Estimation of organ absorbed dose in pediatric chest X-ray examination: a phantom study

Children have a greater risk of developing lifetime cancer and other biological effects from ionizing radiation exposure than adults. The aim of this study was to measure the absorbed dose received by lungs and heart in pediatric chest X-ray examination using nanoDot optically stimulated luminescent dosimeter (OSLD). The X-ray system, Siemens Multix Top was used. A pediatric phantom developed by using beeswax and polyurethane foam was exposed at 50 kVp, 52 kVp, 55 kVp, 57 kVp and 60 kVp, with fixed tube current-exposure time (3 mAs), which is normally used in pediatric clinical chest X-ray examinations. The nanoDot OSLDs were placed in different parts in the thorax of the phantom according to the position of organs in the chest area, which are lungs and heart. For lungs, absorbed dose measurement nanoDot OSLDs were placed in the apex and base at three different depths. The phantom was exposed three times for each kVp value, and the absorbed doses were measured in mGy. The findings show that the measured absorbed dose to the heart increased with the increase in kVp. Overall, a 22% increase in absorbed dose to heart and a 29% increase in lungs with the increase in kVp was recorded. In addition, absorbed dose to the base of left and right lungs was recorded higher up to 9% as compared to the apex of lungs. In conclusion, the absorbed dosage increases with exposure, while the absorbed dose decreases with depth. It is necessary for the radiographer to select an appropriate exposure setting based on the physical characteristics of the pediatric patient

Entrance skin dose (ESD) and bucky table induced backscattered dose (BTI-BSD) in abdominal radiography with nanoDot optically stimulated luminescence dosimeter (OSLD)

In radiography, inconsistencies in patients' measured entrance skin dose (ESD) exist. There is no published research on the bucky table induced backscattered radiation dose (BTI-BSD). Thus, we aimed to ascertain ESD, calculate the BTI-BSD in abdominal radiography with a nanoDot OSLD, and compare the ESD results with the published data. A Kyoto Kagaku PBU-50 phantom (Kyoto, Japan) in an antero-posterior supine position was exposed, selecting a protocol used for abdominal radiography. The central ray of x-ray beam was pointed at the surface of abdomen at the navel, where a nanoDot dosimeter was placed to measure ESD. For the BTI-BSD, exit dose (ED) was determined by placing a second dosimeter on the exact opposite side (backside) of the phantom from the dosimeter used to determine (ESD) with and without bucky table at identical exposure parameters. The BTI-BSD was calculated as the difference between ED with and without bucky table. The ESD, ED, and BTI-BSD were measured in milligray (mGy). ESD mean values with and without bucky table were 1.97 mGy and 1.84 mGy, whereas ED values were 0.062 mGy and 0.052 mGy, respectively. Results show 2-26% lower ESD values with nanoDot OSLD. The BTI-BSD mean value was found to be approximately 0.01 mGy. A local dose reference level (LDRL) can be established using ESD data to safeguard patients from unnecessary radiation. In addition, to minimize the risk of BTI-BSD in patients in radiography, the search for the use or fabrication of a new, lower atomic number material for the bucky table is suggested

Evaluation of quality of images reconstructed from the data acquired in narrow (15%) and standard (20%) symmetrical energy window in conjunction with physical filter in tc-99m spect

Single Photon Emission Computed Tomography (SPECT) is a very useful medical imaging modality for detecting various diseases. However, relative to other medical imaging specialties, such as X-ray and Magnetic Resonance Imaging it has some limitations in terms of dgradation of image quality. Photopeak energy window width and scatter radiation are the factors among others in SPECT imaging that affect the image quality. This study is aimed at evaluating the narrow (15%) and standard (20%) energy window data images with and without physical filter (Zinc (Zn) 0.2mm thick) as scatter radiation absorber. Philips ADAC/Forte dual head SPECT system was used. Carlson’s phantom consisting of cold and hot region inserts, filled with water was scanned. Tc-99m radionuclide (21mCi) was distributed homogeneously into the phantom. Data were acquired by setting 15% and 20% energy windows with and without physical filter. Images were reconstructed using filtered back projection technique with a Butterworth filter of cut-off frequency 0.35/cm and order 5. Chang’s attenuation correction method was applied using 0.12 and 0.13/cm linear attenuation coefficient (LAC) values. Reconstructed images were investigated both qualitatively and quantitatively. Cold and hot region image results indicated that the physical filter improved the contrast and SNR of narrow energy window data images with a 0.13/cm LAC value as compared to standard energy window data images. Furthermore, the detectability of smaller cold and hot regions was enhanced. In conclusion, the use of a physical filter with a narrow energy window provided improved image quality as compared to standard energy window data images. Therefore, it is suggested that further studies should be conducted for the implementation of physical filter technique with narrow energy window in clinical examinations

Can tender and mature coconut water-mixed contrast media provide a diagnostically acceptable radiograph?

Contrast materials are administered into the patient’s body for enhancing the diagnostic performance of imaging modalities in most radiology practices. Adverse effects of contrast material may appear as immediate or delayed reactions in patients. Literature shows that coconut water, contrast media and human blood plasma have some similar properties. Thus, we investigated the use of tender and mature coconut water-mixed radiographic contrast materials to provide a diagnostically acceptable radiograph. The pH and viscosity of coconut water was measured. Six tubes of polyvinyl chloride of 0.3 cm outer diameter, 10 cm long (simulating human blood vessels), filled individually with contrast media, tender, mature coconut water, air, tender coconut water-mixed contrast media and mature coconut water-mixed contrast media were scanned. Coconut water was obtained from coconuts of Pekan, Bukit Setongkol and Pancing Timur areas. Contrast materials used were Iopamiro 370 mg I/mL, Omnipaque 300 mg I/mL and Dotarem. Each piece of the tube was inserted into the hole of the Rando phantom. The phantom was exposed at different exposure settings (70 kVp with 20, 22 and 25 mAs) using Siemens Multix Top X-ray system. ImageJ and Image Quality Criteria Scoring were used to evaluate the image quality of radiographs. Results show that the visibility of tube with contrast media is still the highest in radiographs, in the order of Iopamiro 370 mg I/mL, Omnipaque 300 mg I/mL followed by Dotarem. Results show the mature coconut water-mixed contrast media has the second highest visibility followed by tender coconut water-mixed. From Pancing Timur mature coconut water-mixed Iopamiro 370 mgI/ml provided the highest visibility. In conclusion, tender and mature coconut water-mixed contrast media used in this study has the potential to provide reasonably good quality radiographs. Further investigations are required to test whether the adverse effects of contrast media can be minimized with coconut water-mixed contrast media