Javier Vijande

We review the chromoelectric and chromomagnetic mechanisms that tentatively lead to stable or metastable multiquark configurations. An alternative interpretation of the dynamics is the quark interchange between hadrons, as illustrated in the case of the fully-charm systems.

We review the chromoelectric and chromomagnetic mechanisms that tentatively lead to stable or metastable multiquark configurations. An alternative interpretation of the dynamics is the quark interchange between hadrons, as illustrated in the case of the fully-charm systems.

Brachytherapy is a crucial modality of radiotherapy for cancer, known for its effectiveness in delivering high doses of radiation directly to tumours while sparing surrounding healthy tissues. Despite its clinical importance, recent years have witnessed a concerning decline in its utilization, which negatively impacts patient outcomes. This decline is attributed to several factors, with the inherent complexity of brachytherapy, fair reimbursement policies, and high dexterity being significant barriers. There are silver linings, however, as growing number of applications are seen in continents such as Africa, as well as advances in medical physics technology offering promising solutions to these challenges. This roadmap paper aims to provide a comprehensive overview and preview of advancements in brachytherapy, as well as strategies to address key challenges in four critical areas: ‘Imaging and Image Guidance,’ ‘Treatment Planning,’ ‘Treatment Delivery,’ and ‘Brachytherapy Outcomes.’ We anticipate that these advances will enhance therapeutic efficacy, equipping clinicians worldwide with the tools needed to deliver state-of-the-art cancer treatments and fostering a promising future in oncology care.

We study the production of open-flavor heavy hadrons in relativistic heavy-ion collisions. The hadronization in the quark-gluon plasma is described in the quark coalescence model. We evaluated yields and transverse momentum distributions. A simultaneous study of conventional and exotic hadrons is carried out. The Wigner functions are evaluated using hadron wave functions obtained from a single realistic quark model. Thus, results are presented in a single framework for the production of open-flavor heavy mesons, baryons, and exotic tetraquarks, in particular: D 0 , B 0 , Λ Q , Σ Q , Ξ Q , Ξ Q Q ′ , and T Q Q ′ ( Q , Q ′ = c or b ). The consequences of a partial restoration of chiral symmetry at the hadronization temperature are studied in detail.

Purpose: This work provides the first two clinical test cases for commissioning electronic brachytherapy (eBT) model‐based dose calculation algorithms (MBDCAs) for skin irradiation using surface applicators. Acquisition and Validation Methods: The test cases utilize the INTRABEAM 30 mm surface applicator. Test Case I : water phantom is used to evaluate the algorithm's performance in a uniform medium consisting of a voxelized water cube surrounded by air. Test Case II: Surface eBT represents a heterogeneous medium with four distinct layers: skin tissue, adipose tissue, cortical bone, and soft tissue. Treatment plans for both cases were created and exported into the Radiance treatment planning system (TPS). Dose‐to‐medium calculations were then performed using this Monte Carlo (MC)‐based TPS and compared with MC simulations conducted independently by three different groups using two codes: EGSnrc and PENELOPE. The results agreed within expected Type A and B statistical uncertainties. Data Format and Usage Notes: The dataset is available online at https://doi.org/10.52519/00005. A proprietary file designed for use within Radiance containing CT images and the treatment plan for both test cases, the LINAC modeling, and the CT calibration are included, as well as reference MC and TPS dose data in RTdose format and all files required to run the MC simulations. Potential Applications: This dataset serves as a valuable resource for commissioning eBT MBDCAs and lays the groundwork for developing clinical test cases for other eBT systems. It is also a helpful educational tool for exploring various eBT devices and their advantages and drawbacks. Furthermore, brachytherapy researchers seeking a benchmark for dosimetric calculations in the low‐energy domain will find this dataset indispensable.

Background: Low‐energy x‐ray beams used in electronic brachytherapy (eBT) present significant dosimetric challenges due to their high depth‐dose gradients, the dependence of detector response on materials, and the lack of standardized dose‐to‐water references. These challenges have driven the need for Monte Carlo (MC) simulations to ensure accurate dosimetry. However, discrepancies in the physics models used by different MC systems have raised concerns about their dosimetric consistency, particularly in modeling bremsstrahlung interactions.Purpose: To assess the dosimetric impact of using different physics approaches in three state‐of‐the‐art MC systems for eBT, focusing on the disagreements observed when different MC methods are used to evaluate bremsstrahlung interactions.Methods: The MC studies of the Axxent S700, the Esteya, and the INTRABEAM eBT systems were performed using two EGSnrc applications (egs_brachy and egs_kerma), TOPAS, and PENELOPE‐2018 (PEN18). The fluence spectra and depth doses were compared for simplified x‐ray tube models, which maintain the target mode (transmission or reflection), the target material and thickness, and the surface applicators’ source‐to‐surface distance. An extra simulation was made to evaluate the utility of the simplified models as proxies in predicting the most important characteristics of an accurate applicator's simulation (detailed model of INTRABEAM's 30 mm surface applicator). The EGSnrc applications and PEN18 utilized their default bremsstrahlung angular emission approaches. TOPAS used two physics lists: g4em‐livermore (TOPAS_liv) and g4em‐penelope (TOPAS_pen).Results: The most significant differences between MC codes were observed for the transmission target mode. The bremsstrahlung component of the fluence spectra differed by about 15% on average, comparing PEN18, EGSnrc applications, and TOPAS_liv, with PEN18's fluences consistently lower. EGSnrc and PEN18 agreed within 3% for their characteristic spectrum components. However, PEN18's characteristic lines overreached TOPAS_liv’s by 40%. Those spectral characteristics generated depth dose differences, where PEN18, on average, scored 9% lower than EGSnrc and TOPAS_liv. Considering TOPAS_pen in the transmission mode, PEN18's fluence spectrum presented a lower bremsstrahlung (5%) but a higher characteristic component (10%); these spectral differences compensated, generating depth dose differences within 1% average. In the reflection target mode, EGSnrc and PEN18 agreed within 4% for the bremsstrahlung and characteristic components of the fluence spectra. With TOPAS_pen in the reflection mode, PEN18 presents 12% lower fluences in the bremsstrahlung component but 6% higher characteristic lines. This spectral behavior diminished the depth dose differences up to 3%.Conclusion: This work found considerable disagreements between three state‐of‐the‐art MC systems commonly used in medical applications when simulating bremsstrahlung in eBT. The differences arose when the bremsstrahlung angular distribution and the atomic relaxation processes in the target became relevant. More theoretical and experimental studies are necessary to evaluate the impact of these differences on related calculations.

Background: Brachytherapy (BT) treatments involving temporary high‐dose rate (HDR) sources are extensively employed in clinical practice. Ensuring the consistency of all measurement equipment at the hospital level is crucial, requiring a robust redundancy and consistency program. This enables the institution to verify the stability of the dosimetry system over time.Purpose: To describe, justify, and analyze a component of the redundancy program of the calibration protocols followed by the Radiotherapy Department of the Hospital Universitari i Politècnic La Fe (València, Spain) during the last 10 years for the case of HDR BT as an additional component to ensure long term stability of the measurement equipment.Methods: At the time the HDR BT source is replaced, its Air Kerma Strength (S_K) is measured. By comparing this value with the one obtained at the time of installation (corrected by decay), a clear determination of the stability of the measurement equipment can be performed.Results: Difference between S_K,vendor and S_K,hosp as a function of the measurement date is reported for a 10 years’ period. All measurements are well within the ±3% tolerance level recommended in current international guidelines. Percentage differences of S_K,hosp values at the time of replacement compared to S_K,hosp ones at the time when the source was installed are within the ±0.5% range, reflecting oscillations around a null deviation.Conclusions: The method proposed allows any hospital to ensure a redundancy component of the long‐term stability of all equipment involved in BT measurements in a very simple and time efficient manner. Additionally, it enables the hospital to maintain a detailed log of historical differences, facilitating the identification and correction of potential systematic deviations over time.