Determining Organ Doses from CT with Direct Measurements in Postmortem Subjects: Part 1—Methodology and Validation

Griglock, T; Sinclair, L; Mench, A; Cormack, B; Bidari, Sharatchandra; Rill, Lynn; Arreola, Manuel

doi:10.1148/radiol.2015140968

Cited by 17 publications

(20 citation statements)

References 15 publications

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“…This approach is equivalent to that used in Griglock et al for CT dosimetry in postmortem subjects using NanoDot TM dosimeters in the Toshiba Aquilion ONE Scanner. 29 Table III shows a breakdown of individual organs as a function of point doses for the adult male phantom. For this particular phantom, the 15 organ doses measured were derived from a total of 55 point doses: 6 for lung, 3 for stomach, 4 for liver, 6 for esophagus, 4 for kidney, 13 for colon, 10 for small intestine, 2 for gonads, and 1 for the remaining organs.…”

Section: C Anthropomorphic Phantom Dose Measurementsmentioning

confidence: 99%

Physical validation of a Monte Carlo‐based, phantom‐derived approach to computed tomography organ dosimetry under tube current modulation

et al. 2017

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Section: C Anthropomorphic Phantom Dose Measurementsmentioning

confidence: 99%

Physical validation of a Monte Carlo‐based, phantom‐derived approach to computed tomography organ dosimetry under tube current modulation

et al. 2017

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“…16 Optically stimulated luminescent dosimeters (OSLDs) were inserted into the lungs, breasts, liver, stomach, colon, uterus, and ovaries and placed on the skin regions included in the scan range utilizing the methodology described by Griglock et al 17 Organ doses were measured at each table position and corrected for energy and scatter response. The effective diameter was measured for each patient as the square root of the product of their measured AP and LAT diameters, as described in Report 204 of the American Association of Physicists in Medicine.…”

mentioning

confidence: 99%

“…The effective diameter was measured for each patient as the square root of the product of their measured AP and LAT diameters, as described in Report 204 of the American Association of Physicists in Medicine. 16 Optically stimulated luminescent dosimeters (OSLDs) were inserted into the lungs, breasts, liver, stomach, colon, uterus, and ovaries and placed on the skin regions included in the scan range utilizing the methodology described by Griglock et al 17 Organ doses were measured at each table position and corrected for energy and scatter response. 17 CTDI vol values also increased linearly with anterior table shift of Subject 3 (R 2 = 0.98, P < 0.005), shown in Fig.…”

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confidence: 99%

Impact of patient centering in CT on organ dose and the effect of using a positioning compensation system: Evidence from OSLD measurements in postmortem subjects

Barreto

Lamoureux

Olguín

et al. 2019

J Applied Clin Med Phys

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The purpose of this study was to investigate the frequency and impact of vertical mis‐centering on organ doses in computed tomography (CT) exams and evaluate the effect of a commercially available positioning compensation system (PCS). Mis‐centering frequency and magnitude was retrospectively measured in 300 patients examined with chest‐abdomen‐pelvis CT. Organ doses were measured in three postmortem subjects scanned on a CT scanner at nine different vertical table positions (maximum shift ± 4 cm). Organ doses were measured with optically stimulated luminescent dosimeters inserted within organs. Regression analysis was performed to determine the correlation between organ doses and mis‐centering. Methods were repeated using a PCS that automatically detects the table offset to adjust tube current output accordingly. Clinical mis‐centering was >1 cm in 53% and 21% of patients in the vertical and lateral directions, respectively. The 1‐cm table shifts resulted in organ dose differences up to 8%, while 4‐cm shifts resulted in organ dose differences up to 35%. Organ doses increased linearly with superior table shifts for the lung, colon, uterus, ovaries, and skin (R2 = 0.73–0.99, P < 0.005). When the PCS was utilized, organ doses decreased with superior table shifts and dose differences were lower (average 5%, maximum 18%) than scans performed without PCS (average 9%, maximum 35%) at all table shifts. Mis‐centering occurs frequently in the clinic and has a significant effect on patient dose. While accurate patient positioning remains important for maintaining optimal imaging conditions, a PCS has been shown to reduce the effects of patient mis‐centering.

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“…However, this method is difficult to perform and it is hard to measure the dose for complete organs, necessary to determine the average values (Kalender, 2011). Griglock et al (2015) and Sinclair et al (2015) proposed an experimental methodology that allows direct measurements of organ doses from CT examinations of postmortem subjects. To do so, a routine chest-abdomen-pelvis protocol was applied to eight female postmortem subjects and organ doses were evaluated.…”

Section: Diagnostic Reference Level (Drl)mentioning

confidence: 99%

“…Some of the adopted approaches include Monte Carlo simulations while others consider in phantom, in vivo or post-mortem measurements with several kinds of dosimeters (Griglock et al, 2015;Long et al, 2013;Martins, 2015;Sinclair et al, 2015). Organ doses in the adult and pediatric anthropomorphic phantoms using TLDs and OSLDs for three CT protocols were evaluated in the present study, according to the previously described methodology (Section 3.2.5).…”

Section: Organ Doses Evaluationmentioning

confidence: 99%

Avaliação de doses em órgãos em procedimentos de tomografia computadorizada utilizando dosímetros TL e OSL

Martins¹

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Since the development of the first Computed Tomography (CT) equipment in the early 1970s, this diagnostic imaging modality has gone through several improvements. Exclusively digital and high quality images production without superposition of anatomical structures, examinations as fast as five seconds, and the capability of diagnosing important pathologies with no need of exploratory surgeries are some of the great advantages when using this technique. As a consequence, the role of this diagnostic procedure has been widely increasing worldwide. In the US, for instance, 2.2 million CT exams were performed in 1980, only 10 years after its implementation. This number increased to 78.7 million in 2015. As a result, absorbed dose by patients due to this technique has become a concern among radiologists, researchers and manufacturers, leading to the development of different methodologies to evaluate it. Ionization chambers, thermoluminescence (TL) and, more recently, optically stimulated luminescence (OSL) dosimetry, for instance, have been widely applied in order to estimate in vivo organ doses, in post-mortem subjects and in phantoms. Another approach that has been extensively used are the Monte Carlo simulations, which can be applied in comparison with experimental results. An experimental approach to evaluate organ doses in pediatric and adult anthropomorphic phantoms by using TLDs and OSLDs was employed in the present study. Several analyses were performed in order to stablish the best way to achieve the main results in this investigation and the methodology proved to be efficient. The characteristics of the OSLDs were analyzed to verify their applicability for evaluating doses from CT procedures. The characterization included homogeneity, linearity with the incident air kerma, reproducibility, reusability and an energy-dependent response to distinct effective energies evaluation. These dosimeters were applied along with TLDs in an adult and a pediatric anthropomorphic phantoms to evaluate organ doses due to clinical CT protocols. These protocols were selected after an analysis of patient data collected from the

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Determining Organ Doses from CT with Direct Measurements in Postmortem Subjects: Part 1—Methodology and Validation

Abstract: The anatomic and radiation attenuation characteristics of cadavers are comparable to those of living human tissue. This methodology allows direct measurement of organ doses from clinical CT examinations.

Cited by 17 publications

References 15 publications

Physical validation of a Monte Carlo‐based, phantom‐derived approach to computed tomography organ dosimetry under tube current modulation

Physical validation of a Monte Carlo‐based, phantom‐derived approach to computed tomography organ dosimetry under tube current modulation

Impact of patient centering in CT on organ dose and the effect of using a positioning compensation system: Evidence from OSLD measurements in postmortem subjects

Avaliação de doses em órgãos em procedimentos de tomografia computadorizada utilizando dosímetros TL e OSL

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