RESUMO
The 2013/59/Euratom Directive reduced the occupational exposure limits for the lens. Since it has become crucial to estimate the dose absorbed by the lens, we have studied the individual variability of exposed workers' ocular conformations with respect to the data estimated from their personal dosimetry. The anterior eye conformations of 45 exposed workers were acquired using Scheimpflug imaging and classified according to their sight conditions (emmetropia, myopia or hypermetropia). Three eye models were computed, with two lens reconstructions, and implemented in an interventional radiology scenario using Monte Carlo code. The models were dosimetrically analysed by simulating setup A, a theoretical monoenergetic and isotropic photon source (10-150 keV) and setup B, a more realistic interventional setting with an angiographic x-ray unit (50, 75, 100 kV peak). Scheimpflug imaging provided an average anterior chamber depth of (6.4 ± 0.5) mm and a lens depth of (3.9 ± 0.3) mm, together with a reconstructed equatorial lens length of (7.1-10.1) mm. Using these data for model reconstruction, dose coefficients (DCs) were simulated for all ocular structures. Regardless of the eye model used, the DCs showed a similar trend with radiation energy, which highlighted that for the same energy and setup, no significant dependence on ocular morphology and workers' visual conditions was observed. The maximum difference obtained did not exceed 1% for all eye models or structures analysed. Therefore, the individual variabilities of worker ocular anatomy do not require any additional correction, compared to the personal dosimetry data measured with a dedicated lens dosimeter. To estimate the dose absorbed by the other eye structures, it is, instead, essential to know the spectrum of the source that has generated the irradiation, since there are differences between monoenergetic sources and more realistic angiographic units.
Assuntos
Cristalino , Exposição Ocupacional , Humanos , Método de Monte Carlo , Exposição Ocupacional/análise , Doses de Radiação , Dosímetros de Radiação , Radiologia IntervencionistaRESUMO
The effects of soda-lime waste glass, from the recovery of bottle glass cullet, in partial replacement of Na-feldspar for sanitary-ware ceramic production are discussed. Attention is paid to the mullite growth kinetics and to the macroscopic properties of the final output, the latter ones depending on the developed micro-structures and vitrification grade. Measurements have been performed by in situ high temperature X-ray powder diffraction, scanning electron microscopy, thermal dilatometry, water absorption and mechanical testing. Glass substituting feldspar from 30 to 50 wt% allows one (i) to accelerate the mullite growth reaction kinetics, and (ii) to achieve macroscopic features of the ceramic output that comply with the latest technical requirements. The introduction of waste glass leads to (i) a general saving of fuel and reduction of the CO2-emissions during the firing stage, (ii) a preservation of mineral resources in terms of feldspars, and (iii) an efficient management of the bottle glass refuse by readdressing a part of it in the sanitary-ware manufacturing.
Assuntos
Compostos de Cálcio/química , Cerâmica/química , Vidro , Óxidos/química , Dióxido de Silício/química , Hidróxido de Sódio/química , Cinética , Microscopia Eletrônica de Varredura , Difração de PóRESUMO
PURPOSE: During radiological interventional procedures (RIP) the skin of a patient under examination may undergo a prolonged x-ray exposure, receiving a dose as high as 5 Gy in a single session. This paper describes the use of the OneDose(TM) cable-free system based on p-type MOSFET detectors to determine the entrance skin dose (ESD) at selected points during RIP. METHODS: At first, some dosimetric characteristics of the detector, such as reproducibility, linearity, and fading, have been investigated using a C-arc as a source of radiation. The reference setting (RS) was: 80 kV energy, 40 cm × 40 cm field of view (FOV), current-time product of 50 mAs and source to skin distance (SSD) of 50 cm. A calibrated PMX III solid state detector was used as the reference detector and Gafchromic(®) films have been used as an independent dosimetric system to test the entire procedure. A calibration factor for the RS and correction factors as functions of tube voltage and FOV size have been determined. RESULTS: Reproducibility ranged from 4% at low doses (around 10 cGy as measured by the reference detector) to about 1% for high doses (around 2 Gy). The system response was found to be linear with respect to both dose measured with the PMX III and tube voltage. The fading test has shown that the maximum deviation from the optimal reading conditions (3 min after a single irradiation) was 9.1% corresponding to four irradiations in one hour read 3 min after the last exposure. The calibration factor in the RS has shown that the system response at the kV energy range is about four times larger than in the MV energy range. A fifth order and fourth order polynomial functions were found to provide correction factors for tube voltage and FOV size, respectively, in measurement settings different than the RS. ESDs measured with the system after applying the proper correction factors agreed within one standard deviation (SD) with the corresponding ESDs measured with the reference detector. The ESDs measured with Gafchromic(®) films were in agreement within one SD compared to the ESDs measured using the OneDose(TM) system, as well. The global uncertainty associated to the OneDose(TM) system established in our experiments, ranged from 7% to 10%, depending on the duration of the RIP due to fading. These values are much lower than the uncertainty commonly accepted for general diagnostic practices (20%) and of about the same size of the uncertainty recommended for practices with high risk of deterministic side effects (7%). CONCLUSIONS: The OneDose(TM) system has shown a high sensitivity in the kV energy range and has been found capable of measuring the entrance skin dose in RIP.
Assuntos
Radiologia Intervencionista/instrumentação , Radiologia Intervencionista/métodos , Radiometria/instrumentação , Radiometria/métodos , Pele/efeitos da radiação , Algoritmos , Calibragem , Relação Dose-Resposta à Radiação , Desenho de Equipamento , Humanos , Modelos Lineares , Modelos Estatísticos , Modelos Teóricos , Dosagem Radioterapêutica , Reprodutibilidade dos Testes , Fatores de Tempo , Transistores EletrônicosRESUMO
BACKGROUND: To evaluate the association between polymorphisms involved in DNA repair and oxidative stress genes and mean dose to whole breast on acute skin reactions (erythema) in breast cancer (BC) patients following single shot partial breast irradiation (SSPBI) after breast conservative surgery. MATERIALS AND METHODS: Acute toxicity was assessed using vers.3 criteria. single nucleotides polymorphisms(SNPs) in genes: XRCC1(Arg399Gln/Arg194Trp), XRCC3 (A4541G-5'UTR/Thr241Met), GSTP1(Ile105Val), GSTA1 and RAD51(untranslated region). SNPs were determined in 57 BC patients by the Pyrosequencing analysis. Univariate(ORs and 95% CI) and logistic multivariate analyses (MVA) were performed to correlate polymorphic genes with the risk of developing acute skin reactions to radiotherapy. RESULTS: After SSPBI on the tumour bed following conservative surgery, grade 1 or 2 acute erythema was observed in 19 pts(33%). Univariate analysis indicated a higher significant risk of developing erythema in patients with polymorphic variant wt XRCC1Arg194Trp, mut/het XRCC3Thr241Met, wt/het XRCC3A4541G-5'UTR. Similarly a higher erythema rate was also found in the presence of mut/het of XRCC1Arg194Trp or wt of GSTA1. Whereas, a lower erythema rate was observed in patients with mut/het of XRCC1Arg194Trp or wt of XRCC1Arg399Gln. The mean dose to whole breast(p = 0.002), the presence of either mut/het XRCC1Arg194Trp or wt XRCC3Thr241Met (p = 0.006) and the presence of either mut/het XRCC1Arg194Trp or wt GSTA1(p = 0.031) were confirmed as predictors of radiotherapy-induced erythema by MVA. CONCLUSIONS: The Whole breast mean dose together with the presence of some polymorphic genes involved in DNA repair or oxidative stress could explain the erythema observed after SSPBI, but further studies are needed to confirm these results in a larger cohort.
Assuntos
Neoplasias da Mama/genética , Neoplasias da Mama/radioterapia , Eritema/genética , Predisposição Genética para Doença/genética , Polimorfismo de Nucleotídeo Único , Dosagem Radioterapêutica , Idoso , Idoso de 80 Anos ou mais , Neoplasias da Mama/cirurgia , Reparo do DNA/genética , Proteínas de Ligação a DNA/genética , Eritema/etiologia , Feminino , Genótipo , Glutationa S-Transferase pi/genética , Glutationa Transferase/genética , Humanos , Modelos Logísticos , Pessoa de Meia-Idade , Análise Multivariada , Estresse Oxidativo/genética , Estudos Prospectivos , Rad51 Recombinase/genética , Radioterapia Conformacional/efeitos adversos , Radioterapia Conformacional/métodos , Fatores de Risco , Proteína 1 Complementadora Cruzada de Reparo de Raio-XRESUMO
The current framework of radiological protection of occupational exposed medical workers reduced the eye-lens equivalent dose limit from 150 to 20 mSv per year requiring an accurate dosimetric evaluation and an increase understanding of radiation induced effects on Lens cells considering the typical scenario of occupational exposed medical operators. Indeed, it is widely accepted that genomic damage of Lens epithelial cells (LEC) is a key mechanism of cataractogenesis. However, the relationship between apoptosis and cataractogenesis is still controversial. In this study biological and physical data are combined to improve the understanding of radiation induced effects on LEC. To characterize the occupational exposure of medical workers during angiographic procedures an INNOVA 4100 (General Electric Healthcare) equipment was used (scenario A). Additional experiments were conducted using a research tube (scenario B). For both scenarios, the frequencies of binucleated cells, micronuclei, p21-positive cells were assessed with different doses and dose rates. A Monte-Carlo study was conducted using a model for the photon generation with the X-ray tubes and with the Petri dishes considering the two different scenarios (A and B) to reproduce the experimental conditions and validate the irradiation setups to the cells. The simulation results have been tallied using the Monte Carlo code MCNP6. The spectral characteristics of the different X-ray beams have been estimated. All irradiated samples showed frequencies of micronuclei and p21-positive cells higher than the unirradiated controls. Differences in frequencies increased with the delivered dose measured with Gafchromic films XR-RV3. The spectrum incident on eye lens and Petri, as estimated with MCNP6, was in good agreement in the scenario A (confirming the experimental setup), while the mean energy spectrum was higher in the scenario B. Nevertheless, the response of LEC seemed mainly related to the measured absorbed dose. No effects on viability were detected. Our results support the hypothesis that apoptosis is not responsible for cataract induced by low doses of X-ray (i.e. 25 mGy) while the induction of transient p21 may interfere with the disassembly of the nuclear envelop in differentiating LEC, leading to cataract formation. Further studies are needed to better clarify the relationship we suggested between DNA damage, transient p21 induction and the inability of LEC enucleation.
Assuntos
Catarata/etiologia , Dano ao DNA/efeitos da radiação , Células Epiteliais/patologia , Células Epiteliais/efeitos da radiação , Cristalino/citologia , Cristalino/efeitos da radiação , Exposição Ocupacional/efeitos adversos , Doses de Radiação , Raios X/efeitos adversos , Células Cultivadas , Humanos , Método de Monte CarloRESUMO
The purpose of this work is to evaluate the potential third-party radiation exposure from patients undergoing therapy with 131I for ablation of residual thyroid tumor or metastases, based in part on serial measurements of exposure rates. Exposure rate measurements were performed at 1 m and 5 cm from the surface of each treated patient until patient release. Dose estimates based on measured exposure rates were compared with those based on analytic point-source (PSM) and line-source (LSM) models. Effective doses D(∞) to travelers, co-workers and sleeping partners were estimated by using the standard gamma factor (Γ) and the physical half-life or the values derived from measured data. Seven hundred ten patients were studied until the exposure at 1 m was below the constraints of 0.010 mSv. The 131I activities administered ranged from 1.85 to 11.0 GBq (median: 3.7 GBq), according to the therapeutic requirements. Based on the PSM and an experimental Γ, the mean/maximum estimated D(∞) to sleeping partners, partners, travelers, and co-workers were 2.60/20.65, 0.32/2.53, 0.96/7.59, and 0.57/4.50 mSv, respectively. Using the LSM and an experimental Γ, the D(∞) values were 2.41/19.15, 0.32/2.50, 0.83/6.62, and 0.57/4.42 mSv, respectively, while they were almost double using the theoretical Γ. The results presented, based on measured data in a large cohort of 131I-treated thyroid cancer patients, will allow more accurate estimation of potential third-party D(∞) following patient release and thus may be used to better inform physicians and hospital staff on recommendations for patient release and post-release precautions following radioiodine therapies.
Assuntos
Exposição Ambiental/análise , Neoplasias da Glândula Tireoide/radioterapia , Técnicas de Ablação , Adolescente , Adulto , Idoso , Idoso de 80 Anos ou mais , Criança , Família , Feminino , Humanos , Radioisótopos do Iodo/uso terapêutico , Masculino , Pessoa de Meia-Idade , Modelos Biológicos , Metástase Neoplásica , Alta do Paciente , Radiometria , Adulto JovemRESUMO
PURPOSE: This study investigates whether the abscopal effect induced by radiation-therapy (RT) is able to sterilize non-irradiated tumour cells through bystander signals. MATERIAL AND METHODS: Wild-type (wt)-p53 or p53-null HCT116 human colon cancer cells were xenografted into both flanks of athymic female nude mice. When tumours reached a volume of 0.2 cm(3), irradiation was performed, under strict dose monitoring, with a dedicated mobile accelerator designed for intra-Operative-RT (IORT). A dose of 10 or 20 Gy (IR groups), delivered by a 10 MeV electron beam, was delivered to a tumour established in one side flank, leaving the other non-irradiated (NIR groups). A subset of mice were sacrificed early on to carry out short-term molecular analyses. RESULTS: All directly-irradiated tumours, showed a dose-dependent delayed and reduced regrowth, independent of the p53 status. Importantly, a significant effect on tumour-growth inhibition was also demonstrated in NIR wt-p53 tumours in the 20 Gy-irradiation group, with a moderate effect also evident after 10 Gy-irradiation. In contrast, no significant difference was observed in the NIR p53-null tumours, independent of the dose delivered. Molecular analyses indicate that p53-dependent signals might be responsible for the abscopal effect in our model system, via a pro-apoptotic pathway. CONCLUSIONS: We suggest that the interplay between delivered dose and p53 status might help to sterilize out-of-field tumour cells.
Assuntos
Efeito Espectador/efeitos da radiação , Neoplasias/patologia , Neoplasias/radioterapia , Radioterapia/métodos , Proteína Supressora de Tumor p53/metabolismo , Animais , Apoptose , Linhagem Celular Tumoral , Relação Dose-Resposta à Radiação , Elétrons , Feminino , Raios gama , Células HCT116 , Humanos , Imuno-Histoquímica , Camundongos , Camundongos Nus , Transplante de Neoplasias , Radiometria/métodosRESUMO
AIMS AND BACKGROUND: To present the Italian state-of-the-art contribution to radiobiology of external beam radiotherapy, brachytherapy, and radionuclide radiotherapy. METHODS AND STUDY DESIGN: A survey of the literature was carried out, using PubMed, by some independent researchers of the Italian group of radiobiology. Each paper was reviewed by researchers of centers not comprising its authors. The survey was limited to papers in English published over the last 20 years, written by Italian investigators or in Italian institutions, excluding review articles. RESULTS: A total of 135 papers have been published in journals with an impact factor, with an increase in the number of published papers over time, for external beam radiotherapy rather than radionuclide radiotherapy. The quantity and quality of the papers researched constitutes a proof of the enduring interest in clinical radiobiology among Italian investigators. CONCLUSIONS: The survey could be useful to individuate expert partners for an Italian network on clinical radiobiology, addressing future collaborative investigations.
Assuntos
Braquiterapia , Neoplasias/diagnóstico por imagem , Neoplasias/radioterapia , Padrões de Prática Médica , Radiobiologia , Radiologia , Pesquisa Biomédica/tendências , Braquiterapia/tendências , Fracionamento da Dose de Radiação , Relação Dose-Resposta à Radiação , Humanos , Itália , Modelos Teóricos , Medicina Nuclear , Padrões de Prática Médica/normas , Padrões de Prática Médica/tendências , Radioterapia (Especialidade) , Radiobiologia/normas , Radiobiologia/tendências , Radiologia/normas , Radiologia/tendências , Radiologia Intervencionista , CintilografiaRESUMO
PURPOSE: The purpose of this study is to evaluate the radiation dose in patients undergoing liver angiographic procedure and verify the usefulness of different dose measurements to prevent deterministic effects. Gafchromic film, MicroMOSFET data and DIAMENTOR device of the X-ray system were used to characterize the examined interventional radiology (IR) procedure. MATERIALS AND METHODS: A liver embolization procedure, the SIRT (Selective Internal Radiation Therapy), was investigated. The exposure parameters from the DIAMENTOR as well as patient and geometrical data were registered. Entrance skin dose map obtained using Gafchromic film (ESDGAF) in a standard phantom as well as in 12 patients were used to calculate the maximum skin dose (MSDGAF). MicroMOSFETs were used to assess ESD in relevant points/areas. Moreover, the maximum value of five MicroMOSFETs array, due to the extension of treated area and to the relative distance of 2-3 cm of two adjacent MicroMOSFETs, was useful to predict the MSD without interfering with the clinical practice. PCXMC vers.1.5 was used to calculate effective dose (E) and equivalent dose (H). RESULTS: The mean dose-area product (DAPDIAMENTOR) for SIRT procedures was 166 Gycm2, although a wide range was observed. The mean MSDGAF for SIRT procedures was 1090 mGy, although a wide range was experienced. A correlation was found between the MSDGAF measured on a patient and the DAPDIAMENTOR value for liver embolizations. MOSFET and Gafchromic data were in agreement within 5% in homogeneous area and within 20% in high dose gradient regions. The mean equivalent dose in critical organs was 89.8 mSv for kidneys, 22.9 mSv for pancreas, 20.2 mSv for small intestine and 21.0 mSv for spleen. Whereas the mean E was 3.7 mSv (range: 0.5-13.7). CONCLUSIONS: Gafchromic films result useful to study patient exposure and determine localization and amplitude of high dose skin areas to better predict the skin injuries. Then, DAPDIAMENTOR or MOSFET data could offer real-time methods, as on-line dose alert, to avoid any side effects during liver embolization with prolonged duration.
Assuntos
Angiografia/efeitos adversos , Carcinoma Hepatocelular/diagnóstico por imagem , Neoplasias Hepáticas/diagnóstico por imagem , Pele/efeitos da radiação , Adulto , Idoso , Braquiterapia , Carcinoma Hepatocelular/radioterapia , Carcinoma Hepatocelular/cirurgia , Feminino , Humanos , Neoplasias Hepáticas/radioterapia , Neoplasias Hepáticas/cirurgia , Masculino , Pessoa de Meia-Idade , Doses de RadiaçãoRESUMO
OBJECTIVES: To implement a new cost efficacy internal Service for blood component irradiation, we carried out specific procedures and quality assurance reports using the linear accelerators (LINACs) of the Regina Elena Institute (IRE) Radiotherapy Department instead of a dedicated device. METHODS: The technical aspects, quality assurance and regulatory requirements of the internal procedure to set up a local irradiated blood bank have been defined. The LINACs of the IRE Radiotherapy Department were used to deliver a mean dose of 32 Gy and dose accuracy was checked with gafchromic film. The overall time/cost of this procedure was compared with the previous procedure, out-sourcing the irradiation of blood components. RESULTS: A total of 1996 blood component units were internally irradiated in the first year. Moreover, reducing the overall procedure time by a third. Overall cost/bag of external and internal procedures was approx. 66 and 11 , respectively. Thus the average saving of cost/bag was higher than 80%. The use of gafchromic films in all irradiated blood component bags allowed the accuracy of the dose delivered to blood to be checked. CONCLUSIONS: By utilizing LINACs installed in the Radiotherapy Department it is possible to provide an internal blood component irradiation service, capitalizing on internal resources without any inconvenience/discomfort to patients undergoing radiotherapy and satisfying governmental regulatory requirements. The internal irradiation procedures has proven to be safe and feasible, and along with the significant cost/time reduction suggests that it is more advantageous than external procedures.