diff --git a/Dockerfile b/Dockerfile
index b98b4fb..7f0411e 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -1,15 +1,5 @@
-# using rocker r-vers as a base with R 4.2.3
-# https://hub.docker.com/r/rocker/r-ver
-# https://rocker-project.org/images/versioned/r-ver.html
-#
-# sets CRAN repo to use Posit Package Manager to freeze R package versions to
-# those available on 2023-03-31
-# https://packagemanager.rstudio.com/client/#/repos/2/overview
-# https://packagemanager.rstudio.com/cran/__linux__/jammy/2023-03-31+MbiAEzHt
-
-FROM transitionmonitordockerregistry.azurecr.io/rmi_pacta:2021q4_1.0.0
-ARG CRAN_REPO="https://packagemanager.posit.co/cran/__linux__/jammy/2023-10-30"
-RUN echo "options(repos = c(CRAN = '$CRAN_REPO'))" >> "${R_HOME}/etc/Rprofile.site"
+FROM ghcr.io/rmi-pacta/workflow.transition.monitor:main
+# inherit CRAN REPO and R options from base image
 
 # Install R dependencies
 COPY DESCRIPTION /workflow.prepare.pacta.indices/DESCRIPTION
diff --git a/README.md b/README.md
index 3f21c9f..0a8484a 100644
--- a/README.md
+++ b/README.md
@@ -10,14 +10,17 @@ The goal of `workflow.prepare.pacta.indices` is to run indices through PACTA,
 and format them for the Transition Monitor webtool. 
 
 ## Running Prepare PACTA Indices workflow  
+
 ### Required input
 
-The index preparation Dockerfile uses the `transitionmonitordockerregistry/rmi_pacta` docker image as a base image. Pulling this image requires access to the Azure docker registry `transitionmonitordockerregistry`. 
+The index preparation Dockerfile uses the `ghcr.io/rmi-pacta/workflow.transition.monitor` docker image as a base image.
+Although the image is public, pulling public images from GHCR requires authentication.
+
+You can authenticate to GHCR with any valid GitHub Personal Access token
 
-You can log-in to this registry by calling:
 ``` bash
-az acr login --name transitionmonitordockerregistry
-``` 
+echo $GITHUB_PAT | docker login ghcr.io -u <USERNAME> --password-stdin
+```
 
 ### Running in Docker
 The simplest way to run the data preparation process is by using docker.