Using local png as icon in flexdashboard?

How to use a local png picture as an icon in valueBox flexdashboard? since

---
title: "Untitled"
output: 
  flexdashboard::flex_dashboard:
    orientation: columns
    vertical_layout: fill
---

```{r setup, include=FALSE}
library(flexdashboard)

Column {data-width=650}

Chart A

valueBox(value = 1000,  caption = "Death Cases",  icon = "fas fa-heart-broken", 
           color = "red")

Column {data-width=350}

Chart B


Chart C