Study The Protective Value Of Spect Lung Perfusion To Lung Function In Esophageal Cancer Patients Treated With Radiotherapy

Objective1. Use the single-photon emission computed tomography perfusion imagines to guide radiotherapy planning of esophageal cancer patients, so that the beam through the non-functioning lung pulmonary, to evaluate its protective value. 2. To find the advantage by Compare the IMRT with three-dimensional conformal radiotherapy in lung protection advantage.MethodsThe first part is the research of SPECT lung perfusion imaging in radiation treatment planning optimization. Twenty-seven patients with esophagectomy and intrathoracic esophagogastric anastomosis, confirmed by pathology were squamous cell carcinoma. All patients had CT scans and SPECT scans in the same treatment position. The two types of images were accurately registered using methods of the external markers based on Pinnacle3 treatment planning system. Two IMRT plans were generated for each patient (Plan-1 and Plan-2). CT images were used to define tumor target, and SPECT lung perfusion images were used to define a volume of functional lung. Plan 1 aimed to minimize the dose to whole lung according to CT images only, while plan 2 aimed to minimize the dose to functional lung according SPECT lung perfusion. Plan 1 and plan 2 were compared in protecting function lung. The second part is to compare IMRT with three-dimensional conformal radiotherapy in protecting function lung. We still use the twenty-seven patients from part one, confirmed by pathology were squamous cell carcinoma. All patients had CT scans and SPECT scans in the same treatment position. The two types of images were accurately registered using methods of the external markers based on Pinnacle3 treatment planning system. Two plans were generated for each patient (Plan-1 and Plan-2). Plan 1 was a three-dimensional conformal radiotherapy according SPECT lung perfusion. Plan two was an IMRT according SPECT lung perfusion. Plan 1 and plan 2 were compared in protecting function lung.ResultsThe first part: compared with plan 1, FV10,FV20,FV30 decreased, and there were statistical differences(P=0.000,0.000,0.012,respectively); WV10and WV20 also decreased, and there were statistical differences (P=0.000,0.000,respectively); NFV50 increased, and there was statistical difference(P=0.018). The second part: IMRT compared with three-dimensional conformal radiotherapy, WV10,WV20,FV10,FV20 decreased, and there were statistical differences(P=0.001,0.008,0.037,0.001,respectively); But the dose of G95%, P95% differences were smaller, there were no significant differences( P=0.577,0.899, irrespectively); The differences of the maximum spinal dose and the radiation dose received by 30% heart volume between the to methods are smaller, there were no significant differences( P=0.927,0.440, irrespectively).Conclusion1.The dose to functional lung in optimized plan decreased according to SPECT lung perfusion imagines, especially low dose region, thus radiation pneumonitis might be effectively prevented and dose might be escalated.2.Optimized IMRT plan could reduce high dose while increase low dose to functional lung compared with optimized 3DCRT plan. But there is no obvious advantage for the protection of the card and heat.