scholarly journals Nanodosimetry-Based Plan Optimization for Particle Therapy

2015 ◽  
Vol 2015 ◽  
pp. 1-13 ◽  
Author(s):  
Margherita Casiraghi ◽  
Reinhard W. Schulte
Keyword(s):  
Treatment Plan ◽  
Target Volume ◽  
Particle Therapy ◽  
Optimization Strategy ◽  
Plan Optimization ◽  
Treatment Plan Optimization ◽  
Treatment Plans ◽  
Mixed Field ◽  
Single Field ◽  
Mixed Radiation Field

Treatment planning for particle therapy is currently an active field of research due uncertainty in how to modify physical dose in order to create a uniform biological dose response in the target. A novel treatment plan optimization strategy based on measurable nanodosimetric quantities rather than biophysical models is proposed in this work. Simplified proton and carbon treatment plans were simulated in a water phantom to investigate the optimization feasibility. Track structures of the mixed radiation field produced at different depths in the target volume were simulated with Geant4-DNA and nanodosimetric descriptors were calculated. The fluences of the treatment field pencil beams were optimized in order to create a mixed field with equal nanodosimetric descriptors at each of the multiple positions in spread-out particle Bragg peaks. For both proton and carbon ion plans, a uniform spatial distribution of nanodosimetric descriptors could be obtained by optimizing opposing-field but not single-field plans. The results obtained indicate that uniform nanodosimetrically weighted plans, which may also be radiobiologically uniform, can be obtained with this approach. Future investigations need to demonstrate that this approach is also feasible for more complicated beam arrangements and that it leads to biologically uniform response in tumor cells and tissues.

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]

scholarly journals A comparison of two methodologies for radiotherapy treatment plan optimization and QA for clinical trials

2021 ◽  
Vol 22 (10) ◽  
pp. 329-337
Author(s):  
Huaizhi Geng ◽  
Tawfik Giaddui ◽  
Chingyun Cheng ◽  
Haoyu Zhong ◽  
Samuel Ryu ◽  
...  
Keyword(s):  
Clinical Trials ◽  
Treatment Plan ◽  
Plan Optimization ◽  
Treatment Plan Optimization ◽  
Radiotherapy Treatment

OC-0106: Stepwise model-based treatment plan optimization to prevent dypshagia.in head and neck cancer.

2020 ◽  
Vol 152 ◽  
pp. S51-S52
Author(s):  
H. Langendijk ◽  
L. Van den Bosch ◽  
A. Van den Hoek ◽  
E. Oldehinkel ◽  
T. Meijer ◽  
...  
Keyword(s):  
Head And Neck Cancer ◽  
Head And Neck ◽  
Neck Cancer ◽  
Treatment Plan ◽  
Model Based ◽  
Plan Optimization ◽  
Treatment Plan Optimization

scholarly journals A novel index for assessing treatment plan quality in stereotactic radiosurgery

2018 ◽  
Vol 129 (Suppl1) ◽  
pp. 118-124 ◽  
Author(s):  
Alexis Dimitriadis ◽  
Ian Paddick
Keyword(s):  
Stereotactic Radiosurgery ◽  
Treatment Plan ◽  
Efficiency Index ◽  
Target Volume ◽  
Surrounding Tissue ◽  
Plan Quality ◽  
Multiple Target ◽  
Integral Dose ◽  
Plan Optimization ◽  
Dose Volume

OBJECTIVEStereotactic radiosurgery (SRS) is characterized by high levels of conformity and steep dose gradients from the periphery of the target to surrounding tissue. Clinical studies have backed up the importance of these factors through evidence of symptomatic complications. Available data suggest that there are threshold doses above which the risk of symptomatic radionecrosis increases with the volume irradiated. Therefore, radiosurgical treatment plans should be optimized by minimizing dose to the surrounding tissue while maximizing dose to the target volume. Several metrics have been proposed to quantify radiosurgical plan quality, but all present certain weaknesses. To overcome limitations of the currently used metrics, a novel metric is proposed, the efficiency index (η50%), which is based on the principle of calculating integral doses: η50% = integral doseTV/integral dosePIV50%.METHODSThe value of η50% can be easily calculated by dividing the integral dose (mean dose × volume) to the target volume (TV) by the integral dose to the volume of 50% of the prescription isodose (PIV50%). Alternatively, differential dose-volume histograms (DVHs) of the TV and PIV50% can be used. The resulting η50% value is effectively the proportion of energy within the PIV50% that falls into the target. This value has theoretical limits of 0 and 1, with 1 being perfect. The index combines conformity, gradient, and mean dose to the target into a single value. The value of η50% was retrospectively calculated for 100 clinical SRS plans.RESULTSThe value of η50% for the 100 clinical SRS plans ranged from 37.7% to 58.0% with a mean value of 49.0%. This study also showed that the same principles used for the calculation of η50% can be adapted to produce an index suitable for multiple-target plans (Gη12Gy). Furthermore, the authors present another adaptation of the index that may play a role in plan optimization by calculating and minimizing the proportion of energy delivered to surrounding organs at risk (OARη50%).CONCLUSIONSThe proposed efficiency index is a novel approach in quantifying plan quality by combining conformity, gradient, and mean dose into a single value. It quantifies the ratio of the dose “doing good” versus the dose “doing harm,” and its adaptations can be used for multiple-target plan optimization and OAR sparing.

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