Fractionation Scheme Research Articles

Development and validation of a lung biological equivalent dose-based multiregional radiomic model for predicting symptomatic radiation pneumonitis after SBRT in lung cancer patients

BackgroundThis study aimed to develop and validate a multiregional radiomic-based composite model to predict symptomatic radiation pneumonitis (SRP) in non-small cell lung cancer (NSCLC) patients treated with stereotactic body radiation therapy (SBRT).Materials and methods189 patients from two institutions were allocated into training, internal validation and external testing cohorts. The associations between the SRP and clinic-dosimetric factors were analyzed using univariate and multivariate regression. Radiomics features were extracted from seven discrete and three composite regions of interest (ROIs), including anatomical, physical dosimetry, and biologically equivalent dose (BED) dimensions. Correlation filters and Lasso regularization were applied for feature selection and five machine learning algorithms were utilized to construct radiomic models. Multiregional radiomic models integrating features from various regions were developed and undergone performance test in comparison with single-region models. Ultimately, three models—a radiomic model, a dosimetric model, and a combined model—were developed and evaluated using receiver operating characteristic (ROC) curve, model calibration, and decision curve analysis.ResultsVBED70 (α/β = 3) of the nontarget lung volume was identified as an independent dosimetric risk factor. The multiregional radiomic models eclipsed their single-regional counterparts, notably with the incorporation of BED-based dimensions, achieving an area under the curve (AUC) of 0.816 [95% CI: 0.694–0.938]. The best predictive model for SRP was the combined model, which integrated the multiregional radiomic features with dosimetric parameters [AUC=0.828, 95% CI: 0.701–0.956]. The calibration and decision curves indicated good predictive accuracy and clinical benefit, respectively.ConclusionsThe combined model improves SRP prediction across various SBRT fractionation schemes, which warrants further validation and optimization using larger-scale retrospective data and in prospective trials.

Management of treatment-naïve Koos grade IV vestibular schwannomas using hypofractionated Gamma Knife radiosurgery: a retrospective single-institution study.

While single-fraction Gamma Knife radiosurgery (GKRS) has shown efficacy in managing vestibular schwannomas (VSs), some concerns have been raised regarding its safety profile, particularly in the context of hearing preservation. Hypofractionation has emerged as a promising approach to improving the safety profile. This retrospective, single-institution study evaluated patient outcomes following hypofractionated GKRS (hf-GKRS) for treatment-naïve Koos grade IV VSs. This study involved all patients with treatment-naïve Koos grade IV VSs who underwent hf-GKRS (3 or 5 fractions) between January 2018 and June 2021, with a follow-up period of ≥ 36 months. The outcomes assessed included local control (LC), the preservation of serviceable hearing as determined by the Gardner-Robertson hearing scale, and procedure-related adverse events. Twenty-nine patients (14 females, median age 49 years) were treated with three different dose regimens: 21 patients received 18Gy in 3 fractions, 6 patients received 20Gy in 5 fractions, and 2 patients received 25Gy in 5 fractions. Prior to treatment, 13 patients (44.8%) had serviceable hearing, one (3.4%) presented with facial palsy, and four (13.8%) had trigeminal nerve dysfunction. The median tumor volume was 10.8 cm3. During a median radiological follow-up period of 60 months (range, 36-78 months), LC was achieved in all patients. All 13 patients retained serviceable hearing at the last follow-up. Trigeminal nerve dysfunction occurred in one patient (3.4%), while another patient (3.4%) needed a ventriculoperitoneal shunt insertion due to new-onset hydrocephalus. No new-onset facial palsy was observed. hf-GKRS shows promise as an effective and safe primary or adjuvant treatment for Koos grade IV VSs with non-life-threatening or debilitating symptoms. Future studies with larger cohorts and extended follow-up periods are needed to validate these findings and to refine fractionation schemes.

Investigating the complementarity of thermal and physical soil organic carbon fractions

Abstract. Partitioning soil organic carbon (SOC) in fractions with different biogeochemical stability is useful to better understand and predict SOC dynamics and provide information related to soil health. Multiple SOC partition schemes exist, but few of them can be implemented on large sample sets and therefore be considered relevant options for soil monitoring. The well-established particulate organic carbon (POC) vs. mineral-associated organic carbon (MAOC) physical fractionation scheme is one of them. Introduced more recently, Rock-Eval® thermal analysis coupled with the PARTYSOC machine learning model can also fractionate SOC into active (Ca) and stable SOC (Cs). A debate is emerging as to which of these methods should be recommended for soil monitoring. To investigate the complementarity or redundancy of these two fractionation schemes, we compared the quantity and environmental drivers of SOC fractions obtained on an unprecedented dataset from mainland France. About 2000 topsoil samples were recovered all over the country, presenting contrasting land cover and pedoclimatic characteristics, and analysed. We found that the environmental drivers of the fractions were clearly different, the more stable MAOC and Cs fractions being mainly driven by soil characteristics, whereas land cover and climate had a greater influence on more labile POC and Ca fractions. The stable and labile SOC fractions provided by the two methods strongly differed in quantity (MAOC/Cs=1.88 ± 0.46 and POC/Ca=0.36 ± 0.17; n=843) and drivers, suggesting that they correspond to fractions with different biogeochemical stability. We argue that, at this stage, both methods can be seen as complementary and potentially relevant for soil monitoring. As future developments, we recommend comparing how they relate to indicators of soil health such as nutrient availability or soil structural stability and how their measurements can improve the accuracy of SOC dynamics models.

The Evolving Role of Neoadjuvant Radiation Therapy in Pancreatic Adenocarcinoma.

Pancreatic ductal adenocarcinoma (PDAC) is one of the deadliest cancers. Surgical resection is the most reliable chance for cure, but high rates of positive margins and local failure persist. Neoadjuvant therapies (NAT), including chemotherapy and radiation therapy (RT), are being explored to improve surgical outcomes, particularly in borderline resectable (BRPC) and locally advanced pancreatic cancer (LAPC). This review aims to summarize the current landscape and future directions for neoadjuvant RT (NART) in PDAC. The review includes a detailed analysis of past and ongoing clinical trials investigating various NART approaches in PDAC, with an emphasis on different RT techniques, fractionation schemes, and their integration into multimodal treatment strategies. Early evidence suggests that NART can improve resection margins and local control. However, recent trials, including the Alliance A021501 and LAP-07 trials, have failed to demonstrate significant survival benefits with the addition of RT to NAT. Nevertheless, nuances in trial design and execution continue to keep the question of NART open. Newer approaches, such as stereotactic magnetic resonance-guided adaptive radiation therapy (SMART), show promise in improving local control and survival, but further phase 3 trials are needed. While NART has shown potential in improving local control in PDAC, its impact on overall survival remains unclear. Ongoing trials, particularly those utilizing advanced techniques like SMART, are critical in defining the role of RT in the neoadjuvant setting for PDAC. Collaboration across multidisciplinary teams is essential to optimize treatment strategies and trial outcomes.

Effectiveness of palliative hemostatic radiotherapy for hemoptysis: a prospective single-arm observation study.

Palliative radiotherapy (RT) is commonly used for malignancy-associated hemoptysis. This study aims to determine RT control probability, durability, and influencing factors. This single-institution prospective observational study included patients ≥18 years old with any lung malignancy and active hemoptysis. Hemoptysis severity was captured and monitored via Common Terminology Criteria for Adverse Events (CTCAE) and an in-house developed Patient-Reported Outcome Measure (PROM) tool. Patients were interviewed at enrollment, 2 weeks, 3 months, and 6 months post-treatment. Descriptive statistics, the Kaplan-Meier (KM) method, the Wilcoxon signed-rank test, and Cox regression models were used. From April 2016 to November 2018, 41 patients were enrolled. One patient withdrew consent and was excluded. The median age was 68 years. Most patients were male (67%) with stage 4 (87.5%), lung primary (85%) disease, and Eastern Cooperative Oncology Group (ECOG) performance status ≥2 (55%). The most common fractionation scheme (72.5%) was 2,000 cGy in 5 fractions. Eight patients (20%) passed away before 2-week assessment. Median follow-up was 6.1 months (range, 0.9-6.2 months). The 6-month overall survival (OS) rate was 26% [95% confidence interval (CI): 13-41%]. The 6-month bleeding-related survival (BRS) was 95% (95% CI: 80-99%), and the 6-month freedom from hemoptysis rate was 37% (95% CI: 18-57%). No patient received re-irradiation for their hemoptysis. On univariate analysis, ECOG status (P=0.01) and prior radiation (P=0.006) were strongly associated with freedom from hemoptysis survival. Hemostatic RT remains an effective modality for controlling hemoptysis. The short interval high mortality rate post-RT challenges whether fractionated palliative RT should be used for this patient population. Conducting a large clinical trial with a hemoptysis PROM tool is necessary to identify hemostatic durability and influencing factors properly.

Gel dosimetry: An overview of dosimetry systems and read out methods

Gel dosimetry has emerged over the past three decades in response to a growing need in high-precision radiotherapy to assess, in three dimensions, the absorbed radiation dose, as would be administered in cancer patients.Radiation-induced reaction mechanisms are dependent on the class of gel dosimeter, with four classes emerging as primary dosimeters for use in radiation therapy dose verification: (i) Fricke gel dosimeters contain a Fricke solution consisting of ammonium iron (II) sulfate in an acidic solution of sulfuric acid. In Fricke systems an oxidation of ferrous ions results in a change in the nuclear magnetic resonance (NMR) relaxation rate, which enables reading out Fricke gel dosimeters by use of MRI. The radiation-induced oxidation in Fricke gel dosimeters can also be visualized by adding a redox indicator. (ii) Polymer gel dosimeters exploit the radiation induced polymerization reaction of vinyl monomers and are predominantly read out by quantitative MRI or X-ray CT. (iii) Radiochromic dosimeters do not demonstrate a significant radiation-induced change in NMR properties but can be scanned by use of optical scanners (optical CT). In contrast to Fricke gel dosimeters, radiochromic gel dosimeters do not rely on the oxidation of a metal ion but exhibit a color change upon radiation. (iv) Radiofluorogenic dosimeters become fluorescent when exposed to ionizing radiation and can be read out with a planar scanning light beam.Likewise, the imaging modality used to extract quantitative dose information depends on the class of dosimeter being used, and three primary imaging modalities have emerged in this context: quantitative MRI, x-ray CT, and optical CT imaging. The accuracy and precision of the dose information extracted from gel dosimetry systems depends on both the dosimetric properties of the gel dosimeters and the readout technique, and the optimal readout method depends on the gel dosimeter response.Despite remaining an active field of research and illustrations of the application of gel dosimetry for the validation of clinical dose distributions, the utilization of gel dosimetry as a routine clinical dosimeter has been rather limited. However, with the introduction of new radiotherapy techniques that focus on organ motion compensation, new fractionation schemes, and extreme dose rates, the need for 3D radiation dosimetry is apparent. Even with the need for 3D dosimetry being apparent, gel dosimetry faces continued challenges in areas regarding the extraction of reproducible, accurate, and precise dose information.This review paper focuses on an introduction to gel dosimeter classes; a detailed examination of the three readout techniques with emphasis on the achievable accuracy, precision, and optimization of readout parameters; an outlook on future applications in emerging new radiotherapy techniques. We note that the introduction of theragnostic hybrid MRI-Linacs that combine an MRI-scanner and a clinical linear accelerator create new opportunities for inline polymer gel dosimetry. Likewise, the use of cone beam CT on linear accelerators opens up the possibility to read out gel dosimeters on the linac. Multiple optical CT designs have shown that optical CT gel dosimetry is eminently capable of providing high quality dosimetric information from clinically relevant treatment regimes. As a result, gel dosimetry provides exciting opportunities for 3D radiation dosimetry that were not available even a few years ago. The unique feature set of a properly executed gel dosimetry workflow allows for the extraction of dosimetric information, in 3D, that is not possible with any other dosimetry system and hence gel dosimetry provides exciting opportunities for clinical and research work in the area of radiation dose measurement.

Hybrid ultra-high and conventional dose rate treatments with electrons and photons for the clinical transfer of FLASH-RT to deep-seated targets: A treatment planning study

PurposeThis study explores the dosimetric feasibility and plan quality of hybrid ultra-high dose rate (UHDR) electron and conventional dose rate (CDR) photon (HUC) radiotherapy for treating deep-seated tumours with FLASH-RT. MethodsHUC treatment planning was conducted optimizing a broad UHDR electron beam (between 20–250 MeV) combined with a CDR VMAT for a glioblastoma, a pancreatic cancer, and a prostate cancer case. HUC plans were based on clinical prescription and fractionation schemes and compared against clinically delivered plans. Considering a HUC boost treatment for the glioblastoma consisting of a 15-Gy-single-fraction UHDR electron boost supplemented with VMAT, two scenarios for FLASH sparing were assessed using FLASH-modifying-factor-weighted doses. ResultsFor all three patient cases, HUC treatment plans demonstrated comparable dosimetric quality to clinical plans, with similar PTV coverage (V95% within 0.5 %), homogeneity, and critical OAR-sparing. At the same time, HUC plans delivered a substantial portion of the dose to the PTV (Dmedian of 50–69 %) and surrounding tissues at UHDR. For the HUC boost treatment of the glioblastoma, the first FLASH sparing scenario showed a moderate FLASH sparing magnitude (10 % for D2%,PTV) for the 15-Gy UHDR electron boost, while the second scenario indicated a more substantial sparing of brain tissues inside and outside the PTV (32 % for D2%,PTV, 31 % for D2%,Brain). ConclusionsFrom a planning perspective, HUC treatments represent a feasible approach for delivering dosimetrically conformal UHDR treatments, potentially mitigating technical challenges associated with delivering conformal FLASH-RT for deep-seated tumours. While further research is needed to optimize HUC fractionation and delivery schemes for specific patient cohorts, HUC treatments offer a promising avenue for the clinical transfer of FLASH-RT.

Stereotactic body radiotherapy for spinal oligometastases: a survey on patterns of practice on behalf of the Italian Association of Clinical Oncology and Radiotherapy (AIRO).

The Study Group for the Biology and Treatment of the OligoMetastatic Disease on behalf of the Italian Association of Radiotherapy and Clinical Oncology (AIRO) has conducted a national survey with the aim to depict the current patterns of practice of stereotactic body radiotherapy (SBRT) for spinal oligometastases. The Surveymonkey platform was used to send a 28-items questionnaire focused on demographic, clinical and technical aspects related to SBRT for spinal oligometastases. All the AIRO members were invited to fill the questionnaire. Data were then centralized to a single center for analysis and interpretation. 53 radiation oncologists from 47 centers fulfilled the survey. A complete agreement was observed in proposing SBRT for spinal oligometastases, with the majority considering up to 3 concurrent spine oligometastases feasible for SBRT (73.5%), regardless of spine site (70%), vertebral segment (85%) and morphological features of the lesion (71.7%). Regarding dose prescription, fractionated regimens resulted as the preferred option, either in 3 (58.4%) or five sessions (34%), with a substantial agreement in applying a PTV-margin larger than 1mm (almost 90% of participants), and ideally using both MRI and PET imaging to improve target volume and organs-at-risk delineation (67.9%). This national italian survey illustrates the patterns of practice and the main issues for the indication of SBRT for spinal oligometastases. A substantial agreement in the numerical cut-off and vertebral segment involved for SBRT indication was reported, with a slight heterogeneity in terms of dose prescription and fractionation schemes.

Randomised controlled trials on radiation dose fractionation in breast cancer: systematic review and meta-analysis with emphasis on side effects and cosmesis

ObjectiveTo provide a comprehensive assessment of various fractionation schemes in radiation therapy for breast cancer, with a focus on side effects, cosmesis, quality of life, risks of recurrence, and survival...

Complex of Defense Polypeptides of Wheatgrass (Elytrigia elongata) Associated with Plant Immunity to Biotic and Abiotic Stress Factors.

Plant defense polypeptides play a crucial role in providing plants with constitutive immunity against various biotic and abiotic stressors. In this study, we explored a complex of proteins from wheatgrass (Elytrigia elongata) spikelets to estimate their role in the plant's tolerance to various environmental factors. The current research shows that in vitro protein extracts from E. elongata spikelets possess antifungal activity against certain Fusarium species, which are specific cereal pathogens, at concentrations of 1-2 mg/mL. In this study, we reproduced these antifungal activities using a 4 mg/mL extract in artificial fungal infection experiments on wheat grain (Triticum aestivum) under controlled laboratory conditions. Furthermore, the tested extract demonstrated a protective effect on Saccharomyces cerevisiae exposed to hyper-salinity stress at a concentration of 2 mg/mL. A combined scheme of fractionation and structural identification was applied for the estimation of the diversity of defense polypeptides. Defensins, lipid-transfer proteins, hydrolase inhibitors (cereal bifunctional trypsin/alpha-amylase inhibitors from a Bowman-Birk trypsin inhibitor), and high-molecular-weight disease resistance proteins were isolated from the extract. Thus, wheatgrass spikelets appear to be a reservoir of defense polypeptides. Our findings contribute to a deeper understanding of plant defense proteins and peptides and their involvement in the adaptation to various stress factors, and they reveal the regulatory effect at the ecosystem level.

Temporary halo fixation and radiotherapy as alternative to long-construct spondylodesis in patients with multiple unstable cervical metastases

Background and purposeCurrently no minimally invasive surgical treatment exists to provide immediate stability for unstable cervical/cervicothoracic metastases. Long-construct spondylodesis carries a high complication risk and has severe impact on residual range of motion. This study explores temporary halo fixation and radiotherapy as an alternative to long-construct cervical spondylodesis. Materials and methodsThis retrospective cohort study included twenty patients with multiple unstable cervical metastases treated between 2013–2023. All patients underwent halo fixation for an intended duration of three months to allow for safe reossification of lytic lesions following radiotherapy, with a dose fractionation scheme best suited to the histological origin of the tumor. ResultsImmobilization with halo fixation lasted a median 83 days (range, 41–132 days). Radiotherapy started on average 7 days after halo fixation (range, −35–118 days). The median pain score at baseline was 8, and was 0 at halo removal and at last follow-up. All patients had no or minor neurological deficits at baseline and did not develop new neurological deficits. At halo removal, 17/18 patients showed radiographic evidence of reossification. The majority of patients experienced minor limitations or had full range of motion of the neck at last follow-up. ConclusionPatients with multiple unstable cervical metastases treated with halo fixation and radiotherapy showed complete pain response or substantial pain reduction, reossification of the vertebrae and a, mostly, preserved range of motion. In selected neurologically intact patients, this treatment might be a patient-friendly alternative to fixation. Prospective evaluation of this treatment combination is needed.

A virtual element scheme for the time-fractional parabolic PDEs over distorted polygonal meshes

We extend the virtual element method to the two-dimensional time-fractional parabolic PDE, characterized by a fractional derivative of order α∈(0,1) in time. To illustrate the working of this fractional virtual element scheme, a numerical investigation of the following time-fractional problem over distorted polygonal meshes is conducted. cDtαu(z,t)−Δu=f(z,t)inz∈Ω,t∈(0,T],where Ω is a spatial domain, α is fractional order, and t is time variable. Our methodology is based on the fundamental technical component, fractional version of the Grunwald–Letnikov approximation. We prove the method’s well-posedness, that is the approximate solution’s existence and uniqueness. The fully discrete scheme inherently maintains stability and consistency by leveraging the discrete maximal regularity and the energy projection operator. The convergence in the L2-norm and H1-norm over distorted mesh configuration is validated by numerical results, underlining the practical effectiveness of the proposed method.

Response characterization of radiochromic OC-1 films in photon, electron, and proton beams.

Radiochromic film (RCF) dosimeters with their high spatial resolution and tissue equivalent properties are conveniently used for two-dimensional and small-field dosimetry. OC-1 is a new model of RCF dosimeter that was commercially introduced recently. Due to its novelty there is a need to characterize its response in various radiation beam types. To study the response of OC-1 RCFs to megavoltage clinical x-ray, electron, and proton beams, as well as kilovoltage x-ray beams used in a small animal research irradiator. OC-1 RCFs were cut into ∼4×4 cm2 pieces. RCF samples were irradiated at various dose levels in the range 0.5-120Gy using different modalities; a small animal radiation research platform (SARRP) (220 kVp), a medical linear accelerator (6 MV, 10 MV, 15 MV, 6 MV FFF, 10 MV FFF photon beams, as well as 6 and 20 MeV electron beams), and a gantry-mounted proton therapy synchrocyclotron. In order to study any dependency on the fractionation scheme, same dose was delivered at several fractions to a set of films. Different dose rates in the range 200-600 MU/min were delivered to a set of films to investigate any dose rate dependency. The films were scanned pre-irradiation and at 48h post-irradiation using a flatbed scanner. The net optical density (OD) was measured for red, green, and blue color channel for each film. The orientation dependency was studied by scanning the films at eight different orientations. In order to study the temporal evolution of the response of the films, film samples were irradiated at 10 and 50Gy using 6 MV photon beams and were scanned upon irradiation at certain time intervals up to 3 months. The spectral response of the films were studied over the visible range using a spectrometer. For megavoltage photon, electron, and plateau region of the proton beams, we did not observe a significant dependency on the beam quality, dose rate, and fractionation scheme. At the kV beam, an unusual over-response was observed in the films' net OD. An orientation dependency in the response of the films with a sinusoidal trend was observed. The response of the films increased with time following a double or triple exponential trend. The spectral absorption peaks were blue-shifted with dose. OC-1 RCFs were found to be reliable dosimeters with no significant energy dependency in MV range for photon and electron beams including the FFF beams. They over-respond when irradiated bykV x-ray beams compared to MV x-ray beams. Caution must be exercised to maintain the orientation of the films when scanning. Due to the temporal growth in the net OD of the films, same post-irradiation time interval must be used for scanning the calibration and test films.

Stereotactic Radiosurgery in Metastatic Spine Disease-A Systemic Review of the Literature.

This study investigated the efficacy of stereotactic radiosurgery (SRS) in managing spinal metastasis. Traditionally, surgery was the primary approach, but SRS has emerged as a promising alternative. The study aims to evaluate the efficacy of stereotactic radiosurgery in the management of spinal metastasis in terms of local tumor control, patient survival, and quality of life, identifying both advantages and limitations of SRS. Through an extensive literature search in PubMed with cross-referencing, relevant full-text-available papers published between 2012 and 2022 in English or German were included. The search string used was "metastatic spine diseases AND SRS OR stereotactic radiosurgery". There is growing evidence of SRS as a precise and effective treatment. SRS delivers high radiation doses while minimizing exposure to critical neural structures, offering benefits like pain relief, limited tumor growth, and a low complication rate, even for tumors resistant to traditional radiation therapies. SRS can be a primary treatment for certain metastatic cases, particularly those without spinal cord compression. SRS appears to be a preferable option for oligometastasis and radioresistant lesions, assuming there are no contraindications. Further research is necessary to refine treatment protocols, determine optimal radiation dose and fractionation schemes, and assess the long-term effects of SRS on neural structures.

Energy characteristics of a deep-sea mining pump under solid-phase interaction

Deep-sea mining pumps (DMPs) are the crucial power equipment for the hydraulic lift deep-sea mining system. The efficiency and sustainability are greatly affected by the particle conveyance capacity and erosion pattern. To investigate the energy performance, particle conveyance capacity, and erosion pattern of the DMP, different inlet particle volume fraction (IPVF) schemes are investigated using the Euler-Euler method. The data indicates that as the IPVF increases, the head and shaft power increase gradually, and the flow rate at the highest efficiency is consistently 1.5Qd. Additionally, the fluctuation range of the conveyance capacity index decreases as the flow rate increases. At an IPVF of 15%, the particles exhibit a backflow phenomenon, resulting in poor particle conveyance capacity. As the flow rate increases, the erosion rate (ER) of the impeller (IMP) decreases and then increases, and the ER of the space guide vane (SGV) gradually decreases, resulting in a more stable flow state. The erosion distribution of the IMP blades is mainly concentrated on the suction surface. The erosion distribution on the SGV blades is primarily concentrated on the middle and rear of the pressure surface, as well as the middle and front of the suction surface.

Cloud Radiative Feedback to the Large‐Scale Atmospheric Circulation Greatly Reduces Monsoon‐Season Wet Bias Over the Tibetan Plateau in Climate Modeling

AbstractOver‐estimation of summer precipitation over the Tibetan Plateau (TP) is a well‐known and persistent problem in most climate models. This study demonstrates the impact of a Gaussian Probability Density Function cloud fraction scheme on rainfall simulations using the Weather Research and Forecasting model. It is found that this scheme in both 0.1° and 0.05° resolutions significantly reduces the wet bias through both local feedbacks and large‐scale dynamic process. Specifically, increased cloud water/ice content with this scheme reduces surface shortwave radiation, and consequently surface heat fluxes and evapotranspiration. This, in turn, dampens the large‐scale thermal effect of the TP and weakens the exaggerated monsoon circulation and low‐level moisture convergence. It is this large‐scale dynamic process that contributes the most (∼70%) to the wet bias reduction. Although this paper presents a modeling study, it highlights the cloud radiative feedback to the large‐scale dynamics and precipitation over the TP.

Hypofractionated proton and carbon ion beam radiotherapy for sacrococcygeal chordoma (ISAC): An open label, randomized, stratified, phase II trial

IntroductionSacrococcygeal chordomas have high recurrence rates and are challenging to treat. MethodsIn this phase II prospective, randomized, stratified trial, the safety and feasibility of hypofractionated ion radiation therapy were investigated. The primary focus was monitored through the incidence of Grade 3–5 NCI-CTC-AE toxicity. Secondary endpoints included local progression-free (LPFS) and overall survival (OS). ResultsThe study enrolled 82 patients with primary (87 %) and recurrent (13 %) inoperable or incompletely resected sacral chordomas from January 2013 to July 2022, divided equally into proton therapy (Arm A) and carbon ion beam therapy (Arm B) groups, each receiving a total dose of 64 Gy (RBE) in 16 fractions, 5–6 fractions per week. Overall 74 % of patients received no previous surgery and 66 % of tumors were confirmed by a brachyury staining. The mean and median Gross Tumor Volume at the time of treatment (GTV) was 407 ml and 185 ml, respectively. The median follow-up of the surviving patients was 44.7 months, and the 2-year and 4-year OS rates were 96 % and 81 %, respectively. Factors such as smaller GTV and younger age trended towards better OS. The LPFS after 2-year and 4-year was 84 % and 70 %, respectively. Male gender emerged as a significant predictor of LPFS. There was no significant difference between the treatment groups. We observed five grade 4 wound healing disorders (6 %). ConclusionThe initial response rates were promising; however local control was not sustained. More comparative research on fractionation schemes is essential to refine treatment approaches for inoperable sacral chordoma.

Asymptotically compatible energy of variable-step fractional BDF2 scheme for the time-fractional Cahn–Hilliard model

Abstract A novel discrete gradient structure of the variable-step fractional BDF2 formula approximating the Caputo fractional derivative of order $\alpha \in (0,1)$ is constructed by a local-nonlocal splitting technique, that is, the fractional BDF2 formula is split into a local part analogue to the two-step backward differentiation formula (BDF2) of the first derivative and a nonlocal part analogue to the L1-type formula of the Caputo derivative. Then a local discrete energy dissipation law of the variable-step fractional BDF2 implicit scheme is established for the time-fractional Cahn–Hilliard model under a weak step-ratio constraint $0.3960\le \tau _{k}/\tau _{k-1}<r^{*}(\alpha )$, where $\tau _{k}$ is the $k$th time-step size and $r^{*}(\alpha )\ge 4.660$ for $\alpha \in (0,1)$. The present result provides a practical answer to the open problem in [SINUM, 57: 218-237, Remark 6] and significantly relaxes the severe step-ratio restriction [Math. Comp., 90: 19–40, Theorem 3.2]. More interestingly, the discrete energy and the corresponding energy dissipation law are asymptotically compatible with the associated discrete energy and the energy dissipation law of the variable-step BDF2 method for the classical Cahn–Hilliard equation, respectively. To the best of our knowledge, such type energy dissipation law is established at the first time for the variable-step L2 type formula of Caputo’s derivative. Numerical examples with an adaptive stepping procedure are provided to demonstrate the accuracy and the effectiveness of our proposed method.

Improved image denoising through fractional anisotropic diffusion and resolution-tailored differentiation in the Fourier domain

Fractional-order anisotropic diffusion-based denoising of images has been implemented in the literature through fractional differentiation in the Fourier domain. Furthermore, Fourier transform of the schemes on half-integer or integer mesh points has been used for the differentiation of images. In this paper, differentiation in the Fourier domain is proposed using schemes on fractional mesh points, aiming to enhance the performance of the algorithm. This can be regarded as employing fractional schemes at various resolutions, governed by a parameter of resolution within the range of (0.5, 1). Variations in resolution affect the pixel neighborhood by incorporating additional information from interpolated pixels. Experiments conducted on a reference image dataset, using three quantitative measures, demonstrate that the proposed method surpasses the method from the literature for higher values of the parameter of resolution. The improvement is particularly noticeable at higher noise levels, where the proposed method consistently outperforms the method from the literature across all values of the parameter of resolution. As a side effect, the proposed method is less time-consuming than the original method, as it requires higher time steps within the numerical scheme. Experiments and stability analysis show that the proposed method reduces the number of iterations by three to four times compared to the original method.

Saving lives, saving earth: hypofractionation and carbon footprint.

The healthcare system contributes approximately 5% of global greenhouse gas emissions, yet the environmental impact of radiotherapy treatments remains inadequately assessed. We selected all breast cancer patients (1959 patients) treated with adjuvant radiotherapy between 2015 and 2023 in one institution. We analyzed the CO2 emissions associated with travel. We also selected 60 patients randomly to analyze treatment-associated carbon emissions. We compared three different fractionation schemes: normofractionation (25-30 fractions, fx), hypofractionation (15-18fx), and ultra-hypofractionation (5-6fx). Our study revealed a significant reduction in carbon emissions within the 5-fractions group compared to the 15-fractions group (26.69kg vs 57.13kg, p < 0.001), saving approximately the CO2 emissions associated with the electricity consumption of an average Spanish household for 12 days, or the emissions of a passenger flying from Madrid to Barcelona. Most of the carbon footprint of radiotherapy is due to travel. Hypofractionation could be an appropriate solution to protect the environment.