Michał Spych, Leszek Gottwald, Małgorzata Klonowicz, Michał Biegała, Robert Bibik, Jacek Fijuth number of patients had diagnosis of large cell tumour volume and pulmonary hilum lymph nodes. carcinoma. In the remaining 3 (8.8%) patients the The prescribed dose was 66.0 Gy for this patient. precise pathological diagnosis was not established. All patients were irradiated using a conventional In these cases non-small cell lung cancer was dosage schedule. recognized. The basis of statistical analysis was occurrence of acute post-radiation pneumonitis in this group Treatment technique of patients. Intensity of early toxicity was evaluated once a week during radiotherapy, and then every All patients were treated according to the 4 weeks, for six months after the end of treatment. Radiotherapy Department’s homogeneous in-house A modified RTOG/EORTC toxicity score was used. protocol. Patients were positioned and fixed using The toxicity score modification involved changing a breast board with arms abducted over the head. the corticosteroid administration from grade 3 to Preliminary treatment volume localization was done grade 2 on the above-mentioned scale. The using a simulator. The planning CT scans were sent introduced change allowed us to single out a group to the Medical Physics Department, where of patients with indirect degree of post-radiation treatment volumes as well as critical organs and acute reaction course. Corticosteroid administration radiation dose were defined using the Varian Eclipse induced relatively rapid amelioration of respiratory treatment planning system. Every case was planned system functioning in this group of patients, individually using three-dimensional conformal without the necessity of hospitalization. In the technique. Treatment volumes were defined presented statistical analysis the main endpoint according to the 50 and 62 ICRU (the International was the occurrence of radiation pneumonitis of Commission on Radiation Units and Measurements) grade 2 or higher according to the modified reports. The gross tumour volume (GTV) was RTOG/EORTC toxicity score, with clinical delineated as the tumour with enlarged mediastinal manifestation of moderate effort dyspnoea with lymph nodes (lymph nodes larger than 1 cm in non-productive persistent cough, subfebrile body computed tomography study). Next the clinical temperature and necessity of corticosteroid target volume (CTV) was defined as a volume which administration. In case of any uncertainty of included the GTV and some subclinical disease. The pathogenesis of a patient’s ailments, which could CTV was usually created by adding a symmetrical suggest local recurrence or tumour progression, margin of 5 mm to the GTV. Then an additional computed tomography of the chest was performed tissue margin around the CTV was created to as well as cardiological consultation to eliminate eliminate the respiratory motion effect and other causes of respiratory failure. potential inaccuracy of patient and radiation source setup. By adding these margins the planning Statistical analysis target volume (PTV) was created. Margins around the CTV, in the range 1.0-1.5 cm, usually were The Kaplan-Meier estimator was used to asymmetrical, and were dependent on respiratory evaluate the risk of radiation pneumonitis motion and tumour site. Correctness of treatment development in the analysed patient group. plan realization was checked on a simulator, Student’s t-test, as a statistical method, was used where treatment fields were transmitted to the to define differences between mean values of patient’s skin, and served in the computer target volumes, mean doses cumulated in lung system simultaneously. Treatment fields setup tissue as well as lung volumes receiving specified repeatability was evaluated through the simulator ionizing radiation doses, in groups of patients with and accelerator image fusion and geometric error and without clinical manifestation of post-radiation measurement. Twenty-one (64.8%) patients had pneumonitis. Patient-related factors included in the ipsilateral mediastinal lymph nodes irradiated analysis were: age, sex, tumour size, clinical stage, electively. For precise delineation of individual Karnofsky Performance Status, use of induction mediastinal lymph node groups, Mountain and chemotherapy, and haemoglobin concentration Dresler’s classification modified by Chapet was before radiotherapy. Factors related to treatment used. The radiation dose in the elective volume techniques included in the analysis were: clinical was prescribed at a level of 50.0 Gy. Next the dose target volumes and planning target volumes in cm3, was escalated to the tumour and enlarged volumes of lung tissue which received a dose from mediastinal lymph nodes, and it was contained 10 Gy to 60 Gy, and mean lung doses. Finally, within 66.0-68 Gy. For 11 (32.3%) patients the “large univariate and multivariate analysis was carried out, field” technique was used, which included tumour to single out factors which could describe the and ipsilateral mediastinal lymph nodes. The total toxicity risk most precisely. Lung tissue, as an organ dose between 66.0 Gy and 68.0 Gy was prescribed at risk, was defined separately in every case as: the in this group of patients. One patient was treated ipsilateral lung, contralateral lung, and total lung using the “small field” technique, limited to the volume. A p value < 0.05 was considered significant. 758 Arch Med Sci 5, October / 2010