The incidence and mortality of breast cancer are increasing year by year. Image-guided radiotherapy (IGRT) after breast cancer surgery is one of the important ways of comprehensive treatment of breast cancer, but the frequency of IGRT and additional radiation damage are one of the key problems of clinical attention. To investigate the impact of different orthogonal image-guided frequencies on positioning error correction, plan target volume (PTV) margin expansion, and dose distribution in postoperative radiotherapy for breast cancer patients, providing a reference for the optimal orthogonal image-guided frequency in clinical practice for post-surgical breast cancer radiotherapy patients. From January 2021 to January 2022, 61 patients undergoing postoperative intensity-modulated radiation therapy (IMRT) for breast cancer at Fujian Medical University Union Hospital were selected. Prior to each radiation session, initial setup errors were measured as the control group (Group A) using real-time orthogonal images aligned with digitally reconstructed radiographs (DRR). Automatic couch adjustments were then performed based on alignment results within specified error tolerances to determine residual setup errors. Data collected were categorized into experimental Groups B1 to B5 based on different verification frequencies (every 1 to 5 days). Statistical analysis was conducted on the grouped data to calculate PTV expansion margins under different error conditions and assess their impact on dose. In the study involving 61 patients, a total of 915 datasets were collected. The initial setup errors in three translational directions were (3.57 ± 3.48) mm, (2.76 ± 2.60) mm, and (2.65 ± 2.28) mm, respectively. With increasing verification frequency, residual setup errors gradually decreased. Under daily verification frequency, residual errors were (1.65 ± 0.90) mm, (1.60 ± 0.94) mm, and (1.56 ± 0.90) mm in the three translational directions. Pairwise comparisons between control and experimental groups indicated that differences were statistically significant except between B3 Vs B4, and B4 Vs B5. Based on setup error calculations under different verification frequencies, the reference PTV expansion margins decreased with increasing frequency. Specifically, under daily verification, the calculated PTV expansion reference values reduced from initial uncorrected setup errors of 6.53 mm, 5.07 mm, and 4.01 mm to 1.26 mm, 1.41 mm, and 1.29 mm, respectively. The differences between verification frequencies of every 3 days, 4 days, and 5 days were minimal. Finally, virtual error plans were designed in the treatment planning system based on average errors for each group of patients. Deviations in target area doses were statistically significant compared to the original plan across different imaging frequencies. Daily image-guided setup verification (including correction) effectively reduces setup errors in postoperative breast cancer IGRT. Variations exist in the efficacy of error correction and its impact on PTV expansion and dose among different verification frequencies. Higher frequencies exhibit more significant error correction effects, necessitating smaller PTV expansions. At the same time, daily image guidance can reduce the dose of the heart and left lung. Further follow-up studies are required to track the impact of these deviations on dose and clinical efficacy.

LATTICE radiation therapy (LRT), a 3D spatially fractionated radiation therapy (SFRT), creates high-dose vertices through three-dimensional focusing to generate peak-valley dose distributions while sparing normal tissues. This study assessed its efficacy and toxicity in patients with metastatic and/or bulky tumors. Patients with unresectable bulky and/or metastatic tumors treated with LRT between 4/2017 and 2/2021 were enrolled and retrospectively reviewed. Descriptive statistics were used to summarize patient data. Overall survival (OS) and local control (LC) were estimated using Kaplan-Meier analysis and a competing risk model with death as a competing event, respectively. Clinical response and toxicities were also assessed. A total of 76 patients with 85 lesions were analyzed, including 63 (82.9%) with metastatic disease and 60 lesions (70.6%) classified as bulky tumors. 65.9% (56/85) of patients received one fraction with a median vertex dose of 15 Gy (range, 10–20 Gy), after 30 Gy in two fractions (14, 16.5%). At a median follow-up of 11.6 months, the disease control rate was 91.8%, including 2.4% complete remission, 48.2% partial remission, and 41.2% stable disease. By the end of follow-up, 16 patients (21.1%) remained alive without disease progression. Among the 60 deceased patients, 55 (91.7%) died from disease progression, while 5 (8.3%) died from non-cancer-related causes. Median OS and LC were 11.2 months and 13.7 months, respectively, with 1-year OS and LC rates of 45.9% and 51.9%. Additionally, the local failure rate at 1 year, calculated with death as a competing risk, was 21.2%. Symptomatic improvement was observed in all patients, with no LRT-associated acute or late grade 3+ toxicity. With approximately 50% local control at 1 year, symptom palliation in all patients, and low toxicity, LRT represents a feasible and promising therapeutic strategy for patients with large unresectable tumors, particularly in settings where conventional radiotherapy is limited by toxicity concerns.

PURPOSE:In Monte Carlo (MC) simulations of medical electron linear accelerator (linac) rooms using FLUKA, time-consuming modeling and simulation of the accelerator head are typically required, and FLUKA cannot directly read the phase space files (PSF) for accelerator heads provided by the IAEA. To address this, this study aimed to establish and validate the accuracy of a radiation model for an accelerator room within FLUKA using a virtual source, thereby enhancing the applicability of FLUKA for the design and evaluation of rooms housing different medical electron linacs. METHODS:The 6 MV photon beam from a Varian 23EX linac was modeled as consisting of primary photons, scattered photons, and contaminant electrons. Their energy spectra and spatial distributions were represented by mathematical formulas. Python code was used to sample particle information (type, position, direction, energy, weight) from this mathematically defined virtual source, generating a FLUKA-readable PSF. A room radiation model was then established in FLUKA. Its accuracy was validated by comparing simulated and measured percentage depth dose (PDD) and off-axis ratios (OAR) in a water tank, as well as comparing simulated and measured dose equivalent rates at selected points inside the accelerator room. RESULTS:The deviation between simulated and measured PDD was within 1%, and that for the OAR was within 2%. At gantry angles of 0° and 90° (with the head oriented toward the maze inner entrance), the simulated dose-equivalent rates at the points of interest inside the treatment room closely agreed with the measured values. CONCLUSION:The phase-space file sampled from the virtual source can faithfully reproduce the beam characteristics in FLUKA. The agreement between simulation and measurement at the points of interest demonstrates that the room radiation model established in FLUKA using the virtual source accurately reflects the actual radiation field in the treatment room. This approach replaces the need for simulating the accelerator head model and improves the efficiency of using FLUKA for radiation protection studies on rooms equipped with different medical electron linear accelerators.

SHP2 is a mediator in tumor-related signaling pathway, a suppressor of PD-1, associated with solid tumors and leukemias. SHP2 is recognized as a driver in myeloid leukemia. Inhibition of SHP2 has potential to reverse progression of myeloid leukemia, rather than eradicating differentiated leukemic cells. However, SHP2's bifunctional roles-encompassing both phosphatase-dependent and -independent activities-pose challenges for therapeutic targeting. SHP2 inhibitors, like JAB3312, is limited to inhibiting phosphatase activity and evaluated in combination regimens rather than as standalone therapies. To address limitations, we developed a PROTACs with a novel, high-affinity as warhead. This strategy enables complete degradation of SHP2, we developed a novel SHP2 degrader TDS0593, exhibited superior preclinical performance. In vitro, TDS0593 achieved dose-dependent SHP2 degradation, with a Dmax of 91.7% and a DC50 of 1.145 nM in MV411 leukemia cells. Mechanistic studies confirmed TRD209 acts via ubiquitin-proteasome pathway, as validated by TAK-243 and MG132 blockade assays. In vivo, TDS0593 demonstrated potent antitumor efficacy. In MV411 xenograft models, at 2.5 mg/kg (QD) achieved >90% TGI, a 5 mg/kg (QD) dose resulted in complete TGI. In order to established mouse model, leukemia HSC from donor mice with CD45.2 cells has been transplanted into CD45.1 mice. In murine models, administration of TDS0593 resulted in a significant reduction in proportion of myeloid cells both in PB and BM. The number of myeloid stem and progenitor cells in the BM approached normal levels. TDS0593 corrects the aberrant differentiation pathway of hematopoietic stem cells to a certain extent, highlighting its potential as an etiological treatment for myeloid leukemia. Notably, TRD209 showed greater potency in solid tumor PDX, with a 0.5 mg/kg (QD) dose achieving >99% TGI. Immunohistochemical analysis confirmed suppression of p-ERK1/2 expression in tumors either. TDS0593 represents a first-in-class SHP2 degrader with potential to overcome the limitations of current inhibitors by targeting both phosphatase-dependent and -independent activities. TDS0593 offer a novel strategy for the treatment of myeloid leukemia by correcting aberrant myeloid-biased differentiation of HSC/HSPC. This innovative approach aims to rectify the underlying dysregulation in hematopoietic differentiation processes, achieving efficacy in myeloid leukemia. Junrong Liu, Liying Zhou, Xiaobo Li, Wenming Li. Revolutionizing cancer treatment with the first SHP2 PROTAC [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2025; Part 2 (Late-Breaking, Clinical Trial, and Invited Abstracts); 2025 Apr 25-30; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2025;85(8_Suppl_2):Abstract nr LB194.

Objective To perform a multicenter evaluation of planning quality and dosimetric accuracy for intensity-modulated radiotherapy (IMRT) and volumetric modulated arc therapy (VMAT), using both standardized American Association of Physicists in Medicine (AAPM) Task Group 119 (TG-119) test cases and complex real-world clinical scenarios. The goal is to comprehensively assess the overall implementation accuracy of IMRT systems across multiple institutions. Methods Four TG-119 test cases and five clinical cases—including nasopharyngeal carcinoma (T2/T4), esophageal carcinoma, breast carcinoma, and cervical carcinoma—were selected. Five radiotherapy centers in Fujian Province independently generated IMRT and VMAT plans using their respective treatment planning systems and linear accelerator models, adhering to the prescription guidelines from both TG-119 report and Fujian Cancer Hospital. Then the plan quality scores (QS) across multicenters were compared. Meanwhile the dosimetric delivery accuracy of these plans were evaluated through point dose measurements, 2D planar and 3D volumetric dose verification. Subsequently, inter-center comparisons were performed for point dose deviations (DD) and γ passing rates based on the 3%/2 ​mm criteria. Finally, confidence limits (CLs) were calculated for QS, DD and γ passing rates to quantify the consistency in plan quality and dosimetric performance. Results In TG-119 test cases, CL values of plan quality score, point dose deviation, 3D γ passing rate were 0.6, 0.037, 9.09 for IMRT, and 0.66, 0.032 and 8.20 for VMAT, respectively. In clinical cases, they were 2.74, 0.031 and 8.85 for IMRT, 2.86, 0.033 and 7.62 for VMAT, respectively. All results met established quality assurance (QA) thresholds, with increased variability observed in more complex clinical scenarios. Conclusion This multicenter study validated the clinical feasibility and dosimetric reliability of IMRT and VMAT systems by integrating standardized benchmarks with real-world clinical cases. The derived regional CL provide practical reference values for evaluating the performance of existing or newly implemented IMRT/VMAT systems, thereby supporting standardization and enhancing confidence in clinical application.

Boron Neutron Capture Therapy (BNCT), often referred to as the ‘cell knife,’ represents a binary, tumor-selective therapeutic modality that minimizes damage to surrounding healthy tissues. This review provides a comprehensive clinical perspective on BNCT, addressing the radiobiological mechanisms and summarizing related clinical trials, with a particular emphasis on glioma and head and neck cancers. Furthermore, the paper touches upon the synergistic potential of BNCT when integrated with other treatment modalities, such as proton and carbon ion radiotherapy, alternative neutron capture therapies, ultrasound, and immunotherapy. These combined approaches may offer promising avenues for future research, potentially enhancing the therapeutic index and expanding the applicability of BNCT in oncological practice.

Perineural invasion (PNI) is widely recognized as a significant indicator of tumor aggressiveness and poor prognosis. In patients with stage II colorectal cancer, the presence of PNI may suggest a higher risk of disease recurrence. Therefore, evaluating the potential benefits of adjuvant chemotherapy in this high-risk subgroup is of considerable clinical relevance. Nonetheless, the therapeutic efficacy of such treatment remains a matter of ongoing debate. A retrospective study was conducted on data from patients with stage II rectal cancer (RC) obtained from the Surveillance, Epidemiology, and End Results database (2013-2014) of the National Cancer Institute. Kaplan-Meier survival analysis was performed to estimate survival rates, and group comparisons were conducted using the log-rank test. Univariate and multivariate Cox proportional hazards regression analyses were employed to assess the associations between clinicopathological factors and both overall survival (OS) and cancer-specific survival (CSS). Among the 1372 patients included in the analysis, 144 (10.5%) exhibited PNI. The presence of PNI was significantly associated with carcinoembryonic antigen levels, T stage, and receipt of chemotherapy. Cox proportional hazards regression analysis identified age, carcinoembryonic antigen levels, PNI, radiotherapy, chemotherapy, T stage, and the number of regional lymph nodes examined as independent prognostic factors for both OS and CSS. Additionally, postoperative chemotherapy was associated with improved OS and CSS in patients with stage II RC. PNI is a poor prognostic factor for stage II RC patients. Postoperative chemotherapy improved the prognosis of stage II RC patients with PNI(+).

Methods The study utilized the cumulative results of 1,200 iSCOUT system scans from 80 breast cancer patients as research data. Initially, based on literature review and clinical practice experience, factors influencing patient positioning errors during treatment were identified, and relevant information was collected. This process yielded 13 feature values to serve as input variables for the machine learning model. The classification of the maximum positioning error in three translational directions was used as the output of the machine learning model. The maximum positioning error for each scan was categorized into two classes based on a 3mm threshold, which served as the target value for the machine learning model.Feature selection was performed using XGBoost to calculate feature importance, and the features were ranked accordingly. The top n most important features were selected for further analysis. The research data was then split into training and validation sets in an 8:2 ratio. A predictive model was trained using the training set, and its performance was preliminarily evaluated using the validation set. Finally, the predictive results of a predictive model were compared with those of reference models, including SVM-SVC and DecisionTreeClassifier, to assess the performance differences across models. Results Among the various training models, XGBoost showed higher accuracy. A predictive model constructed in this study achieved the highest prediction accuracy for patient .positioning errors on the 4th to 7th days of treatment, with a maximum accuracy of 71.87%. Conclusion Machine learning algorithms have demonstrated the capability to predict instances where a patient's positioning error exceeds 3mm. However, ongoing efforts are required to enhance their accuracy. To optimize iSCOUT image-guided frequency, enhance radiotherapy efficacy, and reduce radiotherapy side effects, more feature parameters need to be identified for model training.

The aim of the present study was to develop a prediction model for set-up error distribution in breast cancer image-guided radiotherapy (IGRT) using a Gaussian mixture model (GMM). To achieve this, the image-guided set-up errors data of 80 patients with breast cancer were selected, and the GMM was used to develop the set-up errors distribution prediction model. The predicted error center points, covariance and probability were calculated and compared with the planning target volume (PTV) margin formula. A total of 1,200 sets of set-up errors in IGRT for breast cancer were collected. The results of the Gaussian model parameters showed that the set-up errors were mainly in the direction of mu 1-mu 4 center points. All the raw errors in the lateral, longitudinal and vertical directions were -6.30-4.60, -5.40-1.47 and -2.70-1.70 mm, respectively. According to the probability of each center, the set-up error was most likely to shift in the mu 1 direction, reaching 0.53. The set-up errors of the other three centers, mu 2, mu 3 and mu 4, were 0.11, 0.34 and 0.12, respectively. According to the covariance parameters of the GMM, the maximum statistical standard deviation of the set-up errors reached 29.06. In conclusion, the results of the present study demonstrated that the GMM can be used to quantitatively describe and predict the distribution of set-up errors in IGRT for breast cancer, and these findings could be useful as a reference for set-up error control and tumor PTV expansion in breast cancer radiotherapy without routine, daily IGRT.

PurposeThe Xsight lung tracking system (XLTS) utilizes an advanced image processing algorithm to precisely identify the position of a tumor and determine its location in orthogonal x-ray images, instead of finding fiducials, thereby minimizing the risk of fiducial insertion-related side effects. To assess and gauge the effectiveness of CyberKnife Synchrony in treating liver tumors located in close proximity to or within the diaphragm, we employed the Xsight diaphragm tracking system (XDTS), which was based on the XLTS.MethodsWe looked back at the treatment logs of 11 patients (8/11 [XDTS], 3/11 [Fiducial-based Target Tracking System-FTTS]) who had liver tumors in close proximity to or within the diaphragm. And the results are compared with the patients who undergo the treatment of FTTS. The breathing data information was calculated as a rolling average to reduce the effect of irregular breathing. We tested the tracking accuracy with a dynamic phantom (18023-A) on the basis of patient-specific respiratory curve.ResultsThe average values for the XDTS and FTTS correlation errors were 1.38 +/- 0.65 versus 1.50 +/- 0.26 mm (superior-inferior), 1.28 +/- 0.48 versus 0.40 +/- 0.09 mm (left-right), and 0.96 +/- 0.32 versus 0.47 +/- 0.10 mm(anterior-posterior), respectively. The prediction errors for two methods of 0.65 +/- 0.16 versus 5.48 +/- 3.33 mm in the S-I direction, 0.34 +/- 0.10 versus 1.41 +/- 0.76 mm in the A-P direction, and 0.22 +/- 0.072 versus 1.22 +/- 0.48 mm in the L-R direction. The coverage rate of FTTS slightly less than that of XDTS, such as 96.53 +/- 8.19% (FTTS) versus 98.03 +/- 1.54 (XDTS). The prediction error, the motion amplitude, and the variation of the respiratory center phase were strongly related to each other. Especially, the higher the amplitude and the variation, the higher the prediction error.ConclusionThe diaphragm has the potential to serve as an alternative to gold fiducial markers for detecting liver tumors in close proximity or within it. We also found that we needed to reduce the motion amplitude and train the respiration of the patients during liver radiotherapy, as well as control and evaluate their breathing.

Objectives Accurate beam modelling is essential for dose calculation in stereotactic radiation therapy (SRT), such as CyberKnife treatment. However, the present deep learning methods only involve patient anatomical images and delineated masks for training. These studies generally focus on traditional intensity-modulated radiation therapy (RT) plans. Nevertheless, this paper aims to develop a deep CNN-based method for CyberKnife plan dose prediction about brain cancer patients. It utilized modelled beam information, target delineation, and patient anatomical information.Methods This study proposes a method that adds beam information to predict the dose distribution of CyberKnife in brain cases. A retrospective dataset of 88 brain and abdominal cancer patients treated with the Ray-tracing algorithm was performed. The datasets include patients' anatomical information (planning CT), binary masks for organs at risk (OARs) and targets, and clinical plans (containing beam information). The datasets were randomly split into 68, 6, and 14 brain cases for training, validation, and testing, respectively.Results Our proposed method performs well in SRT dose prediction. First, for the gamma passing rates in brain cancer cases, with the 2 mm/2% criteria, we got 96.7% +/- 2.9% for the body, 98.3% +/- 3.0% for the planning target volume, and 100.0% +/- 0.0% for the OARs with small volumes referring to the clinical plan dose. Secondly, the model predictions matched the clinical plan's dose-volume histograms reasonably well for those cases. The differences in key metrics at the target area were generally below 1.0 Gy (approximately a 3% difference relative to the prescription dose).Conclusions The preliminary results for selected 14 brain cancer cases suggest that accurate 3-dimensional dose prediction for brain cancer in CyberKnife can be accomplished based on accurate beam modelling for homogeneous tumour tissue. More patients and other cancer sites are needed in a further study to validate the proposed method fully.Advances in knowledge With accurate beam modelling, the deep learning model can quickly generate the dose distribution for CyberKnife cases. This method accelerates the RT planning process, significantly improves its operational efficiency, and optimizes it.

Objective: This prospective study aims to evaluate acute irradiation-induced xerostomia during radiotherapy by utilizing the normalized iodine concentration (NIC) derived from energy spectrum computed tomography (CT) iodine maps. Methods: In this prospective study, we evaluated 28 patients diagnosed with nasopharyngeal carcinoma. At 4 distinct stages of radiotherapy (0, 10, 20, and 30 fractions), each patient underwent CT scans to generate iodine maps. The NIC of both the left and right parotid glands was obtained, with the NIC at the 0-fraction stage serving as the baseline measurement. After statistically comparing the NIC obtained in the arterial phase, early venous phase, late venous phase, and delayed phase, we chose the late venous iodine concentration as the NIC and proceeded to analyze the variations in NIC at each radiotherapy interval. Using the series of NIC values, we conducted hypothesis tests to evaluate the extent of change in NIC within the parotid gland across different stages. Furthermore, we identified the specific time point at which the NIC decay exhibited the most statistically significant results. In addition, we evaluated the xerostomia grades of the patients at these 4 stages, following the radiation therapy oncology group (RTOG) xerostomia evaluation standard, to draw comparisons with the changes observed in NIC. Results: The NIC in the late venous phase exhibited the highest level of statistical significance ( P < .001). There was a noticeable attenuation in NIC as the RTOG dry mouth grade increased. Particularly, at the 20 fraction, the NIC experienced the most substantial attenuation ( P < .001), a significant negative correlation was observed between the NIC of the left, right, and both parotid glands, and the RTOG evaluation grade of acute irradiation-induced xerostomia ( P < .001, r = −0.46; P < .001, r = −0.45; P < .001, r = −0.47). The critical NIC values for the left, right, and both parotid glands when acute xerostomia occurred were 0.175, 0.185, and 0.345 mg/ml, respectively, with AUC = 0.73, AUC = 0.75, and AUC = 0.75. Conclusion: The NIC may be used to evaluate changes in parotid gland function during radiotherapy and acute irradiation-induced xerostomia.

e22005 Background: For pediatric rhabdomyosarcoma (RMS), IRSG risk stratification is based on two distinct staging systems that differ according to whether surgery is performed. Its complexity hinders its effective clinical application to a certain extent. We aimed to develop a simple, practical, and reproducible risk stratification model to offer treatment guidance for RMS. Methods: We conducted a retrospective study based on the Surveillance, Epidemiology, and End Results (SEER) database obtained from SEER*Stat software, version 8.4.0. Multivariate Cox regression analysis was used to identify independent prognostic factors in RMS. Later, prognostic factors were integrated to construct an OS prediction nomogram. Recursive partitioning analysis (RPA) was performed to stratify the risk of the patients. Results: A total of 223 patients with pediatric RMS were ultimately included in this study. All patients received chemotherapy, and most received radiotherapy (98.2%). The median follow-up time was 93.0 months, and the overall median survival time was not reached. Multivariate Cox analysis revealed that histology (hazard ratio [HR] = 2.2374, P = 0.031), tumor size (HR = 3.403, P = 0.008), and M classification (HR = 2.060, P = 0.028) were independent factors for OS in RMS. A nomogram was constructed to predict accuracy toward individual OS with a training C-index of 0.698 and a validation C-index of 0.781. Compared to the IRSG risk stratification, the risk groups stratified by RPA allowed for significant distinction between survival curves in our cohort (for 3-y OS, IDI = 0.04454772, P = 0.022; for 5-y OS, IDI = 0.05452665, P = 0.015). Conclusions: The risk stratification model constructed by RPA could help clinicians to identify patients with poor outcomes and assist them in making treatment and surveillance decisions.

Objective:To explore the tracking accuracy of the surface optically guided tracking system (OGTS) in radiotherapy.Methods:Phantom verification and clinical trial verification were adopted. Specialized equipment was employed for the phantom verification. Specifically, the displacement of the optical markers as they moved from a predetermined position to the target position on the reflector ball platform was captured using the OGTS, and then the obtained displacement was compared with the fixed distance within the phantom to calculate the accuracy and repeatability of the OGTS. For the clinical trial verification, 45 patients treated with radiotherapy, which consisted of 15 cases with head, breast, and rectal tumors each, were selected to investigate the tracking accuracy and repeatability of the OGTS. For each patient, the values derived from the image-guided positioning system (IGPS) and the OGTS before and after image-guided setup error correction during three times of fractionated radiotherapy were randomly obtained. The translational errors of each error correction were also recorded. Before radiotherapy, patients′ setup errors were corrected and relevant data were obtained using the IGPS. The correction result of translation errors obtained using the IGPS served as a gold standard to verify the accuracy of the OGTS in monitoring the translational motion of patients. Finally, the comprehensive translational deviation of both method was calculated.Results:The phantom measurements showed that the comprehensive translational deviation for tracking accuracy and tracking repeatability of the OGTS had a maximum deviation and a standard deviation of 0.18 mm and 0.03 mm, respectively. The clinical trial result indicated that the tracking accuracy of IGPS and OGTS exhibited statistically significant differences only for the head in the z direction ( t = 2.21, P < 0.05). Conversely, no statistically significant differences were observed for the head in the remaining directions or for the breast and rectum in the three translational directions ( P > 0.05). The analysis showed that comprehensive translational deviations for the head, breast, and rectum derived from OGTS and IGPS were (0.91±0.62), (1.64±1.30), and (1.52±1.29) mm, respectively, satisfying the requirement that the deviations should be below 2 mm. Conclusions:The OGTS, featuring easy operation and high tracking accuracy, can assist the IGPS in real-time respiratory monitoring during radiotherapy.

Objective:To investigate the necessity and feasibility of the virtual simulation teaching experiment software of the bronchoscopy intelligent navigation-based fiducial marker implantation technology in the clinical application of radiotherapy.Methods:This study developed a 3D virtual operation and interactive system using the Unity3D engine, tools including 3Dmax and Maya, and the SQL database. The scenes in the system were produced using the currently popular next-generation production process. Targeting the priorities and difficulties in the implantation of fiducial markers, the system developed in this study allowed for simulated demonstration and training based on 12 steps and 10 knowledge points. Internal tests and remote evaluation tests were adopted in this system to obtain the test result of each subject. Then, the application value of the system was analyzed based on the test result.Results:As of May 1, 2022, the system had received 2 409 views and 425 test participants, with an test completion rate of 100% and an experiment pass rate of 96.5%. Moreover, this system won unanimous praise from 167 users, primarily including the students majoring in multilevel medical imaging technology and medical imaging science from the Fujian Medical University, as well as the radiotherapy-related staff of this university.Conclusions:The virtual simulation teaching experiment software of the bronchoscopy intelligent navigation-based fiducial marker implantation technology can be applied to the teaching of students and the training of related professionals.

精准放疗已成为现代医学的发展趋势.三维调强放射治疗照射野大小和肿瘤一致,但人体的不自主运动会引起靶区的位置发生改变.为减小患者放疗时由于动态靶区的运动带来的剂量不确定性,常采用补偿技术,包括屏气技术、门控技术、腹部压迫技术、4D-CT技术和实时追踪技术.目前实时追踪技术对肿瘤动态靶区的放射治疗起关键性作用,大多数是借助X射线、超声、磁共振、磁定位等,可作为一种精确的运动管理方法.本文旨在对实时追踪引导动态靶区放射治疗的研究进展作一综述,以期为探寻更精准、无辐射、无创的可用于动态靶区的实时追踪技术提供研究思路.

Background and purpose We aimed to explore the necessity of the external iliac lymph nodes (EIN) along with inguinal nodes (IN) region in clinical target volume (CTV) for rectal carcinomas covering the anal canal region. Materials and methods This research premise enrolled 399 patients who had primary low rectal cancer detected below the peritoneal reflection via magnetic resonance imaging (MRI) and were treated with neoadjuvant radiotherapy (NRT), without elective EIN along with IN irradiation. We stratified the patients into two groups based on whether the lower edge of the rectal tumor extended to the anal canal (P group, n = 109) or not (Rb group, n = 290). Comparison of overall survival (OS), locoregional recurrence-free survival (LRFS), disease-free survival (DFS), as well as distant metastasis-free survival (DMFS) were performed via inverse probability of treatment weighting (IPTW) along with multivariable analyses. We compared the EIN and IN failure rates between the two groups via the Fisher and Gray’s test. Results P group showed a similar adjusted proportion along with five-year cumulative rate of EIN failure compared with the Rb group. The adjusted proportion and five-year cumulative rate of IN failure in the P group was higher in comparison to the Rb group. There were no remarkable differences in the adjusted five-year OS, DFS, DMFS or LRFS between the two groups. Anal canal involvement (ACI) exhibited no effect on OS, LRFS, DFS, or DMFS. Conclusions During NRT for rectal cancer with ACI, it may be possible to exclude the EIN and IN from the CTV.

Objective The present study aimed to investigate the dose differences and radiobiological assessment between Anisotropic Analytical Algorithm (AAA) and Acuros External Beam (AXB) with its 2 calculation models, namely, dose-to-water (AXB-Dw) and dose-to-medium (AXB-Dm), on esophageal carcinoma radiotherapy treatment plans. Materials and methods The AXB-Dw and AXB-Dm plans were generated by recalculating the initial 66 AAA plans using the AXB algorithm with the same monitor units and beam parameters as those in the original plan. The dosimetric and radiobiological assessment parameters were calculated for the planning target volume (PTV) and organs at risk (OARs). The gamma agreement for the PTV and the correlation between it and the volume of the air cavity and bone among the different algorithms were compared simultaneously. The dose discrepancy between the theoretical calculation and treatment planning system (TPS) when switching from AXB-Dm to AXB-Dw was analyzed according to the composition of the structures. Results The PTV dose of AXB-Dm plans was significantly smaller than that of the AAA and AXB-Dw plans (P < .05), except for D 2 . The difference values for AAA vs AXB-Dm (∆ D x,(AAA-AXB,Dm) ) and AXB-Dw vs AXB-Dm (∆ D x,(AXB,Dw-AXB,Dm) ) were 1.94% [1.27%, 2.64%] and 1.95% [1.56%, 2.27%], respectively. For the spinal cord and heart, there were obvious differences between the AAA vs AXB-Dm (spinal cord: 1.15%, heart: 2.89%) and AXB-Dw vs AXB-Dm (spinal cord: 1.88%, heart: 3.25%) plans. For the lung, the differences between AAA vs AXB-Dm and AAA vs AXB-Dw were significantly larger than those of AXB-Dm vs AXB-Dw. Compared to the case of AAA and AXB-Dw, the decrease in biologically effective dose (BED 10 , α β = 10 ) of AXB-Dm due to dose non-uniformity exceeded 6.5%, even for a small σ . The average values of equivalent uniform dose in the AAA, AXB-Dw, and AXB-Dm plans were 52.03±.39 Gy, 52.24 ± .81 Gy, and 51.13 ± .47 Gy, respectively. The tumor control probability (TCP) results for PTV in the AAA, AXB-Dw, and AXB-Dm plans were 62.29 ± 1.57%, 62.82 ± 1.69%, and 58.68±1.88%, respectively. With the 2%/2 mm and 3%/3 mm acceptance criteria, the mean values of Δ γ AAA AXB − Dw , Δ γ AAA AXB − Dm , and Δ γ AXB − Dm AXB − Dw were 87.24, 63.3, and 64.81% vs 97.86, 91.77, and 89.25%, respectively. The dose discrepancy between the theoretical calculation and TPS when switching from AXB-Dm to AXB-Dw was approximately 1.63%. Conclusions The AAA and AXB-Dw algorithms overestimated the radiobiological parameters when the tumor particularly consisted of nonuniform tissues. A relatively small dose difference could cause a significant reduction in the corresponding TCP. Dose distribution algorithms should be carefully chosen by physicists and oncologists to improve tumor control, as well as to optimize OARs protection.

OBJECTIVE:To investigate clinical utility of a new immobilization method in image-guided intensity-modulated radiotherapy (IMRT) for breast cancer patients after radical mastectomy. MATERIALS AND METHODS:Forty patients with breast cancer who underwent radical mastectomy and postoperative IMRT were prospectively enrolled. The patients were randomly and equally divided into two groups using both a carbon-fiber support board and a hollowed-out cervicothoracic thermoplastic mask (Group A) and using only the board (Group B). An iSCOUT image-guided system was used for acquiring and correcting pretreatment setup errors for each treatment fraction. Initial setup errors and residual errors were obtained by aligning iSCOUT images with digitally reconstructed radiograph (DRR) images generated from planning CT. Totally 600 initial and residual errors were compared and analyzed between two groups, and the planning target volume (PTV) margins before and after the image-guided correction were calculated. RESULTS:The initial setup errors of Group A and Group B were (3.14±3.07), (2.21±1.92), (2.45±1.92) mm and (3.14±2.97), (2.94±3.35), (2.80±2.47) mm in the left-right (LAT), superior-inferior (LONG), anterior-posterior (VERT) directions, respectively. The initial errors in Group A were smaller than those in Group B in the LONG direction (P < 0.05). No significant difference was found in the distribution of three initial error ranges (≤3 mm, 3-5 mm and > 5 mm) in each of the three translational directions for the two groups (P > 0.05). The residual errors of Group A and Group B were (1.74±1.03), (1.62±0.92), (1.66±0.91) mm and (1.70±0.97), (1.68±1.18), (1.58±0.98) mm in the three translational directions, respectively. No significant difference was found in the residual errors between two groups (P > 0.05). With the image-guided correction, PTV margins were reduced from 8.01, 5.44, 5.45 mm to 3.54, 2.99, 2.89 mm in three translational directions of Group A, respectively, and from 8.14, 10.89, 6.29 mm to 2.67, 3.64, 2.74 mm in those of Group B, respectively. CONCLUSION:The use of hollowed-out cervicothoracic thermoplastic masks combined with a carbon-fiber support board showed better inter-fraction immobilization than the single use of the board in reducing longitudinal setup errors for breast cancer patients after radical mastectomy during IMRT treatment course, which has potential to reduce setup errors and improve the pretreatment immobilization accuracy for breast cancer IMRT after radical mastectomy.