A multiple-image-based method to evaluate the performance of deformable image registration in the pelvis.

A multiple-image-based method to evaluate the performance of deformable image registration in the pelvis. Phys Med Biol. 2016 Jul 29;61(16):6172-6180 Authors: Saleh Z, Thor M, Apte AP, Sharp G, Tang X, Veeraraghavan H, Muren L, Deasy J Abstract Deformable image registration (DIR) is essential for adaptive radiotherapy (RT) for tumor sites subject to motion, changes in tumor volume, as well as changes in patient normal anatomy due to weight loss. Several methods have been published to evaluate DIR-related uncertainties but they are not widely adopted. The aim of this study was, therefore, to evaluate intra-patient DIR for two highly deformable organs-the bladder and the rectum-in prostate cancer RT using a quantitative metric based on multiple image registration, the distance discordance metric (DDM). Voxel-by-voxel DIR uncertainties of the bladder and rectum were evaluated using DDM on weekly CT scans of 38 subjects previously treated with RT for prostate cancer (six scans/subject). The DDM was obtained from group-wise B-spline registration of each patient's collection of repeat CT scans. For each structure, registration uncertainties were derived from DDM-related metrics. In addition, five other quantitative measures, including inverse consistency error (ICE), transitivity error (TE), Dice similarity (DSC) and volume ratios between corresponding structures from pre- and post- registered images were computed and compared with the DDM. The DDM varied acro...
Source: Physics in Medicine and Biology - Category: Physics Authors: Tags: Phys Med Biol Source Type: research

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Conclusions: Based on daily diagnostic quality CT imaging and voxel-wise dose accumulation, we demonstrated for the first time that daily, but not weekly imaging resulted in only negligible deviations of the applied from the planned doses for prostate intensity-modulated radiotherapy. Therefore, weekly imaging may not be adequately reliable for adaptive treatment delivery techniques for prostate. This work will contribute to devising adaptive re-planning strategies for prostate radiotherapy.
Source: Frontiers in Oncology - Category: Cancer & Oncology Source Type: research
Conclusions Several model systems are now available to characterize the MSC-tumour interplay in the TME. These offer early promise in establishing robust preclinical platforms for the identification of crucial molecular pathways and for the assessment of clinical efficacy of novel drugs to inhibit cancer development and progression. However, selection of the right model for a given study should be shaped on the purpose, and should also consider fixed biological, biochemical, and biophysical parameters according to the specific tumour type. Finally, in order to get reliable and useful results to be translated to the clinic...
Source: Frontiers in Oncology - Category: Cancer & Oncology Source Type: research
Abstract External beam radiation therapy for prostate cancer can result in urinary, sexual, and rectal side effects, often impairing quality of life. A polyethylene glycol-based product, SpaceOAR© hydrogel (SOH), implanted into the connective tissue between the prostate gland and rectum can significantly reduce the dose received by the rectum and hence risk of rectal toxicity. The optimal way to manage the hydrogel and rectal structures for plan optimization is therefore of interest. In 13 patients, computerized tomography (CT) scans were taken pre- and post-SpaceOAR© implant. A prescription of 60 G...
Source: Journal of Applied Clinical Medical Physics - Category: Physics Authors: Tags: J Appl Clin Med Phys Source Type: research
CONCLUSIONS: Variations in the bladder and rectal volume can significantly dislocate the prostate and OARs, which can negatively impact the dose delivered to these organs. This warrants proper preparation of patients during treatment and imaging sessions, especially when imaging required longer scan times such as MR protocols. PMID: 30821881 [PubMed - as supplied by publisher]
Source: Journal of Applied Clinical Medical Physics - Category: Physics Authors: Tags: J Appl Clin Med Phys Source Type: research
Abstract Machine learning for image segmentation could provide expedited clinic workflow and better standardization of contour delineation. We evaluated a new model using deep decision forests of image features in order to contour pelvic anatomy on treatment planning CTs. 193 CT scans from one UK and two US institutions for patients undergoing radiotherapy treatment for prostate cancer from 2012-2016 were anonymized. A decision forest autosegmentation model was trained on a random selection of 94 images from Institution 1 and tested on 99 scans from Institution 1, 2, and 3. The accuracy of model contours was measu...
Source: Physics in Medicine and Biology - Category: Physics Authors: Tags: Phys Med Biol Source Type: research
CONCLUSION: The planned dose escalation was not received by more than half-of-the patients. Robustness of the prostate target (CTV67.5) should therefore be better prioritized in these patients given the low toxicity profile. Estimates of delivered dose were less conservative for dose-accumulation due to interaction of random organ motion with the dose matrix. PMID: 29941300 [PubMed - as supplied by publisher]
Source: Radiotherapy and Oncology : journal of the European Society for Therapeutic Radiology and Oncology - Category: Radiology Authors: Tags: Radiother Oncol Source Type: research
This study's purpose is to develop and evaluate an automated method for adaptation of IMPT plans in near real-time to the anatomy of the day. We developed an automated treatment plan adaptation method using (1) a restoration of spot positions (Bragg peaks) by adapting the energies to the new water equivalent path lengths; and (2) a spot addition to fully cover the target of the day, followed by a fast Reference Point Method optimization of the spot weights resulting in a Pareto optimal plan for the daily anatomy. The method was developed and evaluated using 8-10 repeat CT scans of 11 prostate cancer patients, prescrib...
Source: Physics in Medicine and Biology - Category: Physics Authors: Tags: Phys Med Biol Source Type: research
1458Objectives: Physiological renal excretion of 68Ga labelled PSMA may complicate the assessment of pelvic region in prostate carcinoma, with prostatic lesion being obscured by the high radio tracer bladder activity. Thereby can lead to problems in differentiating the pelvic lymph nodes from ureteral activity and challenges in local invasion of prostate carcinoma into the surrounding structures (seminal vesicles, urinary bladder and rectum.The aim of this retrospective study was to assess the utility of diuretic 68Ga-PSMA PET/CT imaging in the loco-regional staging of locally advanced prostate carcinoma. Materials and met...
Source: Journal of Nuclear Medicine - Category: Nuclear Medicine Authors: Tags: Prostate Posters Source Type: research
Conclusions: Our deep learning based method for fast automated analysis of the prostate gland in PET/CT studies showed good agreement with manually obtained measurements and pathology-derived weight of the prostatectomy specimens suggesting that this approach may become a promising adjunct to quantitative assessment of PET/CT studies in prostate cancer patients. The method is now open for validation in future prospective clinical trials.
Source: Journal of Nuclear Medicine - Category: Nuclear Medicine Authors: Tags: Prostate Posters Source Type: research
Abstract PURPOSE: To demonstrate the feasibility and to evaluate the tumour control probability (TCP) and normal tissue complication probability (NTCP) of IMRT dose painting using (68)Ga-HBED-CC PSMA PET/CT for target delineation in prostate cancer (PCa). METHODS AND MATERIALS: 10 patients had PSMA PET/CT scans prior to prostatectomy. GTV-PET was generated on the basis of an intraprostatic SUVmax of 30%. Two IMRT plans were generated for each patient: Plan(77) which consisted of whole-prostate IMRT to 77Gy, and Plan(95) which consisted of whole-prostate IMRT to 77Gy and a simultaneous integrated boost to the ...
Source: Radiotherapy and Oncology : journal of the European Society for Therapeutic Radiology and Oncology - Category: Radiology Authors: Tags: Radiother Oncol Source Type: research
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