Quantitative assessment of nonsolid pulmonary nodule volume with computed tomography in a phantom study

Lee

Quant. Imaging Med. Surg

2019

Background: To investigate whether monoenergetic images captured with dual-layer spectral computed tomography (CT) can improve the repeatability of subsolid nodule measurement, and whether this approach can further reduce the radiation dose of CT while maintaining its measurement repeatability. Methods: An anthropomorphic phantom with simulated subsolid nodules at three different levels was repeatedly scanned with both conventional single-energy CT and dual-layer spectral CT. A proxy for the measurement repeatability in the National Lung Screening Trial (proxy for NLST) was calculated with the typical CT protocol used in NLST. Using the dual-layer spectral CT, monoenergetic images of 40 to 110 keV, with an interval of 10 keV, were generated. The average diameter and volume of a total of 15,120 nodules in 840 CT images were measured by using a commercially-available computer-aided detection (CAD) system. The repeatability coefficient (RC), %RC, and 95% confidence intervals (CIs) of each image set were calculated and compared. Results: At the same tube voltage and tube current-time product, monoenergetic images resulted in significantly lower RC than the proxy for NLST, indicating that measurement repeatability was enhanced. When the radiation dose was lowered by 30% or 55%, monoenergetic images showed significantly lower RC at high-energy keV than the proxy for NLST. The estimated measurement repeatability from monoenergetic images with 30% or 55% lower radiation dose was comparable to the repeatability from conventional singleenergy CT images with standard radiation dose and iterative reconstruction. Conclusions: Monoenergetic images captured by using dual-layer spectral CT can improve the repeatability of subsolid nodule measurement. The use of monoenergetic images would allow lung cancer screening with a lower radiation dose, while maintaining comparable measurement repeatability.

Section: Discussioncontrasting

confidence: 61%

Section: Original Articlementioning

confidence: 99%

Section: Original Articlementioning

confidence: 99%

Section: Original Articlementioning

confidence: 99%

See 2 more Smart Citations

Improved repeatability of subsolid nodule measurement in low-dose lung screening with monoenergetic images: a phantom study

Lee

Quant. Imaging Med. Surg

2019

Quant. Imaging Med. Surg.

“…For example, if an error of observation or measurement of the longest diameter is made by the radiologist, an inappropriate classification into "no further follow-up indicated" would be rendered. Ultimately this could result in a failure to diagnose a growing lung cancer (3). So in addition to subjective observation, a computer-aided diagnosis (CAD) system may play a crucial role in the evaluation of pulmonary nodules (4).…”

Section: Introductionmentioning

confidence: 99%

Lung nodules assessment in ultra-low-dose CT with iterative reconstruction compared to conventional dose CT

Jin¹,

Zhang²,

Zhang³

et al. 2018

Our study suggests that detection of lung nodules with ultra-low-dose CT can yield an excellent image quality and optimal diagnostic values as compared to the standard dose CT. Therefore, CT scan with low voltage of 80 kV CT scan can be leveraged to improve the diagnosis and surveillance of lung nodules measured less than 30 mm in diameter. Further investigation with a larger sample size is warranted to confirm our findings, particularly the increased CT values of large nodules and the greater volume of solid nodules after exposure to low-dose CT scan.

Optimisation of Radiological Protection in Digital Radiology Techniques for Medical Imaging

2023

Ann ICRP

Use of medical imaging continues to increase, making the largest contribution to the exposure of populations from artificial sources of radiation worldwide. The principle of optimisation of protection is that ‘the likelihood of incurring exposures, the number of people exposed, and the magnitude of their individual doses should all be kept as low as reasonably achievable (ALARA), taking into account economic and societal factors’. Optimisation for medical imaging involves more than ALARA – it requires keeping individual patient exposures to the minimum necessary to achieve the required medical objectives. In other words, the type, number, and quality of images must be adequate to obtain the information needed for diagnosis or intervention. Dose reductions for imaging or x-ray-image-guided procedures should not be used if they degrade image quality to the point where the images are inadequate for the clinical purpose. The move to digital imaging has provided versatile acquisition, post-processing, and presentation options, and enabled wide and often immediate availability of image information. However, because images are adjusted for optimal viewing, the appearance may not give any indication if the dose is higher than necessary. Nevertheless, digital images provide opportunities for further optimisation, and allow the application of artificial intelligence methods. Optimisation of radiological protection for digital radiology (radiography, fluoroscopy, and computed tomography) involves selection and installation of equipment, design and construction of facilities, choice of optimal equipment settings, day-to-day methods of operation, quality control programmes, and ensuring that all personnel receive proper initial and career-long training. The radiation dose levels that patients receive also have implications for doses to staff. As new imaging equipment incorporates more options to improve performance, it becomes more complex and less easily understood, so operators have to be given more extensive training. Ongoing monitoring, review, and analysis of performance is required that feeds back into the improvement and development of imaging protocols. Several different aspects relating to optimisation of protection that need to be developed are set out in this publication. The first is collaboration between radiologists/other radiological medical practitioners, radiographers/medical radiation technologists, and medical physicists, each of whom have key skills that can only contribute to the process effectively when individuals work together as a core team. The second is appropriate methodology and technology, with the knowledge and expertise required to use each effectively. The third relates to organisational processes which ensure that required tasks, such as equipment performance tests, patient dose surveys, and review of protocols, are carried out. There is wide variation in equipment, funding, and expertise around the world, and the majority of facilities do not have all the tools, professional teams, and expertise to fully embrace all the possibilities for optimisation. Therefore, this publication sets out broad levels for aspects of optimisation that different facilities might achieve, and through which they can progress incrementally: Level D – preliminary; Level C – basic; Level B – intermediate; and Level A – advanced. Guidance from professional societies can be invaluable in helping users to evaluate systems and aid in adoption of best practice. Examples of systems and activities that should be in place to achieve the different levels are set out. Imaging facilities can then evaluate the arrangements they already have, and use this publication to guide decisions about the next actions to be taken in optimising their imaging services.