Assessing quality assurance of multi-leaf collimator using the structural similarity index.

PURPOSE: This study aims to evaluate the viability of utilizing the Structural Similarity Index (SSI*) as an innovative imaging metric for quality assurance (QA) of the multi-leaf collimator (MLC). Additionally, we compared the results obtained through SSI* with those derived from a conventional Gamma index test for three types of Varian machines (Trilogy, Truebeam, and Edge) over a 12-week period of MLC QA in our clinic. METHOD: To assess sensitivity to MLC positioning errors, we designed a 1 cm slit on the reference MLC, subsequently shifted by 0.5-5 mm on the target MLC. For evaluating sensitivity to output error, we irradiated five 25 cm × 25 cm open fields on the portal image with varying Monitor Units (MUs) of 96-100. We compared SSI* and Gamma index tests using three linear accelerator (LINAC) machines: Varian Trilogy, Truebeam, and Edge, with MLC leaf widths of 1, 0.5, and 0.25 mm. Weekly QA included VMAT and static field modes, with Picket fence test images acquired. Mechanical uncertainties related to the LINAC head, electronic portal imaging device (EPID), and MLC during gantry rotation and leaf motion were monitored. RESULTS: The Gamma index test started detecting the MLC shift at a threshold of 4 mm, whereas the SSI* metric showed sensitivity to shifts as small as 2 mm. Moreover, the Gamma index test identified dose changes at 95MUs, indicating a 5% dose difference based on the distance to agreement (DTA)/dose difference (DD) criteria of 1 mm/3%. In contrast, the SSI* metric alerted to dose differences starting from 97MUs, corresponding to a 3% dose difference. The Gamma index test passed all measurements conducted on each machine. However, the SSI* metric rejected all measurements from the Edge and Trilogy machines and two from the Truebeam. CONCLUSIONS: Our findings demonstrate that the SSI* exhibits greater sensitivity than the Gamma index test in detecting MLC positioning errors and dose changes between static and VMAT modes. The SSI* metric outperformed the Gamma index test regarding sensitivity across these parameters.

V4D: Voxel for 4D Novel View Synthesis.

Neural radiance fields have made a remarkable breakthrough in the novel view synthesis task at the 3D static scene. However, for the 4D circumstance (e.g., dynamic scene), the performance of the existing method is still limited by the capacity of the neural network, typically in a multilayer perceptron network (MLP). In this article, we utilize 3D Voxel to model the 4D neural radiance field, short as V4D, where the 3D voxel has two formats. The first one is to regularly model the 3D space and then use the sampled local 3D feature with the time index to model the density field and the texture field by a tiny MLP. The second one is in look-up tables (LUTs) format that is for the pixel-level refinement, where the pseudo-surface produced by the volume rendering is utilized as the guidance information to learn a 2D pixel-level refinement mapping. The proposed LUTs-based refinement module achieves the performance gain with little computational cost and could serve as the plug-and-play module in the novel view synthesis task. Moreover, we propose a more effective conditional positional encoding toward the 4D data that achieves performance gain with negligible computational burdens. Extensive experiments demonstrate that the proposed method achieves state-of-the-art performance at a low computational cost.

Evaluation of intrafraction couch shifts for proton treatment delivery in head-and-neck cancer patients: Toward optimal imaging frequency.

PURPOSE: Treatment planning for head-and-neck (H&N) cancer, in particular oropharynx, nasopharynx, and paranasal sinus cases, at our center requires noncoplanar proton beams due to the complexity of the anatomy and target location. Targeting accuracy for all beams is carefully evaluated by using image guidance before delivering proton beam therapy (PBT). In this study, we analyzed couch shifts to evaluate whether imaging is required before delivering each field with different couch angles. METHODS: After the Institutional Review Board approval, a retrospective analysis was performed on data from 28 H&N patients treated with PBT. Each plan was made with two-to-three noncoplanar and two-to-three coplanar fields. Cone-beam computed tomography and orthogonal kilovoltage (kV) images were acquired for setup and before delivering each field, respectively. The Cartesian (longitudinal, vertical, and lateral) and angular (pitch and roll) shifts for each field were recorded from the treatment summary on the first two fractions and every subsequent fifth fraction. A net magnitude of the three-dimensional (3D) shift in Cartesian coordinates was calculated, and a 3D vector was created from the 6 degrees of freedom coordinates for transforming couch shifts in the system coordinate to the beam's-eye view. RESULTS: A total of 3219 Cartesian and 2146 angular shift values were recorded for 28 patients. Of the Cartesian shifts, 2069 were zero (64.3%), and 1150 (35.7%) were nonzero (range, -7 to 11 mm). Of the angular shifts, 1034 (48.2%) were zero, and 1112 (51.8%) were nonzero (range, -3.0° to 3.2°). For 17 patients, the couch shifts increased toward the end of the treatment course. We also found that patients with higher body mass index (BMI) presented increased net couch shifts (p < 0.001). With BMI < 27, all overall net shift averages were <2 mm, and overall maximum net shifts were <6 mm. CONCLUSIONS: These results confirm the need for orthogonal kV imaging before delivering each field of H&N PBT at our center, where a couch rotation is involved.

Readiness for Radiation Treatment Continuity: Survey on Contingency Plans Against Cyberattacks.

Purpose: Cyberattacks on health care systems have been on the rise over the past 5 years. Formulation and implementation of a robust postattack business continuity plan and/or contingency plan (CP) is essential for minimal disruption to patient care. The level of awareness and planning within the radiation oncology community for cyberattacks is not clear. This study was undertaken to survey and assess cyberattack CP awareness and preparedness. Methods and Materials: A survey instrument comprising 5 questions on awareness and preparedness of cyberattack CPs was e-mailed to 150 radiation oncology departments. Recipients included 105 institutions with residency programs in therapeutic medical physics, as listed by the Commission on Accreditation of Medical Physics Education Program (usually either school-based or large institutional settings), and 45 additional smaller settings within the United States, representing community practices. Results: Forty-three responses were deemed evaluable for analysis. Forty-two percent (18 respondents) of respondents responded that they are well-aware of the concept of a cyberattack CP. A large discrepancy in awareness exists between larger hospitals (LH) that have 5 or more treatment machines and smaller hospitals (SH) that have 4 or fewer, 54% versus 24 % (P < .05). Fifty-eight percent of respondents considered it "essential" to have such a plan in place, and 28% considered it "desirable" to do so but not practical. Nine percent regarded a cyberattack CP as unnecessary. No significant differences in responses were noted among different types or sizes of institutions on this issue. Sixty-two percent of LH responded that they were either preparing or evaluating a CP, compared with only 29% of SH (P = .03). However, no respondents explicitly replied that they already had a CP in place in their practices. Conclusions: The importance of cyberattack preparedness and implementation does not seem to be well-recognized in radiation oncology. Both the awareness and the preparedness of SH are substantially less than those of LH. Specific and ongoing education efforts in parallel with development of appropriate programs are needed to counter the increasingly pervasive and complex threat of cyberattacks.

A study of skin marker alignment using different diamond-shaped light fields for prone breast external-beam radiation therapy.

For breast cancer patients treated in the prone position with tangential fields, a diamond-shaped light field (DSLF) can be used to align with corresponding skin markers for image-guided radiation therapy (IGRT). This study evaluates and compares the benefits of different DSLF setups. Seventy-one patients who underwent daily tangential kilovoltage (kV) IGRT were categorized retrospectively into four groups: (1) DSLF field size (FS) = 10 × 10 cm2 , gantry angle = 90° (right breast)/270° (left breast), with the same isocenter as treatment tangential beams; (2) same as group 1, except DSLF FS = 4 × 4 cm2 ; (3) DSLF FS = 4 × 4-6 × 8 cm2 , gantry angle = tangential treatment beam, off-isocenter so that the DSLF was at the approximate breast center; and (4) No-DSLF. We compared their total setup time (including any DSLF/marker-based alignment and IGRT) and relative kV-based couch shift corrections. For groups 1-3, DSLF-only dose distributions (excluding kV-based correction) were simulated by reversely shifting the couch positions from the computed tomography plans, which were assumed equivalent to the delivered dose when both DSLF and IGRT were used. For patient groups 1-4, the average daily setup time was 2.6, 2.5, 5.0, and 8.3 min, respectively. Their mean and standard deviations of daily kV-based couch shifts were 0.64 ± 0.4, 0.68 ± 0.3, 0.8 ± 0.6, and 1.0 ± 0.6 cm. The average target dose changes after excluding kV-IGRT for groups 1-3 were-0.2%, -0.1%, and +0.4%, respectively, whereas DSLF-1 was most efficient in sparing heart and chest wall, DSLF-2 had lowest lung Dmax ; and DSLF-3 maintained the highest target coverage at the cost of highest OAR dose. In general, the use of DSLF greatly reduces patient setup time and may result in smaller IGRT corrections. If IGRT is limited, different DSLF setups yield different target coverage and OAR dose sparing. Our findings will help DSLF setup optimization in the prone breast treatment setting.

Is a weekly qualitative picket fence test sufficient? A proposed alternate EPID-based weekly MLC QA program.

PURPOSE: Well-designed routine multileaf collimator (MLC) quality assurance (QA) is important to assure external-beam radiation treatment delivery accuracy. This study evaluates the clinical necessity of a comprehensive weekly (C-Weekly) MLC QA program compared to the American Association of Physics in Medicinerecommended weekly picket fence test (PF-Weekly), based on our seven-year experience with weekly MLC QA. METHODS: The C-Weekly MLC QA program used in this study includes 5 tests to analyze: (1) absolute MLC leaf position; (2) interdigitation MLC leaf position; (3) picket fence MLC leaf positions at static gantry angle; (4) minimum leaf-gap setting; and (5) volumetric-modulated arc therapy delivery. A total of 20,226 QA images from 16,855 tests (3,371 tests × 5) for 11 linacs at 5 photon clinical sites from May 2014 to June 2021 were analyzed. Failure mode and effects analysis was performed with 5 failure modes related to the 5 tests. For each failure mode, a risk probability number (RPN) was calculated for a C-Weekly and a PF-Weekly MLC QA program. The probability of occurrence was evaluated from statistical analyses of the C-Weekly MLC QA. RESULTS: The total number of failures for these 16,855 tests was 143 (0.9%): 39 (27.3%) for absolute MLC leaf position, 13 (9.1%) for interdigitation position, 9 (6.3%) for static gantry picket fence, 2 (1.4%) for minimum leaf-gap setting, and 80 (55.9%) for VMAT delivery. RPN scores for PF-Weekly MLC QA ranged from 60 to 192 and from 48 to 96 for C-Weekly MLC QA. CONCLUSION: RPNs for the 5 failure modes of MLC QA tests were quantitatively determined and analyzed. A comprehensive weekly MLC QA is imperative to lower the RPNs of the 5 failure modes to the desired level (<125); those from the PF-Weekly MLC QA program were found to be higher (>125). This supports the clinical necessity for comprehensive weekly MLC QA.

Analysis of genetic characteristics of 436 children with dysplasia and detailed analysis of rare karyotype.

Chromosomal abnormality is one of the important causes of dysplasia in children. However, due to regional and ethnic differences, the reported rates of chromosomal abnormalities in patients with dysplasia vary greatly. Moreover, the clinical manifestations in children with rare chromosomal diseases were heterogeneous. So, we retrospectively analyzed the karyotype results of 436 children with dysplasia and conducted a detailed analysis of rare chromosomal diseases. The results showed that chromosomal abnormalities were present in 181 of 436 cases. Intellectual disability, dysmorphology, congenital malformations, the disorder of sexual development, and short stature were the main five clinical symptoms in children with chromosomal abnormalities. Moreover, 136 cases of Trisomy 21 (Tri21) were detected, of which 130 were standard Tri21, 5 were robertsonian Tri21, and 1 was chimera type. In addition, 16 cases of rare abnormal karyotype, including complex Tri21, complex Turner syndrome, 4p-syndrome, 18q-syndrome, and 5p-syndrome, were also detected. In summary, chromosome abnormality is one of the important causes of dysplasia in children. Furthermore, prenatal screening and diagnosis could play a great significance in preventing dysplasia in children. In addition, the retrospective analysis of rare cases is valuable for clinical diagnosis and risk assessment of recurrence.

Insight into atmospheric deposition and spatial distribution of bioavailable iron in the glaciers of northeastern Tibetan Plateau.

Iron (Fe) is an essential micronutrient in glacial ecosystems and modulates global biogeochemical cycles. To find out the deposition concentration, multiple origins and release form of iron in various glacier areas of central Asia, this study investigated the total Fe (TFe) and dissolved-Fe (dFe, diameter < 0.45 or <0.2 µm) deposition in glaciers and snowpack of northeast Tibetan Plateau, based on snow and meltwater sampling in ablation period of 2014-2017. The composition and concentration of dFe in the samples were measured, and the spatial distribution and temporal variations of dFe in glacial surface snow and meltwater runoff were investigated. Results showed that average TFe and dFe contents exhibited a generally heterogeneous geographic distribution that varied from north to south. The northern locations in eastern Tianshan Mountains (e.g. Miaoergou Glacier) showed the highest TFe and dFe values, followed by Yuzhufeng Glacier of eastern Kunlun Mountains, whereas the Qilian Mountains locations displayed relatively lower TFe and dFe contents spanning a wide range. Based on the good correlation between TFe and dFe, we infer that aeolian dust and anthropogenic aerosols, and their chemical interactions are likely the important origins for dFe deposition. In meltwater runoff the peak values of dFe release flux appeared in July, with maximum appeared earlier (the early of July) than TFe (the end of July). Moreover, the annual dFe release flux from Laohugou glacier terminus meltwater runoff is estimated to be 1740 kg yr-1 (with 9256 kg yr-1 for TFe), and meltwater showed higher mean concentration of dFe than that of glacier snowpack. We also provided a conceptual framework showing the multiple origins and transport dynamics of dissolved Fe along the atmosphere-glacier-meltwater runoff path. Compared to Fe release in other global glacier/ice-sheet, the TP glacier is an important potential dFe reservoir and may have a profound effect on regional downstream ecosystem through Fe biochemistry cycle.

Semi-Supervised Segmentation of Radiation-Induced Pulmonary Fibrosis From Lung CT Scans With Multi-Scale Guided Dense Attention.

Computed Tomography (CT) plays an important role in monitoring radiation-induced Pulmonary Fibrosis (PF), where accurate segmentation of the PF lesions is highly desired for diagnosis and treatment follow-up. However, the task is challenged by ambiguous boundary, irregular shape, various position and size of the lesions, as well as the difficulty in acquiring a large set of annotated volumetric images for training. To overcome these problems, we propose a novel convolutional neural network called PF-Net and incorporate it into a semi-supervised learning framework based on Iterative Confidence-based Refinement And Weighting of pseudo Labels (I-CRAWL). Our PF-Net combines 2D and 3D convolutions to deal with CT volumes with large inter-slice spacing, and uses multi-scale guided dense attention to segment complex PF lesions. For semi-supervised learning, our I-CRAWL employs pixel-level uncertainty-based confidence-aware refinement to improve the accuracy of pseudo labels of unannotated images, and uses image-level uncertainty for confidence-based image weighting to suppress low-quality pseudo labels in an iterative training process. Extensive experiments with CT scans of Rhesus Macaques with radiation-induced PF showed that: 1) PF-Net achieved higher segmentation accuracy than existing 2D, 3D and 2.5D neural networks, and 2) I-CRAWL outperformed state-of-the-art semi-supervised learning methods for the PF lesion segmentation task. Our method has a potential to improve the diagnosis of PF and clinical assessment of side effects of radiotherapy for lung cancers.

Gastrointestinal bleeding with Klippel-Trenaunay syndrome: a case report.

BACKGROUND: Gastrointestinal bleeding caused by gastrointestinal tract involvement in patients with Klippel-Trenaunay syndrome (KTS) is extremely rare and often overlooked. Case presentation A 9-year-old girl who presented with chronic gastrointestinal bleeding was admitted to our hospital. Laboratory examinations revealed microcytic hypochromic anemia and a positive fecal occult blood test. Computed tomography (CT) of the lower limbs combined with physical examination confirmed KTS. The pelvic CT showed concentric thickening of the sigmoid colon and rectum, with progressive enhancement after the administration of a contrast agent. Colonoscopy demonstrated vascular malformations of the sigmoid colon and rectum. The patient was finally diagnosed with KTS with gastrointestinal tract involvement. The patient improved after receiving conservative treatment. CONCLUSIONS: A suspicion of gastrointestinal tract involvement as an etiology for gastrointestinal bleeding should not be overlooked in patients with KTS. Endoscopy and imaging modalities can synergistically help diagnose this condition.

Comparison of the dosimetric accuracy of proton breast treatment plans delivered with SGRT and CBCT setups.

PURPOSE: To compare the dosimetric accuracy of surface-guided radiation therapy (SGRT) and cone-beam computed tomography (CBCT) setups in proton breast treatment plans. METHODS: Data from 30 patients were retrospectively analyzed in this IRB-approved study. Patients were prescribed 4256-5040 cGy in 16-28 fractions. CBCT and AlignRT (SGRT; Vision RT Ltd.) were used for treatment setup during the first three fractions, then daily AlignRT and weekly CBCT thereafter. Each patient underwent a quality assurance CT (QA-CT) scan midway through the treatment course to assess anatomical and dosimetric changes. To emulate the SGRT and CBCT setups during treatment, the planning CT and QA-CT images were registered in two ways: (1) by registering the volume within the CTs covered by the CBCT field of view; and (2) by contouring and registering the surface surveyed by the AlignRT system. The original plan was copied onto these two datasets and the dose was recalculated. The clinical treatment volume (CTV): V95% ; heart: V25Gy , V15Gy , and mean dose; and ipsilateral lung: V20Gy , V10Gy , and V5Gy , were recorded. Multi and univariate analyses of variance were performed to assess the differences in dose metric values between the planning CT and the SGRT and CBCT setups. RESULTS: The CTV V95% and lung V20Gy , V10Gy , and V5Gy dose metrics were all significantly (p < 0.01) lower on the QA-CT in both the CBCT and SGRT setup. The differences were not clinically significant and were, on average, 1.4-1.6% lower for CTV V95% and 1.8%-6.0% lower for the lung dose metrics. When comparing the lung and CTV V95% dose metrics between the CBCT and SGRT setups, no significant difference was observed. This indicates that the SGRT setup provides similar dosimetric accuracy as CBCT. CONCLUSION: This study supports the daily use of SGRT systems for the accurate dose delivery of proton breast treatment plans.

Conformal Radiation Therapy in Patients With Cardiovascular Implantable Electronic Devices: Proposed Practical Implementation of the 2019 American Association of Physicists in Medicine Task Group No. 203 Risk-Stratified Interrogation Schedule.

PURPOSE: Radiation therapy (RT) in patients with cardiac implantable electronic devices (CIED) carries a risk of device malfunction from radiation exposure. We sought to evaluate the incidence of CIED malfunction in a cohort of patients treated with modern RT techniques. METHODS AND MATERIALS: A retrospective analysis of 193 CIED patients treated with RT between 2000 and 2018 was conducted. All patients underwent pre-, intra-, and post-RT CIED interrogations. Patient demographics, CIED details, RT details, including total dose, modality, treatment site, CIED distance from RT field, treatment planning system maximum dose and in vivo dose estimates, and CIED malfunction data were analyzed. RESULTS: CIEDs in use were mainly pacemakers (single-chamber 10%, dual-chamber 49%) and defibrillators (35%). Patients received a median RT dose of 50 Gy (range, 7-80 Gy), treated with 3-dimensional CRT (47%), intensity modulated RT/volumetric modulated arc therapy (38%), and stereotactic body radiation therapy (10%). Neutron producing energies were used in 13% of the treatments. A strong correlation was noted between treatment planning system estimated maximum dose and in vivo estimated CIED dose when the CIED distance from the treatment field was >3 cm. However, in vivo measurements provide a lower estimated absorbed dose for CIED devices <3 cm from the RT field. During a median follow-up of 24 months (range, 7-64 months), 2 adverse CIED-related events were recorded: a spontaneous defibrillator discharge and a pacemaker malfunction subsequently causing ventricular tachycardia. Both patients received stereotactic body radiation therapy to the thorax, with CIED dose of 5 and 19.2 cGy, respectively. Both events occurred 2 years posttreatment without any intra- or post-RT CIED interrogations changes noted. CONCLUSIONS: In this series of patients treated with modern RT techniques, we observed a CIED malfunction rate of 1.04%. These low event rates establish the safety of delivering modern RT in CIED patients with the possibility of reducing the burden of intra- and posttreatment CIED monitoring.

Toward automation of initial chart check for photon/electron EBRT: the clinical implementation of new AAPM task group reports and automation techniques.

PURPOSE: The recently published AAPM TG-275 and the public review version of TG-315 list new recommendations for comprehensive and minimum physics initial chart checks, respectively. This article addresses the potential development and benefit of initial chart check automation when these recommendations are implemented for clinical photon/electron EBRT. METHODS: Eight board-certified physicists with 2-20 years of clinical experience performed initial chart checks using checklists from TG-275 and TG-315. Manual check times were estimated for three types of plans (IMRT/VMAT, 3D, and 2D) and for prostate, whole pelvis, lung, breast, head and neck, and brain cancers. An expert development team of three physicists re-evaluated the automation feasibility of TG-275 checklist based on their experience of developing and implementing the in-house and the commercial automation tools in our institution. Three levels of initial chart check automation were simulated: (1) Auto_UMMS_tool (which consists of in-house program and commercially available software); (2) Auto_TG275 (with full and partial automation as indicated in TG-275); and (3) Auto_UMMS_exp (with full and partial automation as determined by our experts' re-evaluation). RESULTS: With no automation of initial chart checks, the ranges of manual check times were 29-56 min (full TG-315 list) and 102-163 min (full TG-275 list), which varied significantly with physicists but varied little at different tumor sites. The 69 of 71 checks which were considered as "not fully automated" in TG-275 were re-evaluated with more automation feasibility. Compared to no automation, the higher levels of automation yielded a great reduction in both manual check times (by 44%-98%) and potentially residual detectable errors (by 15-85%). CONCLUSION: The initial chart check automation greatly improves the practicality and efficiency of implementing the new TG recommendations. Revisiting the TG reports with new technology/practice updates may help develop and utilize more automation clinically.

Reproducibility of a novel, vacuum-assisted immobilization for breast stereotactic radiotherapy.

A novel, breast-specific stereotactic radiotherapy device has been developed for delivery of highly conformal, accelerated partial breast irradiation. This device employs a unique, vacuum-assisted, breast cup immobilization system that applies a gentle, negative pressure to the target breast with the patient in the prone position. A device-specific patient loader is utilized for simulation scanning and device docking. Prior to clinical activation, a prospective protocol enrolled 25 patients who had been or were to be treated with breast conservation surgery and adjuvant radiotherapy for localized breast cancer. The patients underwent breast cup placement and two separate CT simulation scans. Surgical clips within the breast were mapped and positions measured against the device's integrated stereotactic fiducial/coordinate system to confirm reproducible and durable immobilization during the simulation, treatment planning, and delivery process for the device. Of the enrolled 25 patients, 16 were deemed eligible for analysis. Seventy-three clips (median, 4; mean, 4.6; range, 1-8 per patient) were mapped in these selected patients on both the first and second CT scans. X, Y, and Z coordinates were determined for the center point of each clip. Length of vector change in position was determined for each clip between the two scans. The mean displacement of implanted clips was 1.90 mm (median, 1.47 mm; range, 0.44-6.52 mm) (95% CI, 1.6-2.20 mm). Additional analyses stratified clips by position within the breast and depth into the immobilization cup. Overall, this effort validated the clinically utilized 3-mm planning target volume margin for accurate, reliable, and precise employment of the device.

Immune checkpoint inhibition in patients treated with stereotactic radiation for brain metastases.

PURPOSE: Stereotactic radiation therapy (SRT) and immune checkpoint inhibitors (ICI) may act synergistically to improve treatment outcomes but may also increase the risk of symptomatic radiation necrosis (RN). The objective of this study was to compare outcomes for patients undergoing SRT with and without concurrent ICI. METHODS AND MATERIALS: Patients treated for BMs with single or multi-fraction SRT were retrospectively reviewed. Concurrent ICI with SRT (SRT-ICI) was defined as administration within 3 months of SRT. Local control (LC), radiation necrosis (RN) risk and distant brain failure (DBF) were estimated by the Kaplan-Meier method and compared between groups using the log-rank test. Wilcoxon rank sum and Chi-square tests were used to compare covariates. Multivariate cox regression analysis (MVA) was performed. RESULTS: One hundred seventy-nine patients treated with SRT for 385 brain lesions were included; 36 patients with 99 lesions received SRT-ICI. Median follow up was 10.3 months (SRT alone) and 7.7 months (SRT- ICI) (p = 0.08). Lesions treated with SRT-ICI were more commonly squamous histology (17% vs 8%) melanoma (20% vs 2%) or renal cell carcinoma (8% vs 6%), (p < 0.001). Non-small cell lung cancer (NSCLC) compromised 60% of patients receiving ICI (n = 59). Lesions treated with SRT-ICI had significantly improved 1-year local control compared to SRT alone (98 and 89.5%, respectively (p = 0.0078). On subset analysis of NSCLC patients alone, ICI was also associated with improved 1 year local control (100% vs. 90.1%) (p = 0.018). On MVA, only tumor size ≤2 cm was significantly associated with LC (HR 0.38, p = 0.02), whereas the HR for concurrent ICI with SRS was 0.26 (p = 0.08). One year DBF (41% vs. 53%; p = 0.21), OS (58% vs. 56%; p = 0.79) and RN incidence (7% vs. 4%; p = 0.25) were similar for SRT alone versus SRT-ICI, for the population as a whole and those patients with NSCLC. CONCLUSION: These results suggest SRT-ICI may improve local control of brain metastases and is not associated with an increased risk of symptomatic radiation necrosis in a cohort of predominantly NSCLC patients. Larger, prospective studies are necessary to validate these findings and better elucidate the impact of SRT-ICI on other disease outcomes.

A multi-center analysis of single-fraction versus hypofractionated stereotactic radiosurgery for the treatment of brain metastasis.

BACKGROUND: Hypofractionated-SRS (HF-SRS) may allow for improved local control and a reduced risk of radiation necrosis compared to single-fraction-SRS (SF-SRS). However, data comparing these two treatment approaches are limited. The purpose of this study was to compare clinical outcomes between SF-SRS versus HF-SRS across our multi-center academic network. METHODS: Patients treated with SF-SRS or HF-SRS for brain metastasis from 2013 to 2018 across 5 radiation oncology centers were retrospectively reviewed. SF-SRS dosing was standardized, whereas HF-SRS dosing regimens were variable. The co-primary endpoints of local control and radiation necrosis were estimated using the Kaplan Meier method. Multivariate analysis using Cox proportional hazards modeling was performed to evaluate the impact of select independent variables on the outcomes of interest. Propensity score adjustments were used to reduce the effects confounding variables. To assess dose response for HF-SRS, Biologic Effective Dose (BED) assuming an α/ß of 10 (BED10) was used as a surrogate for total dose. RESULTS: One-hundred and fifty six patients with 335 brain metastasis treated with SF-SRS (n = 222 lesions) or HF-SRS (n = 113 lesions) were included. Prior whole brain radiation was given in 33% (n = 74) and 34% (n = 38) of lesions treated with SF-SRS and HF-SRS, respectively (p = 0.30). After a median follow up time of 12 months in each cohort, the adjusted 1-year rate of local control and incidence of radiation necrosis was 91% (95% CI 86-96%) and 85% (95% CI 75-95%) (p = 0.26) and 10% (95% CI 5-15%) and 7% (95% CI 0.1-14%) (p = 0.73) for SF-SRS and HF-SRS, respectively. For lesions > 2 cm, the adjusted 1 year local control was 97% (95% CI 84-100%) for SF-SRS and 64% (95% CI 43-85%) for HF-SRS (p = 0.06). On multivariate analysis, SRS fractionation was not associated with local control and only size ≤2 cm was associated with a decreased risk of developing radiation necrosis (HR 0.21; 95% CI 0.07-0.58, p < 0.01). For HF-SRS, 1 year local control was 100% for lesions treated with a BED10 ≥ 50 compared to 77% (95% CI 65-88%) for lesions that received a BED10 < 50 (p = 0.09). CONCLUSIONS: In this comparison study of dose fractionation for the treatment of brain metastases, there was no difference in local control or radiation necrosis between HF-SRS and SF-SRS. For HF-SRS, a BED10 ≥ 50 may improve local control.

Machine learning for radiation outcome modeling and prediction.

AIMS: This review paper intends to summarize the application of machine learning to radiotherapy outcome modeling based on structured and un-structured radiation oncology datasets. MATERIALS AND METHODS: The most appropriate machine learning approaches for structured datasets in terms of accuracy and interpretability are identified. For un-structured datasets, deep learning algorithms are explored and a critical view of the use of these approaches in radiation oncology is also provided. CONCLUSIONS: We discuss the challenges in radiotherapy outcome prediction, and suggest to improve radiation outcome modeling by developing appropriate machine learning approaches where both accuracy and interpretability are taken into account.

[Lung sounds can be used as an indicator for assessing severity of chronic obstructive pulmonary disease at the initial diagnosis].

OBJECTIVE: To assess the value of pulmonary auscultation for evaluating the severity of chronic obstructive pulmonary disease (COPD) at the initial diagnosis. METHODS: The patients with newly diagnosed COPD in our hospital between May, 2016 and May, 2019 were enrolled in this study. According to the findings of pulmonary auscultation, the lung sounds were classified into 5 groups: normal breathing sounds, weakened breathing sounds, weakened breathing sounds with wheezing, obviously weakened breathing sounds, and obviously weakened breathing sounds with wheezing. The pulmonary function of the patients was graded according to GOLD guidelines, and the differential diagnosis of COPD from asthmatic asthma COPD overlap (ACO) was made based on the GOLD guidelines and the European Respiratory Criteria. RESULTS: A total of 1046 newly diagnosed COPD patients were enrolled, including 949 male and 97 female patients with a mean age of 62.6± 8.71. According to the GOLD criteria, 88.1% of the patients were identified to have moderate or above COPD, 50.0% to have severe or above COPD; a further diagnosis of ACO was made in 347 (33.2%) of the patients. ANOVA analysis showed significant differences in disease course, FEV1, FEV1%, FEV1/FVC, FVC, FVC% and mMRC among the 5 auscultation groups (P < 0.001), but FENO did not differ significantly among them (P=0.097). The percentage of patients with wheezing in auscultation was significantly greater in ACO group than in COPD group (P < 0.001). Spearman correlation analysis showed that lung sounds was significantly correlated with disease severity, FEV1, FEV1%, FVC and FVC% of the patients (P < 0.001); Multiple linear regression analysis showed that a longer disease course, a history of smoking and lung sounds were all associated with poorer lung functions and a greater disease severity. CONCLUSIONS: Lung sounds can be used as an indicator for assessing the severity of COPD at the initial diagnosis.

A practical cyberattack contingency plan for radiation oncology.

PURPOSE: This article presents a solution for continuing radiation therapy without interruption in the event of a cyberattack to the radiation oncology information systems (ROIS). This process could be easily deployed to any radiation oncology practice, with little clinical overhead or burden. METHODS AND MATERIALS: The solution automatically retrieves all essential information from the clinical ROIS for each under-treatment patient and periodically (e.g., daily) saves these data to a dedicated secure server for recovery. In the event that the clinical ROIS is not functioning as a result of a cyberattack, this essential information is used to build a new secondary ROIS server to continue radiotherapy treatments until the main ROIS is recovered. Once the cyberattack threat is cleared, the clinical ROIS server is rebuilt from the institution's enterprise backup. The newly accumulated treatment information for each patient is then exported from the secondary ROIS to bring the clinical ROIS up to date. RESULTS: The Department of Radiation Oncology at the University of Maryland Medical System implemented this solution for clinical use with the Varian ARIA ROIS in the management of ~250 daily radiotherapy treatments, inclusive of a proton center. This solution was determined to be a feasible and affordable business continuity plan for the radiation oncology practice by minimizing radiation treatment downtime to a couple of hours in a simulated cyberattack drill. CONCLUSIONS: The proposed solution can achieve continuation of radiation therapy treatment without treatment breaks in the event of a cyberattack. It also provides cushion time for radiation oncology departments to rebuild their clinical ROIS systems from the enterprise data backup.