Research on Using IMRT Plan for Preoperative Rectal Cancer Patients

Aims: Research the possibility of using IMRT for rectal cancer patients in preoperative radiotherapy. Methods and Material: The research object is the preoperative radiotherapy plan for rectal cancer patients. The research group made two plans (IMRT, 3DCRT) for each image series of 34 rectal cancer patients who have received preoperative radiotherapy in Hanoi Oncology Hospital;and then compared the dose distribution on PTV, bladder, intestine, femoral bones, the average MU, and QA results of two types of plan. Results: The 95% isodose line and 50% isodose of IMRT plan are closer than those of 3DCRT plan. The average dose of PTV in IMRT plan and 3DCRT plan are 5006 ± 23 cGy and 5036 ± 42 cGy, respectively. The HTCI and HI values of IMRT and 3D plan are 0.97 ± 0.026 and 5.37 ± 1.32;1.00 ± 0.003 and 7.08 ± 0.88. About the dose of organ at risk: The maximum dose, average dose on the right, left femoral head in the IMRT plan are less than those values in the 3DCRT plan (6.2 Gy, 6 Gy, 7.4 Gy, 9 Gy, respectively). The maximum dose and average dose on the bladder of the IMRT plan are smaller than those values of the 3DCRT plan (5.3 Gy, 1.5 times, respectively). The maximum dose and average dose of intestine in the IMRT plan was less than those values in the 3DCRT plan (4.3 Gy, 1.54 times, respectively). The MU number of IMRT plan is 1.5 times bigger than that of 3DCRT plan. Gamma index of IMRT plan is better than that of 3DCRT plan (99% compared with 97%). Conclusions: Using IMRT plan in preoperative radiotherapy for rectal cancer patients can still ensure covered PTV as well as the 3D PLAN. Furthermore, the dose of PTV in the IMRT plan is more uniform than those in the 3D plan, and the dose effect on the OAR surrounding PTV is much lower than when using the 3D plan. When IMRT plan were used to treat the preoperative rectal cancer patients, the LINAC took more time than when using 3DCRT plan.

Analyzing Planning Techniques for Whole Brain Radiotherapy

Aims: This study compares data between the Field in Field planning and Wedge planning techniques to figure out which technique has better dose coverage and distribution for PTV, and, if using FiF technique for whole brain treatment, how many beams will have better plan. Methods: 56 patients, who need to radiate whole brain with 30 Gy/10 fractions, have been selected for this study. Four plans have been made for each patient (FiF1—one subfield per field plan, FiF2—two subfields per field plan, FiF3—three subfields per field plan, and a Wedge plan). Results: The results of Field in Field plans including Compare dose distribution on the transverse CT slice, plan evaluation using DVH, number MU of plan, Dmax, HI, HTCI, DmaxPTV, DmeanPTV. Volume of PTV with the dose over 105% prescribed dose, dose of organ at risk, and Quality Assurance (QA) plan, are better than those of Wedge plan. Conclusions: Plans using Field in Field technique has better coverage, is more homogeneous in dose distribution than plan using Wedge technique. When using Field in Field technique for whole brain radiotherapy, using three subfields per field has better result than two subfields per field and one subfield per field.

Analyze the Dose Results Calculated with AAA Algorithm in Eclipse Software of New Treatment Planning System

In this paper,the authors investigate the differences between the dose results calculated with AAA(Anisotropic Analytical Algorithm)algorithm in Eclipse 13.0 treatment planning system,which has just commissioned,with the measured doses.The AAA algorithm in the Eclipse software is used to calculate the absolute dose,relative dose in profile line,and percent depth dose of some specific field size in Blue Phantom.The calculated dose results were compared with measured dose based on Technical Reports Series No.430 of International Atomic Energy Agency(IAEA No.430).The authors have used CC13 ion chamber,Famer Chamber,water phantom,and Omnipro software to measure relative,absolute doses of these fields size.The AAA algorithm was also used to calculate the doses in IMRT(Intensity Modulated Radiotherapy)plan of fifty head and neck cancer patients.These IMRT plans were controlled quality in some points with plastic phantom,and famer chamber FC65.The differences between calculated dose,and measured doses are in the limit of IAEA 430 report.The results of the QA IMRT plan processing are fitting with ESTRO(European Society Therapeutic Radiation Oncology)Booklet No.9.