Şeyda KINAY, Recep KANDEMİR, İlhami ER, Ayşe Nur DEMİRAL, Funda OBUZ

The Effects of the Amount of Bladder Filling on Normal Tissue Doses in 3-dimensional HDR Vaginal Cuff Brachy Therapy

OBJECTIVEThis study aimed to compare the dose-volume parameters of organs at risk (OAR) (bladder, rectum,sigmoid and bowel) for the bladder filling of 50cc versus 150cc in high-dose-rate (HDR) (3-D) vaginalcuff (VC) brachytherapy (BRT).METHODSThe treatment data of eight hysterectomized patients with gynecological malignancy who received postoperative pelvic external radiotherapy (RT)+3-D HDR VC-BRT were analyzed. Recontouring was performed on CT images, and BRT plans were reformed. Proximal 1/3 vagina was treated in all patientsusing a cylinder. A total dose of 18 Gy (3x6Gy) was given (0.5 cm depth from the vaginal mucosa). OARand clinical target volume (CTV) were recontoured in a 3-D manner. Afterwards, treatment planningwas performed by a medical physicist using the BRT treatment planning system. Bladder V50%, D50%and D2cc, rectum D2cc, sigmoid D2cc, bowel D50% and D2cc were recorded from the dose-volumehistograms obtained in the treatment planning system. Paired comparisons were made for the parameters above for the bladder filling of 50cc versus 150cc. Two different amounts of bladder filling werecompared using the Wilcoxon Signed-Rank Test in the SPSS 15.0 statistics program.RESULTSBladder D50% decreased (p=0.012) while bladder D2cc increased (p=0.025) in the case of 150cc bladder filling instead of 50cc. Rectum D2cc showed a statistical trend for increase (p=0.05); however, bowelD50% decreased (p=0.012) in 150cc bladder filling compared to 50cc.CONCLUSIONThe statistically significant decrease in bladder and especially bowel D50% parameters supports fillingthe bladder with 150cc instead of 50cc in 3-D VC-BRT.

PDF

___

1. Madan R, Pathy S, Subramani V, Sharma S, Mohanti BK, Chander S, et al. Comparative evaluation of twodimensional radiography and three dimensional computed tomography based dose-volume parameters for high-dose-rate intracavitary brachytherapy of cervical cancer: a prospective study. Asian Pac J Cancer Prev 2014;15(11):4717–21.
2. Kobzda JD, Cikowska-Wozniak E, Michalska M, Makarewicz R. Three-dimensional dosimetry of the full and empty bladder in high dose rate vaginal cuff brachytherapy. Int J Gynecol Cancer 2014;24(5):923–7.
3. Hung J, Shen S, De Los Santos JF, Kim RY. Imagebased 3D treatment planning for vaginal cylinder brachytherapy: dosimetric effects of bladder filling on organs at risk. Int J Radiat Oncol Biol Phys 2012;83(3):980–5.
4. Stewart AJ, Cormack RA, Lee H, Xiong L, Hansen JL, O’Farrell DA, et al. Prospective clinical trial of bladder filling and three-dimensional dosimetry in high-doserate vaginal cuff brachytherapy. Int J Radiat Oncol Biol Phys 2008;72(3):843–8.
5. Hoskin PJ, Vidler K. Vaginal vault brachytherapy: The effect of varying bladder volumes on normal tissue dosimetry. Br J Radiol 2000;73(872):864–6.
6. Guler OC, Onal C, Acibuci I. Effects of bladder distension on dose distribution of vaginal vault brachytherapy in patients with endometrial cancer. J Contemp Brachytherapy 2015;6(4): 371–6.
7. Pötter R, Haie-Meder C, Van Limbergen E, Barillot I, De Brabandere M, Dimopoulos J, et al; GEC ESTRO Working Group. Recommendations from gynaecological (GYN) GEC ESTRO working group (II): concepts and terms in 3D image-based treatment planning in cervix cancer brachytherapy-3D dose-volume parameters and aspects of 3D image-based anatomy, radiation physics, radiobiology. Radiother Oncol 2006;78(1):67–77.
8. Pötter R, Dimopoulos J, Georg P, Lang S, Waldhausl C, Wachter-Gerstner N, et al. Clinical impact of MRI assisted dose-volume adaptation and dose escalation in brachytherapy of locally advanced cervix cancer. Radiother Oncol 2007; 83(2):148–55.
9. Sanguineti G, Little M, Endres EJ, Sormani MP, Parker BC. Comparison of three strategies to delineate the bowel for whole pelvis IMRT of prostate cancer: Radiother Oncol 2008; 88(1):95–101.
10.Sun B, Yang D, Esthappan J, Garcia-Ramirez J, Price S, Mutic S, et al. Three-dimensional dose accumulation in pseudo-split-field IMRT and brachytherapy for locally advanced cervical cancer. Brachytherapy 2015;14(4):481–9.