ABSTRACT
Objective To explore the dosimetric difference between different radiotherapy technologies in the treatment of early peripheral stage non?small ?cell lung cancer ( NSCLC ) . Methods Four?dimensional computed tomography scans and delineation of target volumes and organs at risk ( OARs) were performed in 5 patients pathologically diagnosed with stage T1/T2 peripheral NSCLC who were admitted from 2014 to 2015. Target volumes contained gross tumor volume (GTV), internal target volume (ITV), and planning target volume (PTV). ITV was contoured on the maximum intensity projection images. PTV was defined as ITV plus a 5 mm margin. OARs contained the heart, lung, esophagus, and spinal cord. The Monaco 5. 0 treatment planning system was used to design three plans. The three?dimensional conformal radiotherapy (3DCRT) plan had 11 fields in the diseased lung covering the PTV plus a 0. 2 cm margin. The sliding window intensity?modulated radiotherapy ( SW?IMRT ) plan had 9 fields in the same areas as the 3DCRT plan. The volumetric modulated arc therapy ( VMAT) plan had the gantry rotating 180° around the diseased lung. The evaluation criteria referred to the RTOG 0618 trial. Comparison was made by paired t test. Results The SW?IMRT plan had a significantly better homogeneity index than the 3DCRT plan ( 1. 03 vs. 1. 24,P= 0. 017 ) . Compared with the VMAT plan, the mean monitor units in the 3DCRT plan was significantly reduced by 24. 5%( P=0. 022) . The V30 and V40 of the 3DCRT plan were significantly reduced by 29. 4% and 28. 4%, respectively, compared with the SW?IMRT plan ( P=0. 003,0. 006) and 56. 7%and 59. 7%, respectively, compared with the VMAT plan ( P=0. 041,0. 019) . Conclusions 3DCRT may be an appropriate radiotherapy method for early stage NSCLC.
ABSTRACT
Objective To study the difference between intensity-modulated radiation therapy (IMRT) and three dimensional conformal radiation therapy (3D-CRT) for pelvic radiation of post-operative treatment with gynecologic malignant tumor. Methods A prospective investigation study was conducted on 183 patients of post-operative patients with whole pelvic radiation therapy of cervical cancer or endometrial cancer in Zhejiang Cancer Hospital [IMRT group (n=85) and 3D-CRT group (n=98)] from Oct. 2015 to Oct. 2016. The two groups received same dose (45 Gy in 25 fractions). Comparison of two groups with radiation dosimetry:the score according to the Radiation Therapy Oncology Group (RTOG) acute radiation injury grading standards before and after radiotherapy reaction, the score from functional assessment of cancer therapy scale-cervix (FACT-Cx) scale and expanded prostate cancer index composite for clinical practice (EPIC-CP) scale were also analyzed. Results (1) There were no significant effect with age, culture level, family economic condition and ratio of radiochemotherapy between two groups (all P>0.05). (2) Dosimetric comparison for IMRT vs 3D-CRT:the average dose of planning target volume (PTV) decreased(46.1 ± 0.4) vs(46.4 ± 0.5)Gy, V45 dose percentage increased(95.2 ± 1.0)%vs (93.3 ± 2.0)%, intestinal bag dose of V40 decreased(24.4 ± 6.8)%vs (36.5 ± 15.9)%, rectal V40 dose percentage decreased(73.9 ± 12.3)%vs (85.4 ± 8.4)%, and lower rectal V45 dose percentage(32.8 ± 13.4)%vs (71.5 ± 13.7)%, bladder V40 dose percentage decreased(55.5 ± 13.0)% vs (84.4 ± 13.0)%. Bone marrow V20 lower:(67.9 ± 5.4)% vs (79.5 ± 6.6)%, V10 lower:(82.1 ± 6.0)% vs (86.3 ± 6.6)%; there were significant differences (all P0.05). (3) Acute radiation injury classification for IMRT vs 3D-CRT:big or small intestine:Ⅱ-Ⅲreaction [13%(11/85) vs 24% (24/98); χ2=3.925, P=0.048], there was significant difference. Bladder: Ⅲ reaction [19% (16/85) vs 26% (25/98); χ2=1.171, P=0.279], there was no significant difference. Radiochemotherapy of bone marrow suppression:Ⅲ-Ⅳreaction (14/20), the incidence rate [26%(14/54) vs 31%(20/65);χ2=0.339, P=0.562], the difference was not statistically significant. (4) Quality of life scale by FACT-Cx scale in IMRT vs 3D-CRT:there were no significant difference before radiotherapy (82 ± 16 vs 85 ± 16;t=1.279, P=0.203), while there was significant difference after radiotherapy (76 ± 14 vs 71 ± 18;t=-2.160, P=0.032). EPIC-CP scale score:before radiotherapy they were (16±7 vs 15±6;t=-0.174, P=0.862) ,but after radiotherapy (18±7 vs 22± 7; t=3.158, P=0.002), there was significant difference between them. Before and after radiotherapy, the increased EPIC-CP scale of the IMRT group vs 3D-CRT group were 3 ± 4 and 6 ± 4, the 3D-CRT group was significantly higher, the difference was statistically significant (t=5.500, P=0.000). Conclusion IMRT has shown that there are a significant benefit for the post-operative patients with cervical cancer and endometrial cancer compared to 3D-CRT.