Effect of bladder distention on bladder base dose in gynaecological intracavitary high dose rate brachytherapy (original) (raw)
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Journal of applied clinical medical physics / American College of Medical Physics, 2016
The purpose of this study was to investigate the concurrent effects of tandem length and bladder volume on dose to pelvic organs at risk (OARs) in HDR intracavitary brachytherapy treatment of cervical cancer. Twenty patients with locally advanced cervical cancer were selected for brachytherapy using Rotterdam applicators. The patients were CT scanned twice with empty and full bladder. Two treatment plans were prepared on each of the image sets. Patients were categorized into two groups; those treated with a tandem length of 4 cm or smaller (T ≤ 4 cm) and those with tandem length larger than 4 cm (T > 4 cm). Only one tandem tip angle of 30° was studied. Dose-volume histograms (DVHs) of OARs were calculated and compared. Bladder dose was significantly affected by both bladder volume and tandem physical length for T ≤ 4 cm. This was reflected on the values obtained for D2cm³, D1cm³, and D0.1cm³ for both empty and full bladder cases. When T > 4 cm, no correlation could be establis...
Journal of Contemporary Brachytherapy, 2017
Purpose: The aim of this study is to compare 3D dose volume histogram (DVH) parameters of bladder and other organs at risk with different bladder filling protocol during high-dose-rate intracavitary brachytherapy (HDR-ICBT) in cervical cancer, and to find optimized bladder volume. Material and methods: This dosimetric study was completed with 21 patients who underwent HDR-ICBT with computed tomography/magnetic resonance compatible applicator as a routine treatment. Computed tomography planning was done for each patient with bladder emptied (series 1), after 50 ml (series 2), and 100 ml (series 3) bladder filling with a saline infusion through the bladder catheter. Contouring was done on the Eclipse Planning System. 7 Gy to point A was prescribed with the standard loading patterns. Various 3D DVH parameters including 0.1 cc, 1 cc, 2 cc doses and mean doses to the OAR's were noted. Paired t-test was performed. Results: The mean (± SD) bladder volume was 64.5 (± 25) cc, 116.2 (± 28) cc, and 172.9 (± 29) cc, for series 1, 2, and 3, respectively. The 0.1 cm 3 ,1 cm 3 , 2 cm 3 mean bladder doses for series 1, series 2, and series 3 were 9.
International Journal of Radiation Oncology*Biology*Physics, 2008
Purpose: To investigate the effect of bladder filling on dosimetry and to determine the best bladder dosimetric parameter for vaginal cuff brachytherapy. Methods and Materials: In this prospective clinical trial, a total of 20 women underwent vaginal cylinder highdose-rate brachytherapy. The bladder was full for Fraction 2 and empty for Fraction 3. Dose-volume histogram and dose-surface histogram values were generated for the bladder, rectum, and urethra. The midline maximal bladder point (MBP) and the midline maximal rectal point were recorded. Paired t tests, Pearson correlations, and regression analyses were performed. Results: The volume and surface area of the irradiated bladder were significantly smaller when the bladder was empty than when full. Of the several dose-volume histogram and dose-surface histogram parameters evaluated, the bladder maximal dose received by 2 cm 3 of tissue, volume of bladder receiving 5050% of the dose, volume of bladder receiving 5070% of the dose, and surface area of bladder receiving 5050% of the dose significantly predicted for the difference between the empty vs. full filling state. The volume of bladder receiving 5070% of the dose and the maximal dose received by 2 cm 3 of tissue correlated significantly with the MBP. Bladder filling did not alter the volume or surface area of the rectum irradiated. However, an empty bladder did result in the nearest point of bowel being significantly closer to the vaginal cylinder than when the bladder was full. Conclusions: Patients undergoing vaginal cuff brachytherapy treated with an empty bladder have a lower bladder dose than those treated with a full bladder. The MBP correlated well with the volumetric assessments of bladder dose and provided a noninvasive method for reporting the MBP dose using three-dimensional imaging. The MBP can therefore be used as a surrogate for complex dosimetry in the clinic. Ó 2008 Elsevier Inc.
Journal of Contemporary Brachytherapy, 2013
Purpose: Distension and shape of urinary bladder may vary during intracavitary brachytherapy (ICBT) for cervical cancer, significantly affecting doses to bladder, rectum , sigmoid colon and small intestine and consequently late radiation toxicities. This study is to evaluate the effects of different fixed volume bladder distention on dosimetry, assessed by three dimensional image based planning, in different organs at risk during the treatment of cervical cancer with ICBT. Material and methods: Forty seven cervical cancer patients (stage IB to IVA) were qualified for ICBT following external beam radiotherapy. Urinary bladder was distended with different volumes of normal saline instilled by a Foley's catheter. Planning CT scans were performed after insertion of applicators and three dimensional treatment planning was done on Brachyvision ® treatment planning system (Varian Medical Systems, Palo Alto, CA). Dose volume histograms were analyzed. Bladder, rectum, sigmoid colon and small intestine doses were collected for individual plans and compared, based on the amount of bladder filling. Results: Mean dose to the bladder significantly decreased with increased bladder filling. However, doses to the small volumes (0.1 cc, 1 cc, 2 cc) which are relevant for brachytherapy, did not change significantly with bladder filling for bladder, rectum or sigmoid colon. Nevertheless, all dose values of small intestine are decreased significantly with bladder filling. Conclusions: Bladder distension has no significant effect on doses received during brachytherapy by relevant volumes of bladder, rectum and sigmoid colon except intestine where values are decreased with bladder distension. A larger study with clinical correlation of late toxicities is essential for proper evaluation of this strategy.
International Journal of Gynecological Cancer, 2014
The objectives of the study were to assess the bladder doses during vaginal cuff brachytherapy and to examine the effect of bladder filling on normal tissue dosimetry by means of computed tomography. Materials and Methods: A total number of 45 women were enrolled in a prospective clinical trial. Patients were treated with the application of a single-line source vaginal cylinder. All the patients were asked to consume 400 mL of water 40 minutes before computed tomography scans were taken. For each patient, 2 treatment plans were performedVone with full bladder and the other one when the bladder was emptied. A dose-volume histogram and the equivalent of 2-Gy dose for full and empty bladder were calculated. Doses to the bowels in 2 states of the bladder were estimated. Results: Thirty-five patients received a lower dose to the empty bladder than to the filled organ. The average dose difference was 0.5 Gy. Ten patients received a lower dose to the full bladder than to the empty one. However, in this case, the difference amounted only to 0.2 Gy on average. Dose parameters (the maximal dose received by 0.1 cm 3 of tissue and the maximal dose received by 2 cm 3 of tissue) were lower in the empty state, but the volumetric parameters (the percent of bladder volume receiving Q50% of the prescribed dose and the percent of bladder volume receiving Q80% of the prescribed dose) were higher in the empty state of the bladder. Doses to the bowels seemed to be higher in the empty bladder. However, none of the doses exceeded the limitations. Conclusions: The results have shown that in most cases, the dose to the empty bladder is lower than when the bladder is full. Simultaneously, the doses to the bowels increase proportionally in the empty state of the bladder comparing to the full organ. Protection of the bowels, which are more radiosensitive, suggests treating the patients in the full state of the bladder. Early and late bowel toxicity should be investigated to establish clear standards of treatment.
International Journal of Radiation Oncology*Biology*Physics, 2008
Purpose: To quantify the effect of bladder volume on the dose distribution during intracavitary brachytherapy for cervical cancer. Methods and Patients: The study was performed on 10 women with cervical cancer who underwent brachytherapy treatment. After insertion of the brachytherapy applicator, the patients were transferred to the computed tomography unit. Two sets of computed tomography slices were taken, including the pelvis, one with an empty bladder and one after the bladder was filled with saline. The target and critical organs were delineated by the radiation oncologist and checked by the expert radiologist. The radiotherapy plan was run on the Plato planning system, version 14.1, to determine the dose distributions, dose-volume histograms, and maximal dose points. The doses and organ volumes were compared with the Wilcoxon signed ranks test on a personal computer using the Statistical Package for Social Sciences, version 11.0, statistical program. Results: No significant difference regarding the dose distribution and target volumes between an empty or full bladder was observed. Bladder fullness significantly affected the dose to the small intestine, rectum, and bladder. The median of maximal doses to the small intestine was significantly greater with an empty bladder (493 vs. 284 cGy). Although dosimetry revealed lower doses for larger volumes of bladder, the median maximal dose to the bladder was significantly greater with a full bladder (993 vs. 925 cGy). The rectal doses were also affected by bladder distension. The median maximal dose was significantly lower in the distended bladder (481vs. 628 cGy). Conclusions: Bladder fullness changed the dose distributions to the bladder, rectum, and small intestine. The clinical importance of these changes is not known and an increase in the use of three-dimensional brachytherapy planning will highlight the answer to this question. Ó 2008 Elsevier Inc.
Journal of Contemporary Brachytherapy, 2015
Purpose: High-dose-rate brachytherapy (HDR-BT) alone is an adjuvant treatment option for stage I intermediaterisk endometrial cancer after complete surgical resection. The aim of this study was to determine the value of the dose reported to ICRU bladder point in predicting acute urinary toxicity. Oncologic results are also presented. Material and methods: One hundred twenty-six patients were treated with postoperative HDR-BT 24 Gy (4 × 6 Gy) per ICRU guidelines for dose reporting. Cox analysis was used to identify variables that affected local control. The mean bladder point dose was examined for its ability to predict acute urinary toxicity. Results: Two patients (1.6%) developed grade 1 gastrointestinal toxicity and 12 patients (9.5%) developed grades 1-2 urinary toxicity. No grade 3 or greater toxicity was observed. The mean bladder point dose was 46.9% (11.256 Gy) and 49.8% (11.952 Gy) for the asymptomatic and symptomatic groups, respectively (p = 0.69). After a median follow-up of 36.8 months, the 3-year local failure and 5-year cancer-specific and overall survival rates were 2.1%, 100%, and 94.6%, respectively. No pelvic failure was seen in this cohort. Age over 60 years (p = 0.48), lymphatic invasion (p = 0.77), FIGO histological grade (p = 0.76), isthmus invasion (p = 0.68), and applicator type (cylinder × ovoid) (p = 0.82) did not significantly affect local control. Conclusions: In this retrospective study, ICRU bladder point did not correlate with urinary toxicity. Four fractions of 6 Gy HDR-BT effected satisfactory local control, with acceptable urinary and gastrointestinal toxicity.
Journal of Contemporary Brachytherapy
Purpose: Interstitial brachytherapy (ISBT) is often used as post-external beam radiotherapy (EBRT) to treat locally advanced gynecological malignancies. Female urethra is in close proximity to the target during ISBT. However, it has not been evaluated as an organ-at-risk (OAR). Overlapping symptoms caused by radiation-induced bladder toxicity vs. urethral toxicity make it difficult to identify and report urethral toxicities separately. This was a retrospective study to estimate dose-volume parameters of female urethra during high-dose-rate ISBT. Material and methods: Data of 24 patients with gynecological malignancies treated by ISBT were selected. Urethra and periurethral regions were retrospectively contoured. Mean volume, D max , D mean , D 2cc , D 1cc , D 0.5cc , D 0.2cc , and D 0.1cc were documented. Unpaired t-test was used for comparison of means. Results: 20/24 Ca. cervix, 1/24 Ca. vagina, and 3/24 Ca. vaginal vault received 6-6.5 Gy in 4 ISBT fractions. Mean urethral length was 3.54 ±0.55 cm. Mean doses received by urethra per BT fraction were D max = 4.23 ±1.32 Gy, D mean = 2.71 ±1.01 Gy, D 0.2cc = 3.31 ±1.07, and D 0.1cc = 3.54 ±1.09 Gy. Comparison of total BT 2 Gy equivalent dose (EQD 2) with 4 fractions for urethra between patients with (9/24) and without anterior vaginal wall (15/24) involvement included D mean