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Jeremy Millar - One of the best experts on this subject based on the ideXlab platform.
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high dose rate Brachytherapy in combination with conformal external beam radiotherapy in the treatment of prostate cancer
Brachytherapy, 2010Co-Authors: Daniel R Zwahlen, N Andrianopoulos, Bronwyn Matheson, Gillian M Duchesne, Jeremy MillarAbstract:Abstract Purpose To report long-term outcomes for treatment of prostate cancer using dose escalation with high-dose-rate (HDR) Brachytherapy and 3-dimensional conformal external beam radiotherapy (3DCRT), and compare them with outcomes for treatment of prostate cancer with 3DCRT alone at the same institution. Methods and Materials From 1998 to 2003, 587 patients were treated for clinically localized prostate cancer. Patients received either 3DCRT (median, 46 Gy) with a single HDR Brachytherapy Implant (196 patients) delivering a fractionated dose of 18 Gy (combined group) or 3DCRT (median, 70 Gy; 387 patients; “3DCRT alone”). There were 41.9% patients with intermediate-risk and 42.6% with high-risk disease. In all, 441 patients (75.1%) received neoadjuvant and 116 patients (19.8%) received adjuvant androgen deprivation therapy. The American Society of Therapeutic Radiology and Oncology Phoenix definition for biochemical failure was used. Results The median followup was 5.5 years. The 5- and 7-year biochemical control (BC) rates were 82.5% and 80.3%, respectively, for the combined group and 81.3% and 71%, respectively, for 3DCRT alone; for overall survival, they were 91.9% and 89.5% vs. 88.7% and 86.2%, respectively, whereas for cause-specific survival, they were 96.9% and 96.1% vs. 97.6% and 96.2%, respectively. Cox proportional hazard regression analysis for BC revealed that low Gleason grade, HDR Brachytherapy combined with 3DCRT, and adjuvant androgen deprivation therapy were significant in predicting BC. Radiation Therapy Oncology Group Grade 3 late urinary and rectal morbidity rates were 7.1% and 0%, respectively. No Grade ≥4 reactions were detected. Conclusions HDR Brachytherapy combined with 3DCRT was associated with improved BC and minimal toxicity in patients with unfavorable prostate cancer compared with conventional 3DCRT.
Daniel R Zwahlen - One of the best experts on this subject based on the ideXlab platform.
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high dose rate Brachytherapy in combination with conformal external beam radiotherapy in the treatment of prostate cancer
Brachytherapy, 2010Co-Authors: Daniel R Zwahlen, N Andrianopoulos, Bronwyn Matheson, Gillian M Duchesne, Jeremy MillarAbstract:Abstract Purpose To report long-term outcomes for treatment of prostate cancer using dose escalation with high-dose-rate (HDR) Brachytherapy and 3-dimensional conformal external beam radiotherapy (3DCRT), and compare them with outcomes for treatment of prostate cancer with 3DCRT alone at the same institution. Methods and Materials From 1998 to 2003, 587 patients were treated for clinically localized prostate cancer. Patients received either 3DCRT (median, 46 Gy) with a single HDR Brachytherapy Implant (196 patients) delivering a fractionated dose of 18 Gy (combined group) or 3DCRT (median, 70 Gy; 387 patients; “3DCRT alone”). There were 41.9% patients with intermediate-risk and 42.6% with high-risk disease. In all, 441 patients (75.1%) received neoadjuvant and 116 patients (19.8%) received adjuvant androgen deprivation therapy. The American Society of Therapeutic Radiology and Oncology Phoenix definition for biochemical failure was used. Results The median followup was 5.5 years. The 5- and 7-year biochemical control (BC) rates were 82.5% and 80.3%, respectively, for the combined group and 81.3% and 71%, respectively, for 3DCRT alone; for overall survival, they were 91.9% and 89.5% vs. 88.7% and 86.2%, respectively, whereas for cause-specific survival, they were 96.9% and 96.1% vs. 97.6% and 96.2%, respectively. Cox proportional hazard regression analysis for BC revealed that low Gleason grade, HDR Brachytherapy combined with 3DCRT, and adjuvant androgen deprivation therapy were significant in predicting BC. Radiation Therapy Oncology Group Grade 3 late urinary and rectal morbidity rates were 7.1% and 0%, respectively. No Grade ≥4 reactions were detected. Conclusions HDR Brachytherapy combined with 3DCRT was associated with improved BC and minimal toxicity in patients with unfavorable prostate cancer compared with conventional 3DCRT.
Woulfe Peter - One of the best experts on this subject based on the ideXlab platform.
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Optical fbre based real‑time measurements during an LDR prostate Brachytherapy Implant simulation: using a 3D printed anthropomorphic phantom
'Springer Science and Business Media LLC', 2021Co-Authors: Woulfe Peter, Byrne L., Doyle A. J., Kam W., Martyn Michael, O'sullivan F. J., O'keeffe S.Abstract:peer-reviewedAn optical fibre sensor based on radioluminescence, using the scintillation material terbium doped gadolinium oxysulphide (Gd2O2S:Tb) is evaluated, using a 3D printed anthropomorphic phantom for applications in low dose-rate (LDR) prostate Brachytherapy. The scintillation material is embedded in a 700 µm diameter cavity within a 1 mm plastic optical fibre that is fixed within a Brachytherapy needle. The high spatial resolution dosimeter is used to measure the dose contribution from Iodine-125 (I-125) seeds. Initially, the effects of sterilisation on the sensors (1) repeatability, (2) response as a function of angle, and (3) response as a function of distance, are evaluated in a custom polymethyl methacrylate phantom. Results obtained in this study demonstrate that the output response of the sensor, pre- and post-sterilisation are within the acceptable measurement uncertainty ranging from a maximum standard deviation of 4.7% pre and 5.5% post respectively, indicating that the low temperature sterilisation process does not damage the sensor or reduce performance. Subsequently, an LDR Brachytherapy plan reconstructed using the VariSeed treatment planning system, in an anthropomorphic 3D printed training phantom, was used to assess the suitability of the sensor for applications in LDR Brachytherapy. This phantom was printed based on patient anatomy, with the volume and dimensions of the prostate designed to represent that of the patient. I-125 Brachytherapy seeds, with an average activity of 0.410 mCi, were Implanted into the prostate phantom under transrectal ultrasound guidance; following the same techniques as employed in clinical practice by an experienced radiation oncologist. This work has demonstrated that this sensor is capable of accurately identifying when radioactive I-125 sources are introduced into the prostate via a Brachytherapy needl
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Optical fbre based real‑time measurements during an LDR prostate Brachytherapy Implant simulation: using a 3D printed anthropomorphic phantom
'The Nature Conservancy', 2021Co-Authors: Woulfe Peter, O\u27sullivan F. J., Byrne L., Doyle A. J., Kam W., Martyn Michael, O\u27keeffe S.Abstract:An optical fibre sensor based on radioluminescence, using the scintillation material terbium doped gadolinium oxysulphide (Gd2O2S:Tb) is evaluated, using a 3D printed anthropomorphic phantom for applications in low dose-rate (LDR) prostate Brachytherapy. The scintillation material is embedded in a 700 µm diameter cavity within a 1 mm plastic optical fibre that is fixed within a Brachytherapy needle. The high spatial resolution dosimeter is used to measure the dose contribution from Iodine-125 (I-125) seeds. Initially, the effects of sterilisation on the sensors (1) repeatability, (2) response as a function of angle, and (3) response as a function of distance, are evaluated in a custom polymethyl methacrylate phantom. Results obtained in this study demonstrate that the output response of the sensor, pre- and post-sterilisation are within the acceptable measurement uncertainty ranging from a maximum standard deviation of 4.7% pre and 5.5% post respectively, indicating that the low temperature sterilisation process does not damage the sensor or reduce performance. Subsequently, an LDR Brachytherapy plan reconstructed using the VariSeed treatment planning system, in an anthropomorphic 3D printed training phantom, was used to assess the suitability of the sensor for applications in LDR Brachytherapy. This phantom was printed based on patient anatomy, with the volume and dimensions of the prostate designed to represent that of the patient. I-125 Brachytherapy seeds, with an average activity of 0.410 mCi, were Implanted into the prostate phantom under transrectal ultrasound guidance; following the same techniques as employed in clinical practice by an experienced radiation oncologist. This work has demonstrated that this sensor is capable of accurately identifying when radioactive I-125 sources are introduced into the prostate via a Brachytherapy needl
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Machine Learning in Prediction of Prostate Brachytherapy Rectal Dose Classes at Day 30
Irish Pattern Recognition & Classification Society, 2018Co-Authors: Leydon Patrick, Sullivan Frank, Jamaluddin Faisal, Woulfe Peter, Greene Derek, Curran, Kathleen M.Abstract:The Irish Machine Vision and Image Processing Conference (IMVIP 2015), Dublin, Ireland, 26-28 August 2015A retrospective analysis of Brachytherapy Implant data was carried out on 351 patients that underwent permanent I125 Brachytherapy for treatment of low-risk prostate cancer. For each patient, the dose received by 2cm3 of the rectum (D2cc) 30 days post Implant was defined as belonging one of two classes, ”Low” and ”High” depending on whether or not it was above or below a particular dose threshold. The aim of the study was to investigate the application of a number of machine learning classification techniques to intra-operative Implant dosimetry data for prediction of rectal dose classes determined 30 days post Implant. Algorithm performance was assessed in terms of its true and false positive rates and Receiver Operator Curve area based on a 10-fold cross validation procedure using Weka software. This was repeated for a variety of dose class thresholds to determine the point at which the highest accuracy was achieved. The highest ROC areas were observed at a threshold of D2cc = 90 Gy, with the highest area achieved by Bayes Net (0.943). At more clinically useful thresholds of D2cc = 145 Gy, classification was less reliable, with the highest ROC area achieved by Bayes Net (0.613).Irish Research Counci
Gabor Fichtinger - One of the best experts on this subject based on the ideXlab platform.
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we c 330a 03 seed segmentation in c arm fluoroscopy for Brachytherapy Implant reconstruction
Medical Physics, 2006Co-Authors: S Vikal, Ameet Kumar Jain, Anton Deguet, Danny Y Song, Gabor FichtingerAbstract:Purpose: Intra‐operative dosimetry in prostate Brachytherapy critically depends on discerning the 3‐D locations of Implanted seeds. The accuracy of 3‐D seed reconstruction step is, in turn, limited by the accuracy with which the position and orientation of individual Implanted seed in the fluoroscopic images can be found. A method for robustly segmenting the seeds in fluoroscopic images is proposed here. Methods and Materials: The process of determining the locations and orientations of Implanted seeds is sub‐divided into three main steps. In the first step, the image is segmented by shape‐size based morphological approach to eliminate background noise and do away with non‐uniform brightness of the image, to get seed‐like regions. These regions are either single seeds or overlapping multiple seed clusters. In the second step, the regions are analyzed and classified definitively, in a two‐phase statistical process coupled with information extraction from original intensity image, into two classes: single seed and overlapping multiple seed cluster. In the third step, the region belonging to overlapping multiple seed cluster is resolved into its constituent individual seeds through a simple and novel technique. Results: The proposed algorithm was tested on a set of ten clinical fluoroscopic images. The algorithm correctly determines the seeds with overall average of 99.57%. The clusters are not correctly resolved only in two images (2 clusters each, 1.7% and 1.6% of total seeds in respective Implants). One false positive (noise labeled as seed) each is reported in two images, both the cases being where the tip of catheter appears to be of the size and shape of seed. Conclusions: The algorithm builds on an existing framework of morphological processing and provides further improvements in classification and cluster resolution. The algorithm appears to be robust and accurate despite the poor resolution of clinical images.
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incorporating seed orientation in Brachytherapy Implant reconstruction
Medical Imaging 2006: Visualization Image-Guided Procedures and Display, 2006Co-Authors: Yu Zhou, Ameet Kumar Jain, Gregory S Chirikjian, Gabor FichtingerAbstract:Intra-operative quality assurance and dosimetry optimization in prostate Brachytherapy critically depends on the ability of discerning the locations of Implanted seeds. Various methods exist for seed matching and reconstruction from multiple segmented C-arm images. Unfortunately, using three or more images makes the problem NP-hard, i.e. no polynomial-time algorithm can provably compute the complete matching. Typically, a statistical analysis of performance is considered sufficient. Hence it is of utmost importance to exploit all the available information in order to minimize the matching and reconstruction errors. Current algorithms use only the information about seed centers, disregarding the information about the orientations and length of seeds. While the latter has little dosimetric impact, it can positively contribute to improving seed matching rate and 3D Implant reconstruction accuracy. It can also become critical information when hidden and spuriously segmented seeds need to be matched, where reliable and generic methods are not yet available. Expecting orientation information to be useful in reconstructing large and dense Implants, we have developed a method which incorporates seed orientation information into our previously proposed reconstruction algorithm (MARSHAL). Simulation study shows that under normal segmentation errors, when considering seed orientations, Implants of 80 to 140 seeds with the density of 2.0- 3.0 seeds/cc give an average matching rate >97% using three-image matching. It is higher than the matching rate of about 96% when considering only seed positions. This means that the information of seed orientations appears to be a valuable additive to fluoroscopy-based Brachytherapy Implant reconstruction.
Thomas A Dipetrillo - One of the best experts on this subject based on the ideXlab platform.
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clinically evident fat necrosis in women treated with high dose rate Brachytherapy alone for early stage breast cancer
International Journal of Radiation Oncology Biology Physics, 2001Co-Authors: David E Wazer, David Lowther, Teresa Boyle, Kenneth Ulin, Andrew C Neuschatz, Robin Ruthazer, Thomas A DipetrilloAbstract:Abstract Purpose: To investigate the incidence of and variables associated with clinically evident fat necrosis in women treated on a protocol of high-dose-rate (HDR) Brachytherapy alone without external-beam whole-breast irradiation for early-stage breast carcinoma. Methods and Materials: From 6/1997 until 8/1999, 30 women diagnosed with Stage I or II breast carcinoma underwent surgical excision and postoperative irradiation via HDR Brachytherapy Implant as part of a multi-institutional clinical Phase I/II protocol. Patients eligible included those with T1, T2, N0, N1 (≤ 3 nodes positive), M0 tumors of nonlobular histology with negative surgical margins, no extracapsular lymph-node extension, and a negative postexcision mammogram. Brachytherapy catheters were placed at the initial excision, re-excision, or at the time of axillary sampling. Direct visualization, surgical clips, ultrasound, or CT scans assisted in delineating the target volume defined as the excision cavity plus 2-cm margin. High activity 192 Ir (3–10 Ci) was used to deliver 340 cGy per fraction, 2 fractions per day, for 5 consecutive days to a total dose of 34 Gy to the target volume. Source position and dwell times were calculated using standard volume optimization techniques. Dosimetric analyses were performed with three-dimensional postImplant dose and volume reconstructions. The median follow-up of all patients was 24 months (range, 12–36 months). Results: Eight patients (crude incidence of 27%) developed clinically evident fat necrosis postImplant in the treated breast. Fat necrosis was determined by clinical presentation including pain and swelling in the treated volume, computed tomography, and/or biopsy. All symptomatic patients (7 of 8 cases) were successfully treated with 3 to 12 months of conservative management. Continuous variables that were found to be associated significantly with fat necrosis included the number of source dwell positions ( p = 0.04), and the volume of tissue which received fractional doses of 340 cGy, 510 cGy, and 680 cGy ( p = 0.03, p=0.01, and p = 0.01, respectively). Other continuous variables including patient age, total excised tissue volume, tumor size, number of catheters, number of days the catheters were in place, planar separation, dose homogeneity index (DHI), and uniformity index (UI) were not significant. Discrete variables including the presence/absence of DCIS, sentinel versus full axillary nodal assessment, receptor status, presence/absence of diabetes, and the use of chemotherapy or hormone therapy were not found to have a significant association with the risk of fat necrosis. Conclusions: In this study of HDR Brachytherapy of the breast tumor excision cavity plus margin, treatment was planned and delivered in accordance with the dosimetric parameters of the protocol resulting in a high degree of target volume dose homogeneity. Nonetheless, at a median follow-up of 24 months, a high rate of clinically definable fat necrosis occurred. The overall Implant volume as reflected in the number of source dwell positions and the volume of breast tissue receiving fractional doses of 340, 510, and 680 cGy were significantly associated with fat necrosis. Future dosimetric optimization algorithms for HDR breast Brachytherapy will need to include these factors to minimize the risk of fat necrosis.