corresponding to an integrated luminosity of 9  fb^{-1}. In addition, the properties of the known Ξ_{b}^{*0}, Ξ_{b}^{'-} and Ξ_{b}^{*-} resonances are measured with improved precision. The new decay mode of the Ξ_{b}^{0} baryon to the Ξ_{c}^{+} π^{-} π^{+} π^{-} final state is observed and exploited for the first time in these measurements.

Precision Measurement of CP Violation in the Penguin-Mediated Decay B_{s}^{0}→ϕϕ

A flavor-tagged time-dependent angular analysis of the decay B_{s}^{0}→ϕϕ is performed using pp collision data collected by the LHCb experiment at the center-of-mass energy of 13 TeV, corresponding to an integrated luminosity of 6  fb^{-1}. The CP-violating phase and direct CP-violation parameter are measured to be ϕ_{s}^{ss[over ¯]s}=-0.042±0.075±0.009  rad and |λ|=1.004±0.030±0.009, respectively, assuming the same values for all polarization states of the ϕϕ system. In these results, the first uncertainties are statistical and the second systematic. These parameters are also determined separately for each polarization state, showing no evidence for polarization dependence. The results are combined with previous LHCb measurements using pp collisions at center-of-mass energies of 7 and 8 TeV, yielding ϕ_{s}^{ss[over ¯]s}=-0.074±0.069  rad and |λ|=1.009±0.030. This is the most precise study of time-dependent CP violation in a penguin-dominated B meson decay. The results are consistent with CP symmetry and with the standard model predictions.

[Safety of the strategy of minimizing intestinal resection during surgery for pelvic radiation- induced terminal small intestinal stenosis]

Objective: To investigate the efficacy of strategies for minimizing small bowel resection during surgery for pelvic radiation-induced terminal small intestinal stenosis in preventing postoperative complications such as anastomotic leakage and short bowel syndrome. Methods: This was a retrospective cohort study. There are two subtypes of chronic radiation enteritis (CRE) with combined intestinal stenosis and intestinal obstruction: (1) Type I: terminal ileal lesions with a normal ileal segment of 2-20 cm between the ileal lesion and ileocecal junction; and (2) Type II: the lesion is located in the small bowel at a distance from the ileocecal region, usually accompanied by extensive damage to the bowel segments outside the lesion. The indications for minimal bowel resection are as follows: (1) diagnosis of Type I small bowel CRE; (2) absence of radiological evidence of rectosigmoid damage; and (3) absence of colonic obstruction. The contraindications are: (1) stenotic, penetrating lesions of the distal cecum; (2) emergency surgery; (3) recurrence of malignant tumor or history of radiotherapy for recurrent malignant tumor; (4) interval between radiotherapy and surgery <6 months; and (5) history of preoperative small bowel resection or abdominal chemotherapy. Case data of 40 patients with Type I CRE who met the above criteria and had undergone minimal bowel resection between April 2017 and December 2019 were retrospectively analyzed (minimal bowel resection group; including 13 patients from Jinling Hospital, 16 from the Ninth People's Hospital Affiliated to Shanghai Jiao Tong University School of Medicine, and 11 from the Affiliated Hospital of Xuzhou Medical University). Forty patients with Type I CRE who had undergone resection of intestinal stenosis lesions and the ileocecal region between October 2015 and March 2017 were included as historical controls (conventional resection group; all from Jinling Hospital). The specific strategy for minimal bowel resection was one-stage partial ileal resection+ileo anastomosis+protective small bowel stoma. In contrast, conventional resection comprised ileocecal resection+ileocecal-ascending colon anastomosis. Postoperative complications, intraoperative and postoperative recovery, and changes in postoperative quality of life were analyzed in both groups. The severity of postoperative complications was assessed by Clavien-Dindo and the Comprehensive Complication Index (CCI). Karnofsky performance scores (KPS) were used to evaluate the quality of life of patients in the two groups preoperatively and postoperatively. The higher the KPS score, the better the quality of life. Results: Baseline patient characteristics did not differ significantly between the two groups (P>0.05). Compared with the conventional resection group, the length of small bowel resected in the minimal bowel resection group (51 [20-200] cm vs. 91 [60-200] cm, Z=5.653, P<0.001), duration of postoperative total enteral nutrition [9 (3-18) days vs. 12 (4-50) days, Z=2.172, P=0.030], and duration of postoperative hospital stay [17 (9-24) days vs 29 (13-57) days, Z=6.424, P<0.001] were shorter; all of these differences are statistically significant. The overall incidence of postoperative complications was lower in the minimal bowel resection group than in the conventional resection group [20.0% (8/40) vs. 70.0% (28/40), χ2=19.967, P<0.001], These comprised short bowel syndrome [5.0% (2/40) vs. 25.0% (10/40), χ2=6.274, P=0.012], anastomotic leakage or fistula [2.5% (1/40) vs. 22.5% (9/40), χ2=7.314, P=0.014], and pleural effusion [7.5% (3/40) vs. 25.0% (10/40), χ2=4.500, P=0.034], all of which occurred less often in the minimal bowel resection than conventional resection group. The CCI index was also lower in the minimal bowel resection group than in the conventional resection group [CCI>40: 2.5% (1/40) vs. 12.5% (5/40), Z=18.451, P<0.001]. KPS scores were higher in the minimal bowel resection group 1 and 3 months postoperatively than they had been 1 day preoperatively (79.9±4.7 vs. 75.3±4.1, 86.2±4.8 vs. 75.3±4.1, both P<0.05). In the minimal bowel resection group, seven patients were satisfied with their current quality of life and refused to undergo stoma reduction at follow-up and one deferred stoma reduction because of rectal bleeding. The remaining 32 patients underwent stoma reduction 3 to 12 months after surgery, 26 of whom underwent ileo-cecal anastomosis. The remaining six underwent resection of the stoma and anastomosis of the ileum to the ascending colon. Conclusions: The strategy of minimal small bowel resection in patients with radiation-induced bowel injuries reduces the length of resected small bowel, decreases the risk and severity of postoperative complications, and is associated with a better prognosis and quality of life than conventional resection.

[Characteristics and impact factors of SARS-CoV-2 infection in adult patients with relapsed/refractory B-cell non-Hodgkin lymphoma receiving chimeric antigen receptor T-cell therapy]

Objective: To explore the clinical characteristics and treatment of COVID-19 infection in patients with relapsed/refractory B-cell non-Hodgkin lymphoma before and after receiving chimeric antigen receptor T-cell therapy, and study the influencing factors of severe COVID-19 infection in these patients. Methods: The data of 59 patients with relapsed/refractory B-cell non-Hodgkin lymphoma who received chimeric antigen receptor T-cell therapy at the Department of Hematology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology and Department of Hematology, the Second Affiliated Hospital, College of Medicine, Zhejiang University between December 2017 and February 2023, and who were infected with novel coronavirus between December 2022 and February 2023 were retrospectively studied. Patients were divided into light, medium, severe, and critical groups, and the differences between the groups were analyzed using the chi-square test. A univariate logistic regression model was used to evaluate the contribution of each variable and its relationship with severe infection. The chi-square and Fisher's exact tests were used to analyze the differences between the B-cell aplasia and B-cell recovery (BCR) groups. Results: Of the 59 pre- and post-infusion infections, 39 (66.1%) led to mild COVID-19, 9 (15.3%) resulted in moderate COVID-19, 10 (16.9%) resulted in severe COVID-19, and 1 (1.7%) led to critical COVID-19. Moroever, age greater than 55 years, having received autologous hematopoietic stem cell transplantation, progressive disease status, and B-cell aplasia at the time of diagnosis of COVID-19 infection are factors affecting severe infection. Patients with B-cell aplasia had a more severe infection with COVID-19 (P<0.001), a longer duration (P=0.015), a longer antiviral therapy course (P<0.001), and a higher hospitalization rate (P<0.001) than the BCR group. Conclusion: Active prevention and treatment of COVID-19 infection remains a crucial issue requiring urgent attention in managing patients with relapsed/refractory B-cell non-Hodgkin lymphoma treated with chimeric antigen receptor T-cell therapy.

[Efficacy and safety analysis of the zanubrutinib-based bridging regimen in chimeric antigen receptor T-cell therapy for relapsed/refractory diffuse large B-cell lymphoma]

Objective: To further elucidate the clinical efficacy and safety of a combination regimen based on the BTK inhibitor zebutanil bridging CD19 Chimeric antigen receptor T cells (CAR-T cells) in the treatment of relapsed/refractory diffuse large B-cell lymphoma (r/r DLBCL) . Methods: Twenty-one patients with high-risk r/r DLBCL were treated with a zanubrutinib-based regimen bridging CAR-T between June 2020 and June 2023 at the Department of Hematology, Tongji Hospital, Tongji University and the Second Affiliated Hospital of Zhejiang University, and the efficacy and safety were retrospectively analyzed. Results: All 21 patients were enrolled, and the median age was 57 years (range: 38-76). Fourteen patients (66.7%) had an eastern cooperative oncology group performance status score (ECOG score) of ≥2. Eighteen patients (85.7%) had an international prognostic index (IPI) score of ≥3. Three patients (14.3%) had an IPI score of 2 but had extranodal infiltration. Fourteen patients (66.7%) had double-expression of DLBCL and seven (33.3%) had TP53 mutations. With a median follow-up of 24.8 (95% CI 17.0-31.6) months, the objective response rate was 81.0%, and 11 patients (52.4%) achieved complete remission. The median progression-free survival (PFS) was 12.8 months, and the median overall survival (OS) was not reached. The 1-year PFS rate was 52.4% (95% CI 29.8% -74.3%), and the 1-year OS rate was 80.1% (95% CI 58.1% -94.6%). Moreover, 18 patients (85.7%) had grade 1-2 cytokine-release syndrome, and two patients (9.5%) had grade 1 immune effector cell-associated neurotoxicity syndrome. Conclusion: Zanubrutinib-based combination bridging regimen of CAR-T therapy for r/r DLBCL has high efficacy and demonstrated a good safety profile.

[Efficacy and safety of fourth-generation CD19 CAR-T expressing IL7 and CCL19 along with PD-1 monoclonal antibody for relapsed or refractory large B-cell lymphoma]

Objective: This study systematically explore the efficacy and safety of fourth-generation chimeric antigen receptor T-cells (CAR-T), which express interleukin 7 (IL7) and chemokine C-C motif ligand 19 (CCL19) and target CD19, in relapsed or refractory large B-cell lymphoma. Methods: Our center applied autologous 7×19 CAR-T combined with tirelizumab to treat 11 patients with relapsed or refractory large B-cell lymphoma. The efficacy and adverse effects were explored. Results: All 11 enrolled patients completed autologous 7×19 CAR-T preparation and infusion. Nine patients completed the scheduled six sessions of tirolizumab treatment, one completed four sessions, and one completed one session. Furthermore, five cases (45.5%) achieved complete remission, and three cases (27.3%) achieved partial remission with an objective remission rate of 72.7%. Two cases were evaluated for disease progression, and one died two months after reinfusion because of uncontrollable disease. The median follow-up time was 31 (2-34) months, with a median overall survival not achieved and a median progression-free survival of 28 (1-34) months. Two patients with partial remission achieved complete remission at the 9th and 12th months of follow-up. Therefore, the best complete remission rate was 63.6%. Cytokine-release syndrome and immune effector cell-associated neurotoxicity syndrome were controllable, and no immune-related adverse reactions occurred. Conclusion: Autologous 7×19 CAR-T combined with tirelizumab for treating relapsed or refractory large B-cell lymphoma achieved good efficacy with controllable adverse reactions.

Determination of Spin-Parity Quantum Numbers for the Narrow Structure near the pΛ[over ¯] Threshold in e^{+}e^{-}→pK^{-}Λ[over ¯]+c.c

A narrow structure in the pΛ[over ¯] system near the mass threshold, named as X(2085), is observed in the process e^{+}e^{-}→pK^{-}Λ[over ¯] with a statistical significance greater than 20σ. Its spin and parity are determined for the first time to be J^{P}=1^{+} in an amplitude analysis, with a statistical significance greater than 5σ over other quantum numbers (0^{-},1^{-} and 2^{+}). The pole positions of X(2085) are measured to be M_{pole}=(2084_{-2}^{+4}±9)  MeV and Γ_{pole}=(58_{-3}^{+4}±25)  MeV, where the first uncertainties are statistical and the second ones are systematic. The analysis is based on the study of the process e^{+}e^{-}→pK^{-}Λ[over ¯] and uses the data samples collected with the BESIII detector at the center-of-mass energies sqrt[s]=4.008, 4.178, 4.226, 4.258, 4.416, and 4.682 GeV with a total integrated luminosity of 8.35  fb^{-1}.

Measurement of the Λ_{b}^{0}→Λ(1520)μ^{+}μ^{-} Differential Branching Fraction

The branching fraction of the rare decay Λ_{b}^{0}→Λ(1520)μ^{+}μ^{-} is measured for the first time, in the squared dimuon mass intervals q^{2}, excluding the J/ψ and ψ(2S) regions. The data sample analyzed was collected by the LHCb experiment at center-of-mass energies of 7, 8, and 13 TeV, corresponding to a total integrated luminosity of 9  fb^{-1}. The result in the highest q^{2} interval, q^{2}>15.0  GeV^{2}/c^{4}, where theoretical predictions have the smallest model dependence, agrees with the predictions.

Measurement of Ultra-High-Energy Diffuse Gamma-Ray Emission of the Galactic Plane from 10 TeV to 1 PeV with LHAASO-KM2A

The diffuse Galactic γ-ray emission, mainly produced via interactions between cosmic rays and the interstellar medium and/or radiation field, is a very important probe of the distribution, propagation, and interaction of cosmic rays in the Milky Way. In this Letter, we report the measurements of diffuse γ rays from the Galactic plane between 10 TeV and 1 PeV energies, with the square kilometer array of the Large High Altitude Air Shower Observatory (LHAASO). Diffuse emissions from the inner (15°10  TeV). The energy spectrum in the inner Galaxy regions can be described by a power-law function with an index of -2.99±0.04, which is different from the curved spectrum as expected from hadronic interactions between locally measured cosmic rays and the line-of-sight integrated gas content. Furthermore, the measured flux is higher by a factor of ∼3 than the prediction. A similar spectrum with an index of -2.99±0.07 is found in the outer Galaxy region, and the absolute flux for 10≲E≲60  TeV is again higher than the prediction for hadronic cosmic ray interactions. The latitude distributions of the diffuse emission are consistent with the gas distribution, while the longitude distributions show clear deviation from the gas distribution. The LHAASO measurements imply that either additional emission sources exist or cosmic ray intensities have spatial variations.

Precise Measurement of the e^{+}e^{-}→D_{s}^{*+}D_{s}^{*-} Cross Sections at Center-of-Mass Energies from Threshold to 4.95 GeV

The process e^{+}e^{-}→D_{s}^{*+}D_{s}^{*-} is studied with a semi-inclusive method using data samples at center-of-mass energies from threshold to 4.95 GeV collected with the BESIII detector operating at the Beijing Electron Positron Collider. The Born cross sections of the process are measured for the first time with high precision in this energy region. Two resonance structures are observed in the energy-dependent cross sections around 4.2 and 4.4 GeV. By fitting the cross sections with a coherent sum of three Breit-Wigner amplitudes and one phase-space amplitude, the two significant structures are assigned masses of (4186.8±8.7±30) and (4414.6±3.4±6.1)  MeV/c^{2}, widths of (55±15±53) and (122.5±7.5±8.1)  MeV, where the first errors are statistical and the second ones are systematic. The inclusion of a third Breit-Wigner amplitude is necessary to describe a structure around 4.79 GeV.

[A study on alveolar ridge augmentation guided by orthodontic forced eruption in patients with severe periodontitis]

Objective: To evaluate the clinical effect of alveolar bone augmentation in teeth with severe periodontitis using orthodontic forced eruption. Methods: Twelve patients (5 males and 7 females) with severe periodontitis and malocclusion who visited the Department of Orthodontics and Department of Periodontology, Peking University School and Hospital of Stomatology from October 2018 to May 2022 were included in this retrospective study. The age was (38.8±6.6) years (24-49 years). A total of 16 maxillary incisors that could not be retained due to severe periodontitis were included. The orthodontic fixed appliance was used to extrude the teeth. Cone-beam CT (CBCT) images of the patients before and after orthodontic forced eruption were collected. The voxel-based registration was used to superpose the images before and after orthodontic forced eruption. The height, thickness, and apical alveolar bone area were measured on the sagittal plane. The alveolar bone volume before and after orthodontic forced eruption was measured using three-dimensional reconstruction technique, and the influencing factors related to the alveolar volume change were analyzed. Results: The results of this study showed that the eruption distance of the teeth was (2.37±0.82) mm, and the alveolar bone height increased by (1.11±0.79) and (0.98±0.79) mm (t=3.73, P=0.010; t=4.85, P<0.001). The proximal and distal alveolar bone height increased by (1.10±0.78) and (0.86±1.08) mm, respectively (t=5.59, P<0.001; t=3.18, P=0.006). The alveolar bone thickness decreased (0.30±0.31) mm (t=-3.75, P=0.002) and alveolar bone area increased (6.84±5.86) mm2 (t=3.71, P<0.001). The alveolar bone volume increased (53±49) mm3 (t=4.38, P<0.001). The alveolar bone volume was moderately positively correlated with eruption distance, apical and mesial alveolar bone thickness (r=0.55, P=0.028; r=0.63, P=0.008; r=0.67, P=0.005). Conclusions: Orthodontic forced eruption results in a favorable increase of the alveolar bone in the upper incisor that cannot be retained due to severe periodontitis, which provides better periodontal hard tissue conditions for subsequent dental implant.

First Experimental Study of the Purely Leptonic Decay D_{s}^{*+}→e^{+}ν_{e}

Using 7.33  fb^{-1} of e^{+}e^{-} collision data taken with the BESIII detector at the BEPCII collider, we report the first experimental study of the purely leptonic decay D_{s}^{*+}→e^{+}ν_{e}. Our data contain a signal of this decay with a statistical significance of 2.9σ. The branching fraction of D_{s}^{*+}→e^{+}ν_{e} is measured to be (2.1_{-0.9_{stat}}^{+1.2}±0.2_{syst})×10^{-5}, corresponding to an upper limit of 4.0×10^{-5} at the 90% confidence level. Taking the total width of the D_{s}^{*+} [(0.070±0.028)  keV] predicted with the radiative D_{s}^{*+} decay from the lattice QCD calculation as input, the decay constant of the D_{s}^{*+} is determined to be f_{D_{s}^{*+}}=(214_{-46_{stat}}^{+61}±44_{syst})  MeV, corresponding to an upper limit of 354 MeV at the 90% confidence level.

Dosimetric Advantages of Online Adaptative Radiotherapy for Cervical Cancer on 1.5T MR-Linac

PURPOSE/OBJECTIVE(S)

Online adaptative radiotherapy (ART) strategy can be applied to account for inter-fraction organ motion while limiting organ at risk (OAR) dose. This study aims to evaluate tumor target and OARs inter- and intrafraction motion using online MRI during the full course of MR-Linac radiotherapy fractions. Furthermore, quantify the dosimetric consequences of online adaptative compared with non-adaptative radiotherapy (non-ART) in cervical cancer.

MATERIALS/METHODS

Six cervix cancer patients were treated with 150 fractions on the 1.5 T Unity MR-Linac. Each fraction, pre-treatment MRI scans were obtained at the start of every treatment session, and post-treatment MRI scans were obtained at the end of every treatment session. A total 300 MR images were included in this study and the CTV, bladder and rectum were delineated on each MRI by the same radiation oncologist. The inter-fraction and intrafraction changes of contours were evaluated by dice similarity coefficient (DSC), Hausdorff distance (HD), volume difference (ΔV). The reference treatment plans were generated using step-and-shoot IMRT and utilized 9 beam groups on original CT. Then, the online adaptative treatment plans were obtained by re-optimizing based on the contours on daily pre-treatment MRI by "adapt to shape" workflow using the same beam parameters and optimization objectives from the reference plans. Non-ART plans for each patient were generated by recalculating the dose from the reference plans on daily online MRI by "adapt to position" workflow. CTV coverage and OARs constraints were used to compare ART and non-ART plans.

RESULTS

The results showed that large inter-fraction anatomical changes limited the efficacy of radiation therapy (CTV: DSC: 0.89±0.03, HD: 20.83±5.05mm, ΔV: 1.21%±5.44%; Bladder: DSC: 0.68±0.18, HD: 30.58±15.75mm, ΔV: -10.17%±61.19%; Rectum: DSC: 0.69±0.09, HD: 22.98±12.03mm, ΔV: 21.01%±20.59%).The intrafraction anatomical changes were smaller (CTV: DSC: 0.96±0.01, HD: 8.85±3.54mm, ΔV: -0.64%±1.90%; Bladder: DSC: 0.90±0.07, HD: 14.62±9.56mm, ΔV: 19.83%±21.71%; Rectum: DSC: 0.98±0.04, HD: 2.90±4.27mm, ΔV: 0.13%±5.04%) . Non-ART showed inadequate primary CTV coverage in 30% of the daily fractions. Online adaptative plans improved CTV coverage significantly (p<0.001) to 99%. Compared with non-ART, online ART decreased the fraction dose to bladder and rectum indicated by significant (p<0.001) improvements for daily D50%, D2% and Dmean.

CONCLUSION

In cervical cancer radiotherapy, a non-adaptive strategy led to inadequate target coverage for individual patients. Online adaptative radiotherapy corrected for day-to-day anatomical variations and resulted in adequate target coverage in all fractions. The dose to rectum and bladder was decreased significantly when applying online adaptative radiotherapy.

Radiotherapy for Liver Cancer: An International Multi-Centre Pooled Analysis of 925 Cases

PURPOSE/OBJECTIVE(S)

Primary and secondary liver cancer incidence is growing and has a poor prognosis. The standard use of radiation has been hampered by studies with a wide range of patients, different management protocols and varied outcomes. To overcome this heterogeneity in the literature, larger and higher-level trials are warranted, but, so far, have been difficult to implement. Therefore, pooled analyses may offer the best way to determine the benefit of radiation, identify treatment parameters needed to optimize treatment techniques, and identify patient factors that allow for better patient selection.

MATERIALS/METHODS

Patients with liver cancer treated by radiotherapy at centers in Canada, United States and Australia was pooled. Patient and treatment characteristics were noted, as well as the clinical outcomes of local control within 1 year, recurrence and mortality. Stepwise Cox proportional hazards models were used to identify significant predictors for recurrence and mortality. Patients were stratified by center, and primary versus metastatic disease.

RESULTS

A total of 925 patients were included in this study. Mean age was 67 years, and 45% had a primary diagnosis of hepatocellular carcinoma. 1-year local control rate was 80%. Median survival was 1.8 years (1.9 years for primary liver cancer, and 1.4 years for metastatic liver cancer). Higher total dose and BED was associated with better survival. Median time to recurrence was 1.5 years. Higher total dose was associated with lower risk of recurrence CONCLUSION: As one of the largest pooled analyses in hepatic cancer, this international multi-center study provides pragmatic data on clinical outcomes of patients receiving radiotherapy for liver cancer. This database may assist in better selection of patients for future studies and answer questions such as what is the optimal dose and which patients benefit from treatment.

Inter-fractional Assessment during MR-guided Online Adaptive Radiotherapy for Glioblastoma

PURPOSE/OBJECTIVE(S)

Magnetic resonance image (MRI) guided radiation therapy has the potential to improve outcomes for glioblastoma by adapting to tumor changes during radiation therapy. This study aimed to assess the feasibility and potential benefits of MR-guided online adaptive radiotherapy (MRgOART) for patients with glioblastoma.

MATERIALS/METHODS

Twenty consecutive patients with glioblastoma were treated with MRgOART of 60 Gy in 30 fractions by the 1.5 T MR-Linac. The MRgOART fractions employed daily MR scans and the contours were utilized to create each adapted plan. The gross tumor volume (GTV) and clinical target volume (CTV) were delineated on MRI of pre-treatment simulation (Fx0) and all fractions (Fx1, Fx2, Fx3 ... Fx30) to evaluate the inter-fractional changes. These changes were quantified using absolute/relative volume (∆V), Dice similarity coefficient (DSC) and Hausdorff distance (HD) metrics. The reference treatment plans were generated using step-and-shoot IMRT and utilized 7-9 beam groups on original CT. Before the treatment, a synthetic CT (sCT) quality assurance (QA) process was performed to assess the dose accuracy of bulk relative electron density (rED) assignment for online MRI based treatment plan in terms of gamma analysis, point dose comparison and dose volume histogram (DVH) parameters. Then, the online adaptative treatment plans were obtained by re-optimizing based on the contours on daily pre-treatment MRI by "adapt to shape" workflow. Non-adaptive plans for each patient were generated by recalculating the dose from the reference plans on daily online MRI by "adapt to position" workflow. GTV and CTV coverage and organ at risk (OAR) constraints were used to compare non-adaptive and adaptive plans.

RESULTS

For both criteria, the 1%/1mm (98.58%±0.15%) and 2%/2mm (99.88%±0.18%) gamma passing rate results were always clinically acceptable in sCT QA process. The differences on point dose and DVH parameters between the plans based on sCT and original CT were less than 1%. A total of 20 patients with 600 fractions were evaluated. The results showed that large inter-fractional changes for GTV limited the efficacy of radiation therapy (DSC: 0.78±0.08, HD: 20.94±3.64mm, ∆V: 2.92%±6.36%). The inter-fractional CTV changes were smaller (DSC: 0.91±0.04, HD: 15.31±3.09mm, ∆V: 1.41%±1.29%). GTV coverage of non-adaptive plans was below the prescribed coverage in 228/600 fractions (38%), with 90 (15%) failing by more than 10%. For CTV coverage of non-adaptive plans, the changes were less than 5%. Online adaptative plans improved GTV and CTV coverage significantly (p<0.001) to 99%. The adaptive plans also had lower dose to whole brain than non-adaptive plans (p<0.001).

CONCLUSION

Significant inter-fractional tumor changes could be found during radiotherapy in patients with glioblastoma treated by the 1.5 T MR-Linac. Daily MR-guided re-optimization of treatment plans corrected for day-to-day anatomical variations and resulted in adequate target coverage in all fractions.

Adaptive Auto-Segmentation for MRI-Guided Online Adaptive Radiotherapy of Cervical Carcinoma

PURPOSE/OBJECTIVE(S)

Accurate and efficient delineation of organs and targets on session images is critical in MRI-guided online adaptive radiotherapy (MRgOART). This study proposes a registration-guided deep learning image segmentation framework to assist online delineation of cervical carcinoma.

MATERIALS/METHODS

A total of 300 T2-weighted MR images were acquired for patients with cervical carcinoma treated by a 1.5T Unity MR-Linac. The CTV, bladder, rectum, pelvic bone and femoral joints were delineated on each MRI by the same radiation oncologist. To overcome these obstacles to online MRI segmentation, we propose a registration-guided DL (RgDL) segmentation framework that integrates image registration algorithms and DL segmentation models. Firstly, the DL segmentation model was trained using nnU-net. Then, for each treatment fraction, the deformable image registration (DIR) algorithm generates initial contours from previous treatment fraction, which were used as guidance by DL model to obtain the accurate current segmentation. The segmentation accuracy of alone DIR, DL and RgDL were evaluated by dice similarity coefficients (DSC) and other distance-based metrics.

RESULTS

Compared to the baseline approaches using the DIR and the DL alone, RgDL achieved a DSC of 91.12% on CTV, higher than DIR and DL alone by 15.54% and 10.13%. The DSC of RgDL were improved to 95.58%, 93.65%, 87.8% and 94.84% for bladder, pelvic bone, rectum and femoral joints, higher than DIR and DL alone by 9.61% on average.

CONCLUSION

The proposed adaptive auto-segmentation method can achieve accurate and efficient segmentation and potentially overcome these obstacles to MRgOART.

A Pilot Trial of Consolidation Bevacizumab after Hypo-Fractionated Concurrent Chemoradiotherapy in Patients with Unresectable Locally Advanced Non-Squamous Non-Small-Cell Lung Cancer

PURPOSE/OBJECTIVE(S)

To assess the feasibility of adding bevacizumab consolidation into hypo-fractionated concurrent chemoradiotherapy (hypo-CCRT) in patients with unresectable locally advanced non-squamous non-small cell lung cancer (LA-NS-NSCLC).

MATERIALS/METHODS

Eligible patients were treated with hypo-RT (40 Gy in 10 fractions) followed by hypo-boost (24-28 Gy in 6-7 fractions) combined with concurrent weekly chemotherapy. Patients completed the hypo-CCRT without≥G2 toxicities then received consolidation bevacizumab every 3 weeks for up to 1 year, or disease progression or unacceptable treatment related toxicities. The primary endpoint was the risk of G4 or higher hemorrhage. The secondary endpoint was progression-free survival (PFS), overall survival (OS), locoregional failure-free survival (LRFS), distant metastasis-free survival (DMFS) and objective response rate (ORR). All time-to-event endpoints (OS, PFS, LRFS and DMFS) were measured from the start of radiotherapy.

RESULTS

From December 2017 to July 2020, a total of 27 patients were analyzed with a median follow-up duration of 28.0 months. One patient (3.7%) developed G5 hemorrhage during bevacizumab consolidation. Besides, there were 7 patients (25.9%) had G3 cough and 3 patients (11.1%) had G3 pneumonitis. The ORR was 92.6% of the whole cohort. The median OS was 37.0 months (95% confidence interval, 8.9-65.1 months), the median PFS was 16.0 months (95% confidence interval, 14.0-18.0 months), the median LRFS was not reached and the median DMFS was 18.0 months.

CONCLUSION

This pilot study met its goal of demonstrating the tolerability of consolidation bevacizumab after hypo-CCRT. Further investigation of antiangiogenic and immunotherapy combinations in LA-NSCLC is warranted while G3 respiratory toxicities is worth considering.

Analysis of Institutional DIBH Coaching Program for Surface Guided-DIBH Patients

PURPOSE/OBJECTIVE(S)

Our institute has implemented a surface guided-DIBH (SG-DIBH) coaching program which involves consultation, pre-treatment (CT-sim) and treatment. We would like to analyze the effectiveness of the program.

MATERIALS/METHODS

A total of 72 left breast cancer patients between 1st Apr 2022 to 9th Dec 2022 were registered for radiation treatment. During consultation, oncologist selected suitable patients based on the following criteria: a) age of 18-70; b) left breast cancer, right breast cancer with internal mammary nodes irradiation or dextrocardia; c) no lung/cardiac disease history & d) volunteer for SG-DIBH technique. The eligible patients were then trained by the coaching therapist using a teaching video and practiced at home. During CT simulation, patients were assessed according to the DIBH evaluation form. The evaluation components included patient's compliancy and understanding, the differences of lateral skin marking (free breathing, FB vs DIBH), duration of breath hold and reproducibility. Patients who passed the evaluation were scanned under both FB and DIBH for SG-DIBH treatment. IMRT-FFF 6 to 7 fields were planned. During SG-DIBH treatment, first 3 fractions and weekly CBCT were taken. Patients were encouraged to continue DIBH practice at home throughout whole course of the treatment and they were given 3 identical survey forms (5 questions) at the beginning, middle and end of treatment. The measure for the success of this coaching program would be number of breath-holds, duration of treatment time, treatment accuracy (CBCT matching) and survey results.

RESULTS

There were 48 patients who were eligible for DIBH coaching program, however, only 24 patients had passed the coaching evaluation and 20 patients were treated with SG-DIBH technique successfully. The mean of number of breath-hold and treatment time was 7 times and 7.9 minutes. Total of 123 CBCT images were studied. The setup errors were (0.242±0.180) cm, (0.152±0.137) cm, (0.202±0.165) cm, (0.684±0.640) degrees, (0.816±0.767) degrees, (0.912±0.707) degrees in lateral, longitudinal, vertical, pitch, roll and yaw directions. According to the survey analysis, the number of times to practice at home decreased as the treatment went by. An improvement was seen in patients' self-evaluation in mastering DIBH technique with proper coaching program (from 60% to 90%). Patients' anxiety in performing DIBH were alleviated greatly towards the end of the treatment (from 47% to 15%). 100% of the patients were willing to go for DIBH treatment if given a second chance and additional suggestions claimed that professional clinical teams and coaching program were important for their DIBH treatment journey.

CONCLUSION

A comprehensive DIBH coaching program can effectively identify SG-DIBH patient's suitability. Patient compliancy, treatment accuracy and treatment experience can be enhanced with good coaching program. The involvement of clinical team from consultation to pre-treatment and treatment stage is essential for a successful SG-DIBH treatment.

Frameless Linear Accelerator (LINAC) Based Radiosurgery (SRS) vs. Framed Gamma Knife SRS for Idiopathic Trigeminal Neuralgia (TN)

PURPOSE/OBJECTIVE(S)

Stereotactic radiosurgery (SRS) is an effective treatment for idiopathic trigeminal neuralgia (TN). Conventional treatment is done through frame-based solution due to small target and high radiation dose. More recently, LINAC based frameless SRS technique has been established as a patient friendly alternative. Herein we compared our single institution experience of LINAC based frameless SRS vs frame-based gamma knife SRS for TN. The hypothesis is LINAC based frameless SRS can provide equivalent dosimetric and clinical outcome as compared frame-based gamma knife treatment.

MATERIALS/METHODS

Patients with idiopathic TN who received SRS treatment (LINAC based frameless treatment or Gamma knife framed treatment) at our institution from 2015-2022 were included. A minimum follow up of 1 year was required. Patient data was extracted from electronic medical records and radiation treatment planning system. Pain intensity was evaluated utilizing a modified 0-4 Barrow Neurological Institute (BNI) pain intensity score, and then dichotomized where BNI score 0-2 represented response to treatment and BNI score 3-4 represented no response. Statistical analysis was conducted with a linear regression model accounting for race, gender, prior pain, pain distribution including laterality and branch involvement, medication regimen at time of treatment, previous radiation treatment, and prior procedures. Response was then compared between both modalities overall and within each sub-group with chi-square testing and linear regression.

RESULTS

A total of 81 patients were identified, 14 patients were excluded due to lack of adequate follow-up, leaving 67 for analysis. 12 (17.9%) were male and, 55 (82.1%) were female. All patients were managed with medication prior to SRS treatment. 5 (7.5%) had rhizotomy and 13 (19.4) had microvascular decompression, and 8 (11.9%) had previous gamma-knife radiosurgery prior to SRS treatment at our institution. Of the 67 patients, 23 (34.3%) received frame-based gamma knife SRS, 44(65.7%) received frameless LINAC treatment. 58 (86.6%) radiation naïve patients received 90 Gy in 1 fraction, while out of the 9 who had previously had intracranial radiation treatment 7 (10.4%) received 70 Gy and 2 (3%) received 80 Gy all prescribed to 100% isodose line. All patients were treated with 4 mm cone. There was no significant difference in brainstem dose between these two techniques. Between LINAC-based or Gamma Knife modalities rate of pain control (77.3 % vs 82.6 %, respectively, p = 0.61) as well as toxicity in facial numbness (31.8% vs 21.7%, respectively, p = 0.38) showed no statistical difference. There was no statistically significant signal (p > 0.05) detected within the subgroups analyzed. The linear regression model also showed no significant difference.

CONCLUSION

LINAC based frameless SRS provides comparable dosimetry and pain control for TN as compared to frame-based gamma knife treatment. It is a patient friendly solution for patients with TN.

Influence of Eyes Movement on Lens Dose during MR-Guided Radiotherapy for Brain Tumor

PURPOSE/OBJECTIVE(S)

Modern radiotherapy techniques achieve highly conformal target doses while avoiding organs at risk such as lens. The magnitude of eyes movement and its influence on lens dose is unclear. The lens dose is relevant for cataract formation. This study aims to evaluate the movement-range of lens and its influence on dose distribution during MR-guided radiotherapy for brain cancer patients.

MATERIALS/METHODS

Fifty patients with brain cancer who were treated with MR-guided radiotherapy on 1.5 T MR-Linac were included in this study. All patients underwent a pre-treatment MRI and post-treatment MRI for each fraction. The eyes and lens were delineated on each MR image by a radiation oncologist. The reference treatment plans based original CT were recalculated on each MRI by "adapt to position" workflow. Then, we created planning risk volume (PRV) for lens by adding population margin and reoptimized the reference plans to evaluate the dose changes for lens. Inter-fraction and intrafraction variability for eyes and lens were evaluated with the Dice similarity coefficient (DSC), the Hausdorff distance (HD) and mean distance to agreement (MDA). Differences in daily dose (Dmax and Dmean) for eyes and lens were assessed.

RESULTS

A total of 300 MR images were analyzed in this study. The eyes motion was observed (minimum DSC: 0.57; maximum HD: 10.53; maximum MDA: 3.13). And the obvious lens motion also was found (minimum DSC: 0.01; maximum HD: 10.78; maximum MDA: 5.68). The maximum dose changes for eyes were up to 34.1% and the mean dose changes were up to 18.1%. The maximum dose changes for lens were up to 97.9% and the mean dose changes for eyes were up to 89%. When the reoptimized plans were generated by PRV lens, the dose changes were decreased nearly to 0.

CONCLUSION

Eyes movements in all radiotherapy fractions result in higher lens doses and potentially increase cataract formation rate. Adding margin expansions in treatment planning, to account for eyes motion, is the feasible approach to limit lens dose.

Defect-Engineered ZIF-Derived Non-Pt Cathode Catalyst at 1.5 mg cm-2 Loading for Proton Exchange Membrane Fuel Cells

Due to the sluggish kinetics of the oxygen reduction reaction (ORR) by non-Pt based catalyst, high loading of catalyst is required to achieve satisfactory fuel cell performance, which inevitably leads to the increase of the catalyst layer thickness with serious mass transport resistance. Herein, a defective zeolitic imidazolate framework (ZIF) derived Co/Fe-N-C catalyst with small mesopores (2-4 nm) and high density of CoFe atomic active sites are prepared by regulating the Fe dosage and pyrolysis temperature. Molecular dynamics simulation and electrochemical tests indicate that > 2 nm mesopores show insignificant influence on the diffusion process of O2 and H2 O molecules, leading to the high utilization of active sites and low mass transport resistance. The proton exchange membrane fuel cell (PEMFC) shows a high-power density of 755 mW cm-2 with only 1.5 mg cm-2 of non-Pt catalyst in the cathode. No apparent performance loss caused by concentration difference can be observed, in particular in the high current density region (1 A cm-2 ). This work emphasizes the importance of small mesopore design in the Co/Fe-N-C catalyst, which is anticipated to provide essential guidance for the application of non-Pt catalysts.

End-to-End Verification and Dosimetric Comparative Study of Brainlab Monte Carlo and Eclipse Acuros XB Photon Dose Calculation Algorithm for VMAT SRS Planning

PURPOSE/OBJECTIVE(S)

We commissioned the Brainlab Monte Carlo Dose Calculation Algorithm for VMAT SRS planning and verified it by measurements and comparisons with two other algorithms: Pencil beam and Eclipse Acuros. The end-to-end verification and dosimetric comparative study results are reported in this abstract.

MATERIALS/METHODS

Brainlab Elements Cranial SRS (v3.0) provides single lesion planning using VMAT optimization, thus allowing dose modulation with MLC leaf positioning, dose rate, and gantry speed. We commissioned and performed quality assurance for the available dose calculation algorithms, including Pencil Beam (PB) algorithm with only reference beam data (RBM PB) and PB with full beam data (Elements PB), and Monte Carlo (MC) algorithm XVMC. Calculation between the two were compared to each other and to Acuros XB dose calculation algorithm by Varian. Open field MLC, static cone, dynamic MLC, and conical cone plans were calculated with each algorithm. IBA CC01 ionization chamber was used for each measurement, and small field correction factors as determined in TRT-483 were applied. End-to-end tests were performed using an anthropomorphic stereotactic end-to-end verification (STEEV) phantom from CIRS and a phantom/diode array, StereoPHAN/SRSMapCHECK from SunNuclear. Each phantom was CT scanned with 0.5 mm slice thickness. Four clinical plans were optimized in Brainlab Elements Treatment Planning System (TPS). Each plan was calculated with the following algorithms: Elements PB, RBM PB, MC, and Acuros XB with 1 mm dose grid size. The delivered dose was measured with a SunNuclear SRSMapCHECK diode array detector. The calculated dose was compared with the measured dose by Gamma analysis with DTA 1%/1mm, 2%/1mm, and 3%/1mm.

RESULTS

The results of point dose measurements for field size larger than 1 × 1 cm2 among measured dose, dose calculated by pencil beam algorithms, and dose calculated by Monte Carlo algorithm were in excellent agreement (1.45% ± 0.7%). For the small rectangular field sizes (0.4 × 1, 0.2 × 1 cm2), Monte Carlo calculation showed superior accuracy and robustness to pencil beam algorithm when compared with measured dose, with percent dose difference 13% and -2.2%, respectively. Monte Carlo calculation have higher gamma results compared with pencil beam algorithm due more accurate calculations with heterogenous materials. Acuros XB showed comparable accuracy with MC in terms of gamma passing rate.

CONCLUSION

The SRS MapCHECK measurement agrees dosimetrically with the plans calculated by Pencil Beam algorithm and the Monte Carlo algorithm XVMC by Brainlab, as well as the Acuros XB dose calculation algorithm by Varian. Point dose calculation for small field dosimetry and gamma analysis using SRS MapCHECK both showed that Monte Carlo algorithm is more robust and is superior in regions of heterogenous materials. Therefore, we recommend that Monte Carlo algorithm for dose calculation be used in clinical SRS and SRT cases.

Towards Automated Dosimetric Analysis of the Bladder Trigone: Deep-Learning-Based Joint Segmentation and Landmark Localization

PURPOSE/OBJECTIVE(S)

The bladder trigone dosimetry is hypothesized to have a stronger correlation with post-SBRT urinary toxicity than that of the entire bladder. However, the trigone tends to move significantly between simulation and daily treatment. Its small size, large daily motion, and proximity to the target lead to potentially consequential but unaccounted-for dosimetric uncertainties. Manual segmentation of the structure can be inconsistent and time-consuming, even with MR-guided RT. Here, we propose and demonstrate a deep-learning-based framework for joint segmentation and landmark localization to support deformable registration and comprehensive dosimetric analysis.

MATERIALS/METHODS

A total of 30 patients were randomly selected for training, and 20 were held out for testing. Each patient had 1 simulation and 5 daily pre-treatment images obtained from a clinical 0.35T MR Linac. The trigone is defined as the triangular bladder section among three landmarks (2 ureteral orifices and the internal urethral orifice). In the manual contouring process, the 3 landmarks were identified first, followed by trigone segmentation. The proposed joint method uses a modified 3D nnU-Net with 2 decoders, one for segmentation and the other for landmark localization. The shared encoder is expected to extract features useful for both tasks. The joint framework was compared with a baseline method using two separate 3D nnU-Nets for landmark localization and trigone segmentation, respectively. Since the trigone is small (∼2% of the bladder volume), we further experimented with a second-stage prediction mimicking the human contouring process. The predicted landmarks from the first stage were used to crop the trigone region, and a second network was trained on cropped images. Evaluation metrics included the Dice score, 95% Hausdorff distance (HD95), and average surface distance (ASD) for segmentation, and Euclidean distance (ED) between the predicted and ground truth landmarks for localization.

RESULTS

The quantification metrics are summarized in the table below. The joint approach shows similar Dice performance to the baseline method but markedly better HD95 by 13%. For landmark localization, the proposed method is similar to the baseline, but the integration of the segmentation task stabilizes the training process. The two-stage approach further improves HD95, ASD, and ED by 27%, 24%, and 19%.

CONCLUSION

Combining segmentation and landmark localization exhibits a synergistic effect. The proposed two-stage approach provided additional improvement. Future studies will explore the deformable registration of the trigone based on the segmentation and landmark detection, as well as analyze cumulated dose distribution.

Combining Dosimetric and Radiomics Features for the Prediction of Radiation Pneumonitis in Locally Advanced Non-Small Cell Lung Cancer by Machine Learning

PURPOSE/OBJECTIVE(S)

This study aimed to analyze the dosimetric factors and radiomics features of tumor and lungs in locally advanced non-small cell lung cancer (LANSCLC) to establish machine learning models and improve the prediction of grade (G) 2 radiation pneumonitis (RP).

MATERIALS/METHODS

This study retrospectively collected data of 284 LANSCLC patients underwent concurrent chemoradiotherapy (CCRT) to a median dose of 64 Gy in 20-33 fractions between 2013 and 2021. Of this cohort, 21.1% of patients had ≥ G2 RP. There were 4 regions of interest (ROIs) had been identified in planning computed tomography images: gross tumor volume (GTV), ipsilesional lung (IL), contralesional lung (CL), and total lung (TL). We calculated the dose-volume histogram (DVH) from the lowest dose to the maximum dose increasing by degrees with 1 Gy, and extracted a total of 172 radiomics features from all the 4 ROIs. We selected the best predictors for classifying 2 groups of patients using a sequential backward elimination support vector machine model.

RESULTS

The best predictors for ≥ G2 RP were the combination of 8 radiomics features and 7 dosimetric factors in training group, and the validation group achieved an area under the curve (AUC) of 0.847 (accuracy, 80.38%; sensitivity, 78.95%; specificity, 81.82%). The eight radiomic features included 2 from GTV while 1, 2 and 3 from IL, CL and TL, respectively. For dosimetric factors, V65 of GTV, V20, V50 and V55 of IL, V10 of CL, V20 and V55 of TL appeared to be significantly related to symptomatic RP. These dosimetric factors should be constrained to less than 99.2%, 50.0%, 17.5%, 13.0%, 39.5%, 32.0%, and 6.6%, respectively.

CONCLUSION

Combining dosimetric factors and radiomics features within GTV, IL, CL and TL can improve the prediction of symptomatic RP in LANSCLC patients treated with CCRT. The results suggested the importance of V65 of GTV, V20, V50 and V55 of IL, V10 of CL, V20 and V55 of TL as predictors of symptomatic RP and provide useful information for optimization of treatment planning in the era of combination of radiotherapy and immunotherapy.