Objective: To evaluate the exposure parameters, radiation protection, absorbed dose and radiographic image quality of the DIOX ® intraoral portable radiography device. Methods: The exposure parameters were measured using the Xi UNFORS detector. Operator exposure to secondary radiation was measured using the 1800cc ionization chamber coupled to the electrometer. The absorbed dose (D) in the patient was calculated using TLD-100H positioned in the Alderson RANDO anthropomorphic simulator. The quality of the radiographic digital image was assessed by comparing radiographic images obtained from two conventional devices (CS 2200 ® , Carestream Health; Heliodent plus ® , Sirona Dental Systems GMbH) with the radiological simulator of the upper molar region RMI (Radiation Measurements Instruments), using three acquisition sensors: Kodak RVG 5000 ® and Kodak PSP ® , Eastman Kodak Company, Rochester, NY; EVO Micro Image ® , Brazil. Results:The DIOX intraoral portable radiographic device demonstrated reliability in relation to the performance of the standard evaluated parameters, except for the diameter of the radiation field (5.8 mm) less or greater. No evidence of device head radiation was detected. The Pb lead protection of the apparatus attenuates the secondary radiation, thus protecting the operator. However, it was observed that the region of the operator's gonads was the most exposed during the measurements. In the Alderson RANDO anthropomorphic simulator, the highest value of D was in the region corresponding to the submandibular and lingual glands of the left side (0.568 mGy). The image quality of the DIOX portable radiographic apparatus presented quality standards equivalent to those produced by the two conventional radiographic devices. conclusion: The DIOX intraoral portable radiography device demonstrated reliability in relation to the quality control and radioprotection criteria, according to international standards. Results obtained demonstrated the safe use of the DIOX intraoral portable radiography device and indicated the need for debate and change in international sanitary oversight standards regarding the use of portable XR devices in dentistry.

Purpose: Use the methodology developed by the National Research Council Canada (NRC), for Fricke Dosimetry, to determine the G‐value used at Ir‐192 energies. Methods: In this study the Radiology Science Laboratory of Rio de Janeiro State University (LCR),based the G‐value determination on the NRC method, using polyethylene bags. Briefly, this method consists of interpolating the G‐values calculated for Co‐60 and 250 kV x‐rays for the average energy of Ir‐192 (380 keV). As the Co‐60 G‐value is well described at literature, and associated with low uncertainties, it wasn't measured in this present study. The G‐values for 150 kV (Effective energy of 68 keV), 250 kV (Effective energy of 132 keV)and 300 kV(Effective energy of 159 keV)were calculated using the air kerma given by a calibrated ion chamber, and making it equivalent to the absorbed to the Fricke solution, using a Monte Carlo calculated factor for this conversion. Instead of interpolations, as described by the NRC, we displayed the G‐values points in a graph, and used the line equation to determine the G‐ value for Ir‐192 (380 keV). Results: The measured G‐values were 1.436 ± 0.002 µmol/J for 150 kV, 1.472 ± 0.002 µmol/J for 250 kV, 1.497 ± 0.003 µmol/J for 300 kV. The used G‐value for Co‐60 (1.25 MeV) was 1,613 µmol/J. The R‐square of the fitted regression line among those G‐value points was 0.991. Using the line equation, the calculate G‐value for 380 KeV was 1.542 µmol/J. Conclusion: The Result found for Ir‐192 G‐value is 3,1% different (lower) from the NRC value. But it agrees with previous literature results, using different methodologies to calculate this parameter. We will continue this experiment measuring the G‐value for Co‐60 in order to compare with the NRC method and better understand the reasons for the found differences.

Purpose: To compare absorbed dose to water standards for HDR brachytherapy dosimetry developed by the Radiological Science Laboratory of Rio de Janeiro State University (LCR) and the National Research Council, Canada (NRC). Methods: The two institutions have separately developed absorbed dose standards based on the Fricke dosimetry system. There are important differences between the two standards, including: preparation and read‐out of the Fricke solution, irradiation geometry of the Fricke holder in relation to the Ir‐192 source, and determination of the G‐value to be used at Ir‐192 energies. All measurements for both standards were made directly at the NRC laboratory (i.e., no transfer instrument was used) using a single Ir‐192 source (microSelectron v2). In addition, the NRC group has established a self‐consistent method to determine the G‐value for Ir‐192, based on an interpolation between G‐values obtained at Co‐60 and 250kVp X‐rays, and this measurement was repeated using the LCR Fricke solution to investigate possible systematic uncertainties. Results: G‐values for Co‐60 and 250 kVp x‐rays, obtained using the LCR Fricke system, agreed with the NRC values within 0.5 % and 1 % respectively, indicating that the general assumption of universal G‐values is appropriate in this case. The standard uncertainty in the determination of G for Ir‐192 is estimated to be 0.6 %. For the comparison of absorbed dose measurements at the reference point for Ir‐192 (1 cm depth in water, perpendicular to the seed long‐axis), the ratio Dw(NRC)/Dw(LCR) was found to be 1.011 with a combined standard uncertainty of 1.7 %, k=1. Conclusion: The agreement in the absorbed dose to water values for the LCR and NRC systems is very encouraging. Combined with the lower uncertainty in this approach compared to the present air‐kerma approach, these results reaffirm the use of Fricke solution as a potential primary standard for HDR Ir‐192 brachytherapy.

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Purpose: To compare conversion coefficient of KERMA free in air to glandular dose, in mammography, simulated to BR12 model and a realistic breast voxel model. Method and Materials: We simulate the glandular dose (Dg) and KERMA free in air (Kai), using the Monte Carlo program MCNP (version 4B) to estimate the conversion coefficient (cg) of KERMA free in air at entrance skin in glandular dose. The computational universe generated to simulate a mammographic procedure mimics LORAD III mammographic equipment. The focal spot of molybdenum irradiates photons isotropically in a solid angle of 16.8°. The bucky is 0.6190 m far from de focal spot. Above the model there is a PMMA compress paddle 0.002 m thicker. The add filtration (30 μm Mo thicker and 25 μm Rh thicker) was located at 0.050 m far from the focal spot. Tow spectra were used in voxel model simulations: 28 kVp with Mo add filtration and 30 kVp with Rh add filtration. Results: The cg presented on Mo/Rh simulation was 1.5 times larger than the presented on Mo/Mo simulation. Comparing the voxel model to the BR12 model we have actually a super estimation on both simulated cg values: 3.4 times considering the simulation with Mo/Mo target/filter combination, and 2.4 times considering the simulation with Mo/Rh target/filter combination. Conclusion: The cg values show a decrease of 58.7% considering the Mo/Rh target/filter combination and a decrease of 70.2% considering the Mo/Mo target/filter combination, to the realistic breast model as comparative pattern. These variation on cg are probably caused by the definition of a non‐anthropomorphic model composed by an homogeneous distribution of tissues as pattern, that makes unviable the observation of the absorbed energy by each tissue; and because this model do not consider the position of glandular tissue in the real breast geometry.