scholarly journals Monte Carlo Calculation of Radioimmunotherapy with90Y-,177Lu-,131I-,124I-, and188Re-Nanoobjects: Choice of the Best Radionuclide for Solid Tumour Treatment by Using TCP and NTCP Concepts

2015 ◽  
Vol 2015 ◽  
pp. 1-15 ◽  
Author(s):  
S. Lucas ◽  
O. Feron ◽  
B. Gallez ◽  
B. Masereel ◽  
C. Michiels ◽  
...  
Keyword(s):  
Treatment Efficacy ◽  
Solid Tumour ◽  
Normal Tissue ◽  
Monte Carlo Calculation ◽  
Normal Tissue Complication Probability ◽  
Small Cell ◽  
Small Cell Lung ◽  
Tumour Control ◽  
Improve Treatment ◽  
Tumour Control Probability

Radioimmunotherapy has shown that the use of monoclonal antibodies combined with a radioisotope like131I or90Y still remains ineffective for solid and radioresistant tumour treatment. Previous simulations have revealed that an increase in the number of90Y labelled to each antibody or nanoobject could be a solution to improve treatment output. It now seems important to assess the treatment output and toxicity when radionuclides such as90Y,177Lu,131I,124I, and188Re are used. Tumour control probability (TCP) and normal tissue complication probability (NTCP) curves versus the number of radionuclides per nanoobject were computed with MCNPX to evaluate treatment efficacy for solid tumours and to predict the incidence of surrounding side effects. Analyses were carried out for two solid tumour sizes of 0.5 and 1.0 cm radius and for nanoobject (i.e., a radiolabelled antibody) distributed uniformly or nonuniformly throughout a solid tumour (e.g., Non-small-cell-lung cancer (NSCLC)).90Y and188Re are the best candidates for solid tumour treatment when only one radionuclide is coupled to one carrier. Furthermore, regardless of the radionuclide properties, high values of TCP can be reached without toxicity if the number of radionuclides per nanoobject increases.

scholarly journals Theoretical derivation and clinical dose-response quantification of a unified multi-activation (UMA) model of cell survival from a logistic equation

BJR|Open ◽  
2021 ◽  
Vol 3 (1) ◽  
Author(s):  
Shidong Li
Keyword(s):  
Cell Survival ◽  
Normal Tissue ◽  
Dose Range ◽  
Normal Tissue Complication Probability ◽  
Order Reaction ◽  
Second Order Reaction ◽  
X Ray ◽  
Tumour Control ◽  
Tumour Control Probability ◽  
X Ray Imaging

Objective: To theoretically derive a unified multiactivation (UMA) model of cell survival after ionising radiation that can accurately assess doses and responses in radiotherapy and X-ray imaging. Methods: A unified formula with only two parameters in fitting of a cell survival curve (CSC) is first derived from an assumption that radiation-activated cell death pathways compose the first- and second-order reaction kinetics. A logit linear regression of CSC data is used for precise determination of the two model parameters. Intrinsic radiosensitivity, biologically effective dose (BED), equivalent dose to the traditional 2 Gy fractions (EQD2), tumour control probability, normal-tissue complication probability, BED50 and steepness (Γ50) at 50% of tumour control probability (or normal-tissue complication probability) are analytical functions of the model and treatment (or imaging) parameters. Results: The UMA model has almost perfectly fit typical CSCs over the entire dose range with R2≥0.99. Estimated quantities for stereotactic body radiotherapy of early stage lung cancer and the skin reactions from X-ray imaging agree with clinical results. Conclusion: The proposed UMA model has theoretically resolved the catastrophes of the zero slope at zero dose for multiple target model and the bending curve at high dose for the linear quadratic model. More importantly, it analytically predicts dose–responses to various dose–fraction schemes in radiotherapy and to low dose X-ray imaging based on these preclinical CSCs. Advances in knowledge: The discovery of a unified formula of CSC over the entire dose range may reveal a common mechanism of the first- and second-order reaction kinetics among multiple CD pathways activated by ionising radiation at various dose levels.

scholarly journals Influence of Urethra Sparing on Tumor Control Probability and Normal Tissue Complication Probability in Focal Dose Escalated Hypofractionated Radiotherapy: A Planning Study Based on Histopathology Reference

2021 ◽  
Vol 11 ◽  
Author(s):  
Simon K. B. Spohn ◽  
Ilias Sachpazidis ◽  
Rolf Wiehle ◽  
Benedikt Thomann ◽  
August Sigle ◽  
...  
Keyword(s):  
Dose Escalation ◽  
Normal Tissue ◽  
Normal Tissue Complication Probability ◽  
Tumor Control ◽  
Planning Study ◽  
Tumour Control ◽  
Tumour Control Probability ◽  
Psma Pet ◽  
Pet Ct ◽  
Dose Constraints

PurposeMultiparametric magnetic resonance tomography (mpMRI) and prostate specific membrane antigen positron emission tomography (PSMA-PET/CT) are used to guide focal radiotherapy (RT) dose escalation concepts. Besides improvements of treatment effectiveness, maintenance of a good quality of life is essential. Therefore, this planning study investigates whether urethral sparing in moderately hypofractionated RT with focal RT dose escalation influences tumour control probability (TCP) and normal tissue complication probability (NTCP).Patients and Methods10 patients with primary prostate cancer (PCa), who underwent 68Ga PSMA-PET/CT and mpMRI followed by radical prostatectomy were enrolled. Intraprostatic tumour volumes (gross tumor volume, GTV) based on both imaging techniques (GTV-MRI and -PET) were contoured manually using validated contouring techniques and GTV-Union was created by summing both. For each patient three IMRT plans were generated with 60 Gy to the whole prostate and a simultaneous integrated boost up to 70 Gy to GTV-Union in 20 fractions by (Plan 1) not respecting and (Plan 2) respecting dose constraints for urethra as well as (Plan 3) respecting dose constraints for planning organ at risk volume for urethra (PRV = urethra + 2mm expansion). NTCP for urethra was calculated applying a Lyman-Kutcher-Burman model. TCP-Histo was calculated based on PCa distribution in co-registered histology (GTV-Histo). Complication free tumour control probability (P+) was calculated. Furthermore, the intrafractional movement was considered.ResultsMedian overlap of GTV-Union and PRV-Urethra was 1.6% (IQR 0-7%). Median minimum distance of GTV-Histo to urethra was 3.6 mm (IQR 2 – 7 mm) and of GTV-Union to urethra was 1.8 mm (IQR 0.0 – 5.0 mm). The respective prescription doses and dose constraints were reached in all plans. Urethra-sparing in Plans 2 and 3 reached significantly lower NTCP-Urethra (p = 0.002) without significantly affecting TCP-GTV-Histo (p = p > 0.28), NTCP-Bladder (p > 0.85) or NTCP-Rectum (p = 0.85), resulting in better P+ (p = 0.006). Simulation of intrafractional movement yielded even higher P+ values for Plans 2 and 3 compared to Plan 1.ConclusionUrethral sparing may increase the therapeutic ratio and should be implemented in focal RT dose escalation concepts.

Sign in / Sign up

Export Citation Format

Share Document