Development of an additional filtration system by 3D printing for the implementation of new X-ray beam qualities used in diagnostic radiology.

The Calibration Laboratory (LCI) of the Nuclear and Energy Research Institute (IPEN-/CNEN) offers calibration services for radiation measurements instruments used in radiation protection, diagnostic radiology and radiotherapy. LCI produces radiation qualities and irradiation conditions which are in accordance with the national and international standard requirements. In order to establish the recommended radiation qualities for diagnostic radiology, X-ray beams generated in laboratory are modified for the irradiation conditions found in equipment routinely used in healthcare services. In this work, a new additional filtration system was developed to be adapted to the existing filter system at LCI. The new filter support can be coupled to the PTW Bench Control installed at the LCI X-ray system. Using a FDM 3D printer, a support model and a set of drawers were developed for the placement of additional filters. The models were also developed to fit each specific drawer of each filter to be used in the laboratory routine, coupled to the specific sensors that fit the spaces of the support part. Additionally, a microcontroller based on Arduino, micro switches, low- and high-level programming, allow checking of drawer status and integration of information with the laboratory control system. The system allows the recognition of the filter inserted in the drawer from sensors attached to the support. Tests were carried out to verify the usability of the system in the routine, adding Ag (silver) and Cu (copper) filters, for the characterization of attenuated radiation beams of interest in diagnostic radiology

Measurement of the quantity practical peak voltage in the radiology practice

OBJETIVO: O objetivo deste trabalho foi estudar a grandeza practical peak voltage (PPV), determinada a partir da forma de onda de tensão aplicada a tubos radiológicos, e compará-la com algumas definições de kVp para diferentes tipos de geradores: monofásico (onda completa, clínico), trifásico (seis pulsos, clínico) e potencial constante (industrial). MATERIAIS E MÉTODOS: O trabalho envolveu a comparação do PPV medido invasivamente (utilizando um divisor de tensão) com a resposta de dois medidores comerciais não invasivos, além dos valores de outras grandezas usadas para medição da tensão de pico aplicada ao tubo de raios X, e a análise da variação do PPV com a ondulação percentual da tensão (ripple). RESULTADOS: Verificou-se que a diferença entre o PPV e as definições mais comuns de tensão de pico aumenta com o ripple. Os valores de PPV variaram em até 3% e 5%, respectivamente, na comparação entre medições invasivas e não invasivas feitas com os equipamentos trifásico e monofásico. CONCLUSÃO: Os resultados demonstraram que a principal grandeza de influência que afeta o PPV é o ripple da tensão. Adicionalmente, valores de PPV obtidos com medidores não invasivos devem ser avaliados considerando que eles dependem da taxa de aquisição e da forma de onda adquirida pelo instrumento.OBJECTIVE: The present study was aimed at evaluating the practical peak voltage (PPV) determined from the voltage waveform applied to x-ray tubes and comparing it with some kVp definitions for different types of x-ray equipment: single-phase (full-wave) and three-phase (six-pulse) clinical x-ray generators, and an industrial constant potential apparatus. MATERIALS AND METHODS: The study involved the comparison between invasively measured PPV (with voltage dividers) and values obtained with two commercial noninvasive meters, besides values of other quantities utilized for measuring the x-ray tube peak voltage. The PPV variation with the voltage ripple was also analyzed in the present study. RESULTS: The authors observed that the difference between PPV and the most common peak voltage definitions increases with the ripple. PPV values varied up to 3% and 5%, respectively, in the comparison between invasive and non-invasive measurements with single-phase and three-phase devices. CONCLUSION: The results demonstrated that voltage ripple is the main quantity influencing the invasive or non-invasive PPV determination. Additionally, non-invasively measured PPV values should be evaluated taking into consideration their dependence on the data sample rate and waveform obtained by the device.Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq