scholarly journals Dosimetric Validation of a GAN-Based Pseudo-CT Generation for MRI-Only Stereotactic Brain Radiotherapy

Cancers ◽  
2021 ◽  
Vol 13 (5) ◽  
pp. 1082
Author(s):  
Vincent Bourbonne ◽  
Vincent Jaouen ◽  
Clément Hognon ◽  
Nicolas Boussion ◽  
François Lucia ◽  
...  
Keyword(s):  
At Risk ◽  
Brain Metastases ◽  
Stereotactic Radiotherapy ◽  
Organs At Risk ◽  
Treatment Plan ◽  
Ct Scans ◽  
Generative Adversarial Network ◽  
Electronic Density ◽  
Planning Ct ◽  
Synthetic Ct

Purpose: Stereotactic radiotherapy (SRT) has become widely accepted as a treatment of choice for patients with a small number of brain metastases that are of an acceptable size, allowing for better target dose conformity, resulting in high local control rates and better sparing of organs at risk. An MRI-only workflow could reduce the risk of misalignment between magnetic resonance imaging (MRI) brain studies and computed tomography (CT) scanning for SRT planning, while shortening delays in planning. Given the absence of a calibrated electronic density in MRI, we aimed to assess the equivalence of synthetic CTs generated by a generative adversarial network (GAN) for planning in the brain SRT setting. Methods: All patients with available MRIs and treated with intra-cranial SRT for brain metastases from 2014 to 2018 in our institution were included. After co-registration between the diagnostic MRI and the planning CT, a synthetic CT was generated using a 2D-GAN (2D U-Net). Using the initial treatment plan (Pinnacle v9.10, Philips Healthcare), dosimetric comparison was performed using main dose-volume histogram (DVH) endpoints in respect to ICRU 91 guidelines (Dmax, Dmean, D2%, D50%, D98%) as well as local and global gamma analysis with 1%/1 mm, 2%/1 mm and 2%/2 mm criteria and a 10% threshold to the maximum dose. t-test analysis was used for comparison between the two cohorts (initial and synthetic dose maps). Results: 184 patients were included, with 290 treated brain metastases. The mean number of treated lesions per patient was 1 (range 1–6) and the median planning target volume (PTV) was 6.44 cc (range 0.12–45.41). Local and global gamma passing rates (2%/2 mm) were 99.1 CI95% (98.1–99.4) and 99.7 CI95% (99.6–99.7) respectively (CI: confidence interval). DVHs were comparable, with no significant statistical differences regarding ICRU 91′s endpoints. Conclusions: Our study is the first to compare GAN-generated CT scans from diagnostic brain MRIs with initial CT scans for the planning of brain stereotactic radiotherapy. We found high similarity between the planning CT and the synthetic CT for both the organs at risk and the target volumes. Prospective validation is under investigation at our institution.

scholarly journals Clinical Validation and Treatment Plan Evaluation Based on Auto-Delineation of the Clinical Target Volume for Prostate Cancer Radiotherapy

2022 ◽  
Author(s):  
Jing Shen ◽  
Yinjie TAO ◽  
Hui GUAN ◽  
Hongnan ZHEN ◽  
Lei HE ◽  
...  
Keyword(s):  
Prostate Cancer ◽  
At Risk ◽  
Organs At Risk ◽  
Treatment Plan ◽  
Statistical Significance ◽  
Locally Advanced ◽  
Target Volume ◽  
Ct Scans ◽  
Dice Similarity Coefficient ◽  
Treatment Plans

Abstract Purpose Clinical target volumes (CTV) and organs at risk (OAR) could be auto-contoured to save workload. The goal of this study was to assess a convolutional neural network (CNN) for totally automatic and accurate CTV and OAR in prostate cancer, while also comparing anticipated treatment plans based on auto-contouring CTV to clinical plans. Methods From January 2013 to January 2019, 217 computed tomography (CT) scans of patients with locally advanced prostate cancer treated at our hospital were collected and analyzed. CTV and OAR were delineated with a deep learning based method, which named CUNet. The performance of this strategy was evaluated using the mean Dice similarity coefficient (DSC), 95th percentile Hausdorff distance (95HD), and subjective evaluation. Treatment plans were graded using predetermined evaluation criteria, and % errors for clinical doses to the planned target volume (PTV) and organs at risk(OARs) were calculated. Results The defined CTVs had mean DSC and 95HD values of 0.84 and 5.04 mm, respectively. For one patient's CT scans, the average delineation time was less than 15 seconds. When CTV outlines from CUNetwere blindly chosen and compared to GT, the overall positive rate in clinicians A and B was 53.15% vs 46.85%, and 54.05% vs 45.95%, respectively (P>0.05), demonstrating that our deep machine learning model performed as good as or better than human demarcation Furthermore, 8 testing patients were chosen at random to design the predicted plan based on the auto-courtoring CTV and OAR, demonstrating acceptable agreement with the clinical plan: average absolute dose differences of D2, D50, D98, Dmean for PTV are within 0.74%, and average absolute volume differences of V45, V50 for OARs are within 3.4%. Without statistical significance (p>0.05), the projected findings are comparable to clinical truth. Conclusion The experimental results show that the CTV and OARs defined by CUNet for prostate cancer were quite close to the ground reality.CUNet has the potential to cut radiation oncologists' contouring time in half. When compared to clinical plans, the differences between estimated doses to CTV and OAR based on auto-courtoring were small, with no statistical significance, indicating that treatment planning for prostate cancer based on auto-courtoring has potential.

scholarly journals Planning CT Scans for the Treatment of HDR Vaginal Vault Brachytherapy: An Evaluation of Its Role to Determine the Dose to the Organs at Risk

Brachytherapy ◽  
2015 ◽  
Vol 14 ◽  
pp. S84-S85 ◽  
Author(s):  
Tracey Rose ◽  
Deidre Batchelar ◽  
Bart Robertson ◽  
Juanita Crook ◽  
David Petrik ◽  
...  
Keyword(s):  
At Risk ◽  
Organs At Risk ◽  
Vaginal Vault ◽  
Ct Scans ◽  
Planning Ct

Analysis of rectal dose during prostate stereotactic body radiotherapy in MR-guided radiotherapy.

2021 ◽  
Vol 39 (6_suppl) ◽  
pp. 242-242
Author(s):  
Kobika Sritharan ◽  
Alex Dunlop ◽  
Adam Mitchell ◽  
Jonathan Mohajer ◽  
Gillian Smith ◽  
...  
Keyword(s):  
At Risk ◽  
Stereotactic Body Radiotherapy ◽  
Organs At Risk ◽  
Treatment Plan ◽  
Adaptive Radiotherapy ◽  
Post Treatment ◽  
Rectal Dose ◽  
Dose Constraint ◽  
Fraction Dose ◽  
Rectal Filling

242 Background: The Unity MR-Linac combines a 7-MV Linac with 1.5T magnetic resonance (MR) imaging capability and it enables adaptive radiotherapy, whereby the target and organs at risk are recontoured and a plan is optimised daily. During treatment a session MR image is taken first, on which the target and organs-at-risk are contoured, and a plan created. A verification image is taken prior to dose delivery to identify intra-fractional changes. If present, the daily treatment plan is shifted to reflect the anatomy. A post-treatment image is acquired at the end of treatment. This study evaluates the dosimetric changes to the rectum caused by intra-fractional changes during treatment delivery for prostate stereotactic body radiotherapy (SBRT) calculated on the verification and post-treatment images. Methods: The first five patients treated on the MR-Linac with 5-fraction SBRT to the prostate are included in this study. For each patient, the rectum was contoured on the verification and post-treatment MR images for each of the five fractions. The dose delivered to the rectum with the original treatment plan was then calculated on each image and the V36Gy rectal dose constraint was noted. Results: Out of the 25 fractions, a post treatment image was not performed in one fraction; 24 fractions were therefore analysed in total. The rectal V36Gy dose constraint exceeded the mandatory target of 2cc on 50% of the verification images and 46% of the post-treatment images. In 6 fractions the rectal V36Gy was greater than 2cc on both the verification and post-treatment images suggesting this rectal constraint was exceeded throughout treatment. In 17% of patients, the volume of rectum receiving 36Gy increased at each timepoint an image was taken during the treatment workflow. Conclusions: The rectal V36Gy dose constraint is susceptible to minor changes in rectal filling, which may often lead to higher than the accepted dose constraint. Thus, a single planning CT scan is unlikely to be representative of dose delivered. Adaptive radiotherapy can reduce this uncertainty somewhat, but intra-fraction dose re-optimisation would be required to ensure the rectal V36Gy remains acceptable at all times.

The potential of shape-based treatment plan optimization for pancreatic IMRT treatments to spare organs at risk and allow for dose escalation to the tumor PTV.

2011 ◽  
Vol 29 (4_suppl) ◽  
pp. 316-316
Author(s):  
S. F. Petit ◽  
B. Wu ◽  
M. Kazhdan ◽  
A. Dekker ◽  
P. Simari ◽  
...  
Keyword(s):  
Pancreatic Cancer ◽  
At Risk ◽  
Normal Tissue ◽  
Organs At Risk ◽  
Treatment Plan ◽  
Spatial Relation ◽  
Pancreatic Cancer Patient ◽  
Target Volume ◽  
Plan Optimization ◽  
Treatment Plan Optimization

316 Background: Due to the low dose tolerance of the organs at risk (OARs) in the abdomen the tumor dose for pancreatic cancer patient is restricted to 50-60 Gy in 1.8-2.0 Gy fractions when combined with chemotherapy. The goal of this study was to develop a system that can determine the minimal radiation dose to the OARs of each individual patient that is achievable while maintaining adequate tumor coverage. This could guide treatment planners to spare the OARs to the fullest extent. When the minimal doses to the OAR are achieved, the total plan can be upscaled until the normal tissue dose constraints are met, allowing for an increase in tumor dose without increased normal tissue toxicity. Methods: The minimal achievable dose to the OARs depends on its proximity to the planning target volume (PTV). The overlap volume histogram (OVH) was used to describe the spatial relation of each OAR to the PTV. A database of 33 patients, treated with IMRT, was queried to find the lowest achieved dose to an organ for any of the prior patients with less favorable PTV-OAR configurations than the current patient. This minimal dose must also be achievable for the OAR of the new patient. For 25 randomly chosen patients the lowest achievable dose to the liver and kidneys was predicted this way. Then the patients were replanned to verify if this dose could be achieved. The new plans were compared to the original clinical plans. Results: After replanning the predicted achievable dose to the liver was realized within 1 and 2 Gy for more than 86% and 96% of the patients respectively. For the kidneys these numbers were 83% and 96%. The average improvement in terms of mean dose was 1.4 Gy (range 0 – 4.6 Gy) for the liver and 1.7 Gy (range 0 – 6.3 Gy) for the kidneys. This would have allowed an increase in PTV dose of on average 5 Gy (range 0-13 Gy) based on the liver and 8.5 Gy (range 0-38 Gy) based on the kidneys compared to the original plan, without an increase in dose to the bowel, cord, and stomach. Conclusions: The lowest achievable dose to the OARs could accurately be predicted for pancreatic cancer patients within seconds. This can guide dosimetrists to spare the OARs or increase the PTV dose by 5 Gy without increased toxicity. [Table: see text]

Differential vaginal wall dosing in high-dose rate brachytherapy for endometrial cancer: The potential for superior coverage of at-risk areas while preserving organs at risk—An analysis of simulated data.

2019 ◽  
Vol 37 (15_suppl) ◽  
pp. e17121-e17121
Author(s):  
Dhiraj Sinha ◽  
Kellie Alleyne-Mike ◽  
Sherisse De_four ◽  
Naveen Ratan ◽  
Shashidhar Ramesh
Keyword(s):  
At Risk ◽  
Endometrial Cancer ◽  
Organs At Risk ◽  
Treatment Plan ◽  
Small Sample ◽  
External Beam Radiation ◽  
High Dose ◽  
Beam Radiation ◽  
Data Set ◽  
Risk Areas

e17121 Background: The treatment of curable endometrial cancer (EC)involves surgery with adjuvant radiotherapy. Histology of EC is a major determining factor for intracavitary brachytherapy (ICRT) treatment volume in early stage EC. Many guidelines recommend ICRT treatment of an extended volume up to the whole length of the vaginal stump (VS) for cases of high risk histologies (HRH) wherein a differential dosing of proximal and distal VS has the potential to achieve targeted therapeutic doses to at risk areas without compromise to critical structures.We present a simulated novel way to treat the VS by ICRT in cases of EC with HRH. Analysis of the simulated and approved plans allow us to compare the doses to organs at risk (OAR’s). Methods: Seventy-five cases from July 2017-August 2018 were reviewed and twenty-five (25) met the criteria for inclusion in this study. All these cases received External Beam Radiation Therapy (EBRT) dose of 50.4Gy/28. The ICRT simulation CT data-set was subsequently used to generate the study plan which was then compared to the actual treatment plan. In order to treat the whole VS but spare OARs a club-shaped design was proposed. This technique involved treating the upper 1/3 with a prescription point at 0.5cm lateral to the applicator surface and the lower 2/3 with a prescription point at the applicator surface. The length of the VS was defined from the tip of the applicator to 2cm superior to the introitus. The D2cc values for the contoured bladder and rectum were extracted from the treatment plan and used along with the D2cc values from the EBRT treatment to calculate OAR EQD2. QUANTEC Constraints used were (ICRU 83): EQD2 bladder: 90Gy; EQD2 rectum: 75Gy. Once calculated, the results were analyzed and the percent deviation between the proposed plan and the constraints as well as the approved plan were determined. Results: Twelve (12) of twenty-five (25) cases were HRH cases. The club-shaped design to treat the whole VS didn't further compromise the OAR (EQD2: 22% below constraints) or the rectum (EQD2: 1% below constraints). There was only a 2% difference between the final constraints in both treatment techniques. Conclusions: This technique to treat the full VS length can be used without adversely affecting OAR toxicities with superior coverage to at risk areas while maintaining dose constraints to OAR. Results, however, are limited by the small sample size.

scholarly journals Daily dose to organs at risk predicts acute toxicity in pancreatic stereotactic radiotherapy

2020 ◽  
Vol 59 (8) ◽  
pp. 944-948
Author(s):  
Mauro Loi ◽  
Alba Magallon-Baro ◽  
Mustafa Suker ◽  
Casper Van Eijck ◽  
Mischa Hoogeman ◽  
...  
Keyword(s):  
At Risk ◽  
Acute Toxicity ◽  
Stereotactic Radiotherapy ◽  
Organs At Risk ◽  
Daily Dose

scholarly journals Pediatric craniospinal irradiation with a short partial-arc VMAT technique for medulloblastoma tumors in dosimetric comparison

2020 ◽  
Vol 15 (1) ◽  
Author(s):  
Gerhard Pollul ◽  
Tilman Bostel ◽  
Sascha Grossmann ◽  
Sati Akbaba ◽  
Heiko Karle ◽  
...  
Keyword(s):  
At Risk ◽  
Low Dose ◽  
Organs At Risk ◽  
Treatment Plan ◽  
Volumetric Modulated Arc Therapy ◽  
Conformal Radiotherapy ◽  
Dosimetric Comparison ◽  
Pediatric Medulloblastoma ◽  
Treatment Plans ◽  
3D Crt

Abstract Background This study aimed to contrast four different irradiation methods for pediatric medulloblastoma tumors in a dosimetric comparison regarding planning target volume (PTV) coverage and sparing of organs at risk (OARs). Methods In sum 24 treatment plans for 6 pediatric patients were realized. Besides the clinical standard of a 3D-conformal radiotherapy (3D-CRT) treatment plan taken as a reference, volumetric modulated arc therapy (VMAT) treatment plans (“VMAT_AVD” vs. “noAVD” vs. “FullArc”) were optimized and calculated for each patient. For the thoracic and abdominal region, the short partial-arc VMAT_AVD technique uses an arc setup with reduced arc-length by 100°, using posterior and lateral beam entries. The noAVD uses a half 180° (posterior to lateral directions) and the FullArc uses a full 360° arc setup arrangement. The prescription dose was set to 35.2 Gy. Results We identified a more conformal dose coverage for PTVs and a better sparing of OARs with used VMAT methods. For VMAT_AVD mean dose reductions in organs at risk can be realized, from 16 to 6.6 Gy, from 27.1 to 8.7 Gy and from 8.0 to 1.9 Gy for the heart, the thyroid and the gonads respectively, compared to the 3D-CRT treatment method. In addition we have found out a superiority of VMAT_AVD compared to the noAVD and FullArc trials with lower exposure to low-dose radiation to the lungs and breasts. Conclusions With the short partial-arc VMAT_AVD technique, dose exposures to radiosensitive OARS like the heart, the thyroid or the gonads can be reduced and therefore, maybe the occurrence of late sequelae is less likely. Furthermore the PTV conformity is increased. The advantages of the VMAT_AVD have to be weighed against the potentially risks induced by an increased low dose exposure compared to the 3D-CRT method.

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