Initial clinical assessment of "center-specific" automated treatment plans for low-dose-rate prostate brachytherapy (original) (raw)
Related papers
Medical Dosimetry, 2012
Advances in brachytherapy treatment planning systems have allowed the opportunity for brachytherapy to be planned intraoperatively as well as preoperatively. The relative advantages and disadvantages of each approach have been the subject of extensive debate, and some contend that the intraoperative approach is vital to the delivery of optimal therapy. The purpose of this study was to determine whether high-quality permanent prostate implants can be consistently achieved using a preoperative planning approach that allows for, but does not necessitate, intraoperative optimization. To achieve this purpose, we reviewed the records of 100 men with intermediate-risk prostate cancer who had been prospectively treated with brachytherapy monotherapy between 2006 and 2009 at our institution. All patients were treated with iodine-125 stranded seeds; the planned target dose was 145 Gy. Only 8 patients required adjustments to the plan on the basis of intraoperative findings. Consistency and quality were assessed by calculating the correlation coefficient between the planned and implanted amounts of radioactivity and by examining the mean values of the dosimetric parameters obtained on preoperative and 30 days postoperative treatment planning. The amount of radioactivity implanted was essentially identical to that planned (mean planned radioactivity, 41.27 U vs. mean delivered radioactivity, 41.36 U; R 2 = 0.99). The mean planned and day 30 prostate V100 values were 99.9% and 98.6%, respectively. The mean planned and day 30 prostate D90 values were 186.3 Gy and 185.1 Gy, respectively. Consistent, high-quality prostate brachytherapy treatment plans can be achieved using a preoperative planning approach, mostly without the need for intraoperative optimization. Good quality assurance measures during simulation, treatment planning, implantation, and postimplant evaluation are paramount for achieving a high level of quality and consistency.
Radiation Oncology, 2012
Background: Low risk prostate cancers are commonly treated with low dose rate (LDR) brachytherapy involving I-125 seeds. The implementation of a 'live-planning' technique at the Royal Adelaide Hospital (RAH) in 2007 enabled the completion of the whole procedure (i.e. scanning, planning and implant) in one sitting. 'Live-planning' has the advantage of a more reliable delivery of the planned treatment compared to the 'traditional pre-plan' technique (where patient is scanned and planned in the weeks prior to implant). During live planning, the actual implanted needle positions are updated real-time on the treatment planning system and the dosimetry is automatically recalculated. The aim of this investigation was to assess the differences and clinical relevance between the planned dosimetry and the updated real-time implant dosimetry. Methods: A number of 162 patients were included in this dosimetric study. A paired t-test was performed on the D90, V100, V150 and V200 target parameters and the differences between the planned and implanted dose distributions were analysed. Similarly, dosimetric differences for the organs at risk (OAR) were also evaluated. Results: Small differences between the primary dosimetric parameters for the target were found. Still, the incidence of hotspots was increased with approximately 20% for V200. Statistically significant increases were observed in the doses delivered to the OAR between the planned and implanted data; however, these increases were consistently below 3% thus probably without clinical consequences.
Brachytherapy, 2011
Purpose: To perform a dosimetric comparison between a pre-planned technique and a pre-plan based intraoperative technique in prostate cancer patients treated with I-125 permanent seed implantation. Material and methods: Thirty patients were treated with I-125 permanent seed implantation using TRUS guidance. The first 15 of these patients (Arm A) were treated with a pre-planned technique using ultrasound images acquired prior to seed implantation. To evaluate the reproducibility of the prostate volume, ultrasound images were also acquired during the procedure in the operating room (OR). A surface registration was applied to determine the 6D offset between different image sets in arm A. The remaining 15 patients (Arm B) were planned by putting the pre-plan on the intraope rative ultrasound image and then re-optimizing the seed locations with minimal changes to the pre-plan needle locations. Post implant dosimetric analyses included comparisons of V 100 (prostate), D 90 (prostate) and V 100 (rectum). Results: In Arm A, the 6D offsets between the two image sets were θ x =-1.4 ± 4.3; θ y =-1.7 ± 2.6; θ z =-0.5 ± 2.6; X = 0.5 ± 1.8 mm; Y =-1.3 ±-3.5 mm; Z =-1.6 ± 2.2 mm. These differences alone degraded V 100 by 6.4% and D 90 by 9.3% in the pre-plan, respectively. Comparing Arm A with Arm B, the pre-plan based intraoperative optimization of seed locations used in the plans for patients in Arm B improved the V 100 and D 90 in their post-implant studies by 4.0% and 5.7%, respectively. This was achieved without significantly increasing the rectal dose (V 100 (rectum)). Conclusions: We have progressively moved prostate seed implantation from a pre-planned technique to a pre-plan based intraoperative technique. In addition to reserving the advantage of cost-effective seed ordering and efficient OR implantation, our intraoperative technique demonstrates increased accuracy and precision compared to the pre-planned technique.
International Journal of Radiation Oncology*Biology*Physics, 2001
Purpose: The preplanned technique used for permanent prostate brachytherapy has limitations that may be overcome by intraoperative planning. The goal of the American Brachytherapy Society (ABS) project was to assess the current intraoperative planning process and explore the potential for improvement in intraoperative treatment planning (ITP). Methods and Materials: Members of the ABS with expertise in ITP performed a literature review, reviewed their clinical experience with ITP, and explored the potential for improving the technique. Results: The ABS proposes the following terminology in regard to prostate planning process:
Concurrent treatment planning for outpatient high dose rate prostate template implants
International Journal of Radiation Oncology Biology Physics, 1993
Purpose: Since November of 1991, we have treated locally advanced (B2-C) prostate cancer using external beam radiotherapy integrated with outpatient high dose rate interstitial implant boost as part of a Phase II clinical trial. This required (a) rapid, automated planning; (b) incorporation of image data and (c) dose optimization. Methods and Materials: A treatment planning system was designed which integrates imaging and needle guidance with source reconstruction and dose display. All components of treatment planning (reconstruction, optimization, dose prescription, dose display) are largely automated. A rectal reference point was defined which was reproducible and easily verified. No pretreatment planning was required. Results: As of November 1992,83 treatments were delivered using this system. Intra-operative treatment decisions were made possible due to the speed and ease of interpretation of the system. The system has proven satisfactory in the operating room. Rectal doses were calculated for all patients, and ranged from 3579% of the prescribed dose, with a mean of 58%. The first echelon of a Phase II escalating dose trial has been completed, with 22 patients treated over a period of 1 year. Conclusion: Outpatient high dose rate brachytherapy appears to be a practical means of boosting locally advanced prostate cancer patients. Rapid treatment planning is possible incorporating on-line ultrasound images to allow immediate dose optimization to be performed during and after implant placement.
Journal of Applied Clinical Medical Physics, 2005
Recently, various linear source models, for example, 103 Pd RadioCoil ™ , have been introduced to overcome the shortcomings of traditional "seed" type interstitial prostate brachytherapy implants, such as migration and clumping of the seeds. However, the existing prostate treatment-planning systems have not been updated to perform dose calculation for implants with linear sources greater than 1.0 cm in length. In these investigations, two new models are developed for 3D dose calculation for a prostate implant with linear brachytherapy sources using the commercially available treatment-planning systems. The proposed models are referred to as the linear-segmented source (LSS) model and the point-segmented source (PSS) model. The calculated dose distributions obtained by these models for a single linear source have been validated by their comparison with the Monte Carlo-simulated data. Moreover, these models were used to calculate the dose distributions for a multilinear source prostate implant, and the results were compared to "seed" type implants. The results of these investigations show that the LSS model better approximates the linear sources than the PSS model. Moreover, these models have shown a better approximation of the dose distribution from a linear source for 0.5 cm source segments as compared to 1.0 cm source segments. However, for the points close to the longitudinal axis of the source located outside the region bounded by the active length, both models show differences of approximately ±15%. These deficiencies are attributed to the limitations of the TG43 formalism for elongated sources.
Intraoperative optimized inverse planning for prostate brachytherapy: early experience
International Journal of Radiation Oncology*Biology*Physics, 1999
Purpose: To demonstrate the feasibility of an intraoperative inverse planning technique with advanced optimization for prostate seed implantation. Methods and Materials: We have implemented a method for optimized inverse planning of prostate seed implantation in the operating room (OR), based on the genetic algorithm (GA) driven Prostate Implant Planning Engine for Radiotherapy (PIPER). An integrated treatment planning system was deployed, which includes real-time ultrasound image acquisition, treatment volume segmentation, GA optimization, real-time decision making and sensitivity analysis, isodose and DVH evaluation, and virtual reality navigation and surgical guidance. Ten consecutive patients previously scheduled for implantation were included in the series. Results: The feasibility of the technique was established by careful monitoring of each step in the OR and comparison with conventional preplanned implants. The median elapsed time for complete image capture, segmentation, GA optimization, and plan evaluation was 4, 10, 2.2, and 2 min, respectively. The dosimetric quality of the OR-based plan was shown to be equivalent to the corresponding preplan. Conclusion: An intraoperative optimized inverse planning technique was developed for prostate brachytherapy. The feasibility of the method was demonstrated through an early clinical experience. © 1999 Elsevier Science Inc.
Inclusion of radiobiological factors in prostate brachytherapy treatment planning
Journal of Radiotherapy in Practice, 2013
Purpose: Comparison of prostate seed implant treatment plans is currently based on evaluation of dosevolume histograms and doses to the tumour and normal structures. However, these do not account for effects of varying dose-rate, tumour repopulation and other biological effects. In this work, incorporation of the radiobiological response is used to obtain a more inclusive and clinically relevant treatment plan evaluation tool.
Radiotherapy and Oncology, 2004
Background and purpose: The purposes of this multicentric study are (a) the evaluation of four different commercially available treatment planning systems (TPSs) and (b) to verify whether the dosimetric results are comparable, also when considering the inter-observer variabilities and the different scanning protocols used. This work is to be considered a first step to test the value of multicentric studies based on dosimetric evaluation of the quality of the implants.
Brachytherapy
The aim was to evaluate a postprocessing optimization algorithm's ability to improve the spatial properties of a clinical treatment plan while preserving the target coverage and the dose to the organs at risk. The goal was to obtain a more homogenous treatment plan, minimizing the need for manual adjustments after inverse treatment planning. MATERIALS AND METHODS: The study included 25 previously treated prostate cancer patients. The treatment plans were evaluated on dose-volume histogram parameters established clinical and quantitative measures of the high dose volumes. The volumes of the four largest hot spots were compared and complemented with a human observer study with visual grading by eight oncologists. Statistical analysis was done using ordinal logistic regression. Weighted kappa and Fleiss' kappa were used to evaluate intra-and interobserver reliability. RESULTS: The quantitative analysis showed that there was no change in planning target volume (PTV) coverage and dose to the rectum. There were significant improvements for the adjusted treatment plan in: V150% and V200% for PTV, dose to urethra, conformal index, and dose nonhomogeneity ratio. The three largest hot spots for the adjusted treatment plan were significantly smaller compared to the clinical treatment plan. The observers preferred the adjusted treatment plan in 132 cases and the clinical in 83 cases. The observers preferred the adjusted treatment plan on homogeneity and organs at risk but preferred the clinical plan on PTV coverage. CONCLUSIONS: Quantitative analysis showed that the postadjustment optimization tool could improve the spatial properties of the treatment plans while maintaining the target coverage.