What is the main objective of the IXSI?
The goal of the IXSI is to give the clinician the tool to perform activity distribution measurements during the intervention for dosimetry, and allowing for direct succession of the pretreatment safety procedure by the treatment procedure. This improves time-efficiency of the procedure, as patients do not need to be transferred to the nuclear medicine department, which may improve comfort for the patient by limiting the number of sessions, and may prevent errors in repositioning the catheter, which may in turn improve the predictive nature of the 99mTc-MAA pretreatment procedure. We hypothesise that IXSI will have impact on the clinical workflow in terms of improved treatment effectiveness, time efficiency, cost efficiency and patient acceptance.

What are the primary objectives of the IXSI safety study?
The IXSI has already been extensively tested on a technical level, but has not yet been used during radio embolization treatments. The primary objective of the study is to demonstrate the safe application of hybrid imaging in the specific setting of the busy, dynamic intervention room. This will reveal potential, but unforeseen, risks to the patient and the medical personnel. See page Safety Study.

What are the secondary objectives of the IXSI safety study?
The secondary objectives is to image the (hemo-)dynamic processes influencing the microsphere distribution during the administration of 99mTc-MAA , using IXSI and to establish the clinical usability of dosimetry based on interventional SPECT/CBCT using IXSI compared to traditional SPECT/CT based dosimetry after the pretreatment procedure. See page Safety Study.

Why is the first safety study performed on patients? 
There are several reasons we chose to perform a clinical study with patients. We believe that we are not able to demonstrate the safety of the application of hybrid imaging in the specific setting (the busy, dynamic intervention room) without exposing the participating patients to any risks. To date there are no phantoms available which can mimic the properties of a human liver. In order to establish the clinical usability of dosimetry based on interventional SPECT/CBCT using IXSI a realistic liver with tumors is required. A study on animals was considered, for example a study with pigs. However, a study on animals would deprive us from the possibility to examine the experience of the patients of the procedure with the IXSI, which is an integral part of establishing the safety of acquiring 2D and 3D hybrid images using IXSI in an interventional setting.

What are the risks for the patients participating in the study?
The new technology of IXSI is associated with a number of risks including additional ionizing radiation, patient-gantry collision, and extended procedure duration. The risks of participating in this study are low. Patients will receive additional dose from the IXSI. This additional dose delivered by the IXSI is shown to the researcher during the procedure. The total additional radiation in this study is no more than 6.4 mSv. In comparison: the background radiation in the Netherlands is ~2.5 mSv per year. The radiation exposure in the current preliminary phase of the radioembolization is ~14 mSv and the radiation load of a SPECT/CT scan is ~3 mSv. In addition, the radiation dose administered during the radioembolization treatment is more than a thousand times greater than the additional radiation exposure of the IXSI.
We estimate that the risk of a patient-gantry collision will be negligible. The gantry movement is very slow so the researcher can anticipate on a possible collision and stop the movement of the gantry. Furthermore, a collision at such low speeds will have a negligible risk at injury.