The Study On Dosimetric Verification Of¹²⁵I Seed Implantation In Recurrent Pelvic Tumors And The Effect Of Clinical Efficacy

Pelvic malignant tumor recurrence rate is higher after treatment,Takerectal cancer for example,Postoperative recurrence rate is>33%, The localcontrol rate is50%even combinate with irradiation, The3-year survival rate isjust32%if with whole pelvic organ resection.The1-year survival rate ofrecurrent Cervical cancer after the operation or radiotherapy is <20%,and5-year-survival rate is only about10%. The multi modality treament includingsurgical operation,radiotherapy,chemotherapy and biological therapy areapplied to intermediate and advanced pelvic tumors,But Local recurrence anddistant metastasis are one of the leading causes responsible for failure. Thecomplications of intractable pain,fistula formation, bleeding inhibited itsapplication also.Management patients with recurrent Pelvic tumor is achallenge for clinical oncologists.Surgical operation have large trauma andlow radical resection rate. Regional or systemic chemotherapy have a lessefficient,due to fibrous tissue hyperplasia after operation and radiotherapy,anddrugs is not easy to enter.The application of external irradiation is limitedbecause of tumor cells to the hypoxic state,side effects of adiation cystitis,enteritis, intestinal stenosis and history of previous radiotherapy due todifficult to improve the target dose.Radioactive¹²⁵I seeds interstitial implantation is a method ofbrachytherapy treatment. Its the implantation of radioactive seeds into thetumor or tissue invaded by tumor. Through continuousγ-radiation,the targettumor cells will be killed.The technique has the characteristic ofbiophysics that the target will received high dose whereas the surrounding hasdropped steeply.It has a small pathological damage,which limited the scope of5mm away from the¹²⁵I seeds.When adjust the space and the activity ofpartical source, can multiplied improve the tumor target dose.The target area receives high doses of anti-tumor effect,but on the surrounding normal tissuethe damage is small.To enhance the treatment effect as well as to reduce thecomplication.The technique of¹²⁵Iseed implantation in prostate cancer hasreached a mature,In recent years with the application of radioactive seedsinterstitial implantation have received obviously effect in treatment ofrecurrent pelvic tumors,it may serve as a method of salvage therapy applied inrecurrent pelvic tumors.In this study,with three-dimensional compputer treatment planningsystem(TPS),CT and B-ultrasonography and other precision positioningsystem,¹²⁵Iseeds was implants in recurrent pelvic tumors which isunresectable and unsuitable for secondary radiotherapy.According to observethe difference of dose between preimplantation andpostimplantation,efficacy,quality of life score,survival time,complication andso on,to provide the basis for improving efficacy, understanding thedose-effect relationship, quantitativing dose distribution information,promoting and standardizing of seed implantation.Objective: To research the dosimetric difference between thepreimplantation plan and the postimplantation plan and to explore the actualeffect of the difference to efficacy.Methods: Twelve patients with pelvic recurrent malignant tumor weretreated with¹²⁵Iseeds implantation under the guidance of B-ultrasonographyor CT.The pre-plan was accomplished according to the TPS to reconstructtumor three-dimensional image and to calculate the seed number, placementand dose distribution.D₉₀(the dose received by90%of the target)for planningtarget volume was35-145Gy, dosimetric verification was accomplished in oneweek after implantation. The difference of D₈₀,D₉₀,D₁₀₀,V₉₀,V₁₀₀(thepercentage of the PTV volume receiving100%of the prescription dose),V₁₅₀,mPD(minimum peripheral dose),D_mean(mean absorbed dose),PTV volumebetween preimplantation and postimplantation were compared.All the patientswere evaluated with CT examinations every month after the treatment. Thepain relief time, efficacy, the local control rate, survival time, quality of life score (KPS), and complications after operation were observed.Results: There were no difference in D₈₀,D₉₀,V₁₅₀,mPD,D_mean,PTVvolume between preplan and postplan(t=1.89,1.77,1.86,0.438,0.21å’Œ-1.37, P＞0.05),but were difference in D₁₀₀,V₁₀₀,V₁₀₀,(t=2.329,3.592å’Œ3.529, P＜0.05).The follow-up was3-43months and the follow-up ratewas100%. The pain relief rate was85.71%(6/7).Complete remission (CR),partial remission(PR), no change (NC), and progress disease (PD) wereseen in3,5,2, and2patient respectively after3months operation,The overalleffective rate (CR+PR) was66.7%.The1-and2-year local control rates were75.0and33.3%respectively.The patients with the longest survival time is stillalive at the end of follow-up,the median survival time was18months.The1-and2-year survival rates were66.7ï¼…and25ï¼…respectively.The quality of lifescore (KPS) of postoperation was better than preopeation(z=-3.258,P﹤0.05).One patient died of multiple organ failure three months and one died ofextensive metastasis five months after seed implantation,Ten patients hadfever,one patient had pelvic infection. After operation, pelvic X-rayexaminations were conducted to every patients.1case of oarian cancer fall18seeds into abdominal cavity,1case of rectum cancer patients fall off2seeds.one patient had grade two skin reaction.two patients had grade2rectumdamage.one patient had grade2urinary system damage.one patient had vaginarectum fistula9months after operation.one patient recurred1year after seedimplantation.Conclusions:1Expected dosimetric distribution can be achieved basically accordingto dosimetric verification of¹²⁵ISeed implantation, it can control thetumor effectively.2The short-term effect of¹²⁵Iseed implantation is better in recurrentpelvic tumor, especially for relieving pain,improving symptoms andimproving quality of life.¹²⁵Iseed implantation as a safe,effectiveintervention treatment. method is a salvage treatment in the recurrent pelvictumors.