Browsing by Author "Fu, wanyi"

Now showing 1 - 2 of 2
  • Thumbnail Image
    ItemOpen Access
    Clinical Decision Making in CT: Risk Assessment Comparison Across 12 Risk Metrics in Patient Populations
    (Journal of Medical Physics, 2020-06-30) Ria, Francesco; Fu, wanyi; Hoye, Jocelyn; Segars, William; Kapadia, Anuj; Samei, Ehsan
    Purpose The Medical Physics 3.0 initiative aims to enhance direct physicist involvement in clinical decision making to improve patient care. In this involvement, it is crucial to achieve effective and patient-specific radiation risk assessment. CT risk characterization presents a variety of metrics, many of which used as radiation risk surrogates; some are related to the device output (CTDI), whereas others include patient organ risk-, age-, and gender-factors (Effective Dose, Risk Index). It is unclear how different metrics can accurately reflect the radiological risk. This study compared how twelve metrics characterize risk across CT patient populations to inform effective clinical decision making in radiology. Methods This IRB-approved study included 1394 adult CT examinations (abdominopelvic and chest). Organ doses were calculated using Monte Carlo methods. The following risk surrogate metrics were calculated: CTDIvol, DLP, SSDE, DLP-based Effective Dose (EDk), organ-dose-based ED (EDOD), dose to defining organ (stomach- and lungs-ODD), organ-dose-based Risk Index (RI), and 20 y.o. patient Risk Index (RIr). Furthermore, ODD,0, ED0, and RI0 were calculated for a reference patient (ICRP 110). Lastly, an adjusted ED (ED') was computed as the product of RI/RIr and EDOD. A linear regression was applied to assess each metric’s dependency to RI, assumed to be the closest patient risk surrogate. The normalized-slope (nS) and a Minimum Risk Detectability Index (MRDI=RMSE/slope) were calculated for each fit. Results The analysis reported significant differences between the metrics. ED’ showed the best concordance with RI in terms of nS and MRDI. Across all metrics and protocols, nS ranged between 0.37(SSDE) to 1.29(RI0); MRDI ranged between 39.11(EDk) to 1.10(ED’) cancers per 105 patients per 0.1Gy. Conclusion Radiation risk characterization in CT populations is strongly affected by the index used to describe it. When involved in clinical decisions, medical physicists should exercise care in ascribing an implicit risk to factors that do not closely reflect risk.
  • Thumbnail Image
    ItemOpen Access
    Justification of radiological procedures in COVID-19 pandemic based on radiation risk only
    (2020-12-02) Ria, Francesco; Fu, wanyi; Chalian, Hamid; Segars, W; Fricks, Rafael; Khoshpouri, Pegah; Samei, Ehsan
    Purpose. Radiologic procedures are recommended based on benefit-to-risk justification. In X-ray imaging, while the benefit is often immediate for the patient, the associated radiation burden risk is a longer-term effect. Such a temporal gap can bias the justification process in imaging utilization, particularly during a spreading pandemic like COVID-19 in which fast and accurate diagnostic tools are highly needed. Chest CT and chest radiography (CXR) have shown promising results in the diagnosis and management of COVID-19, providing support to the standard RT-PCR test. However, several institutions are discouraging the use of imaging for this purpose, partly due to radiation risk. This study aims to provide quantitative data towards an effective risk-to benefit analysis for the justification of radiological studies in the diagnosis and management of COVID-19 to guide clinicians and decision making. Materials and Methods. The analysis was performed in terms of mortality rate per age group. COVID-19 mortality was extracted from epidemiological data across 159,107 patients in Italy. For radiological risk, the study considered 659 Chest CT scans performed in adult patients. Organ doses were estimated using a Monte Carlo based method and then used to calculate a risk index that was converted into a related 5-year mortality rate (SEER, NCI). Results. COVID-19 mortality showed a rapid rise for ages >30 years old (min: 0.30%; max: 30.20%). Only 1 death was reported in the analyzed patient cohort for ages <20 years old. The mortality rates based on radiation exposure decreased across age groups. The median mortality rate across all ages for Chest CT and CXR were 0.72% (min: 0.46%; max: 1.10%) and 0.03% (min: 0.02%; max: 0.04%), respectively. Conclusions. Radiation risk is not the only factor that should be taken into account for justifying the use of imaging in COVID care; nonetheless, it is an essential factor of consideration. The risk associated with COVID-19, CT, and CXR exhibited different magnitudes and trends across age groups. In higher ages, the risk of COVID-19 far outweighed that of radiological exams. Based on risk comparison alone, CXR and Chest CT are justified for COVID-19 care of patients older than 30 and 50 years old, respectively. Clinical Relevance statement (max 200 characters, with spaces) Towards a comprehensive radiological procedures risk-to-benefit assessment, CT and CXR should not be a priori excluded in the diagnosis and management of the COVID-19.