diff --git a/modules/api/php/models/projectdicomsrow.class.inc b/modules/api/php/models/projectdicomsrow.class.inc
index 356d36ef96f..8cf89e7c199 100644
--- a/modules/api/php/models/projectdicomsrow.class.inc
+++ b/modules/api/php/models/projectdicomsrow.class.inc
@@ -59,9 +59,9 @@ class ProjectImagesRow implements \LORIS\Data\DataInstance
     /**
      * Implements \LORIS\Data\DataInstance interface for this row.
      *
-     * @return string the row data.
+     * @return array the row data.
      */
-    public function toJSON() : string
+    public function jsonSerialize() : array
     {
         $obj      = [
             'Candidate'  => $this->_candid,
@@ -81,7 +81,7 @@ class ProjectImagesRow implements \LORIS\Data\DataInstance
         $obj['Link']       = "/candidates/$candid/$visit/images/$filename";
         $obj['InsertTime'] = date('c', (int) $obj['InsertTime']);
 
-        return json_encode($obj);
+        return $obj;
     }
 
     /**