-// Patient Position (0018,5100) values : HFP = Head First-Prone
-// HFS = Head First-Supine
-// HFDR = Head First-Decubitus Right
-// HFDL = Head First-Decubitus Left
-// FFDR = Feet First-Decubitus Right
-// FFDL = Feet First-Decubitus Left
-// FFP = Feet First-Prone
-// FFS = Feet First-Supine
+// Patient Position (0018,5100) values :
+
+// HFS = Head First-Supine, where increasing (positive axis direction) :
+// X -> to the direction pointed to by the patient's oustretched left arm
+// Y -> to the anterior-to-posterior direction in the patient's body
+// Z -> to the feet-to-head direction in the patient's body
+
+// HFP = Head First-Prone, where increasing (positive axis direction) :
+// X -> to the direction pointed to by the patient's oustretched left arm
+// Y -> to the anterior-to-posterior direction in the patient's body
+// Z -> to the feet-to-head direction in the patient's body
+
+// FFS = Feet First-Supine, where increasing (positive axis direction) :
+// X -> to the direction pointed to by the patient's oustretched left arm
+// Y -> to the anterior-to-posterion direction in the patient's body
+// Z -> to the feet-to-head direction in the patient's body
+
+// FFP = Feet First-Prone, where increasing (positive axis direction) :
+// X -> to the direction pointed to by the patient's oustretched left arm
+// Y -> to the posterior-to-anterior direction in the patient's body
+// Z -> to the feet-to-head direction in the patient's body
+
+// HFDR = Head First-Decubitus Right
+// HFDL = Head First-Decubitus Left
+// FFDR = Feet First-Decubitus Right
+// FFDL = Feet First-Decubitus Left
+
+// we can also find
+
+// SEMIERECT
+// SUPINE
+