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Williams C, Biffin L, Franich R. A model for estimating peak skin dose in CT. Phys Eng Sci Med 2024; 47:539-550. [PMID: 38451465 DOI: 10.1007/s13246-024-01384-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2023] [Accepted: 01/03/2024] [Indexed: 03/08/2024]
Abstract
In interventional radiology patient care can be improved by accurately assessing peak skin dose (PSD) from procedures, as it is the main predictor for tissue-reactions such as erythema. Historically, high skin dose procedures performed in radiology departments were almost exclusively planar fluoroscopy. However, with the increase in use of technologies involving repeated or adjacent computed tomography (CT) such as CT fluoroscopy and multi-modality rooms, the peak skin dose delivered by CT needs to be considered. In this paper, a model to estimate the PSD delivered to a patient undergoing CT has been developed to assist in determining the overall PSD. This model relates the PSD to the device-reported CT Dose Index (CTDIvol) by accounting for a variety of CT technique and patient factors. It includes a novel method for estimating dose contributions as a function of patient or phantom size, scanner geometry, and physical measurement of lateral and depth-based beam profiles. Physical measurements of PSD using radiochromic film on several phantoms have been used to determine needed model parameters. The resulting fitted model was found to agree with measured data to a standard deviation of 5.1% for the data used to fit the model, and 6.8% for measurements that were not used for fitting the model. Two methods for adapting the model for specific scanners are provided, one based on local PSD measurements with radiochromic film and another using CTDIvol measurements. The model, when suitably adapted, can accurately assess individual patients' CT PSD. This information can be integrated with radiation exposure data from other modalities, such as planar fluoroscopy, to predict the overall risk of tissue reactions, allowing for more tailored patient care.
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Affiliation(s)
- Chris Williams
- Canberra Health Services Medical Physics and Radiation Engineering, Canberra, ACT, Australia.
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Jones AK, Kisiel ME, Rong XJ, Tam AL. Validation of a method for estimating peak skin dose from CT-guided procedures. J Appl Clin Med Phys 2021; 22:224-228. [PMID: 33955655 PMCID: PMC8200428 DOI: 10.1002/acm2.13261] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/03/2022] Open
Abstract
A method for estimating peak skin dose (PSD) from CTDIvol has been published but not validated. The objective of this study was to validate this method during CT‐guided ablation procedures. Radiochromic film was calibrated and used to measure PSD. Sixty‐eight patients were enrolled in this study, and measured PSD were collected for 46 procedures. CTDIvol stratified by axial and helical scanning was used to calculate an estimate of PSD using the method [1.2 × CTDIvol(helical) + 0.6 × CTDIvol(axial)], and both calculated PSD and total CTDIvol were compared to measured PSD using paired t‐tests on the log‐transformed data and Bland‐Altman analysis. Calculated PSD were significantly different from measured PSD (P < 0.0001, bias, 18.3%, 95% limits of agreement, −63.0% to 26.4%). Measured PSD were not significantly different from total CTDIvol (P = 0.27, bias, 3.97%, 95% limits of agreement, −51.6% to 43.7%). Considering that CTDIvol is reported on the console of all CT scanners, is not stratified by axial and helical scanning modes, and is immediately available to the operator during CT‐guided interventional procedures, it may be reasonable to use the scanner‐reported CTDIvol as an indicator of PSD during CT‐guided procedures. However, further validation is required for other models of CT scanner.
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Affiliation(s)
- A Kyle Jones
- Department of Imaging Physics, The University of Texas MD Anderson Cancer Center, Houston, TX, USA
| | - Meghan E Kisiel
- Department of Imaging Physics, The University of Texas MD Anderson Cancer Center, Houston, TX, USA
| | - X John Rong
- Department of Imaging Physics, The University of Texas MD Anderson Cancer Center, Houston, TX, USA
| | - Alda L Tam
- Department of Interventional Radiology, The University of Texas MD Anderson Cancer Center, Houston, TX, USA
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Lopez-Rendon X, Stratis A, Zhang G, Coudyzer W, Develter W, Bogaerts R, Bosmans H, Zanca F. Peak skin and eye lens radiation dose from brain perfusion CT: CTDI vol and Monte Carlo based estimations. Eur J Radiol 2020; 126:108950. [PMID: 32199141 DOI: 10.1016/j.ejrad.2020.108950] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2019] [Revised: 03/04/2020] [Accepted: 03/07/2020] [Indexed: 11/16/2022]
Abstract
PURPOSE To quantify the eye lens, peak skin and brain doses associated with head CT perfusion exam by means of thermoluminescent dosimeters (TLDs) measurements in a cadaver and compare them to Monte Carlo (MC) dose estimations as well as to the CTDIvol. METHOD 18 TLDs were inserted in the brain, skin, and eye lenses of a female cadaver head, who underwent a CT brain perfusion scan using a Siemens Definition Flash. The table-toggling protocol used 80 kVp, 200 mAs, 32 × 1.2 mm collimation and 30 sequences. From the CT images, a voxel model was created. Doses were calculated with a MC framework (EGSnrc) and compared to TLD measurements. TLD measurements were also compared to the displayed CTDIvol. RESULTS The average measured doses were: 185 mGy for the eyes lenses, 107 mGy for the skin, 172 mGy for the brain and 273 mGy for the peak skin. The reported CTDIvol of 259 mGy overestimated the averaged organ doses but not the peak skin dose. MC estimated organ doses were 147 mGy for the eyes (average), 104 mGy for the skin and 178 mGy for the brain (-20 %, -3% and 4% difference respect to the TLDs measurements, respectively). CONCLUSIONS CTDIvol remains a conservative metric for average brain, skin and eyes lenses doses. For accurate eye lens and skin dose estimates MC simulations can be used. CTDIvol should be used with caution as it was of the same order of magnitude as the peak skin dose for this protocol and this particular CT scanner.
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Affiliation(s)
- X Lopez-Rendon
- Department of Imaging and Pathology, Division of Medical Physics & Quality Assessment, KU Leuven, Herestraat 49 box 7003, 3000, Leuven, Belgium.
| | - A Stratis
- Department of Imaging and Pathology, Division of Medical Physics & Quality Assessment, KU Leuven, Herestraat 49 box 7003, 3000, Leuven, Belgium
| | - G Zhang
- Department of Radiology, University Hospitals Leuven, Herestraat 49, 3000, Leuven, Belgium
| | - W Coudyzer
- Department of Radiology, University Hospitals Leuven, Herestraat 49, 3000, Leuven, Belgium
| | - W Develter
- Department of Imaging and Pathology, Division of Medical Physics & Quality Assessment, KU Leuven, Herestraat 49 box 7003, 3000, Leuven, Belgium
| | - R Bogaerts
- Laboratory of Experimental Radiotherapy, Department of Oncology, Biomedical Sciences Group, University of Leuven, Leuven, Belgium
| | - H Bosmans
- Department of Imaging and Pathology, Division of Medical Physics & Quality Assessment, KU Leuven, Herestraat 49 box 7003, 3000, Leuven, Belgium; Department of Radiology, University Hospitals Leuven, Herestraat 49, 3000, Leuven, Belgium
| | - F Zanca
- Department of Imaging and Pathology, Division of Medical Physics & Quality Assessment, KU Leuven, Herestraat 49 box 7003, 3000, Leuven, Belgium
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