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HDR brachytherapy in carcinoma cervix: Rectal retractor or gauze packing?
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Abstracts / Brachytherapy 5 (2006) 78–117
ratio between ‘‘single plan and four plan procedure’’ for D2cc and ICRU 38 reference point dose correlated well for bladder (r 5 0.85) and rectum (r 5 0.98). Conclusions: Applying the ‘‘single plan procedure’’ results on average in higher dose values for HR CTV and OARs compared to individual planning. Non-standardized bladder filling and a variable sigmoid position contribute primarily to overdosage. Such cases have to be identified based on comparison of X-ray films, MRI/CT and clinical examination, also imaging the sigmoid. In case of bladder and rectum, the relative change of the ICRU dose values for subsequent implants may help to detect major variations. Whereas individual MRI based treatment planning for each implantation remains the ‘‘gold standard,’’ it seems reasonable to use only one individual MRI based treatment plan for all insertions, taking into account possible variations by clinical and X-ray findings, imaging all OARs by appropriate use of contrast media.
OR-12 Presentation Time: 4:00 PM Effect of dose prescription on HDR vaginal brachytherapy Shidong Li, Ph.D., Ibrahim Aref, M.D., Benjamin Movsas, M.D. Radiation Oncology, Henry Ford Hospital, Detroit, MI. Purpose: The recent ABS survey on vaginal brachytherapy (VBT) by Small, Erickson, and Kwakwa (IJROBP, 2005) shows an increasing trend for VBT in treatment of endometrial cancer. However, there are large variations in the dose prescription for the VBT. The aim of this study is to evaluate the dose prescription effect on the treatment plan for high-doserate (HDR) VBT. Methods and Materials: Optimized treatment plans for HDR VBT are commonly created with prescription doses of 5-7 Gy three fractions prescribed to 0.5 cm beyond the cylinder surface or to the cylinder surface. The vaginal cylinders ranging from 2.0 to 4.0 cm and treatment length ranging from 3 to 8 cm were used for simulation of possible treatment conditions. Multiple points along the entire treatment segment of the vagina with various distances (0, 0.25, 0.5, 0.75, and 1.0 cm) from the surface of the vaginal applicator were marked in addition to the regular dose points at the prescription depths. The 3D isodose clouds (normalized to the presciption dose) as well as the dose distributions in those marked points were used for evaluation of the target coverage, dose uniformity through the target volume (volume within 0.5 cm from applicator surface), and changes from the different optimization and dose prescriptions. Results: A major dose distribution difference exists between the surface dose prescription and the 0.5 cm depth dose prescription. After automatic plus manual optimization, a relative uniform dose distribution (!10% variation) can be achieved on the dose points for both types of prescriptions. However, prescription to the surface provides more uniform dose to all depth layers within the target volume but significantly lower dose to the volume. The 0.5 cm depth description provides higher dose to the volume but very large dose variations (20 - 70%) on the vaginal mucosa that may cause complications. Conclusions: Instead of using the most common 0.5 cm depth prescription, increasing dose per fraction for the vaginal surface prescription might be the optimal approach for HDR VBT.
OR-13 Presentation Time: 4:10 PM Vaginal dose delivered by tandem and ovoid versus tandem and ring in cervical cancer Caroline L Holloway, M.D.,1 Christian Kirisits, D.Sc.,2 Robert A Cormack, Ph.D.,1 Akila N Viswanathan, M.D.1 1Radiation Oncology, Brigham and Women’s Hospital, Dana Farber Cancer Institute, Harvard Medical School, Boston, MA; 2Radiotherapy and Radiobiology, Medical University of Vienna, Vienna, Austria. Purpose: To compare tandem and ovoid (T/O) versus tandem and ring (T/R) high-dose-rate (HDR) brachytherapy doses to the vagina.
Methods and Materials: Between 12/04 and 12/05, 15 patients with cervical cancer received 5.5 Gy/fraction with HDR T/O or T/R. Postimplant CT contours of the bladder, rectum, and vagina and 3D optimization of dose were performed. Inherent uncertainties in contouring were consistent between T/O and T/R. Dose volume histograms (DVH) generated the D2cc for the bladder, rectum, and vagina. A two-tailed t-test compared the dose to the vaginal mucosa: T/O versus T/R; CT (T/Oct, T/ Rct) versus non-CT compatible applicators (T/Onon, T/Rnon); T/O large versus small or medium ovoids; and 2.6 versus 3 cm TR. Results: A total of 70 fractions were administered to 15 patients: 46 fractions were T/O (39 T/Oct, 7 T/Onon), and 24 fractions used T/R (8 T/ Rct, 16 T/Rnon). The mean D2cc for the rectum was T/O 3.2 Gy (1.35.6 Gy), T/R 3.5 Gy (2.0-4.9 Gy) (p 5 0.15); bladder, T/O 4.0 Gy (1.06.4 Gy), T/R 4.3 Gy (3.2-6.6 Gy) (p 5 0.3); vagina, T/O 6.3 Gy (2.819.3 Gy), T/R 7.5 Gy (5.1-13.1 Gy) p 5 0.04; T/Oct 6.0 Gy (2.8-14.6 Gy), T/Rct 8.3 Gy (5.8-13.1 Gy) p 5 0.001, T/Onon 8.0 Gy (5.1-19.3 Gy) and T/ Rnon 7.1 Gy (5.1-9.2 Gy) (p 5 0.48). The vaginal D2cc did not differ significantly by applicator size: T/O large versus medium/small ovoids (p 5 0.66); TR 2.6 cm versus 3 cm TR (p 5 0.9). Conclusions: T/R gives a significantly higher dose to the vaginal wall than does T/O. This difference is seen primarily among CT-compatible applicators. The type of applicator does not influence dose to the bladder or rectum. Clinical correlation is necessary.
OR-14 Presentation Time: 4:20 PM HDR brachytherapy in carcinoma cervix: Rectal retractor or gauze packing? Nikhilesh G Patil, M.D., D.N.B.,1 Vedang Murthy, M.D., D.N.B.,2 Tejpal Gupta, M.D., D.N.B.,3 Umesh Mahantshetty, M.D., D.N.B.,1 Dayananda Sharama, M.Sc., D.R.P.,4 S.K Shrivastava, M.D., D.N.B.,1 K.A Dinshaw, D.M.R.T., F.R.C.R.1 1Radiation Oncology, Tata Memorial Hospital, Mumbai, Maharashtra, India; 2Radiation Oncology, Royal Marsden, NHS Foundation Trust, Sutton, Surry, United Kingdom; 3Radiation Oncology, Advanced Centre for Treatment Research & Education in Cancer (ACTREC), Tata Memorial Centre, Kharghar, Navi-Mumbai, Maharashtra, India; 4Medical Physics, Tata Memorial Hospital, Mumbai, Maharashtra, India. Purpose: Intracavitary brachytherapy is an integral component of any radical radiotherapy regimen for carcinoma cervix. In recent times, highdose-rate (HDR) brachytherapy with its inherent advantages has largely superseded the traditional low dose rate systems. One of the physical advantages of high dose rate has been the applicability of aggressive vaginal retraction and packing, enabling significant reduction in doses to the bladder and rectum. However, evidence regarding the superiority of rectal retractors over gauze packing during HDR brachytherapy is lacking. Aim: We undertook this study to directly compare the efficacy of the two commonly used techniques of retraction viz. gauze packing and rectal retractors in terms of rectal and bladder doses during fractionated HDR brachytherapy for carcinoma cervix. Methods and Materials: Ten patients of carcinoma of the cervix stage IIB planned for fractionated HDR brachytherapy were included in this study. For each patient, the first of the five HDR applications were performed using gauze packing or rectal retractors by random assignment. Subsequently gauze packing and rectal retractors were used alternately for the remaining four fractions. Individual dosimetry was done for each application and the rectal and bladder doses were compared using the Wilcoxon signed rank test. Results: A total of 48 HDR brachytherapy applications were performed. The maximum as well as mean rectal doses were significantly higher in applications where rectal retractors were used in comparison to vaginal gauze packing (p 5 0.001 & 0.003, respectively). The maximum and mean bladder doses were also significantly higher (p 5 0.002 & 0.004, respectively) with retractors. This may have been partly due to the absence of anterior gauze packing when using retractors. Conclusions: Gauze packing was the superior technique with rectal and bladder doses being significantly lower than with a rectal retractor during fractionated HDR brachytherapy for carcinoma cervix.
Abstracts / Brachytherapy 5 (2006) 78–117
ratio between ‘‘single plan and four plan procedure’’ for D2cc and ICRU 38 reference point dose correlated well for bladder (r 5 0.85) and rectum (r 5 0.98). Conclusions: Applying the ‘‘single plan procedure’’ results on average in higher dose values for HR CTV and OARs compared to individual planning. Non-standardized bladder filling and a variable sigmoid position contribute primarily to overdosage. Such cases have to be identified based on comparison of X-ray films, MRI/CT and clinical examination, also imaging the sigmoid. In case of bladder and rectum, the relative change of the ICRU dose values for subsequent implants may help to detect major variations. Whereas individual MRI based treatment planning for each implantation remains the ‘‘gold standard,’’ it seems reasonable to use only one individual MRI based treatment plan for all insertions, taking into account possible variations by clinical and X-ray findings, imaging all OARs by appropriate use of contrast media.
OR-12 Presentation Time: 4:00 PM Effect of dose prescription on HDR vaginal brachytherapy Shidong Li, Ph.D., Ibrahim Aref, M.D., Benjamin Movsas, M.D. Radiation Oncology, Henry Ford Hospital, Detroit, MI. Purpose: The recent ABS survey on vaginal brachytherapy (VBT) by Small, Erickson, and Kwakwa (IJROBP, 2005) shows an increasing trend for VBT in treatment of endometrial cancer. However, there are large variations in the dose prescription for the VBT. The aim of this study is to evaluate the dose prescription effect on the treatment plan for high-doserate (HDR) VBT. Methods and Materials: Optimized treatment plans for HDR VBT are commonly created with prescription doses of 5-7 Gy three fractions prescribed to 0.5 cm beyond the cylinder surface or to the cylinder surface. The vaginal cylinders ranging from 2.0 to 4.0 cm and treatment length ranging from 3 to 8 cm were used for simulation of possible treatment conditions. Multiple points along the entire treatment segment of the vagina with various distances (0, 0.25, 0.5, 0.75, and 1.0 cm) from the surface of the vaginal applicator were marked in addition to the regular dose points at the prescription depths. The 3D isodose clouds (normalized to the presciption dose) as well as the dose distributions in those marked points were used for evaluation of the target coverage, dose uniformity through the target volume (volume within 0.5 cm from applicator surface), and changes from the different optimization and dose prescriptions. Results: A major dose distribution difference exists between the surface dose prescription and the 0.5 cm depth dose prescription. After automatic plus manual optimization, a relative uniform dose distribution (!10% variation) can be achieved on the dose points for both types of prescriptions. However, prescription to the surface provides more uniform dose to all depth layers within the target volume but significantly lower dose to the volume. The 0.5 cm depth description provides higher dose to the volume but very large dose variations (20 - 70%) on the vaginal mucosa that may cause complications. Conclusions: Instead of using the most common 0.5 cm depth prescription, increasing dose per fraction for the vaginal surface prescription might be the optimal approach for HDR VBT.
OR-13 Presentation Time: 4:10 PM Vaginal dose delivered by tandem and ovoid versus tandem and ring in cervical cancer Caroline L Holloway, M.D.,1 Christian Kirisits, D.Sc.,2 Robert A Cormack, Ph.D.,1 Akila N Viswanathan, M.D.1 1Radiation Oncology, Brigham and Women’s Hospital, Dana Farber Cancer Institute, Harvard Medical School, Boston, MA; 2Radiotherapy and Radiobiology, Medical University of Vienna, Vienna, Austria. Purpose: To compare tandem and ovoid (T/O) versus tandem and ring (T/R) high-dose-rate (HDR) brachytherapy doses to the vagina.
Methods and Materials: Between 12/04 and 12/05, 15 patients with cervical cancer received 5.5 Gy/fraction with HDR T/O or T/R. Postimplant CT contours of the bladder, rectum, and vagina and 3D optimization of dose were performed. Inherent uncertainties in contouring were consistent between T/O and T/R. Dose volume histograms (DVH) generated the D2cc for the bladder, rectum, and vagina. A two-tailed t-test compared the dose to the vaginal mucosa: T/O versus T/R; CT (T/Oct, T/ Rct) versus non-CT compatible applicators (T/Onon, T/Rnon); T/O large versus small or medium ovoids; and 2.6 versus 3 cm TR. Results: A total of 70 fractions were administered to 15 patients: 46 fractions were T/O (39 T/Oct, 7 T/Onon), and 24 fractions used T/R (8 T/ Rct, 16 T/Rnon). The mean D2cc for the rectum was T/O 3.2 Gy (1.35.6 Gy), T/R 3.5 Gy (2.0-4.9 Gy) (p 5 0.15); bladder, T/O 4.0 Gy (1.06.4 Gy), T/R 4.3 Gy (3.2-6.6 Gy) (p 5 0.3); vagina, T/O 6.3 Gy (2.819.3 Gy), T/R 7.5 Gy (5.1-13.1 Gy) p 5 0.04; T/Oct 6.0 Gy (2.8-14.6 Gy), T/Rct 8.3 Gy (5.8-13.1 Gy) p 5 0.001, T/Onon 8.0 Gy (5.1-19.3 Gy) and T/ Rnon 7.1 Gy (5.1-9.2 Gy) (p 5 0.48). The vaginal D2cc did not differ significantly by applicator size: T/O large versus medium/small ovoids (p 5 0.66); TR 2.6 cm versus 3 cm TR (p 5 0.9). Conclusions: T/R gives a significantly higher dose to the vaginal wall than does T/O. This difference is seen primarily among CT-compatible applicators. The type of applicator does not influence dose to the bladder or rectum. Clinical correlation is necessary.
OR-14 Presentation Time: 4:20 PM HDR brachytherapy in carcinoma cervix: Rectal retractor or gauze packing? Nikhilesh G Patil, M.D., D.N.B.,1 Vedang Murthy, M.D., D.N.B.,2 Tejpal Gupta, M.D., D.N.B.,3 Umesh Mahantshetty, M.D., D.N.B.,1 Dayananda Sharama, M.Sc., D.R.P.,4 S.K Shrivastava, M.D., D.N.B.,1 K.A Dinshaw, D.M.R.T., F.R.C.R.1 1Radiation Oncology, Tata Memorial Hospital, Mumbai, Maharashtra, India; 2Radiation Oncology, Royal Marsden, NHS Foundation Trust, Sutton, Surry, United Kingdom; 3Radiation Oncology, Advanced Centre for Treatment Research & Education in Cancer (ACTREC), Tata Memorial Centre, Kharghar, Navi-Mumbai, Maharashtra, India; 4Medical Physics, Tata Memorial Hospital, Mumbai, Maharashtra, India. Purpose: Intracavitary brachytherapy is an integral component of any radical radiotherapy regimen for carcinoma cervix. In recent times, highdose-rate (HDR) brachytherapy with its inherent advantages has largely superseded the traditional low dose rate systems. One of the physical advantages of high dose rate has been the applicability of aggressive vaginal retraction and packing, enabling significant reduction in doses to the bladder and rectum. However, evidence regarding the superiority of rectal retractors over gauze packing during HDR brachytherapy is lacking. Aim: We undertook this study to directly compare the efficacy of the two commonly used techniques of retraction viz. gauze packing and rectal retractors in terms of rectal and bladder doses during fractionated HDR brachytherapy for carcinoma cervix. Methods and Materials: Ten patients of carcinoma of the cervix stage IIB planned for fractionated HDR brachytherapy were included in this study. For each patient, the first of the five HDR applications were performed using gauze packing or rectal retractors by random assignment. Subsequently gauze packing and rectal retractors were used alternately for the remaining four fractions. Individual dosimetry was done for each application and the rectal and bladder doses were compared using the Wilcoxon signed rank test. Results: A total of 48 HDR brachytherapy applications were performed. The maximum as well as mean rectal doses were significantly higher in applications where rectal retractors were used in comparison to vaginal gauze packing (p 5 0.001 & 0.003, respectively). The maximum and mean bladder doses were also significantly higher (p 5 0.002 & 0.004, respectively) with retractors. This may have been partly due to the absence of anterior gauze packing when using retractors. Conclusions: Gauze packing was the superior technique with rectal and bladder doses being significantly lower than with a rectal retractor during fractionated HDR brachytherapy for carcinoma cervix.