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surface dose , thyroid, ct scan, computed tomography

Stephen Inkoom, Antonios E Papadakis, Maria Raissaki, Kostas Perisinakis, Cyril Schandorf, John J Fletcher, John Damilakis
This study investigated the effect of bismuth shielding on thyroid dose and image quality in paediatric neck multidetector computed tomography (MDCT) performed with fixed tube current (FTC) and automatic exposure control (AEC). Four paediatric anthropomorphic phantoms representing the equivalent newborn, 1-, 5- and 10-y-old child were subjected to neck CT using a 16-slice MDCT system. Each scan was performed without and with single- and double-layered bismuth shield placed on the skin surface above the thyroid...
April 15, 2017: Radiation Protection Dosimetry
Sercan Akyalcin, Jeryl D English, Kenneth M Abramovitch, Xiujiang J Rong
OBJECTIVE: To measure surface skin dose from various cone-beam computed tomography (CBCT) scanners using point-dosimeters. MATERIALS & METHODS: A head anthropomorphic phantom was used with nanoDOT optically stimulated luminescence (OSL) dosimeters (Landauer Corp., Glenwood, IL) attached to various anatomic landmarks. The phantom was scanned using multiple exposure protocols for craniofacial evaluations in three different CBCT units and a conventional x-ray imaging system...
2013: Head & Face Medicine
A D Goren, R D Prins, L T Dauer, B Quinn, A Al-Najjar, R D Faber, G Patchell, I Branets, D C Colosi
OBJECTIVES: This study aims to demonstrate the effectiveness of leaded glasses in reducing the lens of eye dose and of lead thyroid collars in reducing the dose to the thyroid gland of an adult female from dental cone beam CT (CBCT). The effect of collimation on the radiation dose in head organs is also examined. METHODS: Dose measurements were conducted by placing optically stimulated luminescent dosemeters in an anthropomorphic female phantom. Eye lens dose was measured by placing a dosemeter on the anterior surface of the phantom eye location...
2013: Dento Maxillo Facial Radiology
Ming X Jia, Xu Zhang, Na Li, En Y Wang, Da W Liu, Wei S Cai
The growing use of cone-beam computed tomography (CBCT) for IGRT has increased concerns over the additional radiation dose to patients. The in-field dose of IGRT and the peripheral dose (PD) from kilovoltage CBCT (KV-CBCT) imaging have been well quantified. The purpose of this work is to evaluate the peripheral dose from megavoltage CBCT (MV-CBCT) imaging for nasopharyngeal carcinoma IGRT, to determine the correlation of peripheral dose with MU protocol and imaging field size, and to estimate out-of-field organ-at-risk (OAR) dose delivered to patients...
September 6, 2012: Journal of Applied Clinical Medical Physics
Rani Al-Senan, Deborah L Mueller, Mustapha R Hatab
The purpose of this study was to investigate the possibility of estimating pediatric thyroid doses from CT using surface neck doses. Optically stimulated luminescence dosimeters were used to measure the neck surface dose of 25 children ranging in ages between one and three years old. The neck circumference for each child was measured. The relationship between obtained surface doses and thyroid dose was studied using acrylic phantoms of various sizes and with holes of different depths. The ratios of hole-to-surface doses were used to convert patients' surface dose to thyroid dose...
July 7, 2012: Physics in Medicine and Biology
Emily A Lalone, Anne-Marie V Fox, Angela E Kedgley, Thomas R Jenkyn, Graham J W King, George S Athwal, James A Johnson, Terry M Peters
The study of joint congruency at the glenohumeral joint of the shoulder using computed tomography (CT) and three-dimensional (3D) reconstructions of joint surfaces is an area of significant clinical interest. However, ionizing radiation delivered to patients during CT examinations is much higher than other types of radiological imaging. The shoulder represents a significant challenge for this modality as it is adjacent to the thyroid gland and breast tissue. The objective of this study was to determine the optimal CT scanning techniques that would minimize radiation dose while accurately quantifying joint congruency of the shoulder...
October 21, 2011: Physics in Medicine and Biology
Xinhui Duan, Jia Wang, Jodie A Christner, Shuai Leng, Katharine L Grant, Cynthia H McCollough
OBJECTIVE: The purpose of this study was to evaluate in phantoms the dose reduction to anterior surfaces and image quality with organ-based tube-current modulation in head and thoracic CT. MATERIALS AND METHODS: Organ-based tube-current modulation is designed to reduce radiation dose to superficial radiosensitive organs, such as the lens of the eye, thyroid, and breast, by decreasing the tube current when the tube passes closest to these organs. Dose and image quality were evaluated in phantoms for clinical head and thorax examination protocols with and without organ-based tube-current modulation...
September 2011: AJR. American Journal of Roentgenology
J F Winslow, C J Tien, D E Hintenlang
PURPOSE: The purpose of this study was to characterize relative magnitudes of peripheral dose modulations present in helical MDCT resulting from variation in x-ray tube starting position and phantom position relative to isocenter using a novel methodology that employs direct dosimetric measurements and knowledge of scan geometry. The magnitudes of potential dose savings to specific radiosensitive tissues related to the phase of the quasiperiodic dose distribution are also quantified and compared to similar Monte Carlo based studies...
June 2011: Medical Physics
Deborah L Mueller, Mustapha Hatab, Rani Al-Senan, Stephen M Cohn, Michael G Corneille, Daniel L Dent, Joel E Michalek, John G Myers, Steven E Wolf, Ronald M Stewart
BACKGROUND: Increased utilization of computed tomography (CT) scans for evaluation of blunt trauma patients has resulted in increased doses of radiation to patients. Radiation dose is relatively amplified in children secondary to body size, and children are more susceptible to long-term carcinogenic effects of radiation. Our aim was to measure radiation dose received in pediatric blunt trauma patients during initial CT evaluation and to determine whether doses exceed doses historically correlated with an increased risk of thyroid cancer...
March 2011: Journal of Trauma
Haruhiko Machida, Toshiyuki Yuhara, Mieko Tamura, Tomokazu Numano, Shinji Abe, John M Sabol, Shigeru Suzuki, Eiko Ueno
OBJECTIVE: Using an anthropomorphic phantom, we have investigated the feasibility of digital tomosynthesis (DT) of flat-panel detector (FPD) radiography to reduce radiation dose for sinonasal examination compared to multi-detector computed tomography (MDCT). MATERIALS AND METHODS: A female Rando phantom was scanned covering frontal to maxillary sinus using the clinically routine protocol by both 64-detector CT (120 kV, 200 mAs, and 1.375-pitch) and DT radiography (80 kV, 1...
June 2012: European Journal of Radiology
Di Zhang, Maria Zankl, John J DeMarco, Chris H Cagnon, Erin Angel, Adam C Turner, Michael F McNitt-Gray
PURPOSE: Previous work has demonstrated that there are significant dose variations with a sinusoidal pattern on the peripheral of a CTDI 32 cm phantom or on the surface of an anthropomorphic phantom when helical CT scanning is performed, resulting in the creation of "hot" spots or "cold" spots. The purpose of this work was to perform preliminary investigations into the feasibility of exploiting these variations to reduce dose to selected radiosensitive organs solely by varying the tube start angle in CT scans...
December 2009: Medical Physics
Alanna McDermott, R Allen White, Mike Mc-Nitt-Gray, Erin Angel, Dianna Cody
An anthropomorphic pediatric phantom (5-yr-old equivalent) was used to determine organ doses at specific surface and internal locations resulting from computed tomography (CT) scans. This phantom contains four different tissue-equivalent materials: Soft tissue, bone, brain, and lung. It was imaged on a 64-channel CT scanner with three head protocols (one contiguous axial scan and two helical scans [pitch = 0.516 and 0.984]) and four chest protocols (one contiguous axial scan and three helical scans [pitch = 0...
May 2009: Medical Physics
Homer C Tien, Lorraine N Tremblay, Sandro B Rizoli, Jacob Gelberg, Fernando Spencer, Curtis Caldwell, Frederick D Brenneman
BACKGROUND: Trauma patients often require multiple imaging tests, including computed tomography (CT) scans. CT scanning, however, is associated with high-radiation doses. The purpose of this study was to measure the radiation doses trauma patients receive from diagnostic imaging. METHODS: A prospective cohort study was conducted from June 1, 2004 to March 31, 2005 at a Level I trauma center in Toronto, Canada. All trauma patients who arrived directly from the scene of injury and who survived to discharge were included...
January 2007: Journal of Trauma
A Schaefer, H Seifert, P Donsch, C M Kirsch
AIM: The aim of the study was the determination of the radiation exposure to the patient caused by single-photon transmission measurement for 3D whole-body PET. MATERIAL AND METHOD: Single-photon-transmission measurement is performed using two Cs-137 point-sources (E gamma = 662 keV, A = 2*614 MBq) on a 3D PET scanner (ECAT ART). During a simulation of a whole body transmission scan (axial length: 75 cm, 6 contigous bed positions) dose measurements with thermoluminescent dosimeters were carried out using a thorax and an abdomen phantom...
November 2000: Nuklearmedizin. Nuclear Medicine
J M de Klerk, J W van Isselt, A van Dijk, M E Hakman, F A Pameijer, H P Koppeschaar, P M Zelissen, J P van Schaik, P P van Rijk
UNLABELLED: The effect of radioiodine in the treatment of nontoxic goiter is seldom evaluated quantitatively. The aim of this study was threefold: (a) to assess the effect of 131I on goiter volume, (b) to establish a relationship between CT volume reduction and the amount of radioactivity taken up by the thyroid and (b) to assess the precision of scintigraphic thyroid volume measurements. METHODS: In 27 patients with sporadic nontoxic goiter, the thyroid volume was estimated from a [99mTc]pertechnetate scintigram...
March 1997: Journal of Nuclear Medicine: Official Publication, Society of Nuclear Medicine
A Ekestubbe, A Thilander, K Gröndahl, H G Gröndahl
Tomography is often needed prior to implant surgery to evaluate jaw bone dimensions. Computed tomography (CT) is advocated as an alternative. The purpose of this study was to measure the absorbed doses to radiosensitive organ in the head and neck region when CT is used. Measurements were made with extruded LiF thermoluminescent dosemeters within and on an anthropomorphic phantom examined with a Philips Tomoscan LX CT scanner. Axial scanning was performed for the maxilla and both frontal, perpendicular to the alveolus, and axial for the mandible...
February 1993: Dento Maxillo Facial Radiology
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