diff --git a/diffdrr/drr.py b/diffdrr/drr.py
index a88fecaa0..12a0ccddf 100644
--- a/diffdrr/drr.py
+++ b/diffdrr/drr.py
@@ -65,7 +65,7 @@ def __init__(
         self.air = torch.where(self.volume <= -800)
         self.soft_tissue = torch.where((-800 < self.volume) & (self.volume <= 350))
         self.bone = torch.where(350 < self.volume)
-        self.set_bone_attenuation_multiplier(bone_attenuation_multiplier)
+        self.bone_attenuation_multiplier = bone_attenuation_multiplier
 
     def reshape_transform(self, img, batch_size):
         if self.reshape:
@@ -104,6 +104,8 @@ def forward(
     bone_attenuation_multiplier: float = None,  # Contrast ratio of bone to soft tissue
 ):
     """Generate DRR with rotational and translational parameters."""
+    if not hasattr(self, "density"):
+        self.set_bone_attenuation_multiplier(self.bone_attenuation_multiplier)
     if bone_attenuation_multiplier is not None:
         self.set_bone_attenuation_multiplier(bone_attenuation_multiplier)
 
diff --git a/notebooks/api/00_drr.ipynb b/notebooks/api/00_drr.ipynb
index 87f8ff816..5e36ae690 100644
--- a/notebooks/api/00_drr.ipynb
+++ b/notebooks/api/00_drr.ipynb
@@ -157,7 +157,7 @@
     "        self.air = torch.where(self.volume <= -800)\n",
     "        self.soft_tissue = torch.where((-800 < self.volume) & (self.volume <= 350))\n",
     "        self.bone = torch.where(350 < self.volume)\n",
-    "        self.set_bone_attenuation_multiplier(bone_attenuation_multiplier) \n",
+    "        self.bone_attenuation_multiplier = bone_attenuation_multiplier \n",
     "\n",
     "    def reshape_transform(self, img, batch_size):\n",
     "        if self.reshape:\n",
@@ -220,6 +220,8 @@
     "    bone_attenuation_multiplier: float = None,  # Contrast ratio of bone to soft tissue\n",
     "):\n",
     "    \"\"\"Generate DRR with rotational and translational parameters.\"\"\"\n",
+    "    if not hasattr(self, \"density\"):\n",
+    "        self.set_bone_attenuation_multiplier(self.bone_attenuation_multiplier)\n",
     "    if bone_attenuation_multiplier is not None:\n",
     "        self.set_bone_attenuation_multiplier(bone_attenuation_multiplier)\n",
     "    \n",