Radiation physics

Radiotherapy for adolescents and young adults is complex in several aspects. The population is very heterogeneous and has characteristics derived from both paediatric and adult populations both in terms of pathology (anatomical pathology, response to treatment) and the patient's physical, biological and psychological characteristics. This article reviews the characteristics to be taken into account in adolescent and young adult patients radiotherapy and more particularly in some of the most common diseases.

Mechanistic Monte Carlo simulations calculating DNA damage caused by ionizing radiation are highly dependent on the simulation parameters. In the present study, using the Geant4-DNA toolkit, the impact of different parameters on DNA damage induced in a bacterial cell by X- and gamma-ray irradiation was investigated. Three geometry configurations, including the simple (without DNA details), the random (a random multiplication of identical DNA segments), and the fractal (a regular replication of DNA segments using fractal Hilbert curves), were simulated...

The objective of this study was to investigate patient radiation doses by a dose audit of three common interventional cardiology (IC) procedures: coronary angiography (CA), percutaneous transluminal coronary angioplasty (PTCA) and CA-PTCA procedures performed in IC centres in the Uttarakhand state of India, for the establishment of local diagnostic reference levels (DRLs) and the estimation of average effective dose (Eav ) for these procedures. For each procedure, the values of kerma-area product (PKA ), reference air kerma (Ka,r ), fluoroscopy time (FT) and the number of cine images were recorded from 1233 CA, 458 PTCA and 736 CA-PTCA procedures performed over a 12-month period at 13 IC centres of the state...

Chiral quantum dots (QDs) are promising materials applied in many areas, such as chiral molecular recognition and spin selective filter for charge transport, and can be prepared by facile ligand exchange approaches. However, ligand exchange leads to an increase in surface defects and reduces the efficiencies of radiative recombination and charge transport, which restricts further applications. Here, we investigate the light-induced photoluminescence (PL) enhancement in chiral L- and D-cysteine CdSe QD thin films, providing a strategy to increase the PL...

Effective treatment of failed back surgery syndrome (FBSS) remains challenging despite urgent medical attention requirements. Depression is a contributing factor to the development and poor prognosis of FBSS, and vice versa. We report the case of a patient with FBSS and major depressive disorder (MDD) treated with graded exercise combined with motion-style acupuncture therapy (MSAT). A 53-year-old male veteran who had undergone lumbar discectomy and laminectomy with instrumented fusion was admitted to the hospital with re-current back pain and radiative pain in the left leg...

As a typical thermally activated delayed fluorescence (TADF) emitter with green emission, 4CzIPN has attracted much attention recently. Most studies indicated that 4CzIPN doped in different hosts presented different performances; thus, the hosts should have an obvious influence on its photophysical properties. Herein, the influence of four kinds of hosts, including m-CzPym, m-CzTrz, p-CzPym, and p-CzTrz, on the photophysical properties of 4CzIPN is investigated. Molecular dynamics simulations were performed to simulate the host-guest conformations, and the photophysical properties were studied using the combined quantum mechanics/molecular mechanics method coupled with the thermal-vibration correlation function method...

Use of magnetic resonance (MR) imaging in radiation therapy has increased substantially in recent years as more radiotherapy centers are having MR simulators installed, requesting more time on clinical diagnostic MR systems, or even treating with combination MR linear accelerator (MR-linac) systems. With this increased use, to ensure the most accurate integration of images into radiotherapy (RT), RT immobilization devices and accessories must be able to be used safely in the MR environment and produce minimal perturbations...

Lumbar spinal stenosis is a clinical syndrome that affects more than 200,000 people in the United States annually. It is a common cause of chronic insidious low back pain, especially in older patient populations (mean age = 64 years). Lumbar spinal stenosis is a degenerative condition of the spine leading to narrowing in the spaces around the neurovascular bundles and the classic symptom of low back pain that radiates to the buttocks and lower extremities bilaterally. It is typically a progressive waxing and waning process that may deteriorate over years...

Photon-counting detector (PCD) CT enables routine virtual-monoenergetic image (VMI) reconstruction. We evaluated the performance of an automatic VMI energy level (keV) selection tool on a clinical PCD-CT system in comparison to an automatic tube potential (kV) selection tool from an energy-integrating-detector (EID) CT system from the same manufacturer. 
Approach: Four torso-shaped phantoms (20-50 cm width) containing iodine (2, 5, and 10-mg/cc) and calcium (100 mg/cc) were scanned on PCD-CT and EID-CT...

Spatially fractionated radiation therapy (SFRT) is a therapeutic approach with the potential to disrupt the classical paradigms of conventional radiation therapy. The high spatial dose modulation in SFRT activates distinct radiobiological mechanisms which lead to a remarkable increase in normal tissue tolerances. Several decades of clinical use and numerous preclinical experiments suggest that SFRT has the potential to increase the therapeutic index, especially in bulky and radioresistant tumors. To unleash the full potential of SFRT a deeper understanding of the underlying biology and its relationship with the complex dosimetry of SFRT is needed...

BACKGROUND: In order to ensure adequate radiation protection of critical groups such as staff, caregivers and the general public coming into proximity of nuclear medicine (NM) patients, it is necessary to consider the impact of the radiation emitted by the patients during their stay at the hospital or after leaving the hospital. Current risk assessments are based on ambient dose rate measurements in a single position at a specified distance from the patient and carried out at several time points after administration of the radiopharmaceutical to estimate the whole-body retention...

The development of functional textiles combining conventional apparel with advanced technologies for personal health management (PHM) has garnered widespread attention. However, the current PHM textiles often achieve multifunctionality by stacking functional modules, leading to poor durability and scalability. Herein, a scalable and robust PHM textile is designed by integrating electrical, radiative, and solar heating, electromagnetic interference (EMI) shielding, and piezoresistive sensing performance onto cotton fabric...

A global diabatization scheme, based on the "valence-hole" concept, has been previously applied to model webs of avoided crossings that exist in four electronic-state symmetry manifolds of C2 (1 Πg , 3 Πg , 1 Σu + , and 3 Σu + ). Here, this model is extended to the electronically excited states of four more molecules: CN (2 Σ+ ), N2 (3 Πu ), SiC (3 Π), and Si2 (3 Πg ). Many strangenesses in the spectroscopic observations (e.g., energy level structure, predissociation linewidths, and radiative lifetimes) for all four electronic state systems discussed here are accounted for by this unified model...

BACKGROUND: The chronic, inflammatory skin disease hidradenitis suppurativa (HS) (prevalence: 0.5%-1%, diagnostic delay: 7-10 years) primarily arises in younger adults and frequently coincides with autoimmune comorbidities and unhealthy life-styles (smoking and obesity). These factors are known to increase cancer risk, but despite this, information on cancer occurrence among HS patients is scarce. MATERIALS AND METHODS: A nationwide retrospective register-based study assessing relative risk of cancer - overall and by anatomical site - following HS diagnosis expressed as standardized incidence ratios (SIRs), which is ratios between observed cases among all Danes diagnosed with HS since 1977 and expected cases based on cancer incidence rates of the entire Danish population during the same period...

BACKGROUND: Immune checkpoint inhibitors (ICIs) have significantly improved outcomes in various cancers. ICI treatment is associated with the incidence of immune-related adverse events (irAEs) which can affect any organ. Data on irAEs occurrence in relation to sex- differentiation and their association with gender-specific factors are limited. AIMS: The primary objective of the G-DEFINER study is to compare the irAEs incidence in female and male patients who undergo ICI treatment...

BACKGROUND AND PURPOSE: This large population-based, retrospective, single-center study aimed to identify prognostic factors in patients with brain metastases (BM) from gynecological cancers. MATERIAL AND METHODS: One hundred and forty four patients with BM from gynecological cancer treated with radiotherapy (RT) were identified. Primary cancer diagnosis, age, performance status, number of BM, presence of extracranial disease, and type of BM treatment were assessed...

Anterolisthesis is a condition where a vertebra in the spine slips forward relative to the vertebra below it. Anterolisthesis is often described in terms of the direction of the slippage and the affected vertebrae, such as L5-S1 anterolisthesis, which indicates the slippage occurring between the fifth lumbar vertebra (L5) and the sacral bone (S1). Anterolisthesis can result from various factors, trauma, or congenital abnormalities. The symptoms associated with anterolisthesis can include lower back pain, stiffness, muscle tightness, and neurological symptoms if the slippage compresses nearby nerves...

Process-based forest models combine biological, physical, and chemical process understanding to simulate forest dynamics as an emergent property of the system. As such, they are valuable tools to investigate the effects of climate change on forest ecosystems. Specifically, they allow testing of hypotheses regarding long-term ecosystem dynamics and provide means to assess the impacts of climate scenarios on future forest development. As a consequence, numerous local-scale simulation studies have been conducted over the past decades to assess the impacts of climate change on forests...

Patients undergoing extensive lymph node dissection and radiation are at high risk for not only lymphedema but also painful contracture. In a standard lymphadenectomy, immediate lymphatic reconstruction using a lymphovenous bypass is effective in reconstructing the lymphatic defect. However, a more aggressive nodal clearance leaves the patient with a large cavity and skeletonized neurovascular structures, often resulting in severe contracture, pain, cosmetic deformity, and venous stricture. Adjuvant radiotherapy to the nodal bed can lead to severe and permanent disability despite physical therapy...

BACKGROUND AND PURPOSE: Despite hardware acceleration, state-of-the-art Monte Carlo (MC) dose engines require considerable computation time to reduce stochastic noise. We developed a deep learning (DL) based dose engine reaching high accuracy at strongly reduced computation times. MATERIALS AND METHODS: Radiotherapy treatment plans and computed tomography scans were collected for 350 treatments in a variety of tumor sites. Dose distributions were computed using a MC dose engine for <mml:math xmlns:mml="https://www...