Mechanically-assisted Ventilation in the Treatment of Moving Tumours With Photon and Proton Therapies

Mechanically-assisted Ventilation in the Treatment of Moving Tumours With Photon and Proton Therapies

Added Value of Mechanically-assisted Ventilation in the Treatment of Moving Tumours (Thoracic/Upper Abdomen) With Photon and Proton Therapies.

Mechanical ventilation can be used to impose a completely regular pattern of breathing frequency and inflation volume on the patient for as long as required. This would considerably improve the reproducibility of the internal motion parameters, and thus facilitate the implementation of respiratory-synchronized techniques such as gating, tracking and four-digital optimization.

This will be a three-phase analysis : First, different ventilation modes will be tested and compared on healthy volunteers. This phase will be analysed with a ventilator and with dynamic MRI in order to measure the movement of anatomical structures in each ventilation mode (intra-fraction analysis). Further, we will repeat these exams in order to compare them with the first ones, in order to analyse the reproducibility and baseline shifts (inter-fraction analysis). Here are the different ventilation modes spontaneous breathing physiologic ventilation mode : shallow ventilation mode slow ventilation mode Jet Ventilation mode Second phase will be done with patients that are intended to have a radiation treatment for thoracic or upper abdominal tumors. All the previous ventilation modes will be analysed during repeated MRI, again in order to perform intra- and inter-fraction analysis of the tumor motion. Third phase also concerned patients intended to have a radiation treatment. It will be an in-silico-planning analysis in order to quantify dosimetric outcomes of these ventilation modes.

Dynamic MRI acquisition will be performed at two different time points with 10 healthy volunteers under non-invasive mechanically-assisted ventilation with a respirator. Different modes will be compared (spontaneous, physiologic, shallow, slow and jet ventilation).

Dynamic MRI acquisition will be performed at two different time points with 10 patients (intended for a radiation treatment of their thoracic or upper abdominal tumours) under non-invasive mechanically-assisted ventilation with a respirator. Different modes will be compared (spontaneous, physiologic, shallow, slow and jet ventilation).

Planning 4D-CT will be performed with 10 patients (intended for a radiation treatment of their thoracic or upper abdominal tumours) under non-invasive mechanically-assisted ventilation with a respirator. Different ventilation modes will be compared (spontaneous, physiologic, shallow, slow and jet ventilation).

Mechanically ventilation will be done through facial masks connected to a respirator. Volunteers/patients are fully conscious during the ventilation.

Dynamic MRI acquisition are specific dynamic sequences intended to visualise the motion of internal structures (anatomical structures or tumour) under non-invasive mechanically-assisted ventilation

In order to perform in-silico planning, 4D-CT will be acquired on patients under non-invasive mechanically-assisted ventilation

Measure in millimeters of the internal motion during non-invasive mechanically assisted ventilation, based on MRI images

This analysis will be based on dynamic MRI analysis made with healthy volunteers and also patients on non-invasive mechanically assisted ventilation. A well defined anatomical structure will be selected for the healthy volunteers while the tumor will be tracked in patients.

During all these acquisitions, the tolerance to the non-invasive mechanically assisted ventilation will be assessed by all the participants through a 5-steps scale.

This analysis will be done by comparing the motion of the internal structures/tumors at two different time points (MRI acquisition at two different time points). All these acquisitions will obviously be done in the same conditions on non-invasive mechanically assisted ventilation. Motion reproducibility will be analysed by comparing the baseline positions of anatomical structures/tumors on MRI images and the measures in millimeters of motion of the same anatomical structures/tumors.

This dosimetric comparison will be done in order to assess the impact of non-invasive mechanically-assisted ventilation on dose planning and delivery. Difference in dose (in Gy) to organ at risks will specially be compared through the DVH (dose-volume histogram) analysis.

Inclusion Criteria: No comorbidity for healthy volunteers Cancer patients with either lung or upper abdomen (liver/pancreas) tumours treated with radiation therapy. Exclusion Criteria: severe lung disease or emphysema previous history of pneumothorax claustrophobia