scholarly journals Radiobiological Evaluation of Dosimetric Plans for Stereotactic Radiotherapy for Prostate Cancer According to Fractionation Regimen

2019 ◽  
Vol 100 (5) ◽  
pp. 263-269
Author(s):  
E. S. Sukhikh ◽  
I. N. Sheyno ◽  
L. G. Sukhikh ◽  
A. V. Taletskiy ◽  
A. V. Vertinskiy ◽  
...  
Keyword(s):  
Radiation Therapy ◽  
Total Dose ◽  
Rectal Wall ◽  
Tumor Control ◽  
Anterior Rectal Wall ◽  
Tumor Control Probability ◽  
Equivalent Uniform Dose ◽  
Dose Volume Histograms ◽  
Dose Volume ◽  
Fractionation Regimen

Objective. To determine the most effective irradiation regimen (total dose and dose per fraction) for hypofractionated treatment for prostate carcinomas according the TCP/NTCP radiobiological criteria.Material and methods. Using the tomographic information of five patients with low-risk prostate adenocarcinoma as an example, the authors devised dosimetric radiation therapy plans using the volumetric modulated arc therapy (VMAT) procedure. They considered the range of total doses of 33.5 to 38 Gy administered in 4 and 5 fractions. Based on the equivalent uniform dose concept proposed by A. Niemierko and on the computed differential dose volume histograms, the investigators modeled local tumor control probability (TCP) values, by taking into account the uncertainties of main radiobiological parameters, and estimated normal tissue complication probabilities (NTCP) for the anterior rectal wall as the organ most at risk of irradiation. An effective dosimetric plan was selected according to the UTCP criterion and the probability of complication-free tumor control, i.e. TCP (1 – NTCP).Results. The results of modeling the UTCP criterion show that with a higher total dose, the TCP value increases and so does the NTCP value, therefore the optimal radiation therapy plans are to irradiate with a total dose of 34 Gy over 4 fractions or with a dose of 36–37 Gy over 5 fractions. The difference between the fractionation regimens is that the UTCP value is achieved with a higher TCP value over 4 fractions and with a lower load on the rectal wall over 5 fractions.Conclusion. The choice of a specific fractionation regimen should be determined from the calculated values of differential dose volume histograms for each patient, as well as from radiobiological criteria, such as TCP, NTCP and UTCP.

scholarly journals RADT-30. COPLANAR AND NON-COPLANAR VMAT ARC SETTING FOR GLIOBLASTOMA MULTIFORME – DOSIMETRIC AND RADIOBIOLOGICAL COMPARISONS

2020 ◽  
Vol 22 (Supplement_2) ◽  
pp. ii188-ii188
Author(s):  
Vanessa Moldoveanu ◽  
Mihai Dumitrache ◽  
Xenia Bacinschi ◽  
Luiza Serbanescu ◽  
Rodica Anghel
Keyword(s):  
Glioblastoma Multiforme ◽  
Organs At Risk ◽  
Absorbed Dose ◽  
Target Volume ◽  
Tumor Control ◽  
Normal Brain ◽  
Tumor Control Probability ◽  
Equivalent Uniform Dose ◽  
Dose Volume Histograms ◽  
Arc Setting

Abstract OBJECTIVES To evaluate three different arc arrangements in glioblastoma multiforme (GBM) treatment planning. METHODS Eighteen GBM patients were replanned by using one full arc (1FA), two full coplanar arcs (2FA), and three full non- coplanar arcs (3FA). Dose-volume histograms (DVHs) were used to calculate conformity (CI), homogeneity (HI) and gradient indices (GI), the dose received by 5% (D5%) and 95% (D95%) of the planning target volume (PTV) and maximum (Dmax) and minimum (Dmin) absorbed dose for organs at risk (OARs), including normal brain (brain excluding PTV). General equivalent uniform dose (gEUD) for both PTV and OARs and EUD based tumor control probability (TCP) and normal tissue control probability (NTCP) were calculated as radiobiological parameters. Monitor units (MUs) were also computed and compared. RESULTS All three plans resulted in similar conformity, while 2FA resulted in a better homogeneity than 1FA (0.06vs. 0.07, p=0.007). 2FA vs. 1FA dose analysis for PTV revealed a lower D5% (61.28 vs. 61.37 Gy, p=0.014), a higher D95% (58.7 vs. 58.47 Gy, p=0.008) and a higher TCP (37.73 vs.37.38%, p=0.008). The utilization of 3FA did not significantly change the outcome of PTV but managed to decrease GI in comparison to both 1FA and 2FA (4.11 vs. 5.19 and 5.49, p< 0.05). Regarding NB, 1FA scored a higher Dmax than 2FA (62.32 vs. 61.98 Gy, p=0.005), while 3FA scored a higher Dmin than 1FA and 2FA (2.52 vs. 1.08 and 1.10 Gy, p< 0.05). No difference in NB NTCP was noted between techniques. Furthermore, 3FA yielded more MUs when compared to coplanar patters (566.74 vs. 486.78, p= 0.015 for 1FA and 495.98, p=0.019 for 2FA). CONCLUSION Although all three approaches resulted in clinical admissible outcome, the utilization of complex non-coplanar arrangement resulted in a stepper dose fall off but did not improve PTV results and increased machine MUs.

scholarly journals A Brachytherapy Plan Evaluation Tool for Interstitial Applications

2014 ◽  
Vol 2014 ◽  
pp. 1-6 ◽  
Author(s):  
Surega Anbumani ◽  
N. Arunai Nambiraj ◽  
Sridhar Dayalan ◽  
Kalaivany Ganesh ◽  
Pichandi Anchineyan ◽  
...  
Keyword(s):  
Normal Tissue ◽  
Treatment Plan ◽  
Predictive Ability ◽  
Normal Tissue Complication Probability ◽  
Tumor Control ◽  
Tumor Control Probability ◽  
Evaluation Tool ◽  
Equivalent Uniform Dose ◽  
Plan Evaluation ◽  
Dose Volume Histograms

Radiobiological metrics such as tumor control probability (TCP) and normal tissue complication probability (NTCP) help in assessing the quality of brachytherapy plans. Application of such metrics in clinics as well as research is still inadequate. This study presents the implementation of two indigenously designed plan evaluation modules: Brachy_TCP and Brachy_NTCP. Evaluation tools were constructed to compute TCP and NTCP from dose volume histograms (DVHs) of any interstitial brachytherapy treatment plan. The computation module was employed to estimate probabilities of tumor control and normal tissue complications in ten cervical cancer patients based on biologically effective equivalent uniform dose (BEEUD). The tumor control and normal tissue morbidity were assessed with clinical followup and were scored. The acute toxicity was graded using common terminology criteria for adverse events (CTCAE) version 4.0. Outcome score was found to be correlated with the TCP/NTCP estimates. Thus, the predictive ability of the estimates was quantified with the clinical outcomes. Biologically effective equivalent uniform dose-based formalism was found to be effective in predicting the complexities and disease control.

scholarly journals Intensity-modulated radiotherapy using two static ports of tomotherapy for breast cancer after conservative surgery: dosimetric comparison with other treatment methods and 3-year clinical results

2017 ◽  
Vol 58 (4) ◽  
pp. 529-536 ◽  
Author(s):  
Aiko Nagai ◽  
Yuta Shibamoto ◽  
Masanori Yoshida ◽  
Koji Inoda ◽  
Yuzo Kikuchi
Keyword(s):  
Breast Cancer ◽  
Radiation Therapy ◽  
Adverse Events ◽  
External Beam Radiation ◽  
Radiation Dermatitis ◽  
Tumor Control ◽  
Beam Radiation ◽  
Mean Values ◽  
Intensity Modulated ◽  
Dose Volume

Abstract This study investigated the differences in dose–volume parameters for the breast and normal tissues during TomoDirectTM (TD) intensity-modulated radiation therapy (IMRT), TD-3D conformal radiotherapy (3DCRT) and 3DCRT plans, all using two beams, and analyzed treatment outcomes of two-beam TD-IMRT for breast cancer after breast-conserving surgery. Between August 2011 and January 2015, 152 patients were treated using two-beam TD-IMRT with 50 Gy/25 fractions. Among them, 20 patients with left-sided breast cancer were randomly chosen, and two-beam TD-IMRT, TD-3DCRT and 3DCRT plans were created for each patient. The homogeneity and conformity indices and various dose–volume parameters for the planning target volume and OARs were evaluated. Clinical outcomes were evaluated at 3 years. Toxicities were evaluated using the Common Terminology Criteria for Adverse Events version 4.0. TD-IMRT and TD-3DCRT showed better whole-breast coverage than 3DCRT (P < 0.001). Most of the mean values of dosimetric endpoints for OARs were better in TD-IMRT than in TD-3DCRT and 3DCRT. Overall survival rates were 97.7% and local control rates were 99.1% at 3 years. Regional control and distant metastasis control rates at 3 years were 98.6% and 96.8%, respectively. Twenty-four of the 152 patients had Grade 2 or higher acute radiation dermatitis. Four patients (4/146 = 2.7%) had Grade 2 radiation pneumonitis. There were no late adverse events of Grade 2 or higher. Two-beam TD-IMRT appeared to yield better dose distribution for whole-breast external-beam radiation therapy than TD-3DCRT and two-beam 3DCRT. The treatment appeared to provide low skin toxicity and acceptable tumor control.

Analysis of the Physical and Radiobiological Equivalence of the Calculated and Measured Dose Distributions for Prostate Stereotactic Radiotherapy

2021 ◽  
Vol 66 (3) ◽  
pp. 68-75
Author(s):  
E. Sukhikh ◽  
L. Sukhikh ◽  
A. Vertinsky ◽  
P. Izhevsky ◽  
I. Sheino ◽  
...  
Keyword(s):  
Radiation Therapy ◽  
Dose Distribution ◽  
Three Dimensional ◽  
Anterior Wall ◽  
Dose Distributions ◽  
Stereotactic Radiation ◽  
Dose Volume Histograms ◽  
Dose Volume ◽  
Gamma Index ◽  
Measured Dose

Purpose: Carrying out the analysis of the physical and radiobiological equivalence of dose distributions obtained during the planning of hypofractionated stereotactic radiation therapy of the prostate cancer and verification using a three-dimensional cylindrical dosimeter. Material and Methods: Based on the anatomical data of twelve patients diagnosed with prostate carcinoma, stage T2N0M0 with low risk, plans were developed for stereotactic radiation therapy with volumetric modulates arc therapy (VMAT). The dose per fraction was 7,25 Gy for 5 fractions (total dose 36,25 Gy) with a normal photon energy of 10 MV. The developed plans were verified using a three-dimensional cylindrical ArcCHECK phantom. During the verification process, the three-dimensional dose distribution in the phantom was measured, based on which the values of the three-dimensional gamma index and the dose–volume histogram within each contoured anatomical structures were calculated with 3DVH software. The gamma index value γ (3 %, 2 mm, GN) at a threshold equal to 20 % of the dose maximum of the plan and the percentage of coincidence of points at least 95 % was chosen as a criterion of physical convergence of the calculated and measured dose distribution according to the recommendations of AAPM TG-218. To analyze the radiobiological equivalence of the calculated and measured dose distribution, the local control probability (TCP) and normal tissue complication probability (NTCP) criteria were used based on the calculated and measured dose–volume histograms. Contours of the target (PTV) and the anterior wall of the rectum were used for the analysis. The approach based on the concept of equivalent uniform dose (EUD) by A. Niemierko was used to calculate the values of TCP/NTCP criteria. Results: The results of physical convergence of plans for all patients on the contour of the whole body were higher than 95 % for the criteria γ (3 %, 2 mm, GN). The convergence along the PTV contour is in the range (75.5–95.2)%. The TCP and NTCP values obtained from the measured dose-volume histograms were higher than the planned values for all patients. It was found that the accelerator delivered a slightly higher dose to the PTV and the anterior wall of the rectum than originally planned. Conclusion: The capabilities of modern dosimetric equipment allow us move to the verification of treatment plans based on the analysis of TCP / NTCP radiobiological equivalence, taking into account the individual characteristics of the patient and the capabilities of radiation therapy equipment.

The mean absolute dose deviation–A common metric for the evaluation of dose-volume histograms in radiation therapy

2020 ◽  
Vol 45 (2) ◽  
pp. 186-189 ◽  
Author(s):  
Vincent Vinh-Hung ◽  
Nicolas Leduc ◽  
Dirk Verellen ◽  
Claire Verschraegen ◽  
Giovanna Dipasquale ◽  
...  
Keyword(s):  
Radiation Therapy ◽  
Dose Volume Histograms ◽  
Dose Volume ◽  
The Mean

Radiobiological Models of Tissue Response to Radiation in Treatment Planning Systems

1998 ◽  
Vol 84 (2) ◽  
pp. 140-143 ◽  
Author(s):  
Andrzej Niemierko
Keyword(s):  
Radiation Therapy ◽  
Treatment Planning ◽  
Three Dimensional ◽  
Tissue Response ◽  
Tumor Control ◽  
Practical Implementation ◽  
Target Cells ◽  
Tumor Control Probability ◽  
Planning Systems ◽  
Treatment Planning Systems

Aims To present several biological concepts and models of tissue response to fractionated radiotherapy. To describe practical implementation of these models in three-dimensional treatment planning systems. Methods Models of cell survival, Equivalent Uniform Dose (EUD) and Tumor Control Probability (TCP) are discussed. These models are based on the target-cell hypothesis which assumes that response of organs and tissues to radiation therapy can be explained and mathematically described in terms of survival of the specific target-cells. Results Several formulae for deriving and calculating EUD and TCP for a given three-dimensional dose distribution are presented and discussed. Conclusions Biological models of tissue response to radiation, when used wisely, have a potential to be useful in radiation therapy treatment planning. The models can advance our understanding of the underlying biological mechanisms, and may help in designing new and better treatment strategies. They should be particularly useful in modern conformai radiotherapy where treatment strategy for each patient can be individualized and optimized according to patient characteristics and available technology of delivering sophisticated treatment plans.

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