# README file

## General information

Data Set Title: "Dataset related to VVUQ main activities to assess the credibility of the Bologna Biomechanical Computed Tomogrpahy in silico methodology".

Data Set Author/s: Alessandra Aldieri (Alma Mater Studiorum - University of Bologna; IRCCS Istituto Ortopedico Rizzoli), ORCID 0000-0002-2397-3353; Antonino Amedeo La Mattina (Alma Mater Studiorum - University of Bologna; IRCCS Istituto Ortopedico Rizzoli), ORCID 0000-0002-9927-2393.

Data Set Contributor/s: Marco Viceconti (Alma Mater Studiorum - University of Bologna; IRCCS Istituto Ortopedico Rizzoli), ORCID 0000-0002-2293-1530.

Data Set Contact Person/s: Alessandra Aldieri (Alma Mater Studiorum - University of Bologna; IRCCS Istituto Ortopedico Rizzoli), ORCID 0000-0002-2397-3353, alessandra.aldieri@unibo.it.

Data Set License: The provided data are provided under the Creative Commons Attribution 4.0 International License (CC BY 4.0). To view a copy of this license, visit http://creativecommons.org/licenses/by/4.0/ or send a letter to Creative Commons, PO Box 1866, Mountain View, CA 94042, USA.

Publication Year: 2022

Project Info: In Silico World (Lowering barriers to ubiquitous adoption of In Silico Trials), funded by European Commission, Horizon 2020 Programme. Grant Agreement num. 101016503; https://insilico.world/. CompBioMed2 (A Centre of Excellence in Computational Biomedicine), funded by European Commission, Horizon 2020 Programme. Grant Agreement num. 823712; https://www.compbiomed.eu/. 



## Data set Contents

The data set consists of
  - 1 xlsx file: "VVUQdata.xlsx"
  - 1 README file: "VVUQdata_README.txt"



## Data set documentation

### Abstract

This dataset contains the details (inputs and outputs) of the main VVUQ activities performed in order to assess the credibility of Bologna Biomechanical Computed Tomography (BBCT)-hip according to ASMEV&V40-2018. BBCT-hip model calculates ARF0, the hip fracture risk upon falling, by modelling a fall to the side. In principle, ARF0 is identified by calculating possible impact forces derived from a fall (through a stochastic mathematical model) and by assessing which of those, exceeding the load to failure (determined through a patient-specific finite element model), lead to a fracture event. More in detail, BBCT-hip uses a stochastic mathematical model to simulate 1,000,000 falls of a body of the height and weight equal to those of the patient, each with initial conditions assigned randomly according to specific probability distributions, and for each of these falls predicts the resulting impact force. In parallel, a patient-specific Finite Element (FE) model of the femur informed by the patient’s QCT data is run 28 times, varying the femur orientation at the impact (femoral impact pose). For each impact pose, the load to failure, i.e. the intensity of the force required to fracture the femur, is computed based on principal strains. The FE model-derived loads to failure inform a reduced-order model (response surface) which allows inferring the magnitude of the load to failure for each possible impact direction at a reasonable computational cost. The surrogate biomarker ARF0 is calculated as the ratio of the number of simulated falls that the model predicts would cause a fracture divided by the total number of simulated falls. 

In the "VVUQdata.xlsx" compressed archive you will find the following data:
	- Sheet 'LH_samplesize': convergence analysis on number of computed impact forces (Latin Hypercube sample size). Tested sample sizes and resulting ARF0s values (minimum, maximum nad mean values over 101 simulated subjects) are provided.
	- Sheets '10°ImpactPoses', '5°ImpactPoses', '2°ImpactPoses': convergence analysis on the number of impact poses simulated with the FE model. Results in terms of Minumum Side-Fall strength (MSF), i.e. the lowest load to failure across all the impact poses, amd ARF0 are given for 101 subjects.
	- Sheet 'MeshConvergence': convergence analysis on the tetrahedral mesh size. Errors on principal strains are reported.
	- Sheet 'ElasticitySpatialDiscretisation': convergence analysis on the elasticity spatial discertisation adopted to assign material properties to the FE model. Principal strains and load to failure are reported for one subject along the 28 impact poses.
	- Sheet 'NewtonRaphson': numerical solver error analysis. Tested Newton-Raphson convergence criteria (Tolerance and Norm) and corresponding load to failure in Neutral impact pose (0° intra/extra and abduction angle) are reported for one subject.
	- Sheet 'SegmentationVariability': uncertainities quantification regarding the CT images segmentations performed by four different operators and by same operator four times on the same subjetcs (four in total). Hausdorff distances values and their effect on the ARF0 prediction are provided.
	- Sheet 'MorgansCoeffs': sensitivity analysis on the coefficients used in the power-law relation between density and Young's modulus. MSF, ARF0 and loads to failure for all the impact poses are provided for one subject.
	- Sheet 'CalibrationPhantom': sensitivity analysis on the coefficients used in the linear relation to calibrate the CT images HU values and obtain corresponding density values. MSF, ARF0 and loads to failure for all the impact poses are provided for one subject.
	- Sheet 'AnatomicalLandmarks': uncertainty qualtification on the locations of manually identified femoral anatomical points used to set a local refrence system. The points have been identified by the same operator four different times and by four different operators. Effects of such unceratinties on BBCT-hip outcomes are eveluated. Resulting MSF, ARF0 and loads to failure are provided for one subject.
	- Sheet 'BCs': Sensitivity analysis on the portion of the distal femur to be constrained. MSF, ARF0 and loads to failure are provided for one subject.
	- Sheet 'ContactParameters': sensitivity analysis on the contact parameters employed in the definition of the rigid frictionless contact plane placed at the greater trochanter. The stiffness and penetration tolerance factors tested are reported with load to failure in Neutral impact pose and MSF and ARF0.