A model for estimating peak skin dose in CT.

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.

Effect of Different Anthropometric Body Indexes on Radiation Exposure in Patients Undergoing Cardiac Catheterisation and Percutaneous Coronary Intervention.

BACKGROUND: Patient factors, such as sex and body mass index (BMI), are known to influence patient radiation exposure. Body surface area (BSA) and its association with patient radiation exposure has not been well studied. METHODS AND RESULTS: We analysed height, weight, BMI and BSA in consecutive patients undergoing cardiac catheterisation and percutaneous coronary intervention (PCI) at a high-volume Australian centre between September 2016 and April 2020 to assess their association with dose-area product (DAP, Gycm2). The mean age of the cohort was 64.5 ± 12.3 years with males comprising 68.8% (n = 8100, 5124 diagnostic cardiac catheterisation cases and 2976 PCI cases). Median male BMI was 28.4 kg/m2 [IQR 25.2-32.1] versus 28.8 kg/m2 [24.7-33.7] for females, p = 0.01. Males had higher BSA (2.0 ± 0.2 m2) than females (1.78 ± 0.2 m2), p = 0.001. Each 0.4 m2 increase in BSA conferred a 1.32x fold change in DAP (95% CI 1.29-1.36, p ≤ 0.001). Each 5 kg/m2 increase in BMI was linked to a 1.13x DAP fold change (1.12-1.14, p ≤ 0.001). Male sex conferred a 1.23x DAP fold change (1.20-1.26, p ≤ 0.001). Multivariable modelling with BMI or BSA explained 14% of DAP variance (R2 0.67 vs. 0.53 for both, p ≤ 0.001). CONCLUSIONS: BSA is an important anthropometric measure between the sexes and a key predictor of radiation dose and radiation exposure beyond sex, BMI, and weight.

Is It Safe to Use a Lead Screen During Hip Arthroscopy?

PURPOSE: To assess the radiation attenuation of lead screens in comparison to lead gowns in a simulated hip arthroscopy setting. METHODS: In this quantitative laboratory study, a phantom pelvis was used to simulate the scatter produced by patients during hip arthroscopy. Radiation measurements were taken using a handheld radiation detector positioned perpendicular to the phantom pelvis at 1.5 m and 2 m. Measurements were taken without shielding as a control, behind a lead gown (0.4-mm lead equivalent), and behind a lead screen (0.5-mm lead equivalent). RESULTS: With the detector at 1.5 m perpendicular to the hip, equivalent radiation was attenuated by the lead screen (94%) and the lead gown (94%). With the detector at 2 m perpendicular to the hip, the lead screen at 1.7 m attenuated 95% of radiation. CONCLUSIONS: In hip arthroscopy, using lead screens is a safe and more comfortable alternative to wearing lead gowns. The lead screen should be at least 1.2 m from the radiation source, with the surgeon standing closely behind the screen, fully covered. CLINICAL RELEVANCE: Lead screens can be safely used in hip arthroscopy.