A monte carlo platform for characterization of x-ray radiation dose in ct imaging

Background: Computed tomography (CT) is currently known as a versatile imaging tool in the clinic used for almost all types of cancers. The major issue of CT is the health risk, belonging to X-ray radiation exposure. Concerning this, Monte Carlo (MC) simulation is recognized as a key computational technique for estimating and optimizing radiation dose. CT simulation with MCNP/MCNPX MC code has an inherent problem due to the lack of a fan-beam shaped source model. This limitation increases the run time and highly decreases the number of photons passing the body or phantom. Recently, a beta version of MCNP code called MCNP-FBSM (Fan-Beam Source Model) has been developed to pave the simulation way of CT imaging procedure, removing the need of the collimator. This is a new code, which needs to be validated in all aspects. Objective: In this work, we aimed to develop and validate an efficient computational platform based on modified MCNP-FBSM for CT dosimetry purposes. Material and Methods: In this experimental study, a setup is carried out to measure CTDI100 in air and standard dosimetry phantoms. The accuracy of the developed MC CT simulator results has been widely benchmarked through comparison with our measured data, UK�s National Health Service�s reports (known as ImPACT), manufacturer�s data, and other published results. Results: The minimum and maximum observed mean differences of our simulation results and other above-mentioned data were the 1.5, and 9.79, respectively. Conclusion: The developed FBSM MC computational platform is a beneficial tool for CT dosimetry. © 2021, Shriaz University of Medical Sciences. All rights reserved

Reduction of adverse effects from intravenous acetylcysteine treatment for paracetamol poisoning: a randomised controlled trial:a randomised controlled trial

Copyright © 2014 Bateman et al. Open Access article distributed under the terms of CC BY. Published by Elsevier Ltd. All rights reserved. The trial was funded by Chief Scientist Office, Scotland (award CZB/4/722).Peer reviewedPublisher PD

Tumor dose enhancement by gold nanoparticles in a 6 MV photon beam: a Monte Carlo study on the size effect of nanoparticles

In this study after benchmarking of Monte Carlo (MC) simulation of a 6 MV linac, the simulation model was used for estimation of tumor dose enhancement by gold nanoparticles (GNPs). The 6 MV photon mode of a Siemens Primus linac was simulated and a percent depth dose and dose profiles values obtained from the simulations were compared with the corresponding measured values. Dose enhancement for various sizes and concentrations of GNPs were studied for two cases with and without the presence of a flattening filter in the beam’s path. Tumor dose enhancement with and without the presence of the flattening filter was, respectively 1–5 and 3–10%. The maximum dose enhancement was observed when 200 nm GNPs was used and the concentration was 36 mg/g tumor. Furthermore, larger GNPs resulted in higher dose values in the tumor. After careful observation of the dose enhancement factor data, it was found that there is a poor relation between the nanoparticle size and dose enhancement. It seems that for high energy photons, the dose enhancement is more affected by the concentration of nanoparticles than their size

Dose enhancement in brachytherapy in the presence of gold nanoparticles : a Monte Carlo study on the size of gold nanoparticles and method of modelling

The aim of this study was to evaluate the effect of the size of gold nanoparticles (GNPs) on dose enhancement in brachytherapy with photon emitting sources. Four photon emitting sources, 125I, 169Yb, 103Pd, and 192Ir were simulated and dose rate constant and radial dose functions were compared with published corresponding data for these sources. Dose enhancement factor in the presence of gold nanoparticles of 30 mg/ml concentration was calculated separately for nanoparticles with a diameter of 50, 100 and 200 nm. Gold nanoparticles were simulated precisely as nanospheres utilizing a lattice option in the MCNPX Monte Carlo code and the results were compared with those obtained with a simple model in which gold atoms are distributed uniformly in tumor volume as a simple mixture. Among the four mentioned sources, the dose enhancement related to 125I source is higher. Our results have shown that with gold nanoparticles of higher diameter, the level of dose enhancement is higher in the tested tumor. It has been also observed that the simple model overestimates the dose enhancement factor when compared with the precise model in which nanoparticles are defined according to the Monte Carlo code. In the energy range produced by the brachytherapy sources, the dose enhancement is higher when using brachytherapy sources with lower energy. Among the size range of gold nanoparticles used in medicine, it is predicted that nanoparticles with higher diameter can be more useful when are utilized in brachytherapy. It is also recommended that when calculating dose enhancements, a precise model be used for modelling of nanoparticles in the Monte Carlo simulations

Myelin oligodendrocyte glycoprotein (MOG) associated optic neuritis in a patient with idiopathic intracranial hypertension (IIH) and compressive optic neuropathy case report

Abstract Background Myelin oligodendrocyte glycoprotein-associated disease (MOGAD) has a wide phenotypic expression and should be considered in a differential diagnosis of patients with optic disc edema and increased intracranial pressure because MOGAD can mimic IIH and compressive optic neuropathy. Case presentation A 53-year-old woman with a history of presumed idiopathic intracranial hypertension (“IIH”) presented with new headache and visual loss. She had a BMI of 35.44 kg/m2 and a past medical history significant for depression, hepatitis C, hyperlipidemia, and uterine cancer post-hysterectomy. She had undergone multiple lumboperitoneal shunts for presumed IIH and had a prior pituitary adenoma resection. Her visual acuity was no light perception OD and counting fingers OS. After neuro-ophthalmic consultation, a repeat cranial MRI showed symmetric thin peripheral optic nerve sheath enhancement of the intra-orbital optic nerves OU. Serum MOG antibody was positive at 1:100 and she was treated with intravenous steroids followed by plasma exchange and rituximab. Conclusions This case highlights the importance of considering MOGAD in the differential diagnosis of optic neuropathy. Although likely multifactorial, we believe that the lack of improvement in our case from presumed IIH and despite adequate neurosurgical decompression of a pituitary adenoma with compression of the optic apparatus reflected underlying unrecognized MOGAD. Clinicians should consider repeat imaging of the orbit (in addition to the head) in cases of atypical IIH or compressive optic neuropathy especially when the clinical course or response to therapy is poor or progressive

TST36-Klammernahtoperation bei Rektozelen und Hämorrhoidalprolaps - Ergebnisse der prospektiven deutschen multizentrischen Studie

Introduction: The aim of the study was to evaluate the safety and feasibility of stapled transanal procedures performed by a 36 mm stapling device, the so-called TST36 stapler.Methods: From September 2013 to June 2014 a prospective observational study was carried out by 8 proctology centers in Germany. The Cleveland Clinic Incontinence Score (CCIS) for incontinence and the Altomare ODS score were determined preoperatively. Follow-up examinations were performed after 14 days, one month and 6 months, at this time both scores were reevaluated.Results: 110 consecutive patients (71 women, 39 men) with a mean age of 59.7 years (±13.8 years) were included in the study. The eight participating institutes entered 3 to 31 patients each into the study. The indication for surgery was an advanced hemorrhoidal disease in 55 patients and ODS with rectal intussusception or rectocele in 55 patients. Mechanical problems with stapler introduction occurred in 22 cases (20%) and a partial stapleline dehiscence in 4 cases (3.6%). Additional stitches for bleeding from stapleline were necessary in 86 patients (78.2%). Reintervention was necessary for bleeding 7 times (6.3%). Severe complications during follow-up were stapleline dehiscence in one case and recurrent hemorrhoidal prolapse in 5 cases (4.5%). Altomare ODS score and CCIS improved significantly after surgery.Conclusions: Despite a notable complication rate during surgery and the postoperative period, the TST36 can be considered as an effective tool for low rectal stapling for anorectal prolapse causing hemorrhoids or obstructed defecation.Einführung: Das Ziel der Studie war es, die Sicherheit und Durchführbarkeit der transanalen Klammernahtoperation mit einem neuen 36 mm Stapler, dem so genannten TST36-Stapler zu bewerten.Methoden: Ab September 2013 bis Juni 2014 wurde eine prospektive Beobachtungsstudie von 8 Proktologie-Zentren in Deutschland durchgeführt. Der Cleveland Clinic Inkontinenz-Score (CCIS) für Inkontinenz und der Altomare-ODS-Score wurden präoperativ bestimmt. Follow-up-Untersuchungen wurden nach 14 Tagen, einem Monat und 6 Monaten durchgeführt. Zu diesen Zeitpunkten wurden beide Scores erneut evaluiert.Ergebnisse: 110 Patienten (71 Frauen, 39 Männer) mit einem Durchschnittsalter von 59,7 Jahre (±13,8 Jahre) wurden in die Studie einbezogen. Die acht teilnehmenden Institute rekrutierten jeweils zwischen 3 bis 31 Patienten. Die Indikation zur Operation war ein fortgeschrittener Hämorrhoidalprolaps bei 55 Patienten und ODS mit rektale Invagination oder Rektozele bei 55 Patienten. Mechanische Probleme beim Einführen des Staplers gab es in 22 Fällen (20%) und eine partielle Klammernahtdehiszenz in 4 Fällen (3,6%). Zusätzliche Umstechungen bei Blutungen aus Klammernahtreihe waren bei 86 Patienten (78,2%) erforderlich. Wegen Blutungen waren insgesamt 7 Reinterventionen (6,3%) notwendig. Als schwere Komplikationen während des Follow-up wurden eine Klammernahtdehiszenz und rezidivierender Hämorrhoidalprolaps in 5 Fällen (4,5%) beobachtet. Altomare-ODS-Score und CCIS waren nach der Operation deutlich verbessert.Schlussfolgerungen: Trotz einer offenkundigen peri- und postoperativen Komplikationsrate kann die TST36-Stapleroperation als wirksame Maßnahme zur Behandlung anorektaler Prolapsformen und einer obstruktiven Defäkationsstörung angesehen werden