diff --git a/hazenlib/tasks/acr_geometric_accuracy.py b/hazenlib/tasks/acr_geometric_accuracy.py
new file mode 100644
index 0000000..b71f00b
--- /dev/null
+++ b/hazenlib/tasks/acr_geometric_accuracy.py
@@ -0,0 +1,241 @@
+"""
+ACR Geometric Accuracy
+https://www.acraccreditation.org/-/media/acraccreditation/documents/mri/largephantomguidance.pdf
+
+Calculates geometric accuracy for slices 1 and 5 of the ACR phantom.
+
+This script calculates the horizontal and vertical lengths of the ACR phantom in Slice 1 in accordance with the ACR Guidance.
+This script calculates the horizontal, vertical and diagonal lengths of the ACR phantom in Slice 5 in accordance with the ACR Guidance.
+The average distance measurement error, maximum distance measurement error and coefficient of variation of all distance
+measurements is reported as recommended by IPEM Report 112, "Quality Control and Artefacts in Magnetic Resonance Imaging".
+
+This is done by first producing a binary mask for each respective slice. Line profiles are drawn with aid of rotation
+matrices around the centre of the test object to determine each respective length. The results are also visualised.
+
+Created by Yassine Azma
+yassine.azma@rmh.nhs.uk
+
+18/11/2022
+"""
+
+import sys
+import traceback
+import os
+import numpy as np
+import skimage.morphology
+import skimage.measure
+import skimage.transform
+
+from hazenlib.HazenTask import HazenTask
+
+
+class ACRGeometricAccuracy(HazenTask):
+
+    def __init__(self, **kwargs):
+        super().__init__(**kwargs)
+
+    def run(self) -> dict:
+        results = {}
+        z = []
+        for dcm in self.data:
+            z.append(dcm.ImagePositionPatient[2])
+
+        idx_sort = np.argsort(z)
+
+        for dcm in self.data:
+            if dcm.ImagePositionPatient[2] == z[idx_sort[0]]:
+                try:
+                    result1 = self.get_geometric_accuracy_slice1(dcm)
+                except Exception as e:
+                    print(f"Could not calculate the geometric accuracy for {self.key(dcm)} because of : {e}")
+                    traceback.print_exc(file=sys.stdout)
+                    continue
+
+                results[self.key(dcm)] = result1
+            elif dcm.ImagePositionPatient[2] == z[idx_sort[4]]:
+                try:
+                    result5 = self.get_geometric_accuracy_slice5(dcm)
+                except Exception as e:
+                    print(f"Could not calculate the geometric accuracy for {self.key(dcm)} because of : {e}")
+                    traceback.print_exc(file=sys.stdout)
+                    continue
+
+                results[self.key(dcm)] = result5
+
+        results['reports'] = {'images': self.report_files}
+
+        L = result1 + result5
+        mean_err, max_err, cov_l = self.distortion_metric(L)
+        print(f"Mean relative measurement error is equal to {np.round(mean_err, 2)}mm")
+        print(f"Maximum absolute measurement error is equal to {np.round(max_err, 2)}mm")
+        print(f"Coefficient of variation of measurements is equal to {np.round(cov_l, 2)}%")
+        return results
+
+    def centroid_com(self, dcm):
+        # Calculate centroid of object using a centre-of-mass calculation
+        thresh_img = dcm > 0.25 * np.max(dcm)
+        open_img = skimage.morphology.area_opening(thresh_img, area_threshold=500)
+        bhull = skimage.morphology.convex_hull_image(open_img)
+        coords = np.nonzero(bhull)  # row major - first array is columns
+
+        sum_x = np.sum(coords[1])
+        sum_y = np.sum(coords[0])
+        cx, cy = sum_x / coords[0].shape[0], sum_y / coords[1].shape[0]
+        cxy = (round(cx), round(cy))
+
+        return bhull, cxy
+
+    def horizontal_length(self, res, mask, cxy):
+        dims = mask.shape
+        start_h = (cxy[1], 0)
+        end_h = (cxy[1], dims[0] - 1)
+        line_profile_h = skimage.measure.profile_line(mask, start_h, end_h, mode='reflect')
+        extent_h = np.nonzero(line_profile_h)[0]
+        dist_h = (extent_h[-1] - extent_h[0]) * res[0]
+
+        h_dict = {
+            'Start': start_h,
+            'End': end_h,
+            'Extent': extent_h,
+            'Distance': dist_h
+        }
+        return h_dict
+
+    def vertical_length(self, res, mask, cxy):
+        dims = mask.shape
+        start_v = (0, cxy[0])
+        end_v = (dims[1] - 1, cxy[0])
+        line_profile_v = skimage.measure.profile_line(mask, start_v, end_v, mode='reflect')
+        extent_v = np.nonzero(line_profile_v)[0]
+        dist_v = (extent_v[-1] - extent_v[0]) * res[1]
+
+        v_dict = {
+            'Start': start_v,
+            'End': end_v,
+            'Extent': extent_v,
+            'Distance': dist_v
+        }
+        return v_dict
+
+    def rotate_point(self, origin, point, angle):
+        theta = np.radians(angle)
+        c, s = np.cos(theta), np.sin(theta)
+
+        x_prime = origin[0] + c * (point[0] - origin[0]) - s * (point[1] - origin[1])
+        y_prime = origin[1] + s * (point[0] - origin[0]) + c * (point[1] - origin[1])
+        return x_prime, y_prime
+
+    def diagonal_lengths(self, res, mask, cxy):
+        eff_res = np.sqrt(np.mean(np.square(res)))
+        mask_rotate = skimage.transform.rotate(mask, 45, center=(cxy[0], cxy[1]))
+
+        h_dict = self.horizontal_length(res, mask_rotate, cxy)
+        extent_h = h_dict['Extent']
+
+        origin = (cxy[0], cxy[1])
+        start = (extent_h[0], cxy[1])
+        end = (extent_h[-1], cxy[1])
+        se_x_start, se_y_start = self.rotate_point(origin, start, 45)
+        se_x_end, se_y_end = self.rotate_point(origin, end, 45)
+
+        dist_se = np.sqrt(np.sum(np.square([se_x_end - se_x_start, se_y_end - se_y_start]))) * eff_res
+        se_dict = {
+            'Start': (se_x_start, se_y_start),
+            'End': (se_x_end, se_y_end),
+            'Extent': (se_x_end - se_x_start, se_y_end - se_y_start),
+            'Distance': dist_se
+        }
+
+        v_dict = self.vertical_length(res, mask_rotate, cxy)
+        extent_v = v_dict['Extent']
+
+        start = (cxy[0], extent_v[0])
+        end = (cxy[0], extent_v[-1])
+        sw_x_start, sw_y_start = self.rotate_point(origin, start, 45)
+        sw_x_end, sw_y_end = self.rotate_point(origin, end, 45)
+
+        dist_sw = np.sqrt(np.sum(np.square([sw_x_end - sw_x_start, sw_y_end - sw_y_start]))) * eff_res
+        sw_dict = {
+            'Start': (sw_x_start, sw_y_start),
+            'End': (sw_x_end, sw_y_end),
+            'Extent': (sw_x_end - sw_x_start, sw_y_end - sw_y_start),
+            'Distance': dist_sw
+        }
+
+        return sw_dict, se_dict
+
+    def get_geometric_accuracy_slice1(self, dcm):
+        img = dcm.pixel_array
+        res = dcm.PixelSpacing
+        mask, cxy = self.centroid_com(img)
+
+        h_dict = self.horizontal_length(res, mask, cxy)
+        v_dict = self.vertical_length(res, mask, cxy)
+
+        if self.report:
+            import matplotlib.pyplot as plt
+            fig = plt.figure()
+            fig.set_size_inches(8, 8)
+            plt.imshow(img)
+
+            plt.arrow(h_dict['Extent'][0], cxy[1], h_dict['Extent'][-1] - h_dict['Extent'][0], 1, color='blue',
+                      length_includes_head=True, head_width=5)
+            plt.arrow(cxy[0], v_dict['Extent'][0], 1, v_dict['Extent'][-1] - v_dict['Extent'][0], color='orange',
+                      length_includes_head=True, head_width=5)
+            plt.legend([str(np.round(h_dict['Distance'], 2)) + 'mm',
+                        str(np.round(v_dict['Distance'], 2)) + 'mm'])
+            plt.axis('off')
+            plt.title('Geometric Accuracy for Slice 1')
+
+            img_path = os.path.realpath(os.path.join(self.report_path, f'{self.key(dcm)}.png'))
+            fig.savefig(img_path)
+            self.report_files.append(img_path)
+
+        return h_dict['Distance'], v_dict['Distance']
+
+    def get_geometric_accuracy_slice5(self, dcm):
+        img = dcm.pixel_array
+        res = dcm.PixelSpacing
+        mask, cxy = self.centroid_com(img)
+
+        h_dict = self.horizontal_length(res, mask, cxy)
+        v_dict = self.vertical_length(res, mask, cxy)
+        sw_dict, se_dict = self.diagonal_lengths(res, mask, cxy)
+
+        if self.report:
+            import matplotlib.pyplot as plt
+            fig = plt.figure()
+            fig.set_size_inches(8, 8)
+            plt.imshow(img)
+
+            plt.arrow(h_dict['Extent'][0], cxy[1], h_dict['Extent'][-1] - h_dict['Extent'][0], 1, color='blue',
+                      length_includes_head=True, head_width=5)
+            plt.arrow(cxy[0], v_dict['Extent'][0], 1, v_dict['Extent'][-1] - v_dict['Extent'][0], color='orange',
+                      length_includes_head=True, head_width=5)
+
+            plt.arrow(se_dict['Start'][0], se_dict['Start'][1], se_dict['Extent'][0], se_dict['Extent'][1],
+                      color='purple', length_includes_head=True, head_width=5)
+            plt.arrow(sw_dict['Start'][0], sw_dict['Start'][1], sw_dict['Extent'][0], sw_dict['Extent'][1],
+                      color='yellow', length_includes_head=True, head_width=5)
+
+            plt.legend([str(np.round(h_dict['Distance'], 2)) + 'mm',
+                        str(np.round(v_dict['Distance'], 2)) + 'mm',
+                        str(np.round(sw_dict['Distance'], 2)) + 'mm',
+                        str(np.round(se_dict['Distance'], 2)) + 'mm'])
+            plt.axis('off')
+            plt.title('Geometric Accuracy for Slice 5')
+
+            img_path = os.path.realpath(os.path.join(self.report_path, f'{self.key(dcm)}.png'))
+            fig.savefig(img_path)
+            self.report_files.append(img_path)
+
+        return h_dict['Distance'], v_dict['Distance'], sw_dict['Distance'], se_dict['Distance']
+
+    def distortion_metric(self, L):
+        err = [x - 190 for x in L]
+        mean_err = np.mean(err)
+
+        max_err = np.max(np.absolute(err))
+        cov_l = 100 * np.std(L) / np.mean(L)
+
+        return mean_err, max_err, cov_l

diff --git a/.github/workflows/test_cli.yml b/.github/workflows/test_cli.yml
index 9082b13..203650d 100644
--- a/.github/workflows/test_cli.yml
+++ b/.github/workflows/test_cli.yml
@@ -55,6 +55,11 @@ jobs:
         run: |
           hazen acr_ghosting tests/data/acr/Siemens --report
 
+      - name: test acr_geometric_accuracy
+        if: always()  # will always run regardless of whether previous step fails - useful to ensure all CLI functions tested
+        run: |
+          hazen acr_geometric_accuracy tests/data/acr/Siemens --report
+
       - name: test slice_position
         if: always()  # will always run regardless of whether previous step fails - useful to ensure all CLI functions tested
         run: |
diff --git a/tests/test_acr_geometric_accuracy.py b/tests/test_acr_geometric_accuracy.py
new file mode 100644
index 0000000..0de6d26
--- /dev/null
+++ b/tests/test_acr_geometric_accuracy.py
@@ -0,0 +1,72 @@
+import os
+import unittest
+import pathlib
+import pydicom
+import numpy as np
+
+from hazenlib.tasks.acr_geometric_accuracy import ACRGeometricAccuracy
+from tests import TEST_DATA_DIR, TEST_REPORT_DIR
+
+
+class TestACRGeometricAccuracySiemens(unittest.TestCase):
+    ACR_GEOMETRIC_ACCURACY_DATA = pathlib.Path(TEST_DATA_DIR / 'acr')
+    centre = (128, 129)
+    L1 = 190.43, 186.52
+    L5 = 190.43, 186.52, 189.45, 191.41
+    test_point = (-60.98, -45.62)
+
+    def setUp(self):
+        self.acr_geometric_accuracy_task = ACRGeometricAccuracy(data_paths=[os.path.join(TEST_DATA_DIR, 'acr')],
+                                                                report_dir=pathlib.PurePath.joinpath(TEST_REPORT_DIR))
+        self.dcm = pydicom.read_file(os.path.join(TEST_DATA_DIR, 'acr', 'Siemens', '0.dcm'))
+        self.dcm2 = pydicom.read_file(os.path.join(TEST_DATA_DIR, 'acr', 'Siemens', '4.dcm'))
+
+    def test_object_centre(self):
+        data = self.dcm.pixel_array
+        assert self.acr_geometric_accuracy_task.centroid_com(data)[1] == self.centre
+
+    def test_geo_accuracy_slice1(self):
+        slice1_vals = np.array(self.acr_geometric_accuracy_task.get_geometric_accuracy_slice1(self.dcm))
+        slice1_vals = np.round(slice1_vals, 2)
+        assert (slice1_vals == self.L1).all() == True
+
+    def test_geo_accuracy_slice5(self):
+        slice5_vals = np.array(self.acr_geometric_accuracy_task.get_geometric_accuracy_slice5(self.dcm2))
+        slice5_vals = np.round(slice5_vals, 2)
+        assert (slice5_vals == self.L5).all() == True
+
+    def test_rotate_point(self):
+        rotated_point = np.array(self.acr_geometric_accuracy_task.rotate_point((0, 0), (30, 70), 150))
+        rotated_point = np.round(rotated_point, 2)
+        print(rotated_point)
+        assert (rotated_point == self.test_point).all() == True
+
+
+# class TestACRUniformityPhilips(unittest.TestCase):
+
+class TestACRGeometricAccuracyGE(unittest.TestCase):
+    ACR_GEOMETRIC_ACCURACY_DATA = pathlib.Path(TEST_DATA_DIR / 'acr')
+    L1 = 189.92, 187.89
+    L5 = 189.92, 188.39, 190.43, 189.92
+    distortion_metrics = [-0.59, 2.11, 0.49]
+
+    def setUp(self):
+        self.acr_geometric_accuracy_task = ACRGeometricAccuracy(data_paths=[os.path.join(TEST_DATA_DIR, 'acr')],
+                                                                report_dir=pathlib.PurePath.joinpath(TEST_REPORT_DIR))
+        self.dcm = pydicom.read_file(os.path.join(TEST_DATA_DIR, 'acr', 'GE', '10.dcm'))
+        self.dcm2 = pydicom.read_file(os.path.join(TEST_DATA_DIR, 'acr', 'GE', '6.dcm'))
+
+    def test_geo_accuracy_slice1(self):
+        slice1_vals = np.array(self.acr_geometric_accuracy_task.get_geometric_accuracy_slice1(self.dcm))
+        slice1_vals = np.round(slice1_vals, 2)
+        assert (slice1_vals == self.L1).all() == True
+
+    def test_geo_accuracy_slice5(self):
+        slice5_vals = np.array(self.acr_geometric_accuracy_task.get_geometric_accuracy_slice5(self.dcm2))
+        slice5_vals = np.round(slice5_vals, 2)
+        assert (slice5_vals == self.L5).all() == True
+
+    def test_distortion_metrics(self):
+        metrics = np.array(self.acr_geometric_accuracy_task.distortion_metric(self.L1+self.L5))
+        metrics = np.round(metrics, 2)
+        assert (metrics == self.distortion_metrics).all() == True

[ACR5] Geometric accuracy 
For the geometric accuracy - currently under slice width in hazen - use slice 1 and slice 5 of an ACR_TRA_T1_NORMOFF series. In slice 1, measure the diameter of the phantom: top-to-bottom and left-to-right and on slice 5 measure the diameter of the phantom in 4 directions: top-to-bottom, left-to-right, and both diagonals. The diameter is 190 mm and all lengths should be within ± 2 mm.  Beware that on top of the phantom due to a water bubble there will be a n extended dark area.

Priority: High for ACR 

![image](https://user-images.githubusercontent.com/93722461/146515895-16ef0d2b-817c-428a-8cdf-1526635c8217.png)

tests/test_acr_geometric_accuracy.py::TestACRGeometricAccuracySiemens::test_geo_accuracy_slice1 tests/test_acr_geometric_accuracy.py::TestACRGeometricAccuracySiemens::test_geo_accuracy_slice5 tests/test_acr_geometric_accuracy.py::TestACRGeometricAccuracySiemens::test_object_centre tests/test_acr_geometric_accuracy.py::TestACRGeometricAccuracySiemens::test_rotate_point tests/test_acr_geometric_accuracy.py::TestACRGeometricAccuracyGE::test_distortion_metrics tests/test_acr_geometric_accuracy.py::TestACRGeometricAccuracyGE::test_geo_accuracy_slice1 tests/test_acr_geometric_accuracy.py::TestACRGeometricAccuracyGE::test_geo_accuracy_slice5