Comparison of linac-based fractionated stereotactic radiotherapy and tomotherapy treatment plans for intra-cranial tumors

This study compares and analyzes stereotactic radiotherapy using tomotherapy and linac-based fractionated stereotactic radiotherapy in the treatment of intra-cranial tumors,according to some cases.In this study,linac-based fractionated stereotactic radiotherapy and tomotherapy treatment were administered to five patients diagnosed with intra-cranial cancer in which the dose of 18–20 Gy was applied on 3–5 separate occasions.The tumor dosing was decided by evaluating the inhomogeneous index （II） and conformity index （CI）.Also,the radiation-sensitive tissue was evaluated using low dose factors V1,V2,V3,V4,V5,and V10,as well as the non-irradiation ratio volume （NIV）.The values of the II for each prescription dose in the linacbased non-coplanar radiotherapy plan and tomotherapy treatment plan were （0.125±0.113） and （0.090±0.180）,respectively,and the values of the CI were （0.899±0.149） and （0.917±0.114）,respectively.The low dose areas,V1,V2,V3,V4,V5,and V10,in radiation-sensitive tissues in the linac-based non-coplanar radiotherapy plan fell into the ranges 0.3%–95.6%,0.1%–87.6%,0.1%–78.8%,38.8%–69.9%,26.6%–65.2%,and 4.2%–39.7%,respectively,and the tomotherapy treatment plan had ranges of 13.6%–100%,3.5%–100%,0.4%–94.9%,0.2%– 82.2%,0.1%–78.5%,and 0.3%–46.3%,respectively.Regarding the NIV for each organ,it is possible to obtain similar values except for the irradiation area of the brain stem.The percentages of NIV10%,NIV20%,and NIV30%for the brain stem in each patient were 15%–99.8%,33.4%–100%,and 39.8%–100%,respectively,in the fractionated stereotactic treatment plan and 44.2%–96.5%,77.7%–99.8%,and 87.8%–100%,respectively,in the tomotherapy treatment plan.In order to achieve higher-quality treatment of intra-cranial tumors,treatment plans should be tailored according to the isodose target volume,inhomogeneous index,conformity index,position of the tumor upon fractionated stereotactic radiosurgery,and radiation dosage for radiation-sensitive tissues.

Therapeutic Effects of Stereotactic Radiotherapy on 389 Cases of Brain Glioma

Objective： To investigate the treatment effectiveness and side effects of stereotactic radiotherapy for brain glioma. Methods： From Jun. 1995 to Dec. 1998, 389 cases of brain gliomas were treated by stereotactic radiotherapy, among which 151 cases were treated by stereotactic radiosurgery （SRS） and the other 238 cases, by fractionated stereotactic radiotherapy （FSRT）. In the SRS group, the marginal tumor dose was 20 to 30 Gy （median, 2.6 Gy）. One to 6 isocenters （median, 2.48） and 5 to 21 irradiation arcs （median, 8.45） were applied. In the FSRT group, the per-fraction marginal tumor dose was 8 to 12 Gy with 1 to 6 isocenters （median, 2.53）, 6 to 20 irradiation arcs （median, 8.25） and 2-5 fractions delivered everyday or every other day. Results： Three months after treatment, the complete and partial response rates were 13.9% and 45.7% in SRS group respectively. The stable disease rate was 17.2%. The total effective rate was 76.8%. In FSRT group, the complete and partial remission rates were 19.7% and 47.9% respectively. The stable disease rate was 20.6%. The total effective rate was 88.2%. The total effective rate of FSRT group was higher than that in SRS group （X^2=9.874, P=0.020）. The 1-year, 3-year and 5-year survival rate of all patients was 54.3%, 29.3%, 16.5% respectively. The 1-year, 3-year and 5-year survival rate in SRS group and FSRT group was 52.3% vs 26.5%, 11.9% vs 55.5%, and 31.1 vs 19.3% respectively. There was no significant difference between the two groups （X^2=2.16, P=0.1417）. The brain edema caused by the main radiation was more severe in the SRS group than in FSRT group （X^2=4.916, P=0.027）. Conclusion： It is effective for brain glioma to be treated by stereotactic radiotherapy. Compared with SRS, the FSRT has the advantage of good effect and less side response.

Observation of the therapeutic efficacy of stereotactic radiotherapy in 44 cases of retroperitoneal metastatic tumor

Objective: To investigate the therapeutic effects of stereotactic radiotherapy for retroperitoneal metastatic tumor. Methods: From August 1997 to October 2004, 44 patients with retroperitoneal metastatic tumors were treated with stereotactic radiotherapy. The planning target volume was encompassed by 90%–95% isodose line. Fractional dose was from 6 Gy to 8 Gy, and they were treated 2–3 times per-week and 4–8 times in all. The total radiation doses of PTV were from 32 Gy to 48 Gy. Re- sults: After the radiotherapy, the pain was obviously relieved in 81.8% patients. Three months after completion of radiotherapy passed and then, abdominal CT was performed to evaluate the results. The whole effective rate was 81.8% [CR 27.7% (12/44) and PR 54.5% (24/44)], and six months after radiotherapy, CR was 27.7% (12/44) and PR was 59.1% (26/44). The middle survival time was 12 months. Conclusion: It is suggested that stereotactic radiotherapy for retroperitoneal metastatic tumor is a safe and effective method.