diff --git a/scico/test/linop/xray/test_xray.py b/scico/test/linop/xray/test_xray.py
index cd7c0dcd..714ed5fb 100644
--- a/scico/test/linop/xray/test_xray.py
+++ b/scico/test/linop/xray/test_xray.py
@@ -5,7 +5,8 @@
 import pytest
 
 import scico
-from scico.linop.xray import XRayTransform2D, XRayTransform3D
+import scico.linop
+from scico.linop.xray import XRayTransform2D
 
 
 @pytest.mark.filterwarnings("error")
@@ -71,44 +72,12 @@ def test_apply_adjoint():
     assert y.shape[1] == det_count
 
 
-def test_3d_scaling():
-    x = jnp.zeros((4, 4, 1))
-    x = x.at[1:3, 1:3, 0].set(1.0)
-
-    input_shape = x.shape
-    output_shape = x.shape[:2]
-
-    # default spacing
-    M = XRayTransform3D.matrices_from_euler_angles(input_shape, output_shape, "X", [0.0])
-    H = XRayTransform3D(input_shape, matrices=M, det_shape=output_shape)
-    # fmt: off
-    truth = jnp.array(
-        [[[0.0, 0.0, 0.0, 0.0],
-          [0.0, 1.0, 1.0, 0.0],
-          [0.0, 1.0, 1.0, 0.0],
-          [0.0, 0.0, 0.0, 0.0]]]
-    )  # fmt: on
-    np.testing.assert_allclose(H @ x, truth)
-
-    # bigger voxels in the x (first index) direction
-    M = XRayTransform3D.matrices_from_euler_angles(
-        input_shape, output_shape, "X", [0.0], voxel_spacing=[2.0, 1.0, 1.0]
-    )
-    H = XRayTransform3D(input_shape, matrices=M, det_shape=output_shape)
-    # fmt: off
-    truth = jnp.array(
-        [[[0. , 0.5, 0.5, 0. ],
-          [0. , 0.5, 0.5, 0. ],
-          [0. , 0.5, 0.5, 0. ],
-          [0. , 0.5, 0.5, 0. ]]]
-    )  # fmt: on
-    np.testing.assert_allclose(H @ x, truth)
-
-    # bigger detector pixels in the x (first index) direction
-    M = XRayTransform3D.matrices_from_euler_angles(
-        input_shape, output_shape, "X", [0.0], det_spacing=[2.0, 1.0]
-    )
-    H = XRayTransform3D(input_shape, matrices=M, det_shape=output_shape)
-    # fmt: off
-    truth = None  # fmt: on  # TODO: Check this case more closely.
-    # np.testing.assert_allclose(H @ x, truth)
+def test_matched_adjoint():
+    """See https://github.com/lanl/scico/issues/560."""
+    N = 16
+    det_count = int(N * 1.05 / np.sqrt(2.0))
+    dx = 1.0 / np.sqrt(2)
+    n_projection = 3
+    angles = np.linspace(0, np.pi, n_projection, endpoint=False)
+    A = XRayTransform2D((N, N), angles, det_count=det_count, dx=dx)
+    assert scico.linop.valid_adjoint(A, A.T, eps=1e-5)
diff --git a/scico/test/linop/xray/test_xray_3d.py b/scico/test/linop/xray/test_xray_3d.py
new file mode 100644
index 00000000..d96217a4
--- /dev/null
+++ b/scico/test/linop/xray/test_xray_3d.py
@@ -0,0 +1,66 @@
+import numpy as np
+
+import jax.numpy as jnp
+
+import scico.linop
+from scico.linop.xray import XRayTransform3D
+
+
+def test_matched_adjoint():
+    """See https://github.com/lanl/scico/issues/560."""
+    N = 16
+    det_count = int(N * 1.05 / np.sqrt(2.0))
+    n_projection = 3
+
+    input_shape = (N, N, N)
+    det_shape = (det_count, det_count)
+
+    M = XRayTransform3D.matrices_from_euler_angles(
+        input_shape, det_shape, "X", np.linspace(0, np.pi, n_projection, endpoint=False)
+    )
+    H = XRayTransform3D(input_shape, matrices=M, det_shape=det_shape)
+
+    assert scico.linop.valid_adjoint(H, H.T, eps=1e-5)
+
+
+def test_scaling():
+    x = jnp.zeros((4, 4, 1))
+    x = x.at[1:3, 1:3, 0].set(1.0)
+
+    input_shape = x.shape
+    det_shape = x.shape[:2]
+
+    # default spacing
+    M = XRayTransform3D.matrices_from_euler_angles(input_shape, det_shape, "X", [0.0])
+    H = XRayTransform3D(input_shape, matrices=M, det_shape=det_shape)
+    # fmt: off
+    truth = jnp.array(
+        [[[0.0, 0.0, 0.0, 0.0],
+          [0.0, 1.0, 1.0, 0.0],
+          [0.0, 1.0, 1.0, 0.0],
+          [0.0, 0.0, 0.0, 0.0]]]
+    )  # fmt: on
+    np.testing.assert_allclose(H @ x, truth)
+
+    # bigger voxels in the x (first index) direction
+    M = XRayTransform3D.matrices_from_euler_angles(
+        input_shape, det_shape, "X", [0.0], voxel_spacing=[2.0, 1.0, 1.0]
+    )
+    H = XRayTransform3D(input_shape, matrices=M, det_shape=det_shape)
+    # fmt: off
+    truth = jnp.array(
+        [[[0. , 0.5, 0.5, 0. ],
+          [0. , 0.5, 0.5, 0. ],
+          [0. , 0.5, 0.5, 0. ],
+          [0. , 0.5, 0.5, 0. ]]]
+    )  # fmt: on
+    np.testing.assert_allclose(H @ x, truth)
+
+    # bigger detector pixels in the x (first index) direction
+    M = XRayTransform3D.matrices_from_euler_angles(
+        input_shape, det_shape, "X", [0.0], det_spacing=[2.0, 1.0]
+    )
+    H = XRayTransform3D(input_shape, matrices=M, det_shape=det_shape)
+    # fmt: off
+    truth = None  # fmt: on  # TODO: Check this case more closely.
+    # np.testing.assert_allclose(H @ x, truth)