Monte Carlo modeling and simulation of a new 3D printed phantom for WBC calibration with ballistic gel as a tissue substitute.

Whole-body counter (WBC) systems are used for in vivo monitoring in occupational internal dosimetry, typically calibrated using physical anthropomorphic phantoms. Our research group previously 3D-printed the Reference Female Phantom for Internal Dosimetry (RFPID) without internal organs specifically designed for WBC calibration. The RFPID and it is intended to fill it homogenously with ballistic gel, which is commonly used as a tissue equivalent in ballistic studies.

Feasibility of new polymeric matrices in the production of ferrous sulphate dosimeters.

External beam radiotherapy is a treatment modality that employs high doses for curative or palliative purposes. Safety in such treatments, particularly with high-precision equipment, necessitates strict adherence to quality control protocols to ensure the efficacy of oncological treatments. In this context, chemical dosimeters, particularly the Fricke gel, have emerged as valuable tools for quantitatively analysing absorbed radiation doses.

Comparison of the dosimetry of scandium-43 and scandium-44 patient organ doses in relation to commonly used gallium-68 for imaging neuroendocrine tumours.

Background: Several research groups have explored the potential of scandium radionuclides for theragnostic applications due to their longer half-lives and equal or similar coordination chemistry between their diagnostic and therapeutic counterparts, as well as lutetium-177 and terbium-161, respectively. Unlike the gallium-68/lutetium-177 pair, which may show different in-vivo uptake patterns, the use of scandium radioisotopes promises consistent behaviour between diagnostic and therapeutic radiopeptides. An advantage of scandium's longer half-life over gallium-68 is the ability to study radiopeptide uptake over extended periods and its suitability for centralized production and distribution.

Prognostic value of neutrophil-to-lymphocyte ratio (NLR) and platelet-neutrophil (PN) index in locally advanced rectal cancer patients: a retrospective cohort study.

Introduction: In locally advanced rectal cancers (LARC), tumour node metastasis (TNM) staging is far from optimal. The authors aimed to investigate the value of previously described circulating biomarkers as predictors of prognosis.

Methods: Retrospective analysis of 245 LARC patients diagnosed between January 2010 and December 2022, who underwent neoadjuvant chemoradiotherapy and surgery at two centres.

Impact of perioperative chemotherapy in the treatment of patients with gastric cancer.

Background: Perioperative chemotherapy (PeriCh) is the current standard of care for stage II/III gastric cancer tumors in Europe. However, when it concerns patients who endure complications during PeriCh it is unclear if it increases the risk of postoperative complications and other poorer surgical outcomes. We aim to demonstrate if there is an association between having complications during PeriCh and postoperative complications and histopathological response.

Evaluation of ctDNA in the Prediction of Response to Neoadjuvant Therapy and Prognosis in Locally Advanced Rectal Cancer Patients: A Prospective Study.

"Watch and wait" is becoming a common treatment option for patients with locally advanced rectal cancer (LARC) submitted to neoadjuvant treatment. However, currently, no clinical modality has an acceptable accuracy for predicting pathological complete response (pCR). The aim of this study was to assess the clinical utility of circulating tumor DNA (ctDNA) in predicting the response and prognosis in these patients.

MONTE CARLO SIMULATION OF THE RADIATION SOURCE TERM FROM [18O]H2O CYCLOTRON TARGET BOMBARDMENT WITH PROTONS OF 16.5 MEV.

PET cyclotrons are widely used for producing medical diagnostic radionuclides. The main radionuclide produced in these facilities is the 18F, which is obtained from the [18O (p,n)18F] reaction when 18O-enriched water is bombarded with the proton beams. This work aimed to estimate the radiation source term from the bombardment of an 18O-enriched water target with protons of 16.

Monte Carlo calculation of whole body counter efficiency factors for different computational phantoms.

Individual monitoring can provide an estimate of the radioactivity present in the body of the exposed individuals. Periodic monitoring of occupationally exposed individuals is of great importance in case of accidental incorporation. Computational phantoms and Monte Carlo codes are often used to complement the calibration method of counting systems in internal dosimetry.

Gastric cancer: histological response of tumor and metastatic lymph nodes for perioperative chemotherapy.

Background: Gastric cancer is the fourth cancer most common in the world and the second cause of cancer-related deaths. Perioperative chemotherapy may reduce tumor burden and decrease lymph node invasion, improving R0 resections rates. On the other hand, administered before surgery, chemotherapy may cause fibrosis and tissue edema, with potential increase of surgical difficulty and in the number of post-operative complications.

Calculation of absorbed dose in paediatric phantoms using Monte Carlo techniques for F-FDG and Tc-DMSA and the new TIAC.

The radiopharmaceuticals most commonly used in nuclear medicine are F-FDG and Tc-DMSA, both of which are administered to paediatric and adult patients using the same time activity coefficient. However, the IAEA recommends specific paediatric dosimetry. The aim of this work (TW) was to estimate the absorbed dose for F-FDG and Tc-DMSA using two paediatric voxel phantoms (Baby and Child) by Monte Carlo techniques.

The impact of the prognostic nutritional index (PNI) in gastric cancer.

Background: Regarding the assessment of patients' immune and nutritional status, prognostic nutritional index (PNI) has been reported as a predictive marker for surgical outcomes in various types of cancer. The aim of our study was to evaluate the effect of PNI in prognosis of gastric cancer patients submitted to curative-intent resectional surgery.

Material And Methods: A retrospective analysis with 637 gastric cancer cases submitted to curative-intent surgery, between 2010 and 2017, in an upper GI surgery unit.

Recent Advances in Brachytherapy Using Radioactive Nanoparticles: An Alternative to Seed-Based Brachytherapy.

Interstitial brachytherapy (BT) is generally used for the treatment of well-confined solid tumors. One example of this is in the treatment of prostate tumors by permanent placement of radioactive seeds within the prostate gland, where low doses of radiation are delivered for several months. However, successful implementation of this technique is hampered due to several posttreatment adverse effects or symptoms and operational and logistical complications associated with it.

Can pretreatment blood biomarkers predict pathological response to neoadjuvant chemoradiotherapy in patients with locally advanced rectal cancer?

To investigate the value of previously described pretreatment hematological and biochemical biomarkers as predictors of pathological response. The authors performed a retrospective analysis of 191 patients with locally advanced rectal cancer who underwent long-course neoadjuvant chemoradiotherapy at two Portuguese centers. The authors performed logistic regression analysis to search for predictive markers of pathological complete and good response.

Monte Carlo simulation and dosimetry measurements of an experimental approach for in vitro HDR brachytherapy irradiation.

Irradiation of tumor cell lines is a useful way to investigate the effects of ionizing radiation on biological molecules. We designed an easy and reproducible approach for in vitro experimental high dose rate brachytherapy, which was simulated by a Monte Carlo code and dosimetrically characterized by experimental methods to evaluate the correspondence between planned doses and doses absorbed by the cells. This approach is an acrylic platform containing T25 tissue culture flasks and multiwell tissue culture plates.

In silico dosimetry of low-dose rate brachytherapy using radioactive nanoparticles.

Purpose: Nanoparticles (NPs) with radioactive atoms incorporated within the structure of the NP or bound to its surface, functionalized with biomolecules are reported as an alternative to low-dose-rate seed-based brachytherapy. In this study, authors report a mathematical dosimetric study on low-dose rate brachytherapy using radioactive NPs.

Method: Single-cell dosimetry was performed by calculating cellular S-values for spherical cell model using Au-198, Pd-103 and Sm-153 NPs.

Comparison of dosimetric accuracy of acuros XB and analytical anisotropic algorithm against Monte Carlo technique.

This study reports the comparison between two dose calculation algorithms, Acuros XB 13.5 (AXB) and Analytical Anisotropic Algorithm (AAA) against Monte Carlo (MC) simulations for 3D-Conformal Radiation Therapy (3D-CRT) using a female pelvic rando phantom. 3D-CRT treatment plans were generated on the CT images of rando phantom using AXB and AAA with Source to Axis Distance (SAD) technique.

Monte Carlo assessment of low energy electron range in liquid water and dosimetry effects.

The effects of low energy electrons in biological tissues have proved to lead to severe damages at the cellular and sub-cellular level. It is due to an increase in the relative biological effectiveness (RBE) of these electrons with a decrease in their penetration range. That is, lower the range higher will be its RBE.

Microdosimetric calculations for radionuclides emitting β and α particles and Auger electrons.

This work focuses on the calculation of S-values and radial energy profiles for radionuclides emitting high (Y-90, Sr-89), medium (Re-186, Sm-153) and low-energy (Er-169, Lu-177) β-particles, Auger electrons (In-111, Ga-67, I-123) and α-particles (At-211, Ac-225). Simulations were performed using the EGSnrc and GEANT4-DNA Monte Carlo (MC) codes for a spherical cell geometry. S-values were computed using decay spectra available in literature for Tc-99m and In-111.

Carbapenemase-producing intra-abdominal infection successfully treated with ceftazidime/avibactam plus tigecycline.

Ceftazidime/avibactam combines ceftazidime with a new beta-lactam that successfully that inhibits Amber Class A and D carbapenemases. We report a clinical case of a 61 year-old man with a carbapenemase-producing intra-abdominal infection after an elective abdominal hernia repair. The infection was successfully managed with multiple abdominal surgeries, drainage and combined antibiotic therapy with ceftazidime/avibactam plus tigecycline.

Assessment of radiation-induced secondary cancer risk in the Brazilian population from left-sided breast-3D-CRT using MCNPX.

Objective: The aim of this work was to simulate a 6MV conventional breast 3D conformational radiation therapy (3D-CRT) with physical wedges (50 Gy/25#) in the left breast, calculate the mean absorbed dose in the body organs using robust models and computational tools and estimate the secondary cancer-incidence risk to the Brazilian population.

Methods: The VW female phantom was used in the simulations. Planning target volume (PTV) was defined in the left breast.

Improvement of the WBC calibration of the Internal Dosimetry Laboratory of the CDTN/CNEN using the physical phantom BOMAB and MCNPX code.

The Laboratory of Internal Dosimetry of the Center for Development of Nuclear Technology (LDI/CDTN) is responsible for routine internal monitoring of occupationally exposed individuals. The determination of photon emitting radionuclides in the human body requires calibration of the detector in specific counting geometries. The calibration process uses physical phantoms containing certified activities of the radionuclides of interest.

SOFT-RT: Software for IMRT simulations based on MCNPx code.

Intensity Modulated Radiation Therapy (IMRT) is an advanced treatment technique, widely used in external radiotherapy. This paper presents the SOFT-RT which allows the simulation of an entire IMRT treatment protocol. The SOFT-RT performs a full three-dimensional renderization of a set of patient images, including the definitions of region of interest with organs in risk (OIR), and the target tumor volume and margins (PTV).