Addendum to MIRD Pamphlet No. 28 Kesner, Adam L; Carter, Lukas M; Bolch, Wesley E
The Journal of nuclear medicine (1978),
10/2023, Letnik:
64, Številka:
10
Journal Article
This study sought to determine updated conversion factors (k-factors) that would enable accurate estimation of radiation effective dose (ED) for coronary computed tomography angiography (CTA) and ...calcium scoring performed on 12 contemporary scanner models and current clinical cardiac protocols and to compare these methods to the standard chest k-factor of 0.014 mSv·mGy−1cm−1.
Accurate estimation of ED from cardiac CT scans is essential to meaningfully compare the benefits and risks of different cardiac imaging strategies and optimize test and protocol selection. Presently, ED from cardiac CT is generally estimated by multiplying a scanner-reported parameter, the dose-length product, by a k-factor which was determined for noncardiac chest CT, using single-slice scanners and a superseded definition of ED.
Metal-oxide-semiconductor field-effect transistor radiation detectors were positioned in organs of anthropomorphic phantoms, which were scanned using all cardiac protocols, 120 clinical protocols in total, on 12 CT scanners representing the spectrum of scanners from 5 manufacturers (GE, Hitachi, Philips, Siemens, Toshiba). Organ doses were determined for each protocol, and ED was calculated as defined in International Commission on Radiological Protection Publication 103. Effective doses and scanner-reported dose-length products were used to determine k-factors for each scanner model and protocol.
k-Factors averaged 0.026 mSv·mGy−1cm−1 (95% confidence interval: 0.0258 to 0.0266) and ranged between 0.020 and 0.035 mSv·mGy−1cm−1. The standard chest k-factor underestimates ED by an average of 46%, ranging from 30% to 60%, depending on scanner, mode, and tube potential. Factors were higher for prospective axial versus retrospective helical scan modes, calcium scoring versus coronary CTA, and higher (100 to 120 kV) versus lower (80 kV) tube potential and varied among scanner models (range of average k-factors: 0.0229 to 0.0277 mSv·mGy−1cm−1).
Cardiac k-factors for all scanners and protocols are considerably higher than the k-factor currently used to estimate ED of cardiac CT studies, suggesting that radiation doses from cardiac CT have been significantly and systematically underestimated. Using cardiac-specific factors can more accurately inform the benefit-risk calculus of cardiac-imaging strategies.
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The objective of this study was to compare image quality and clinically significant lesion detection on deep learning reconstruction (DLR) and iterative reconstruction (IR) images of submillisievert ...chest and abdominopelvic CT.
Our prospective multiinstitutional study included 59 adult patients (33 women, 26 men; mean age ± SD, 65 ± 12 years old; mean body mass index weight in kilograms divided by the square of height in meters = 27 ± 5) who underwent routine chest (
= 22; 16 women, six men) and abdominopelvic (
= 37; 17 women, 20 men) CT on a 640-MDCT scanner (Aquilion ONE, Canon Medical Systems). All patients gave written informed consent for the acquisition of low-dose (LD) CT (LDCT) after a clinically indicated standard-dose (SD) CT (SDCT). The SDCT series (120 kVp, 164-644 mA) were reconstructed with interactive reconstruction (IR) (adaptive iterative dose reduction AIDR 3D, Canon Medical Systems), and the LDCT (100 kVp, 120 kVp; 30-50 mA) were reconstructed with filtered back-projection (FBP), IR (AIDR 3D and forward-projected model-based iterative reconstruction solution FIRST, Canon Medical Systems), and deep learning reconstruction (DLR) (Advanced Intelligent Clear-IQ Engine AiCE, Canon Medical Systems). Four subspecialty-trained radiologists first read all LD image sets and then compared them side-by-side with SD AIDR 3D images in an independent, randomized, and blinded fashion. Subspecialty radiologists assessed image quality of LDCT images on a 3-point scale (1 = unacceptable, 2 = suboptimal, 3 = optimal). Descriptive statistics were obtained, and the Wilcoxon sign rank test was performed.
Mean volume CT dose index and dose-length product for LDCT (2.1 ± 0.8 mGy, 49 ± 13mGy·cm) were lower than those for SDCT (13 ± 4.4 mGy, 567 ± 249 mGy·cm) (
< 0.0001). All 31 clinically significant abdominal lesions were seen on SD AIDR 3D and LD DLR images. Twenty-five, 18, and seven lesions were detected on LD AIDR 3D, LD FIRST, and LD FBP images, respectively. All 39 pulmonary nodules detected on SD AIDR 3D images were also noted on LD DLR images. LD DLR images were deemed acceptable for interpretation in 97% (35/37) of abdominal and 95-100% (21-22/22) of chest LDCT studies (
= 0.2-0.99). The LD FIRST, LD AIDR 3D, and LD FBP images had inferior image quality compared with SD AIDR 3D images (
< 0.0001).
At submillisievert chest and abdominopelvic CT doses, DLR enables image quality and lesion detection superior to commercial IR and FBP images.
A Total Dose Irradiation Test System Zhang, Kun; Yan, Na; Yang, Fan ...
Journal of physics. Conference series,
07/2021, Letnik:
1971, Številka:
1
Journal Article
Recenzirano
Odprti dostop
Abstract
In this paper, a set of generalized test system for total dose irradiation test is designed. Through the establishment of related hardware platform and related test chip according to the ...adaptation requirements, the device can be observed in real time under the radiation environment. The total dose test was irradiated with the
60
Co source, and it worked normally when different total doses were selected. In this article, a unit library test chip based on 130nm SOI technology is selected for testing. During the test, the system works stably and functions normally.
X‐ray‐induced photodynamic therapy (X‐PDT) combines both the advantages of radiotherapy (RT) and PDT, and has considerable potential applications in clinical deep‐penetrating cancer therapy. However, ...it is still a major challenge to prepare monodisperse nanoscintillators with uniform size and high light yield. In this study, a general and rapid synthesis method is presented that can achieve large‐scale preparation of monodisperse and uniform silicate nanoscintillators. By simply adjusting the metal dopants, silicate nanoscintillators with controllable size and X‐ray‐excited optical luminescence (450–900 nm) are synthesized by employing a general ion‐incorporated silica‐templating method. To make full use of external radiation, the silicate nanoscintillators are conjugated with photosensitizer rose bengal and arginylglycylaspartic acid (RGD) peptide, making them intrinsically dual‐modal targeted imaging probes. Both in vitro and in vivo experiments demonstrate that the silicate nanosensitizers can accumulate effectively in tumors and achieve significant inhibitory effect on tumor progression under low‐dose X‐ray irradiation, while minimally affecting normal tissues. The insights gained in this study may provide an attractive route to synthesize nanosensitizers to overcome some of the limitations of RT and PDT in cancer treatment.
A metal‐incorporated mesoporous silica nanosensitizer is synthesized, which achieves low‐dose X‐ray‐induced deep‐penetrating photodynamic therapy. This efficient killing of cancer cells is attributed to the synergy of radiotherapy and photodynamic therapy. The present research is of great value to the development of silicate‐based X‐ray‐induced photodynamic therapy for cancer management.
Abstract
Aims
Advances of cardiac computed tomography angiography (CTA) have been developed for dose reduction, but their efficacy in clinical practice is largely unknown. This study was designed to ...evaluate radiation dose exposure and utilization of dose-saving strategies for contrast-enhanced cardiac CTA in daily practice.
Methods and results
Sixty one hospitals from 32 countries prospectively enrolled 4502 patients undergoing cardiac CTA during one calendar month in 2017. Computed tomography angiography scan data and images were analysed in a central core lab and compared with a similar dose survey performed in 2007. Linear regression analysis was performed to identify independent predictors associated with dose. The most frequent indication for cardiac CTA was the evaluation of coronary artery disease in 89% of patients. The median dose-length product (DLP) of coronary CTA was 195 mGy*cm (interquartile range 110–338 mGy*cm). When compared with 2007, the DLP was reduced by 78% (P < 0.001) without an increase in non-diagnostic coronary CTAs (1.7% in 2007 vs. 1.9% in 2017 surveys, P = 0.55). A 37-fold variability in median DLP was observed between the hospitals with lowest and highest DLP (range of median DLP 57–2090 mGy*cm). Independent predictors for radiation dose of coronary CTA were: body weight, heart rate, sinus rhythm, tube voltage, iterative image reconstruction, and the selection of scan protocols.
Conclusion
This large international radiation dose survey demonstrates considerable reduction of radiation exposure in coronary CTA during the last decade. However, the large inter-site variability in radiation exposure underlines the need for further site-specific training and adaptation of contemporary cardiac scan protocols.
The aims of this study were to determine the objective and subjective image quality of high-pitch computed tomography (CT) angiography of the aorta in clinical dual-source photon-counting detector CT ...(PCD-CT) and to compare the image quality to conventional dual-source energy-integrating detector CT (EID-CT) in the same patients at equal radiation dose.
Patients with prior CT angiography of the thoracoabdominal aorta acquired on third-generation dual-source EID-CT in the high-pitch mode and with automatic tube voltage selection (ATVS, reference tube voltage 100 kV) were included. Follow-up imaging was performed on a first-generation, clinical dual-source PCD-CT scanner in the high-pitch and multienergy (QuantumPlus) mode at 120 kV using the same contrast media protocol as with EID-CT. Radiation doses between scans were matched by adapting the tube current of PCD-CT. Polychromatic images for both EID-CT and PCD-CT (called T3D) and virtual monoenergetic images at 40, 45, 50, and 55 keV for PCD-CT were reconstructed. Computed tomography attenuation was measured in the aorta; noise was defined as the standard deviation of attenuation; contrast-to-noise ratio (CNR) was calculated. Subjective image quality (noise, vessel attenuation, vessel sharpness, and overall quality) was rated by 2 blinded, independent radiologists.
Forty patients were included (mean age, 63 years; 8 women; mean body mass index BMI, 26 kg/m2). There was no significant difference in BMI, effective diameter, or radiation dose between scans (all P's > 0.05). The ATVS in EID-CT selected 70, 80, 90, 100, 110, and 120 kV in 2, 14, 14, 7, 2, and 1 patients, respectively. Mean CNR was 17 ± 8 for EID-CT and 22 ± 7, 20 ± 6, 18 ± 5, 16 ± 5, and 12 ± 4 for PCD-CT at 40, 45, 50, 55 keV, and T3D, respectively. Contrast-to-noise ratio was significantly higher for 40 and 45 keV of PCD-CT as compared with EID-CT (both P's < 0.05). The linear regression model (adjusted R2, 0.38; P < 0.001) revealed that PCD-CT reconstruction (P < 0.001), BMI group (P = 0.007), and kV of the EID-CT scan (P = 0.01) were significantly associated with CNR difference, with an increase by 34% with PCD-CT for overweight as compared with normal weight patients. Subjective image quality reading revealed slight differences between readers for subjective vessel attenuation and sharpness, whereas subjective noise was rated significantly higher for 40 and 45 keV (P < 0.001) and overall quality similar (P > 0.05) between scans.
High-pitch PCD-CT angiography of the aorta with VMI at 40 and 45 keV resulted in significantly increased CNR compared with EID-CT with ATVS at matched radiation dose. The CNR gain of PCD-CT increased in overweight patients. Taking into account the subjective analysis, VMI at 45 to 50 keV is proposed as the best trade-off between objective and subjective image quality.
Abstract
The paper considers a method for extending ionizing radiation absorbed dose measurement range by multilayer technology of one-, two-, three- and four-layer radiochromic films. It shows that ...this technology expands the AD measurement range to the small dose region of 10-1000 Gy.
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