Nilsu Çini1, Cenk Umay2, Okan Özdemir3, İlknur Alsan Çetin4, Hakan Epik5, Ayşe Nur Demiral2. 1. Department of Radiation Oncology, Dr. Lütfi Kırdar Kartal Training and Research State Hospital, Kartal, Istanbul, Turkey. 2. Department of Radiation Oncology, Dokuz Eylül University Medical Faculty, Izmir, Turkey. 3. Department of Radiation Oncology, Erzurum Regional Training and Research State Hospital, Yakutiye, Erzurum, Turkey. 4. Department of Radiation Oncology, Marmara University Medical Faculty, Göztepe, Istanbul, Turkey. 5. Department of Physics, Dokuz Eylül University Science Faculty, Tınaztepe, Izmir, Turkey.
Abstract
AIM: Dosimetric comparison of three different techniques in female lymphoma patients who had radiotherapy (RT) to the neck and mediastinum. SETTING AND DESIGN: Retrospective clinical study. MATERIALS AND METHODS: Computerized tomography-simulator images of eight patients were obtained retrospectively. Using 6 MV-X photon energy, RT plans were formed with three different techniques (anterior posterior-posterior anterior 2-field three-dimensional conformal RT [AP-PA 2-field 3D-CRT], 4-field 3D-CRT and "forward" plan intensity modulated RT [FPIMRT]). Comparisons were in terms of homogeneity index (HI), conformity index (CI), and inhomogeneity coefficient for planning target volume (PTV); mean lung dose, V5Gy, V10Gy, V20Gy, V30Gy for lung; Dmean, V7.5Gy, V15Gy, V25Gy for heart; Dmean, V3.5Gy, V10Gy, V20Gy for breast; Dmax for spine; Dmean, V10Gy, V18Gy, V25Gy, V30Gy for thyroid. STATISTICAL ANALYSIS USED: Since nonparametric tests had to be used due to the study population being < 30, Friedman and Wilcoxon signed-rank tests were implemented in trilateral and bilateral comparison of techniques, respectively. For statistical significance, P value was required to be <0.05. RESULTS: When FPIMRT was compared with AP-PA and 4-field techniques with respect to, HI (AP-PA/FPIMRT P: 0.017; 4-field/FPIMRT P: 0.03) and CI (AP-PA/FPIMRT P: 0.018; 4-field/FPIMRT P: 0.042), FPIMRT was more advantageous. In addition, FPIMRT was found more useful in terms of Dmax (AP-PA/FPIMRT P: 0.012; 4-Field/FPIMRT P: 0.012) for spinal cord and Dmean (AP-PA/FPIMRT P: 0.012; 4-field/FPIMRT P: 0.012) for thyroid. CONCLUSION: FPIMRT was superior in terms of PTV homogeneity and conformity. However, it was observed that for normal tissues, FPIMRT was advantageous only for spinal cord and thyroid; but it was not the most advantageous technique for some of the dose-volume parameters of the breast, lung, and heart.
AIM: Dosimetric comparison of three different techniques in female lymphoma patients who had radiotherapy (RT) to the neck and mediastinum. SETTING AND DESIGN: Retrospective clinical study. MATERIALS AND METHODS: Computerized tomography-simulator images of eight patients were obtained retrospectively. Using 6 MV-X photon energy, RT plans were formed with three different techniques (anterior posterior-posterior anterior 2-field three-dimensional conformal RT [AP-PA 2-field 3D-CRT], 4-field 3D-CRT and "forward" plan intensity modulated RT [FPIMRT]). Comparisons were in terms of homogeneity index (HI), conformity index (CI), and inhomogeneity coefficient for planning target volume (PTV); mean lung dose, V5Gy, V10Gy, V20Gy, V30Gy for lung; Dmean, V7.5Gy, V15Gy, V25Gy for heart; Dmean, V3.5Gy, V10Gy, V20Gy for breast; Dmax for spine; Dmean, V10Gy, V18Gy, V25Gy, V30Gy for thyroid. STATISTICAL ANALYSIS USED: Since nonparametric tests had to be used due to the study population being < 30, Friedman and Wilcoxon signed-rank tests were implemented in trilateral and bilateral comparison of techniques, respectively. For statistical significance, P value was required to be <0.05. RESULTS: When FPIMRT was compared with AP-PA and 4-field techniques with respect to, HI (AP-PA/FPIMRT P: 0.017; 4-field/FPIMRT P: 0.03) and CI (AP-PA/FPIMRT P: 0.018; 4-field/FPIMRT P: 0.042), FPIMRT was more advantageous. In addition, FPIMRT was found more useful in terms of Dmax (AP-PA/FPIMRT P: 0.012; 4-Field/FPIMRT P: 0.012) for spinal cord and Dmean (AP-PA/FPIMRT P: 0.012; 4-field/FPIMRT P: 0.012) for thyroid. CONCLUSION: FPIMRT was superior in terms of PTV homogeneity and conformity. However, it was observed that for normal tissues, FPIMRT was advantageous only for spinal cord and thyroid; but it was not the most advantageous technique for some of the dose-volume parameters of the breast, lung, and heart.