DIBH Proton Planning

Image acquisition and treatment under deep inspiration breath hold (DIBH) has been demonstrated to reduce treated volumes and doses to organs at risk (OARs) for photon radiotherapy but has not been investigated in the context of proton radiotherapy. The objective of this registry study is to prospectively evaluate deep inspiration breath hold CT scans for use in proton radiotherapy treatment planning and obtain dosimetric data to assess for changes in target volume, planning volumes and doses both to tumor and organs at risk using the SpiroDynrX (SDX) deep inspiration breath hold system as compared to free breathing and 4D CT scans. Patients will be treated with photon therapy. This is a prospective non-randomized, single arm, single institution registry study of patients undergoing definitive external beam photon radiotherapy in our department. Deep inspiration breath hold CT scans will be obtained in our department in the treatment position at the time of CT simulationin addition to the currently obtained free breathing and 4D CT scans. These scans will all be co-registered with the treatment planning CT. Treatment planning volumes will be delineated by the physician and compared to the results and data for our current standard of care utilizing 4D CT scans. Patients will be treated with breath hold CT using photon radiotherapy but we will prospectively create proton treatment plans which will also be compared to the photon treatment plans used for actual treatment. Variability in tumor localization, target volume definition, doses to organs at risk and treatment planning particularities will be summarized and reported across several modalities, including: 3 dimensional conformal radiation therapy (3DCRT), intensity-modulated x-ray therapy (IMXT) and proton therapy. Correlations will be statistically analyzed and reported in terms of minimum, maximum, average and standard deviation, and other dose volume histogram parameters, and where appropriate, compared with appropriate statistical methods (for example, student t-test).