JOSEMARY ANGELICA CORREA GONCALVES

JOSEMARY ANGELICA CORREA GONCALVES

(Fonte: Lattes)

Resumo

Possui graduação em Física pela Pontifícia Universidade Católica de São Paulo (1987), mestrado em Técnicas e Aplicações Nucleares pelo Instituto de Pesquisas Energéticas e Nucleares (1990), doutorado em Técnicas e Aplicações Nucleares pelo Instituto de Pesquisas Energéticas e Nucleares (1993) e Pós-Doutorado de Curta duração na Universidade de Coimbra com bolsa FAPESP (1997). Foi professora da Pontifícia Universidade Católica de São Paulo entre 1996-2020. Atualmente é pesquisadora titular do Instituto de Pesquisas Energéticas e Nucleares. Tem experiência na área de Engenharia Nuclear, com ênfase em Instrumentação para Medida e Controle de Radiação, atuando principalmente nos seguintes temas: detectores semicondutores de Si, espectrometria e dosimetria de partículas carregadas e radiação eletromagnética, detectores gasosos de catodo resistivo e parâmetros de transporte de elétrons em gases. (Texto extraído do Currículo Lattes em 12 nov. 2021)

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Online electron beam monitoring with a diode-based dosimetry system in routine quality control
2023 - GONCALVES, JOSEMARY A.C.; MANGIAROTTI, ALESSIO; SOMESSARI, ELIZABETH S.R.; NAPOLITANO, CELIA M.; BUENO, CARMEN C.
Dosimetric parameters and radiation tolerance of epitaxial diodes for diagnostic radiology and computed tomography X-rays
2023 - GONCALVES, JOSEMARY A.C.; MANGIAROTTI, ALESSIO; POTIENS, MARIA P.A.; CALDAS, LINDA V.E.; BUENO, CARMEN C.
Characterization of a commercial PIN diode for radiotherapy photon beam dosimetry
2023 - SILVA, IANDRA T.; PIERI, KAREN; ALBINO, LUCAS D.; FONTANA, THIAGO S.; SANTOS, MATHEUS F. dos; ROESLER, ERNESTO; ASFORA, VIVIANE K.; OLIVEIRA, CHARLES; GONCALVES, JOSEMARY A.C.; BUENO, CARMEN C.; KHOURY, HELEN J.
Dosimetric evaluation of an epitaxial silicon diode as an online dosimeter for orthovoltage photon beam radiotherapy
2021 - BUENO, C.C.; GONCALVES, J.A.C.; MANGIAROTTI, A.
The response of a dosimetry system based on an epitaxial silicon diode as an online dosimeter for orthovoltage photon beam radiotherapy has been investigated in this work. To be used as a dosimeter, each diode is housed in a light-tight probe, and its readout electrode is directly connected to the Keithley 6517B electrometer. All current measurements are carried out in short-circuit mode with the diode unbiased and its backplane grounded. The data acquired by the electrometer are directly sent to a personal computer via a GBIP interface controlled by software developed in LabView to analyze the current signals. A Pantak/Seifert X-ray tube is used to irradiate the diode, placed 50.0 cm away in a radiation field of 8 cm, with 10, 25, 30, and 50 kV photons. The dose rate response is investigated for the 50 kV beam by varying the current tube from 2 to 20 mA. As expected, the induced current is linearly dependent on the dose rate within the range of 0.8 and 8.05 mGy/s. The current signals are quite stable, with a repeatability parameter of less than 0.2%. The dose-responses assessed offline by integrating the current signals are linear between 0.5 and 3.0 Gy despite being slightly dependent on the photon energy. However, in this dose range, no dose rate dependence is observed. These results are theoretically supported by dose and dose rate calculations performed assuming the diode is thin compared with the standard values of the minority carrier diffusion lengths in the epitaxial layer. Good agreement is found between calculations and experimental data. Investigations of possible radiation damage produced in the diode through dynamic measurements of dark current and capacitance as a function of the accumulated dose are currently in progress.
Dose rate mapping in an industrial 60Co irradiator using an online photodiode-based dosimetry system
2021 - GONCALVES, J.A.C.; MANGIAROTTI, A.; BUENO, C.C.
In the radiation processing field, any irradiation process is designed to irradiate products uniformly, but in practice, a reasonable variation in the absorbed dose through the product is accepted. However, the irradiation of inhomogeneous or irregularly shaped products gives rise to complex dose variations only assessed through dose mapping. It requires complementary dosimeters bearing good spatial resolution, prompt and easy readout, and cost-effectiveness. These features are found in silicon diodes that, despite all these advantages, are prone to radiation damage. This damage is mitigated with photodiodes whose thicknesses are much smaller than the minority carrier diffusion length at the anticipated accumulated dose. In this work, an in-house dosimetry system based on a thin photodiode is applied for online mapping dose rates, between 3.7 and 52.8 Gy/h, delivered by a Panoramic 60Co industrial facility. The operational principle of these dosimeters relies on the real-time acquisition of the induced currents from the irradiated diode operating in the short-circuit mode without externally applied voltage. Under this condition, the dose is assessed offline via the integration of these current signals. The radial mapping of the radiation field is performed by rotating the diode around the central axis of the panoramic irradiator, covering 360º at intervals of 10º. For comparative purposes, alanine dosimeters are also irradiated together with the diode. The experimental results are benchmarked with Monte Carlo simulations of the dose rate curves. Good agreement between the simulated values and the readings of both dosimeters is found. It reveals that the photodiode-dosimetry system is a reliable alternative to map dose rate fields and the effectiveness of Monte Carlo simulations as a predictive tool for dose rate measurements in an irradiator.
Measurement of the insensitive surface layer thickness of a PIN photodiode based on alpha-particle spectrometry
2022 - PASCOALINO, K.; CAMARGO, F.; GONCALVES, J.A.C.; BUENO, C.C.
In this work, the insensitive layer thickness of a PIN photodiode (SFH206K - Osram) has been measured by varying the incident angle of a collimated monoenergetic alpha particle beam. This technique is based on variations in the path lengths of alpha particles through the insensitive layer and the correspondent energy losses when they impinge on a diode surface at different angles. Therefore, the pulse heights of these alpha particles, closely related to the energies deposited in the active volume of the diode, also depend on their incident angle. So, the difference between the pulse height of alpha particles perpendicularly incident on the diode surface and at any incident angle enables the insensitive layer thickness to be assessed. The result obtained (711  23) nm, less than 1% of the intrinsic layer thickness, besides validating the employed method, demonstrates that the investigated diode is suitable for high resolution charged particle spectrometry.
Dose rate mapping of an industrial 60Co irradiator using an online photodiode-based dosimetry system
2022 - GONCALVES, JOSEMARY A.C.; MANGIAROTTI, ALESSIO; BUENO, CARMEN C.
In this work, a housemade dosimetry system based on a thin photodiode is applied for online mapping of dose rates, between 2.6 and 37.7 Gy/h, delivered by a Panoramic 60Co industrial facility. The operational principle of the dosimeter relies on the real-time acquisition of the induced currents from the irradiated diode operating in the short-circuit mode without externally applied voltage. The radial mapping of the radiation field is performed by rotating the diode around the central axis of the panoramic irradiator, covering 360° at intervals of 18°. The results are benchmarked with alanine dosimeters, Monte Carlo simulations, and reference dose rates retrieved from the facility calibration. The overall consistency of the whole data complies with the maximum response variation (8%, k = 2) recommended by the International Standard Protocols for routine dosimeters in radiation processing dosimetry. It reveals that the photodiode-dosimetry system is a reliable alternative to map dose rate fields and the effectiveness of Monte Carlo simulations as a predictive tool for dose rate measurements in an irradiator.
Transit dose measurements using alanine and diode-based dosimeters
2022 - GONCALVES, J.A.C.; SOMESSARI, E.S.R.; SOMESSARI, S.L.; BUENO, C.C.
The growing interest in low-dose (< 100 Gy) radiation processing applications has raised concerns about accurately measuring the absorbed dose in irradiated materials. Depending on the irradiator design, the transit time due to the radioactive source movement (or the product itself) until the stable irradiation position might affect the predicted absorbed dose. This work aims to evaluate the transit dose in a 60Co Gammacell 220-Nordion irradiator, which has radioactive sources settled at the bottom of a lead shielding. When the facility is on, the product and the dosimeter are mechanically guided down to the irradiation position, and hereafter the selected exposure time starts to be counted. At the end of irradiation, both product and dosimeter rise to the initial position enabling them to be gathered by the operator. The product is continuously irradiated at different dose rates during its fall and rise movement, preventing the transit dose from being obtained straightforward. The experimental approach adopted is to assess the transit time, and thus the transit dose, using an online diode-based dosimetry system previously calibrated against reference standard alanine dosimeters. The agreement between the transit doses attained with the diode (0.41 ± 0.02) Gy and alanine (0.38 ± 0.01) Gy validates the method herein proposed.
Characterization of a thin photodiode as a routine dosimeter for low-dose radiation processing applications
2022 - GONCALVES, JOSEMARY A.C.; MANGIAROTTI, ALESSIO; BUENO, CARMEN C.
The characterization of a dosimetry system based on a commercial PIN photodiode as a routine dosimeter in a 60Co industrial facility is reported. The main parameters of the dose rate response (repeatability, reproducibility, and angular dependence) and the dose response (dependence on both dose rate and accumulated dose) are investigated. The results obtained, within a dose rate range of 3.7–52.8 Gy/h and doses up to 200 Gy, fully adhere to the standard protocols established for radiation processing dosimetry. The diode performance as a routine dosimeter is validated by the good overall agreement with radiochromic films and alanine dosimetry.
Performance characterization of dosimeters based on radiation-hard silicon diodes in gamma radiation processing
2022 - BUENO, C.C.; CAMARGO, F.; GONCALVES, J.A.C.; PASCOALINO, K.; MANGIAROTTI, A.; TUOMINEN, E.; HARKONEN, J.
The dosimetric response of silicon diodes produced with distinct engineering technologies, Magnetic Czochralski (MCz), and standard Float Zone (Fz), has been investigated, aiming at their use for online dosimeters in gamma radiation processing applications. The p+-n-n+ junction diodes, 300 µm thick with an active area of 25 mm2, are operated as online radiation dosimeters in the short-circuit current mode. In this case, the key dosimetric quantity is the dose rate, which is correlated with the output current from the diode subjected to radiation. Thus, the dose is obtained offline by the integration of the corresponding current signal. The irradiations are performed with an industrial Gammacell 60Co facility at 2.3–2.44 kGy/h covering doses up to 275 kGy. Under continuous irradiation, both diodes delivered current signals whose intensities decreased with accumulated doses. Mitigation of this decay has been accomplished by pre-irradiating the devices to 700 kGy. Polynomial functions best represent the dose responses for either pristine or preirradiated diodes. The relevant dosimetric parameters as response stability, charge sensitivity, and repeatability of current signals (<5%) reveal the better performance of the MCz diode. It is important to note that the whole dataset fully complies with the international standard protocols for routine dosimeters in radiation processing dosimetry. Regarding radiation damage, which in unbiased diodes manifests primarily in the decay of current sensitivity, the results also showed greater tolerance of the MCz diode. Based on these studies, large availability, and better cost-effectiveness, it is possible to endorse the potential use of MCz devices as online routine dosimeters in radiation processing applications. However, the data reproducibility with the accumulated dose, the dose lifespan, and the effect of the irradiation conditions (e.g., temperature, relative humidity, and dose fractionating) remain to be investigated. Works in this direction are currently in progress.