diff --git a/docs/source/changelog.rst b/docs/source/changelog.rst
index 2f1498e5..96d34aa8 100644
--- a/docs/source/changelog.rst
+++ b/docs/source/changelog.rst
@@ -14,6 +14,11 @@ library but are still useful. So far, many RadMachine customers have asked for o
 While I disagree with adding one-off analyses to the core library, I also don't want to let the
 code be in secret for no good reason.
 
+VMAT
+^^^^
+
+* The VMAT image identification algorithm was changed slightly to better detect FFF DRMLC/DRGS images.
+
 CT
 ^^
 
diff --git a/pylinac/vmat.py b/pylinac/vmat.py
index 90190e28..ddc5ca63 100644
--- a/pylinac/vmat.py
+++ b/pylinac/vmat.py
@@ -29,7 +29,7 @@
 from .core.image import DicomImage, ImageLike
 from .core.io import TemporaryZipDirectory, get_url, retrieve_demo_file
 from .core.pdf import PylinacCanvas
-from .core.profile import InflectionDerivativeProfile
+from .core.profile import FWXMProfile
 from .core.utilities import ResultBase
 from .settings import get_dicom_cmap
 
@@ -482,7 +482,7 @@ def _draw_segments(self, axis: plt.Axes, show_text: bool):
     @classmethod
     def _median_profiles(
         cls, image1: DicomImage, image2: DicomImage
-    ) -> list[InflectionDerivativeProfile, InflectionDerivativeProfile]:
+    ) -> list[FWXMProfile, FWXMProfile]:
         """Return two median profiles from the open and DMLC image. Only used for visual purposes.
         Evaluation is not based on these profiles."""
         profiles = []
@@ -490,7 +490,7 @@ def _median_profiles(
             img = copy.deepcopy(orig_img)
             img.ground()
             img.check_inversion()
-            profile = InflectionDerivativeProfile(
+            profile = FWXMProfile(
                 np.mean(img.array, axis=0),
                 ground=True,
                 normalization=Normalization.BEAM_CENTER,
diff --git a/tests_basic/test_vmat.py b/tests_basic/test_vmat.py
index 401342e9..38d9bee2 100644
--- a/tests_basic/test_vmat.py
+++ b/tests_basic/test_vmat.py
@@ -360,3 +360,35 @@ class TestDRMLCOverlapGaps(VMATMixin, TestCase):
 
     def test_fail_with_tight_tolerance(self):
         pass
+
+
+class TestHalcyonDRGS(VMATMixin, TestCase):
+    """A Halcyon image is FFF and goes to the edge of the EPID. Causes bad inversion w/o FWXM profile type."""
+
+    klass = DRGS
+    filepaths = ("HalcyonDRGS.zip",)
+    is_zip = True
+    segment_positions = {0: Point(364, 640), 2: Point(547, 640)}
+    segment_values = {
+        0: {"r_dev": 41.4, "r_corr": 1689.2},
+        2: {"r_dev": 28, "r_corr": 1529.5},
+    }
+    avg_abs_r_deviation = 32.64
+    max_r_deviation = 41.4
+    passes = False
+
+
+class TestHalcyonDRMLC(VMATMixin, TestCase):
+    """A Halcyon image is FFF and goes to the edge of the EPID. Causes bad inversion w/o FWXM profile type."""
+
+    klass = DRMLC
+    filepaths = ("HalcyonDRMLC.zip",)
+    is_zip = True
+    segment_positions = {0: Point(433, 640), 2: Point(708, 640)}
+    segment_values = {
+        0: {"r_dev": 1.17, "r_corr": 3602},
+        2: {"r_dev": -0.206, "r_corr": 3552.8},
+    }
+    avg_abs_r_deviation = 0.585
+    max_r_deviation = 1.17
+    passes = True