Preliminary Study Of PET-CT And 3D Ultrasound In The Precise Hypofraction-ated Radiotherapy Of Prostate Cancer

Objective: To explore the application of PET-CT in the delineation of biological target in precise hypofractionated radiotherapy of prostate cancer and the important role of 3D ultrasound in the prostate localization and the protection of the bladder and rectum.Methods: Ten limited period of prostate cancer patients with middle and high risk were divided into A and B groups.Prostate adenocarcinoma was diagnosed by PSA scan and prostate biopsy before radiotherapy.And two groups patients were treated with localization of CT?3D ultrasound and pelvic enhanced MRI.Patients in group A were additional treated with PET-CT with18F-FDG and 11C-CH contrast media.Group A patients used the localization CT,MRI,PET-CT and 3D ultrasound to outline the GTVPET,CTV,RPV,CTVnd,PTV.Group B patients used the localization CT,MRI and 3D ultrasound to outline the CTV,RPV,CTVnd,PTV.Before radiotherapy,3D ultrasonic and CBCT were used to locate the two group of the error data.Finally,the two group data were transmitted to the accelerator to adjust the position of the bed.Observe the acute toxicity of rectal,bladder and hematology in the patients during radiotherapy.The serum PSA and radiographic data were recorded when newly diagnosed?before radiotherapy and after radiotherapy to evaluate the short-term efficacy.Results: The volume of CTV in group A was 71.10 ± 15.78cm3,The volume of CTV in group B was 68.45 ± 14.51cm3,P> 0.05,the volume difference between the two groups was not statistically significant.The volume of GTVPET in group A was 6.83 ± 8.05cm3,was 9.6% of the CTV volume of group A.The biological effective dose(BED)of CTV in group A was 119.74±1.78 Gy.The BED of CTV in group B was 129.20 ±2.70 Gy.The BED of GTVPET in group A was 139.92 ±3.45 Gy.The BED of CTV in group A was less than that in group B,while the BED of GTVPET in group A was higher than that of CTV in group B(P <0.05).There was significant difference between the two groups.The two groups patients' bladder,rectal irradiation volume were within the limits.The displacement error obtained by 3D ultrasound guidance was similar to that obtained by CBCT guidance in the left and right direction and the upper and lower direction,P> 0.05,there was no statistical difference.The displacement error obtained by 3D ultrasonic was 3.4 ± 1.4mm in the front-to-back direction,which was larger than that obtained by CBCT(1.0 ±0.8mm)and P <0.01,The difference was statistically significant.The volume of the bladder and rectum could be measured by 3D ultrasound at the same time,and make sure the bladder and rectal exposure volume were similar to the planned volume.During the process of radiotherapy,two patients in group A had grade 1 myelo-suppression,one patient had grade 1 urinary tract reaction,and two cases had grade 1 rectal reaction.Two patient in group B had grade 1myelosuppression,one had grade 1 rectal reaction.Neither of the two groupshad other serious adverse reactions.According to the change trend chart of PSA,we could know the decline trend of PSA in group A was more significant than that in group B.Conclusion: 1.PET-CT can be tentatively used for the prostate cancer of biological target volume delineation in the precise hypofractionated radio-therapy,to improve the dose of the tumor local lesions(DIL)while reducing the clinical target dose(GTV),and the early adverse effects were similar to conventional-fractionated radiotherapy.2.3D ultrasound can be used to guide the precise radiotherapy of prostate cancer,at the same time ensuring that the actual volume of the bladder and rectum are similar to the positioning volume.