Table 3.

The medical protocol for robotic assisted brachytherapy.

Step	(1)—Preplanning
1.	The patient undergoes a complete non-invasive imagistic investigation (CT—compulsory and MRI—if needed) for the exact definition of the tumor(s) location.
2.	The CT images are analyzed and the following parameters are defined: aThe radiation dosage and type. bThe number of needles. cThe matrix distribution of the needles. dThe linear trajectories which have to avoid the proximity of high-risk areas (organs penetration, blood vessels, nerves) and high-density tissues (cartilages, bones).
3.	Using CT-scan equipment which has an external laser-based fixed coordinate system, the patient position for the procedure is established to enable: aComfortable fixed patient position during the entire procedure (as only local anesthesia will be used); bEasy access to all the predefined trajectories for the robot with the needle insertion module positioned above the patient.
4.	A set of markers is positioned on the patient to enable: aAn accurate reproduction of the patient position with respect to the external laser-based coordinate system; b A clear view of the needle insertion points achieved through: i. Markers highly visible under the CT-scan; ii. A needle guiding plate where the holes of interest are marked.
5.	A second tomography is performed, using the same CT-scan, to validate the positions of all the markers (if needed fine adjustments are made for the final positions).
6.	The relative robot–patient position is optimized to ensure that all the targeted points can be reached (are located within the robot workspace) and the final trajectories are validated.
	(2)—CT-guided robotic brachytherapy
7.	Using the numbered mounting holes the robot is positioned on the mobile CT-scan couch followed by the patient, whose position will be reproduced using the existing markers (step 4). The patient and robot are calibrated with respect to the laser coordinate system and the transformation matrix for the transformation of the patient coordinates into the robot coordinates is introduced.
8.	The robot performs the homing and then positions the needle insertion module in a predefined point, above the patient, but not very far from the area of interest.
9.	The coordinates of the pairs of points (Insertion—Target) are loaded using a secured USB drive to avoid any human errors.
10.	The first needle is positioned from the current (neutral point) into the Insertion point oriented on the linear trajectory defined by the first pair of points. Due to the external markers the doctors will be able to see any misalignments before any invasive action has been performed.
11.	The needle is introduced into the patient at a depth of 40–50 mm followed by a quick scan aimed to validate the trajectory.
12.	If needed, small trajectory corrections are applied.
13.	In case the trajectory has an error higher than 0.2°–0.5° (depending on the target depth) the needle is retracted and introduced again.
14.	The needle is introduced until the targeted point and then released from the insertion module.
	For each following needle the steps 10–14 are repeated until all the needles are in place.
15.	The robot is retracted into the home position to allow full access to the inserted needles.
16.	The needles are connected to dedicated equipment that will deliver the radioactive seeds based on the treatment protocol.
17.	After the treatment the needles are extracted from the patient body and the patient is removed from the CT-scan mobile couch.
18.	The robot is removed, and the procedure is completed.
	(3)—Patient follow-up
19.	The patient evolution is monitored and based on his/her evolution subsequent treatments are scheduled.
20.	All the information is stored in a database recording the robot parameters, procedural times as well as all the medically relevant data such as needle accuracy and treatment efficiency.