Study on patient dosimetry and image quality in digital mammography

Abstract Introduction Digital mammography present many advantages in comparison to conventional mammography, such as high dynamic range and the post-processing of acquired images. One problem is that protocols may not be optimized, resulting in higher absorbed doses to patients. The objective of this work is to evaluate image quality and to estimate mean glandular doses (MGD) in patients submitted to mammography examinations with three digital systems and one screen-film system in Recife, Brazil. Methods To estimate the MGD, the parameters used to acquire images of 5475 patients, with ages between 40 and 64 years and compressed breasts between 2 and 9 cm, were registered. The MGD was calculated by multiplying the incident air kerma with conversion coefficients depending on the anode/filter, breast glandularity and half-value layer. The image quality evaluation of the digital systems was made using objective and subjective European criteria. Results The results showed MGDs in the range of 0.4-10.3 mGy and the higher values were observed with digital systems. It was also observed that in the digital systems the use of compression force is not adequate and the irradiation parameters are not optimized. The images failed to reproduce the pectoral muscle and the contrast-to-noise ratio was not adequate for one system, indicating the need to improve the patient's positioning and the exposure parameters. Conclusion It can be concluded that the use of non-optimized irradiation parameters is causing the higher doses with digital systems, highlighting the insufficient compression force.

Dosimetric evaluation of X-ray examinations of paranasal sinuses in pediatric patients / Avaliação dosimétrica de pacientes pediátricos submetidos a exames radiográficos de seios paranasais

Abstract Objective: To estimate the entrance surface air kerma (Ka,e) and air kerma in the region of radiosensitive organs in radiographs of pediatric paranasal sinuses. Materials and Methods: Patient data and irradiation parameters were collected in examinations of the paranasal sinuses in children from 0 to 15 years of age at two children's hospitals in the city of Recife, PE, Brazil. We estimated the Ka,e using the X-ray tube outputs and selected parameters. To estimate the air kerma values in the regions of the eyes and thyroid, we used thermoluminescent dosimeters. Results: The Ka,e values ranged from 0.065 to 1.446 mGy in cavum radiographs, from 0.104 to 7.298 mGy in Caldwell views, and from 0.113 to 7.824 mGy in Waters views. Air kerma values in the region of the eyes ranged from 0.001 to 0.968 mGy in cavum radiographs and from 0.011 to 0.422 mGy in Caldwell and Waters views . In the thyroid region, air kerma values ranged from 0.005 to 0.932 mGy in cavum radiographs and from 0.002 to 0.972 mGy in Caldwell and Waters views. Conclusion: The radiation levels used at the institutions under study were higher than those recommended in international protocols. We recommend that interventions be initiated in order to reduce patient exposure to radiation and therefore the risks associated with radiological examination of the paranasal sinuses.

Resumo Objetivo: Estimar o kerma no ar na superfície de entrada (Ka,e) e o kerma no ar na região de órgãos radiossensíveis em radiografias pediátricas dos seios paranasais. Materiais e Métodos: Foram coletados os dados dos pacientes e parâmetros de irradiação em exames de seios paranasais de crianças com 0 a 15 anos, em dois hospitais infantis na cidade do Recife, PE. O Ka,e foi estimado utilizando os rendimentos dos tubos de raios X e os parâmetros selecionados. Os valores de kerma no ar nas regiões dos olhos e tireoide foram estimados utilizando dosímetros termoluminescentes. Resultados: Os valores de Ka,e variaram de 0,065 a 1,446 mGy para radiografias cavum, 0,104 a 7,298 mGy para Caldwell e 0,113 a 7,824 mGy para Waters. Os valores de kerma no ar na região dos olhos variaram de 0,001 a 0,968 mGy para cavum e 0,011 a 0,422 mGy para Caldwell e Waters. Na região tireóidea, os valores de kerma no ar variaram de 0,005 a 0,932 mGy para cavum e 0,002 a 0,972 mGy para Caldwell e Waters. Conclusão: Os parâmetros de irradiação utilizados pelas instituições foram mais elevados do que os recomendados em protocolos britânicos. Ações de otimização são recomendadas de modo a contribuir para a redução da radiação nos pacientes e, portanto, os riscos.