Estimating thyroid dose in pediatric CT exams from surface dose measurement

Al-Senan, R; Mueller, Deborah; Hatab, Mustapha R.

doi:10.1088/0031-9155/57/13/4211

Cited by 12 publications

(5 citation statements)

References 23 publications

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“…This system has gained increasing popularity in the medical physics field. [7][8][9][10][11][12] The OSL dosimeters are made of 5-mm diameter and 0.2-mm thick plastic disks infused with Al 2 O 3 :C. The disks are encased in 10 × 10 × 2 mm 3 light-tight plastic holders having a density of 1.03 g/cm 3 . The plastic leaves covering the front and back of the OSL disks are 0.36 mm thick.…”

Section: A Osl Dosimetry System and Atom Phantommentioning

confidence: 99%

A method to acquire CT organ dose map using OSL dosimeters and ATOM anthropomorphic phantoms

Zhang

Gao

et al. 2013

Med. Phys.

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Purpose: To present the design and procedure of an experimental method for acquiring densely sampled organ dose map for CT applications, based on optically stimulated luminescence (OSL) dosimeters "nanoDots" and standard ATOM anthropomorphic phantoms; and to provide the results of applying the method-a dose data set with good statistics for the comparison with Monte Carlo simulation result in the future. Methods: A standard ATOM phantom has densely located holes (in 3 × 3 cm or 1.5 × 1.5 cm grids), which are too small (5 mm in diameter) to host many types of dosimeters, including the nanoDots. The authors modified the conventional way in which nanoDots are used, by removing the OSL disks from the holders before inserting them inside a standard ATOM phantom for dose measurements. The authors solved three technical difficulties introduced by this modification: (1) energy dependent dose calibration for raw OSL readings; (2) influence of the brief background exposure of OSL disks to dimmed room light; (3) correct pairing between the dose readings and measurement locations. The authors acquired 100 dose measurements at various positions in the phantom, which was scanned using a clinical chest protocol with both angular and z-axis tube current modulations. Results: Dose calibration was performed according to the beam qualities inside the phantom as determined from an established Monte Carlo model of the scanner. The influence of the brief exposure to dimmed room light was evaluated and deemed negligible. Pairing between the OSL readings and measurement locations was ensured by the experimental design. The organ doses measured for a routine adult chest scan protocol ranged from 9.4 to 18.8 mGy, depending on the composition, location, and surrounding anatomy of the organs. The dose distribution across different slices of the phantom strongly depended on the z-axis mA modulation. In the same slice, doses to the soft tissues other than the spinal cord demonstrated relatively small variations, with the maximum COV around 11.4%. This might be attributed to the angular mA modulation, the placement of the dosimeters, the chest cavity of the scanned region, and the size of the phantom. Doses to the spinal cord were consistently lower than those to other soft tissues. Conclusions: The method is suited for acquiring densely sampled organ dose maps, and can be used for studying dose distributions relevant to subject size, organ location, and clinical CT protocols.

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Section: A Osl Dosimetry System and Atom Phantommentioning

confidence: 99%

A method to acquire CT organ dose map using OSL dosimeters and ATOM anthropomorphic phantoms

Zhang

Gao

et al. 2013

Med. Phys.

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“…There are several methods to derive ESD. Mortazavi et al [13] used TLD-100, HARSHAW to measure the entrance skin dose, whereas another author Al Senan et al [14] used a device called MicroStar TM to read the values recorded by the optically stimulated luminescence dosimeter. In our present, we used Multi-O-Meter to measure the entrance skin dose.…”

Section: Discussionmentioning

confidence: 99%

Estimation of Entrance Surface Radiation Dose to Thyroid Region in Computed Tomography Brain Examination

Visakh¹,

Sukumar²,

Pradhan³

2019

Asian J Pharm Clin Res

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Objective: The objective of this study was to estimate the entrance surface radiation dose to the thyroid region in a computed tomography (CT) brain scan.Methods: Unfors Multi-O-Meter equipment was used to measure the entrance surface at the thyroid region of adult patients ranging from 18 to 70 years of age. A total of 115 patients were included in the study based on convenience sampling. The Multi-O-Meter was kept at the thyroid region during the scan, and the values for entrance surface dose (ESD) were noted from its monitor after the scan was complete.Results: The obtained data were analyzed and violate normal distribution; therefore, the median and quartiles were computed. The overall median (Q1, Q2), ESD of the patients, was 1.335 (1.213, 1.529) mGy. The minimum and maximum dose values recorded were 1.015 mGy and 1.964 mGy, respectively.Conclusions: The result showed a significant amount of entrance surface radiation dose to the thyroid region while taking a brain scan. This data can be used for optimization of radiation protection while undergoing CT scans of brain to reduce exposure to thyroid region.

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“…This method uses a Monte Carlo technique and computational algorithms to estimate the radiation dose by modeling anthropomorphic photon transport. To account for the size difference between adult and small children, age correction factors provided in the ImPACT spreadsheet were applied to the resulted doses [13,25]. …”

Section: Methodsmentioning

confidence: 99%

“…There have been several previous studies of the radiation dose received in the thyroid during CT scans and estimates have been made of the cancer risk [12,13,14], with the risk estimation being based on the model risk projection, although the number of study samples was very small in some studies. Recently, Pearce et al [15] found that there was a significant association between the estimated radiation doses resulted from CT scans to red bone marrow and brain in childhood and subsequent incidence of leukemia and brain tumors.…”

Section: Introductionmentioning

confidence: 99%

Radiation Dose in the Thyroid and the Thyroid Cancer Risk Attributable to CT Scans for Pediatric Patients in One General Hospital of China

Niu

Chen

et al. 2014

IJERPH

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Objective: To quantify the radiation dose in the thyroid attributable to different CT scans and to estimate the thyroid cancer risk in pediatric patients. Methods: The information about pediatric patients who underwent CT scans was abstracted from the radiology information system in one general hospital between 1 January 2012 and 31 December 2012. The radiation doses were calculated using the ImPACT Patient Dosimetry Calculator and the lifetime attributable risk (LAR) of thyroid cancer incidence was estimated based on the National Academies Biologic Effects of Ionizing Radiation VII model. Results: The subjects comprised 922 children, 68% were males, and received 971 CT scans. The range of typical radiation dose to the thyroid was estimated to be 0.61–0.92 mGy for paranasal sinus CT scans, 1.10–2.45 mGy for head CT scans, and 2.63–5.76 mGy for chest CT scans. The LAR of thyroid cancer were as follows: for head CT, 1.1 per 100,000 for boys and 8.7 per 100,000 for girls; for paranasal sinus CT scans, 0.4 per 100,000 for boys and 2.7 per 100,000 for girls; for chest CT scans, 2.1 per 100,000 for boys and 14.1 per 100,000 for girls. The risk of thyroid cancer was substantially higher for girls than for the boys, and from chest CT scans was higher than that from head or paransal sinus CT scans. Conclusions: Chest CT scans caused higher thyroid dose and the LAR of thyroid cancer incidence, compared with paransal sinus or head CT scans. Therefore, physicians should pay more attention to protect the thyroid when children underwent CT scans, especially chest CT scans.

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Estimating thyroid dose in pediatric CT exams from surface dose measurement

Cited by 12 publications

References 23 publications

A method to acquire CT organ dose map using OSL dosimeters and ATOM anthropomorphic phantoms

A method to acquire CT organ dose map using OSL dosimeters and ATOM anthropomorphic phantoms

Estimation of Entrance Surface Radiation Dose to Thyroid Region in Computed Tomography Brain Examination

Radiation Dose in the Thyroid and the Thyroid Cancer Risk Attributable to CT Scans for Pediatric Patients in One General Hospital of China

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