Mahatma Gandhi Cancer Hospital and Research Institute Dr P. S. Bhattacharyya, MD Radiation Oncologist. Elekta Synergy CT Simulator Flexitron HDR
Computed tomography assisted High Dose Rate Interstitial Brachytherapy in Gynaecologic Malignancies, with Inverse Planning Simulated Annealing ; An Institutional experience. Author-Dr P S Bhattacharyya, MD Co-author-Mr A C prabhu, Med. Phy.
Introduction Ca. Cx - 40% of all cases treated at MGCH EBRT + CDDP 40 mg/m ICRT / IBT GEC Estro guidelines for 3D ICRT MUPIT 2
Aims of the study To report IPSA based 3D HDR IBT in cancer Cervix and Vagina DVH analysis of CTV and OAR
Materials and Methods May 2012 to Dec 2012 Retrospective analysis 34 IBT applications in 17, Ca.Cx / Vagina patients Duration < 3 hrs Median 19 (17-23) needles used 8 – 9.5 Gy X 2 prescibed dose IPSA
Clinical and Histopathological features PRESENTATION Bleeding P/V White discharge Pelvic Pain NO. OF PATIENTS PERCENTAGE HPE Sq. Cell Ca. Adeno Ca SITE Intact Cervix Vault Vagina FIGO STAGE IIB IIIB IIIB with L/3 Vagina involved Total patients studied-17 Median age -56 Yrs.(18-68 yr)
Perineal Template Indications Bad Geometry 47% (08) Ca. Vault area 29% (05) Vaginal and para vaginal involvement 12% (02) Non negotiable cervical OS 06% (01) ICRT high dose to bladder 06% (01) Total No. of patients studied-17
Interstitial applicators Vienna CT-MRI Ring/ Ovoid Applicator Syed Neblett Template
MUPIT Applicator
BED and D EQ Equations BED Ext+HDR = (nd[1+(---)]) + (nd[1+(---)]) D EQ = BED Ext+HDR d d d ref 1+ ( ---- ) n = no. Of fractions d = dose per fraction in Gy a/b = alpha / beta, 10 for tumor, 3 for late effects BED=biologically equivalent dose D Eq= Equivalent dose (Gy) d ref= reference dose, 2 Gy a/b
IPSA Planning
CTV DVH Interpretations CTVRangeMedianBED 10 Tumor effects Dose Eq. Gy D – 8.49 Gy5.82 Gy D – 9.17 Gy8.42 Gy D – 9.60 Gy 8.74 Gy V10085 – %91.13% Median Prescribed dose- 8.8 Gy
OAR DVH Interpretation Bladder Volume cc Range Gy Median dose Gy BED 3 Late effects Dose Eq. Gy Rectal Volume cc Range Gy Median dose Gy BED 3 Late effects Dose Eq. Gy URINARY BLADDER RECTUM Median Prescribed Dose- 8.8 Gy
IPSA isodose distribution
Comparision of bladder dose 0.1 cc bladder dose 12 Gy with ICRT 0.1 cc bladder dose 8.1 Gy with IBT
Limitations of the study All the patients did not recieve 6 cycles of CDDP Total duration of treatment more than 8 weeks Applicator volume in CTV No subdivisions in CTV
Thank you