The Usage Of MRS On Simultaneously Integrated Boost Hypofractionated Radiotherapy Of Biological Target Volume(BTV) In Prostate Cancer Patients:A Preliminary Study

Objective:To investigate the usage of magnetic resonance spectroscopic imaging on biological target volume with simultaneously integrated boost hypofractionated radiotherapy in prostate cancer.Methods:Five prostate cancer patients who were treated with radiotherapy for the first time were enrolled in this study and underwent scans using enhanced CT, conventional MRI, MRS and PET-CT before radiotherapy. Delineate tumor target on CT images combined with MRI, MRS and PET-CT image, name the tumor targets for GTVMRI, BTVMRS and BTVPET-CT, and record their gross tumor volume, respectively. Based on the BTVMRS, radiotherapy in the treatment of pelvic irradiation and IGRT (ultrasound-guided) technique was used to synchronize BTVMRS push the large amount of prostate and seminal vesicle fractionation irradiation method. Observe the acute toxicity of patients of rectum and bladder, the blood in the process of radiotherapy and record serum PSA value in the time of initial diagnosis, before radiotherapy,1 month after the end of radiotherapy and imaging data to evaluate the short-term effect.Results:The volumes of GTVMRI, BTVMRS and BTVPET-CT were different. The average value of GTVMRI, BTVMRS and BTVPET-CT was 3.52± 1.69cm3,6.64 ±2.27 cm3 and 5.47±2.60 cm3, respectively. GTVMRI was different from BTVMRS (P=0.046), while there were no differences between BTVMRS and BTVPET-CT, GTVMRI and BTVPET-CT (P> 0.05). Compared with GTVMRI, BTVMRS increased an average of 89.07%, BTVPET-CT increased an average of 55.52%. Irradiation physics dose and BED were 70.09-73.45Gy and 129.06-135.54 Gy, CTV (the whole prostate and seminal vesicle) irradiation physics dose and BED were 66.02-69.40 Gy and 113.32-124.82 Gy respectively based on BTVMRS. The actual dose of bladder and rectum were in the context of security. In the process of radiotherapy,2 patients arose acute radiation proctitis (grade 1), a patient arose mild acute urinary tract reaction,2 patients arose myelosuppression (grade 2). There were no other serious adverse reactions. In the time of initial diagnosis, before radiotherapy and 1 months after the end of radiotherapy, the serum PSA range were 23.18ng/ml to greater than 100ng/ml,0.47-28.3ng/ml and 0.16-1.90ng/ml. Imaging examination showed that the prostate volume was smaller than before treatment. There were no local or distant failure cases.Conclusions:1. MRS can be tentatively used for prostate cancer of biological target volume delineation with simultaneously integrated boost hypofractionated radiotherapy.2. BTVMRS based pelvic irradiation combined with IGRT (ultrasound-guided) synchronization technology prostate and simultaneously integrated boost hypofractionated radiotherapy was one of effective way for prostate cancer patients,which did not increase the toxicity and reduce the treatment time and medical fees.