Comparison between the ICRU rectal point and modern volumetric parameters in brachytherapy for locally advanced cervical cancer (original) (raw)
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Asian Pacific Journal of Cancer Prevention, 2014
Background: Dosimetric comparison of two dimensional (2D) radiography and three-dimensional computed tomography (3D-CT) based dose distributions with high-dose-rate (HDR) intracavitry radiotherapy (ICRT) for carcinoma cervix, in terms of target coverage and doses to bladder and rectum. Materials and Methods: Sixty four sessions of HDR ICRT were performed in 22 patients. External beam radiotherapy to pelvis at a dose of 50 Gray in 27 fractions followed by HDR ICRT, 21 Grays to point A in 3 sessions, one week apart was planned. All patients underwent 2D-orthogonal and 3D-CT simulation for each session. Treatment plans were generated using 2D-orthogonal images and dose prescription was made at point A. 3D plans were generated using 3D-CT images after delineating target volume and organs at risk. Comparative evaluation of 2D and 3D treatment planning was made for each session in terms of target coverage (dose received by 90%, 95% and 100% of the target volume: D90, D95 and D100 respectively) and doses to bladder and rectum: ICRU-38 bladder and rectum point dose in 2D planning and dose to 0.1cc, 1cc, 2cc, 5cc, and 10cc of bladder and rectum in 3D planning. Results: Mean doses received by 100% and 90% of the target volume were 4.24±0.63 and 4.9±0.56 Gy respectively. Doses received by 0.1cc, 1cc and 2cc volume of bladder were 2.88±0.72, 2.5±0.65 and 2.2±0.57 times more than the ICRU bladder reference point. Similarly, doses received by 0.1cc, 1cc and 2cc of rectum were 1.80±0.5, 1.48±0.41 and 1.35±0.37 times higher than ICRU rectal reference point. Conclusions: Dosimetric comparative evaluation of 2D and 3D CT based treatment planning for the same brachytherapy session demonstrates underestimation of OAR doses and overestimation of target coverage in 2D treatment planning.
Asian Pacific Journal of Cancer Care
Purpose: Dosimetric analysis and effect of different definitions of prescription point “A” to OAR in high dose rate brachytherapy for cervical cancer. Methods and Materials: This retrospective comparative dosimetric study is based on the data of 25 patients with histologically proven cervical carcinoma treated with HDR (high-dose-rate) brachytherapy. Patients received 21 Gy in three fractions (7.0 Gy X three fractions) to point A (AMAN, revised Manchester definition). Further, the patients were replanned with the new point A (AABS) as per the American Brachytherapy Society/ICRU 89 which is defined on CT images. The data compiled was then compared with the data observed from point A (AMAN). Results: When AMAN normalization method was used, the mean dose to the bladder at 0.1cc, 1cc, 2cc and 5cc obtained was 1121.2±54.5, 1058.7±44.1, 875.0±38.6, 780.5±35.9, and 641.2±29.5 cGy respectively. Likewise, using the ICRU-89 point A (ABS) normalization method, the mean dose to 0.1 cc, 0.2 cc,...
Asian Pacific Journal of Cancer Care
Background: Present study compares two high-dose-rate intracavitary brachytherapy (ICBT) planning methods using two-dimensional orthogonal radiography and three-dimensional computed tomography (3D-CT) with regard to dose to target volume and organs at risk (OAR) in carcinoma cervix. Methodology: ICBT plans for 22-patients were compared using 2D planning and three-dimensional computed tomography (3D-CT) planning techniques. 2D treatment plans were generated using 2D-orthogonal images and dose was prescribed at Point A while 3D-CT plans were generated using 3D-CT images after contouring target volume and organs at risk. In 2D planning rectal and bladder doses were assessed as per ICRU-38 and in 3D planning, 0.1cc, 0.2cc, 0.5cc and 1cc doses of bladder and rectum were evaluated. Doses to target and organ at risks (rectum and bladder) were compared for each planning method. Results: Mean dose received by D90, D95 and D100 was 8.05±1.59Gy, 7.19±1.43Gy and 4.79±0.93Gy respectively. ICRU b...
Radiotherapy and Oncology, 2015
To establish dose-volume effect correlations for late bladder and rectum side effects in patients treated for locally advanced cervical cancer with concomitant chemoradiation followed by pulsed-dose rate image-guided adaptive brachytherapy. Material and methods: The dosimetric data, converted in 2 Gy equivalent, from 217 patients were confronted to late morbidity defined as any event lasting or occurring 90 days after treatment initiation. Toxicity was assessed using the CTC-AE 3.0. Probit analyses and Log rank tests were performed to assess relationships. Results: One hundred and sixty-one urinary and 58 rectal events were reported, affecting 98 (45.1%) and 51 (23.5%) patients, respectively. Cumulative incidences for grade 2-4 bladder and rectal morbidity were 24.3% and 9.6% at 3 years, respectively. Significant relationships were observed between grade 2-4 and 3-4 events and D0.1 cm 3 and D2 cm 3 for the bladder and between grade 1-4 and 2-4 event probability and rectal D2 cm 3. The effective doses for 10% grade 2-4 morbidity were 65.3 Gy (59.8-81.3), and 55.4 Gy (15.7-63.6), respectively, for the rectum and bladder. Without considering urinary and rectal incontinence, for which the pertinence of correlating them with D2 cm 3 is questionable, ED10 were 68.5 Gy (62.9-110.6) and 65.5 Gy (51.4-71.6 Gy). When sorting patients according to D2 cm 3 levels, patients with high D2 cm 3 had significantly lower morbidity free survival rates for grade 1-4 and 2-4 urinary and rectal morbidity. Conclusion: Significant dose-volume effect relationships were demonstrated between the modern dosimetric parameters and the occurrence of late rectal and urinary morbidity in patients treated with pulsed-dose-rate brachytherapy. Further studies are required to refine these relationships according to clinical cofactors, such as comorbidities.
Srpski arhiv za celokupno lekarstvo, 2017
Introduction/Objective. The aim of this study was to dosimetric comparison of two-dimensional (2D) with three-dimensional (3D) planning for high-dose-rate intracavitary brachytherapy (HDR-BT) in locally advanced cervical cancer by dose evaluation in given International Commission on Radiation Units and Measurements (ICRU) reference points, as well as in target volume and organs at risk (OAR). Methods. 66 sessions of HDR-BT were performed in 22 patients, with 3D planning, but also virtual 2D plan for dosimetric comparison was made. 2D planning was performed on radiography obtained by C-arm in ICRU points, while 3D planning in volumes delineated on computer tomography. Results. The comparative analysis has indicated a significant mean dose difference of point ?A? left (p=0.00014) and right (p=0.003), through higher doses in 2D and lower doses in 3D reconstructed points "A". According to the dose volume histograms 56.88% and 61.41% mean target volume received 100% and 90% of ...
Journal of Contemporary Brachytherapy
Purpose: Brachytherapy (BRT) is a cornerstone in cervical cancer treatment, with the ultimate goal to maximize the tumor dose while sparing organs at risk (OARs), such as rectum. Several studies evaluated the effect of rectal volume on rectal doses, but the results are inconsistent. This study aimed to evaluate the rectal volume and dose-volume histogram (DVH) relationship in high-dose-rate (HDR) brachytherapy in locally advanced cervical cancer. Material and methods: Planning computed tomography of 65 patients who underwent HDR brachytherapy boost as a component of definitive radiotherapy from March 2016 to February 2018 were reviewed. OARs and target volume were re-delineated by a single physician to decrease interobserver variation. Two sets of plan were generated; in the first set, the dose was prescribed to point A with Manchester system loading pattern, while in the second set, the dose was prescribed to high-risk clinical target volume (HR-CTV) D 90 with inverse planning optimization. The DVH values for rectum, sigmoid, and HR-CTV were generated and correlated with rectal or sigmoidal volume variation. Results: Dose to 2cc (D 2cc), 1cc (D 1cc), and 0.1cc (D 0.1cc) of rectum and sigmoid showed a significant decrease in optimization vs. point A planning (p < 0.0001). HR-CTV D 90 coverage was significantly higher in optimization vs. point A planning (p = 0.041). Rectal volume showed a significant correlation with D 2cc (rs, 0.302, p = 0.014), D 1cc (rs, 0.310, p = 0.012), and D 0.1cc (rs, 0.283, p = 0.02) of rectum in optimization planning. Conclusions: Larger rectal volumes are associated with higher rectal dose parameters during HDR brachytherapy using inverse planning optimization. This method spares OAR, while producing reasonable HR-CTV D 90. Prospective studies are needed to find appropriate technique of rectal volume reduction.
2017
CT-imaging based planning in intracavitary brachytherapy allows optimization of the dose distribution by patient basis. In addition to classical used point dose, the dose-volume histogram (DVH) analysis enables further possibilities for prescribing and reporting the correct dose. A group of 18 patients were treated with 38 fractions using different applicators and CT-based treatment planning. Each application was analyzed in detail. The clinical target volumes were contoured and also the organs at risk. The dose administered to bladder and rectum was analyzed according to ICRU Reports 38 and dose-volume parameters (e.g. D2cc represents the minimal dose for the most irradiated 2 cm). The values of the doses were analyzed including the external beam radiotherapy. Total doses were biologically normalized to conventional 2 Gy fractions (α/β = 10 Gy for target and 3 Gy for organs at risk). Individual changes for active dwell positions and dwell weights are guided by a concept of DVH cons...
Influence of brachytherapy applicators geometry on dose distribution in cervical cancer
Strahlentherapie und Onkologie, 1997
Aim: Although the relationship between the dose delivered to adjacent organs (urinary bladder and rectum) and the frequency and severity of treatment complications has been reported in many series, the factors influencing pelvic dose distribution ate not welt defined. The aim of the study was to assess retrospectively the influence of the size of cervical cancer brachytherapy applicators (ovoids and uterine tandems) on pelvic dose distribution and the impact of various therapy-dependent factors on patient anatomy and on dose distribution in particular applications. Patients and Method: The subject of this study were 356 cervical cancer patients treated with Selectron LDR as a part of their radical radiotherapy. Analysed factors included preceding external beam radiotherapy (EBRT) or brachytherapy applications, use of general anaesthesia for application and the system of pellet loading. Results: Significant correlation was found between the size of applicators and doses to bladder, rectum and points B: larger vaginal applicators produced lower dose in bladder and rectum and higher dose in point B (all p < 0.0001), longer uterine tandems produced lower dose in rectum and higher dose in point B (both p < 0.0001). Significant decrease in the frequency of use of large applicators (ovoids: p < 0.0001, tandems: p = 0.055) and worsening of dose distribution, i.e. higher doses to critical organs (respectively: bladder p = 0.0012, rectum p = 0.02) and lower point B dose (p = 0,0001) were observed at consecutive brachytherapy applications. Similar situation occurred in patients, who received EBRT prior to brachytherapy (ovoids: p < 0.001, tandem: p = 0.04, bladder dose: p=0.009, rectal dose: p=0.073, point B dose: p=0.059). Vaginal applicators were larger (p = 0.026) and the dose distribution was better (bladder: p = 0.023, rectum: p = 0.002, point B: p = 0.0001) in patients who had their insertions performed under general anaesthesia. The comparison of 2 consecutively used systems of pellet loading revealed more favourable dose distribution: lower dose for bladder (p = 0.014) and higher dose for point B (p < 0.0001) for the system, which utilised more sources in ovoids and in the distal part of the uterine tandem, in spite of more frequent use of smaller applicators in this group of patients. In multivariate analysis ovoid size was related to preceding external beam radiotherapy (p = 0.025). Uterine tandem length was dependent on the number of preceding intracavitary applications (p < 0.001) and preceding external beam radiotherapy (p = 0.007). Bladder dose was related to preceding brachytherapy (p = 0.011) and the pattern of pellet loading (p =0.031). Rectal dose was dependent only on the use of general anaesthesia during application (p = 0.001) and point B dose was dependent on the pattern of pellet loading (p < 0.001) and marginally -on the use of preceding external beato radiotherapy (p = 0.06), Conelusions: The results of this study allow for identification of treatment-related factors determining pelvic dose distribution in cervical cancer brachytherapy and may potentially enable optimisation of this distribution in particular clinical situation.