Non-vascular interventional procedures: effective dose to patient and equivalent dose to abdominal organs by means of dicom images and Monte Carlo simulation

This study evaluates X-ray exposure in patient undergoing abdominal extra-vascular interventional procedures by means of Digital Imaging and COmmunications in Medicine (DICOM) image headers and Monte Carlo simulation. The main aim was to assess the effective and equivalent doses, under the hypothesis of their correlation with the dose area product (DAP) measured during each examination. This allows to collect dosimetric information about each patient and to evaluate associated risks without resorting to in vivo dosimetry. The dose calculation was performed in 79 procedures through the Monte Carlo simulator PCXMC (A PC-based Monte Carlo program for calculating patient doses in medical X-ray examinations), by using the real geometrical and dosimetric irradiation conditions, automatically extracted from DICOM headers. The DAP measurements were also validated by using thermoluminescent dosimeters on an anthropomorphic phantom. The expected linear correlation between effective doses and DAP was confirmed with an R(2) of 0.974. Moreover, in order to easily calculate patient doses, conversion coefficients that relate equivalent doses to measurable quantities, such as DAP, were obtained

Assessment of Entrance Skin Dose and Effective Dose of common diagnostic X-ray examinations in Federal Teaching Hospital Gombe, North-Eastern Nigeria

Recently, there has been a wide application of radiation in medicine. This may have adverse effect of radiation protection regulations if not properly observed. A balance must be struck between the benefits of improving human health, and the risks associated with ionizing radiation exposure by radiation workers, patients and the general public. This study evaluated the entrance skin dose (ESD) and patient effective dose (ED) during X-ray diagnostic examinations at Federal Teaching Hospital Gombe, North-eastern, Nigeria. Twenty (20) patient's data were collected for this study. Five (05) most common performed X-ray diagnostic examinations are Anterior Posterior AP (chest), Posterior Anterior (PA) chest, Anterior Posterior (AP) Abdomen, Posterior Anterior (PA) Skull and Lateral (LAT) Skull. The ESD was determined indirectly through measurement of tube potential (kVp), exposure setting or current (mAs) and Film Focus Distance (FSD) which were then used to analyze the ESD while the effective dose (ED) was obtained by addition of the weighing factor multiplied by the equivalent dose. The mean of entrance skin dose and the effectual dose of chest (PA, AP), abdomen (AP) and skull (AP, LATERAL) were found to be 0.466 mGy , 0.509 mGy, 1.027 mGy, 0.810 mGy, 0.928 mGy and 0.040 mSv, 0.030 mSv, 0.006 mSv, 0.001 mSv  and 0.001 mSv  respectively. The entrance skin dose and effective dose values obtained in this study showed that X-ray diagnostic examinations carried out at Federal Teaching Hospital Gombe were lower compared to reference dose values reported in most literatures. The value of patients absorbed dose undergoing X-ray diagnostic examination at Federal Teaching Hospital Gombe is in agreement with ALARA concepts

Does altering the exposure parameters (kV and mAs) affect the entrance skin dose and image quality of paediatric patients undergoing extremity imaging using DR equipment?

Background The field of radiography has seen tremendous advancement in the technologies used to capture and store images. The radiation dose received by patients is kept As Low As Reasonably Achievable (ALARA), whilst producing a diagnostic X-ray. The introduction of Direct Radiography (DR) has been reported to reduce the image quality, and manufacturers are promoting a change in practice from historical imaging techniques. Limited literature is available to support changing practice, causing unrest within the radiographic workforce. Aim Identify how radiology departments can achieve optimum image quality at the lowest radiation dose to the paediatric patient. The study aimed to firstly evaluate current practice by measuring the effect that manipulating exposure parameters (kV and mAs) has on Entrance Skin Dose (ESD) and image quality (IQ) for paediatric patients undergoing DR imaging of their extremities; and secondly to compare the performance (as defined by ESD and image quality across a range of kV and mAs settings) of two different pieces of DR equipment currently in service within the researchers NHS Trust. Method A local evaluation of current practice was undertaken on two different DR systems (DR1 and DR2). Quantitative experiments across a range of exposure parameters (40-63kV and 0.633.1mAs) assessed the effects on ESD and image quality. A patient phantom enabled simulation of a paediatric extremity skin surface. IQ was assessed by three consultant radiologists. Both ESD and IQ results were statistically analysed using a combination of parametric and non-parametric tests. Results All images assessed were of diagnostic image quality. DR1 produced lower ESD and improved image quality compared to DR2. ESD was lowest at 63kV / 0.63mAs on both DR1 and DR2. Optimum contrast was achieved at 42kV / 3.1mAs on DR1 and 40kV / 2.5mAs on DR2. Resolution was highest at 63kV / 0.63mAs for DR1, and did not vary for DR2. Conclusion Image contrast was improved with little increase to the ESD on both DR1 and DR2 when using a low kV, high mAs combination. This study has highlighted differences in both radiation output and image quality between the two DR systems currently in service. Further clinical evaluation is warranted to investigate the reasons for this

CONTROL OF RADIATION EXPOSURE TO PAEDIATRIC PATIENTS AT CONVENTIONAL RADIOLOGY AND CARDIAC CENTERS AT DUBAI HOSPITAL

In view of increasing the number of x-ray examinations over the years, paediatric radiation safety is considered as one of the critical subjects in the modern medical imaging. Paediatric patients are at higher risk from ionizing radiation than adults if they receive same amount of dose. This project was conducted to evaluate paediatric patient radiation dose levels in digital radiology (both fixed and mobile x-ray units) and interventional cardiology at Dubai Hospital. The results of this study are expected to contribute in establishing local and national diagnostic reference levels in United Arab Emirates (UAE). A combination of phantom studies and patient data collection were utilized in this paediatric dosimetry project. The patient data collection was obtained through both manual contributions from radiographers and data obtained from Digital Imaging and Communications in Medicine (DICOM) header. The first method was performed using Polymethyl methacrylate phantom with different thicknesses to represent different age groups of paediatrics; whereas the second method was without phantom where the exposure factors extracted from DICOM header. Then, effective dose was estimated using Monte Carlo dose calculation software. The primary measured and estimated radiation dose quantity was the incident air kerma. The entrance surface air kerma was calculated from the incident air kerma and then executed with the application of appropriate backscatter factors. For the fixed x-ray machine, the radiation dose levels were lower than the recommended values and other published data while for the mobile x-ray the findings were comparable and slightly higher than other surveyors. In interventional cardiology, the radiation dose values were higher compared to other values shown in previous researches. The variation in entrance skin air kerma values between the published data and the findings in this study are related to the use of different equipment, exposure parameters and it is significantly related to the professional awareness towards ionizing radiation hazards. Evidently, the values of effective doses showed that the radiation risk is higher with small ages. In UAE, this study is considered as one of the first structured studies performed on paediatric dosimetry. Further researches are needed to include image viii quality assessment to stress on obtaining optimum image quality with lower radiation dose

Reducing radiation dose for a linear slot scanning digital X-ray machine using a filtration technique

This study describes the development of a filtration technique applied to the Lodox Statscan linear slotscanning digital X-ray system to reduce radiation dose to paediatric patients whilst preserving diagnostic image quality. The Statscan is an FDA approved, commercially available digital X-ray system commonly used for trauma and emergency patients. The Statscan provides significantly lower radiation dose to patients than conventional Xray systems for comparable studies without loss of image quality. This is particularly beneficial in paediatric radiology, where the risks associated with ionizing radiation are much higher. A static dose prediction model for the Statscan which was previously developed at the University of Cape Town has been adapted to create a dynamic dose prediction model which allows the user to adjust the system scanning parameters. The model calculates the patient entrance dose from an energy spectrum generated using the input parameters. The effective dose for a paediatric sized patient is then calculated using a Monte Carlo simulation. The dynamic model allows for variation of the scan parameters and direct observation of the expected dose levels for specific examinations. Filtration is a well-known technique for reducing radiation dose, where a filter material is placed in the path of the X-ray beam to reduce patient exposure to radiation. The dynamic model was used to design a new filtration technique for the paediatric settings on the Statscan

CONTROL OF RADIATION EXPOSURE TO PAEDIATRIC PATIENTS AT CONVENTIONAL RADIOLOGY AND CARDIAC CENTERS AT DUBAI HOSPITAL

In view of increasing the number of x-ray examinations over the years, paediatric radiation safety is considered as one of the critical subjects in the modern medical imaging. Paediatric patients are at higher risk from ionizing radiation than adults if they receive same amount of dose. This project was conducted to evaluate paediatric patient radiation dose levels in digital radiology (both fixed and mobile x-ray units) and interventional cardiology at Dubai Hospital. The results of this study are expected to contribute in establishing local and national diagnostic reference levels in United Arab Emirates (UAE). A combination of phantom studies and patient data collection were utilized in this paediatric dosimetry project. The patient data collection was obtained through both manual contributions from radiographers and data obtained from Digital Imaging and Communications in Medicine (DICOM) header. The first method was performed using Polymethyl methacrylate phantom with different thicknesses to represent different age groups of paediatrics; whereas the second method was without phantom where the exposure factors extracted from DICOM header. Then, effective dose was estimated using Monte Carlo dose calculation software. The primary measured and estimated radiation dose quantity was the incident air kerma. The entrance surface air kerma was calculated from the incident air kerma and then executed with the application of appropriate backscatter factors. For the fixed x-ray machine, the radiation dose levels were lower than the recommended values and other published data while for the mobile x-ray the findings were comparable and slightly higher than other surveyors. In interventional cardiology, the radiation dose values were higher compared to other values shown in previous researches. The variation in entrance skin air kerma values between the published data and the findings in this study are related to the use of different equipment, exposure parameters and it is significantly related to the professional awareness towards ionizing radiation hazards. Evidently, the values of effective doses showed that the radiation risk is higher with small ages. In UAE, this study is considered as one of the first structured studies performed on paediatric dosimetry. Further researches are needed to include image viii quality assessment to stress on obtaining optimum image quality with lower radiation dose