Investigating computed tomography ventilation as a functional imaging modality for lung cancer radiotherapy

This is a validation study of utilising respiratory correlated computed tomography (CT) imaging (e.g, four dimensional CT) in obtaining the distribution of lung ventilation. The CT ventilation imaging will be validated with the gold standard in ventilation imaging, nuclear medicine ventilation imaging. The study participants will undergo (1) a CT imaging session where a four dimensional CT, a static end-inspiration breath hold CT and an end-expiration breath hold CT will be acquired and (2) a nuclear medicine imaging session where a PET-Galligas (alternative will be SPECT-Technegas) ventilation scan will be acquired. The CT ventilation images will then be used to create a functional based radiotherapy treatment plan. A standard anatomical based treatment plan will also be created which the functional based treatment plan will be compared to. We will estimate the difference in dose to the functional lungs (toxicity) between the standard of care anatomical based treatment plan used in radiotherapy planning and the study's functional based treatment plans. Neither of these plans will be used in the any of the study participants' treatments. Summary of imaging scans to be collected per study participant: Two static breath hold CT scans one collected after inhalation and the other after exhalation, One four-dimensional-CT (4D-CT) scan, One Nuclear Medicine ventilation scan (PET-Galligas or SPECT-Technegas). All CT scans will be obtained on the same day in one session on a dual modality PET/CT machine taking approximately 1.5 hour in total to complete. These scans will be collected only once in the study. The static breath hold CT scans will require the patient to hold their breath for 20 seconds during the scan acquisition. Each of the static breath hold CT scans will take less than 1 minute to complete. The 4D-CT scan will take approximately 3 minutes to complete. The nuclear medicine scan will take approximately 15 minutes to complete. In all the scans outlined above the participant will be asked to lie on their back with their arms above their head for the duration the scans. All the scans will be acquired with the use of a respiratory regulator system called the Audiovisual Biofeedback system. The Audiovisual Biofeedback system requires the participant to wear electronic goggles which will display their breathing pattern in the shape of a wave and they will be guided to maintain regular breathing by following the wave pattern during the image acquisitions. The total dose received from all scans in study will be approximately 50 - 70 mSv. The study will be accrue 30 patients over the period of 3 years. This study is specifically aimed at lung cancer patients. As this is not a treatment based study and the data is collected in the treatment phase, the study is open to non-RT treated lung cancer patients, chemotherapy patients. Patients will fall into two groups, the majority of study patients will fall into the RT group (i.e., patients that are to be treated with RT) and a small number of patients will fall into the Non-RT group (i.e., patients treated with chemotherapy). RT Group: Stage I - IV Non-RT Group: Stage IIIB, IV (patients greater than or equal to 65 years old)