- Comparison of testing of collimator and beam alignment, focal spot size with slit camera, and tube current consistency using computed radiography and conventional screen-film systems. [Journal Article]
- JAJ Appl Clin Med Phys 2019; 20(6):160-169
- Conversion to a filmless technique of physical performance testing is becoming a topic of much interest to researchers. We assessed the use of a computed radiography (CR) system with postprocessing s…
Conversion to a filmless technique of physical performance testing is becoming a topic of much interest to researchers. We assessed the use of a computed radiography (CR) system with postprocessing software as an alternative tool for performing the three physical performance tests of an x-ray tube. Collimator and beam alignment, focal spot size, and milliampere second (mAs) linearity, were performed using a CR system. Results were then compared with those obtained from a conventional screen-film (SF) system. The distances of collimator misalignment measured by the SF system were decreased while peak tube voltage (kVp) was increased (mAs was fixed), whereas those measured by CR were independent of exposure level. The degrees of beam collimator misalignment measured by the CR system were not different from those measured by the SF system. The differences in focal spot dimensions measured by SF and CR systems were less than 4% for large and small focal spot size in both width and length. The mAs linearity evaluated by the SF system agreed with those evaluated by the dose measurement at 50 kVp and 4 mAs, as well as 55 kVp and 3.2 mAs, while the mAs linearity test using the CR system agreed with those using the dose measurement method for all exposure levels. In summary, a CR system could be utilized to assess the three physical performance tests of a single x-ray tube, but required more time than an SF system. Medical physicists with image processing skills were needed to perform the analyses.
- Optimization of exposure parameters in dental cone beam computed tomography using a 3-step approach. [Journal Article]
- OSOral Surg Oral Med Oral Pathol Oral Radiol 2018; 126(6):545-552
- CONCLUSIONS: For the CBCT model used in this study, optimization implies the use of the highest kV along with the shortest exposure time and a task-specific mA. The proposed stepwise optimization approach could be applied to any CBCT unit, preferably during commissioning.
- Model evaluation of rapid 4-dimensional lung tomosynthesis. [Journal Article]
- ARAdv Radiat Oncol 2018 Jul-Sep; 3(3):431-438
- CONCLUSIONS: Feasibility depends on the output performance of stationary cold cathode hardware being developed for DTS. Present image receptor technology can accommodate frame acquisition rates.
- ESTIMATION OF RADIATION DOSES FROM ABDOMINAL COMPUTED TOMOGRAPHY SCANS. [Journal Article]
- RPRadiat Prot Dosimetry 2018 Dec 01; 182(2):235-240
- A total of 120 adult female and male patients randomly selected from 10 hospitals in the West Bank and Gaza Strip were investigated for organ and effective doses from abdominal computed tomography sc…
A total of 120 adult female and male patients randomly selected from 10 hospitals in the West Bank and Gaza Strip were investigated for organ and effective doses from abdominal computed tomography scan. The organs considered in this study are liver, stomach and colon. Assessment of radiation doses was performed by using a commercially available Monte Carlo based software VirtualDose™ CT, a product of Virtual Phantoms, Inc. The software utilizes male and female tissue equivalent mathematical phantoms of all ages and sizes from new born up to morbidly obese patients. The corresponding phantom was selected for every patient according to patient's demographic parameters. Patient demographic data, scanning parameters and dose indicators (including patient body mass index (BMI), milliampere-second (mAs), X-ray tube kilovoltage (kVp), computed tomography dose index (CTDIvol), dose length product (DLP), manufacturer, name and type of operated CT scanner) were recorded for every examination. The collected parameters were used to calculate the organ and effective doses for every patient. The highest estimated patient organ doses were 25 mGy for liver, 20 mGy for stomach and 30 mGy for colon for a male patient with BMI of 30 kg/m2 and 90 kg of weight. This patient correspondent effective dose was 9 mSv. The average effective dose for the entire patient population was 5.5 mSv with a range between 2 and 10 mSv. The highest effective dose was found for a female patient with a BMI of 26.6 kg/m2, and 77 kg of weight. This patient correspondent organ doses were 14, 9 and 14 mGy for the liver, stomach and colon, respectively. The average organs doses per patient estimated for patients from all investigated hospitals were 13.1, 7.6 and 13.2 mGy for liver, stomach and colon, respectively. Both effective dose and organ doses increase with BMI and body weight. In general, the estimated radiation doses from abdominal CT examinations in this study are low and comparable with those published in the literature.
- ESTIMATION OF FEMALE RADIATION DOSES AND BREAST CANCER RISK FROM CHEST CT EXAMINATIONS. [Journal Article]
- RPRadiat Prot Dosimetry 2018 Jun 01; 179(4):303-309
- Breast organ doses, effective doses and lifetime attributable risk (LAR) of breast cancer from chest CT scans are presented for 200 female patients surveyed from 10 hospitals in the West Bank and Gaz…
Breast organ doses, effective doses and lifetime attributable risk (LAR) of breast cancer from chest CT scans are presented for 200 female patients surveyed from 10 hospitals in the West Bank and Gaza Strip, Palestine. Patient data were collected and organized in a database from May to November 2016. Data include age (15-80 years), weight, height, and calculated body mass index. Exposure data were also recorded for every examination. Exposure data includes milliampere-second (mAs), X-ray tube kilovoltage (kVp), computed tomography dose index, dose length product, manufacturer, name and type of operated CT scanner. Organ and effective doses were evaluated using a web-based commercially available Monte Carlo software: VirtualDose™CT, a product of Virtual Phantoms, Inc. The software utilizes male and female tissue equivalent phantoms of all ages and sizes including pregnant patients. The corresponding phantom was selected for every patient according to patient's tomographic parameters. Calculated organ doses were used to estimate the LAR of breast cancer according to BEIR VII Phase 2 report. It was found that radiation doses resulting from the same exam vary widely between different hospitals, depending on the parameters used and the type of scanner. For all patients, the breast organ dose ranged from 6.5 to 28 mGy per examination, with an average breast organ dose of 15 mGy. The effective dose from chest CT scan per examination ranged from 3 to 14.7 mSv with an average of 7 mSv. For younger females (15-29 years), the LAR of breast cancer risk was estimated to be around 0.05%. For older female patients (60-79 years), the risk was ~0.001%. It was found that LAR decreases remarkably with patient's age. Values obtained in this study vary between hospitals, they are generally low and consistent with other studies reported worldwide.
- Submillisievert chest dual energy computed tomography: a pilot study. [Journal Article]
- BJBr J Radiol 2018; 91(1082):20170735
- CONCLUSIONS: Routine chest DECT can be performed at sub-mSv doses with good image quality and without loss of relevant diagnostic information. Advances in knowledge: (1) Contrast-enhanced DECT of the chest can be performed at sub-mSv doses, down to mean CTDIvol 1.3 mGy and DLP 51 mGy.cm in patients with body mass index <31 kg m-2. (2) To our knowledge, this is the first time that sub-mSv doses have been successfully applied in a patient study using a dual source DECT scanner.
- General equations for optimal selection of diagnostic image acquisition parameters in clinical X-ray imaging. [Journal Article]
- RPRadiol Phys Technol 2017; 10(4):415-421
- The purpose of this work was to examine the effects of relationship functions between diagnostic image quality and radiation dose on the governing equations for image acquisition parameter variations…
The purpose of this work was to examine the effects of relationship functions between diagnostic image quality and radiation dose on the governing equations for image acquisition parameter variations in X-ray imaging. Various equations were derived for the optimal selection of peak kilovoltage (kVp) and exposure parameter (milliAmpere second, mAs) in computed tomography (CT), computed radiography (CR), and direct digital radiography. Logistic, logarithmic, and linear functions were employed to establish the relationship between radiation dose and diagnostic image quality. The radiation dose to the patient, as a function of image acquisition parameters (kVp, mAs) and patient size (d), was used in radiation dose and image quality optimization. Both logistic and logarithmic functions resulted in the same governing equation for optimal selection of image acquisition parameters using a dose efficiency index. For image quality as a linear function of radiation dose, the same governing equation was derived from the linear relationship. The general equations should be used in guiding clinical X-ray imaging through optimal selection of image acquisition parameters. The radiation dose to the patient could be reduced from current levels in medical X-ray imaging.
- A CONSORT-compliant prospective randomized controlled trial: radiation dose reducing in computed tomography using an additional lateral scout view combined with automatic tube current modulation: Phantom and patient study. [Randomized Controlled Trial]
- MMedicine (Baltimore) 2017; 96(30):e7324
- CONCLUSIONS: AP combined with an additional lateral scout view using ACTM can significantly reduce the radiation dose without compromising image quality in chest screening CT.
- Evaluation of different low-dose multidetector CT and cone beam CT protocols in maxillary sinus imaging: part I-an in vitro study. [Journal Article]
- DRDentomaxillofac Radiol 2017; 46(6):20160323
- CONCLUSIONS: The low-dose MDCT and CBCT protocols are viable methods for maxillary sinus examination as evaluated using the above-mentioned phantom that yield a good diagnostic image quality using E approximately 7 and 11 times lower than that of the standard MDCT, respectively. These findings were evaluated in the in vivo part of this project.
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- Noise Power Characteristics of a Micro-Computed Tomography System. [Journal Article]
- JCJ Comput Assist Tomogr 2017; 41(1):82-89
- CONCLUSIONS: The noise power properties investigated in this study provide important image quality references for refined cone beam system development, optimization, and operations.