Purpose : Although Improve of CT, MRI Radio-diagnosis and Radiation Therapy Planing, but we still use ICRU38 Planning system(2D film-based) broadly. 3-Dimensional ICR plan(CT image based) is not only offer tumor and normal tissue dose but also support DVH information. On this study, we plan irradiation-goal dose on CTV(CTV plan) and irradiation-goal dose on ICRU 38 point(ICRU38 plan) by use CT image. And compare with tumor-dose, rectal-dose, bladder-dose on both planning, and analysis DVH
Method and Material : Sample 11 patients who treated by Ir-192 HDR. After 40Gy external radiation therapy, ICR plan established. All the patients carry out CT-image scanned by CT-simulator. And we use PLATO(Nucletron) v.14.2 planing system. We draw CTV, rectum, bladder on the CT image. And establish plan irradiation- dose on CTV(CTV plan) and irradiation- dose on A-point(ICRU38 plan)
Result : CTV volume() is , rectum volume() is , bladder volume() is sampled 11 patients. The volume including dose is on ICRU plan and on CTV plan. On ICRU planning, the other one’s CTV volume who residual tumor size excess 4cm is not including isodose. 8 patient’s tumor volume who residual tumor size belows 4cm irradiated dose. Bladder dose(recommended by ICRU 38) is on ICRU plan, on CTV plan, and rectal dose is . Bladder and Rectum maximum dose is on ICRU plan, on CTV plan. Therefore CTV plan more less normal issue-irradiated dose than ICRU plan. But one patient case who residual tumor size excess 4cm, Normal tissue dose more higher than critical dose remarkably on CTV plan. over-Irradiated rectal dose(V80rec) is on ICRU plan, on CTV plan. over-Irradiated bladder dose(V80bla) is on ICRU plan, on CTV plan. Likewise, CTV plan more less irradiated normal tissue than ICRU38 plan.
Conclusion : Although, prove effect and stability about previous ICRU plan, if we use CTV plan by CT image, we will reduce normal tissue dose and irradiated goal-dose at residual tumor on small residual tumor case. But bigger residual tumor case, we need more research about effective 3D-planning.
|