The Effects Of Different Bladder Volumes On Dose Changes Of Organs At Risk Using CT Guided3D Brachytherapy For Cervical Cancer

Objective:Analysis of different bladder volume cervical cancer close the normaltissue dose distribution in radiotherapy planning and its influence,In order to reducecomplications after cervical cancer brachytherapy.Selection methods:Selection in January2014-December2014earning mypathology diagnosed with cervical cancer patients,The pathological types:37casessquamous cell carcinomas,3cases of adenocarcinoma, a total of40cases;24-68-year-old age,The average age of55.6years.According to the international association ofgynecology and obstetrics (FIGO) staging: IB2period (3cases),Stage IIB28cases,8stage IIIA,Stage IIIB in1case.Siemens large aperture CT imaging system,High doserate after the iridium-192therapy apparatus,Diacor zephyr patient Transport sledtransfer bed,Medical Oncentra4.3treatment planning system and the target sketchsystem,Utrecht source applicator,Rectal tube dose monitoring.34patients line to putthe same treatment,Six patients disease due to other system or personal reasons notline chemotherapy.Chemotherapy regimens for cisplatin40mg/m2,Once a week.Allof the patients adopt radical radiotherapy:(1) external exposure:The Swedish medicalcompany synergy-platform for linear accelerator,Line15of whom underwent threedimensional optimal radiotherapy,Use the fields cassette illuminate,25routineintensity-modulated radiotherapy,Dose are180cgy/f,Total dose of4500cgy;(2)irradiation:Using Utrecht three tube source applicator,Nuclear company Micro-Selectron HDR high dose rate iridium-192close therapy apparatus,Dose are700cgy/f,1times a week, a total of four times,Dose calculation using linear quadraticequation,Normal tissue alpha/beta=3,Tumor alpha/beta=10.External exposure:Allpatients with the Dutch nuclear tong company SIMULIXHQ simulation positioningmachine downward thermoplastic body membrane fixed position,Application ofSiemens since the open large aperture CT simulation positioning,CT scan with5mmlayer spacing,Up to the edge of10thoracic vertebral ischial tuberosity,Image data into medical Oncentra4.3treatment planning system,Three dimensional conformalintensity modulated radiation therapy (imrt) or plan;(2) close treatment:Cancerpatients after anesthesia effect, ecg, blood pressure, blood oxygenmonitoring,Conventional disinfection vulva after indwelling Foley catheter,Airbaggeneric shadow meglumine was injected in7ml;The doctor for patients receives,sanhe,MRI/CT before and refer to the treatment result is roughly determine uterinesize, position,Near the palace lesions on both sides;Uterine cavity and rigid probeultrasound guided into direct fundus,Remove the probe rigidity,Uterine cavity depthmeasuring probe it and choose the corresponding Angle of uterine cavity sourceapplicator Utrecht,The length of the adjustment of uterine source applicator into theuterine cavity,Uterine cavity source applicator will be implanted into the womb underguided by ultrasound,Vaginal and placed right size box,Both the position of thefixed;For existing palace invaded by patients under the guidance ofultrasound,Determine the need for near the palace into plant parts,And inserted nearthe palace inserted under ultrasound guided needle,Complete source applicator andflocking needle placement.In rectal pressure plate,Fixed source applicator and rectalpressure plate,And rectal dose monitoring tube;Then the patient in the bladderemptying state downward CT simulation positioning,CT scan with2mm layerspacing,To the top of the uterus tube on2cm,Next to the ischiatic tuberosity, under2cm,After the scan image data into the medical of Oncentra4.3treatment planningsystem;Bladder were randomly into a certain volume of physiological saline,Andrepeated CT scans,Repeated CT image data into the medical of Oncentra4.3treatmentplanning system;After the patient into the preparation room waiting for treatmentfrom close range.Target outline by fu department tumor group completed the samesketch experienced doctors.(1) target: external exposure GTV is generally visibletumor,CTV including uterine, cervical, near the palace, skeletons, skeletons, skeletonsin total lymphatic drainage area,Before the obturator lymph drainage area, sacrallymphatic drainage area,Patients with vaginal invaded lower bound to the edge of thetumor target1cm,No vaginal invaded target in patients with lower bound to the edgeof hole closed,For CTV PTV outside enlarge5mm.Normal tissue sketch includingbladder, rectum, sigmoid colon and small intestine, bilateral femoral head.(2) closetreatment target outline:According to the GEC-ESTRO within the recommendedscheme of department of gynaecology,Including: CTVhr including remain visible to the naked eye tumor lesions and cervical entirely,CTVir including CTVhr anddifferent security border to prevent the spread of potential,CTVhr based on directionbefore and after the expansion of5mm, outsideConsidering the limits of bladderrectum normal anatomical structures, at the same time,Head direction extended10mm, lateral relationship10mm.Normal tissue sketch including bladder, rectum,sigmoid colon and small intestine.Physics teacher according to the doctor drew theoutline of the target area, thePrescribed dose and endanger organ set limit to developand optimize the treatment plan,According to the DVH figure evaluation target tumorand endanger the organ doses.(1) external exposure: target PTV dose for95%volumeof about45gy,Intensity-modulated patients with bladder, rectum, sigmoid colon andsmall intestine to meet V40<40%.(2) close treatment:The parameters of evaluationtarget dose have CTVhr-D90,CTVhr-D100,CTVir-D90CTVir-D100,Respectively90%and100%in high dangerous CTV in threatening the minimum dosevolume.Evaluation imperil the parameters of the organ dose for D0. LCC, Dlcc andD2cc,Source applicator adjacent normal tissues respectively0.1,1,2, the minimumdose in cm3;This research program optimization on the basis of CTVhr D90andendanger organ D2cc dose requirement,Ask CTVhr-D90EQD2reached more than85gy,CTVir-D90EQD2reach more than60gy;Bladder D2ccEQD2is less than90gy,Rectum, sigmoid colon and small intestine D2cc EQD2is less than75gy.Planconfirmed,Put a therapy after the introduction of the optimized plan for treatment.Forrandom filling of bladder volume CT simulation positioning again,Repeat the abovesteps.Comparison of bladder0-100,100-200and>100ml,And small intestine,rectum, sigmoid colon and small intestine D0.1cc, D1cc, D2cc changes,Data withstatistics software16.0,Results the average+/-standard deviation form,To havestatistical significance (p <0.05.Results: Bladder volume0-100ml rectum D0.1cc, D1cc, D2cc the bladdervolume increased significantly after100-200ml,Small intestine D0.1cc, D1cc, D2ccin bladder volume of0-100,100-200and>100ml decreased significantly,Everyother normal tissue after bladder emptying and filling illuminated dose has no obviouschange,No statistical difference.Conclusion: Bladder volume is different to the sigmoid colon,Bladder dose lessaffected;Increased bladder volume to reduce quantity of the small intestine by;Without change the rectum by quantity of bladder volume0-100-ml is100-100,>200ml volume is more advantageous to reduce quantity of the small intestine by.