Investigation of a water equivalent depth method for dosimetric accuracy evaluation of synthetic CT.

PURPOSE: To provide a metric that reflects the dosimetric utility of the synthetic CT (sCT) and can be rapidly determined. METHODS: Retrospective CT and atlas-based sCT of 62 (53 IMRT and 9 VMAT) prostate cancer patients were used. For image similarity measurements, the sCT and reference CT (rCT) were aligned using clinical registration parameters. Conventional image similarity metrics including the mean absolute error (MAE) and mean error (ME) were calculated. The water equivalent depth (WED) was automatically determined for each patient on the rCT and sCT as the distance from the skin surface to the treatment plan isocentre at 36 equidistant gantry angles, and the mean WED difference (ΔWED¯) between the two scans was calculated. Doses were calculated on each scan pair for the clinical plan in the treatment planning system. The image similarity measurements and ΔWED¯ were then compared to the isocentre dose difference (ΔDiso) between the two scans. RESULTS: While no particular relationship to dose was observed for the other image similarity metrics, the ME results showed a linear trend against ΔDiso with R2 = 0.6, and the 95 % prediction interval for ΔDiso between -1.2 and 1 %. The ΔWED¯ results showed an improved linear trend (R2 = 0.8) with a narrower 95 % prediction interval from -0.8 % to 0.8 %. CONCLUSION: ΔWED¯ highly correlates with ΔDiso for the reference and synthetic CT scans. This is easy to calculate automatically and does not require time-consuming dose calculations. Therefore, it can facilitate the process of developing and evaluating new sCT generation algorithms.

Mismatch between jar opening demands and wrist torque strength of consumers in Iran.

This study evaluated the potential mismatch between vacuum-sealed jar opening demands and wrist torque strength of 758 (384 males and 374 females) participants aged 5-74 years in Iran. Wrist ulnar/radial (U/R) torque strength of participants and required torque for opening the existing jars (with 2 different sizes - 65 mm and 85 mm diameter lids) were measured using a digital angle torque adaptor and then compared together to identify any potential mismatch between them. The mismatch percentages were defined as the number of participants whose maximal wrist U/R torque strength were lower than the minimum required torque strength for opening the vacuum-sealed jars. Minimum required torque strength for opening the existing 65 mm and 85 mm vacuum-sealed jars were 4.1 Nm and 6.6 Nm, respectively (range = 4.1 Nm to 10.2 Nm). A considerable mismatch (range = 25%-100%) was found between the required torque strength for opening the existing jars and the wrist U/R torque strength of the study population, particularly for females and those aged 5-9 years. A torque limit of 1.8 Nm was proposed for opening jars for the entire population.

Wrist ulnar/radial torque strength measurements among Iranian population: The effects of age, gender, Body Mass Index and hand dominance.

BACKGROUND: Data on the physical strength capabilities of users are essential for designing the safe and usable products. OBJECTIVE: The aims of this study were to characterise the wrist ulnar/radial (U/R) torque strength and individual strength differences among Iranian population. METHODS: The study was conducted among 769 (391 males, 378 females) participants aged 5-74 years in the northwest of Iran. Measurements were carried out with both dominant and non-dominant hands using a digital angle torque adaptor installed in a jar-shaped measuring unit. RESULTS: The results indicated that the mean wrist U/R torque strength exertion by females was 75% of that exerted by males. Strength exertion with the non-dominant hand was 8% lower than strength exertion of the dominant hand. A significant positive association was also found between the wrist U/R torque strength and body mass index. CONCLUSIONS: This additional information on the wrist torque strength can fill the gap in the strength data for Iranian population, or used by health and safety practitioners in the field.