The optimal tomotherapy treatment planning parameters for extremity soft tissue sarcomas

Meyer, P.; Bouhours, Hugo; Dehaynin, N.; Jarnet, D.; Gantier, M.; Karamanoukian, D.; Niederst, C.

doi:10.1016/j.ejmp.2015.05.005

Cited by 6 publications

(7 citation statements)

References 20 publications

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“…In HT, the patient is moved and treated while the beam source rotates, and hence, pitch-dependent ripple-shape dose variations, known as "thread effect" may occur, which adversely affects the dose uniformity on the axial plane [21]. The optimal pitch (expressed as 0.86/n) that can minimize pitch dependence has been empirically proposed in various studies [21][22][23][24]. Nevertheless, there may still be a difference in the dose uniformity.…”

Section: Discussionmentioning

confidence: 99%

Comprehensive clinical evaluation of TomoEQA for patient-specific pre-treatment quality assurance in helical tomotherapy

et al. 2022

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Background Based on a previous study on the feasibility of TomoEQA, an exit detector-based patient-specific pre-treatment quality assurance (QA) method for helical tomotherapy, an in-depth clinical evaluation was conducted. Methods Data of one hundred patients were analyzed to evaluate the clinical usefulness of TomoEQA for patient-specific pre-treatment QA in comparison with the conventional phantom-based method. Additional investigations were also performed under unusual measurement conditions to validate the off-axis region. In addition to the clinical evaluation of TomoEQA, a statistical analysis was conducted to determine the plan parameters that affect the pass/failure results of pre-treatment QA. Results The average and standard deviations of the gamma passing rate and point dose error for TomoEQA were comparable to those of the conventional QA method. For TomoEQA, the average values of the gamma passing rate and point dose error were 96.32% (standard deviation (1 sigma) = 3.94; 95% confidence interval (CI), 95.55 to 97.09) and − 1.12% (standard deviation (1 sigma) = 1.04; CI, − 1.32 to − 0.92), respectively. For the conventional QA method, the average values of the gamma passing rate and point dose error were 95.95% (standard deviation (1 sigma) = 4.35; 95% confidence interval (CI), 95.10 to 96.80) and − 1.20% (standard deviation (1 sigma) = 1.61; CI, − 1.52 to − 0.88), respectively. Further experiments on the off-axis region demonstrated that TomoEQA can provide accurate results for 3D dose analysis, which is inherently difficult in the conventional QA method. Through a statistical analysis based on the results of TomoEQA, it was validated that the total fraction (Total Fx), monitor units, beam-on-time, leaf-of-time below 100 ms, and planning target volume diameter were statistically significant for the pass/failure of the pre-treatment QA results. Conclusions TomoEQA is a clinically beneficial alternative to the conventional phantom-based QA method.

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Section: Discussionmentioning

confidence: 99%

Comprehensive clinical evaluation of TomoEQA for patient-specific pre-treatment quality assurance in helical tomotherapy

et al. 2022

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“…The suggested optimal pitch and MF were 0.215 and 0.25 respectively for prostate cancer patients which provides a balance between BOT and dose distribution (Skórska et al, 2013). Meyer (2015) studied the optimal treatment planning parameters (pitch and MF) for extremity soft tissue sarcomas and stated that the 0.43 pitch value is not optimal, and that for a pitch value of 0.215, optimum MF is more than 2. This same study (Meyer et al, 2015) suggests using pitch 0.287 which could provide an acceptable plan quality and reduced treatment time.…”

Section: Introductionmentioning

confidence: 99%

“…Meyer (2015) studied the optimal treatment planning parameters (pitch and MF) for extremity soft tissue sarcomas and stated that the 0.43 pitch value is not optimal, and that for a pitch value of 0.215, optimum MF is more than 2. This same study (Meyer et al, 2015) suggests using pitch 0.287 which could provide an acceptable plan quality and reduced treatment time. Salz (2015) discussed intensity modulated TBI with TomoDirect ® method using various MF and pitch and stated that IMRT with TomoDirect ® allows a superior homogeneity compared to conventional methods with lung sparing.…”

Section: Introductionmentioning

confidence: 99%

Optimal Combination of Pitch, Modulation Factor and Dosimetric Considerations in Treatment Planning for Total Body Irradiation Using Helical Tomotherapy

Venkatesan

Kataria

Tamilselvan

et al. 2023

Asian Pac J Cancer Prev

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Objective: The aim of this study is to makethe standard total body irradiation (TBI) protocol for Helical tomotherapy© (HT) and to analyze the optimal pitch and modulation factor (MF) with respect to dose homogeneity index (HI), target dose coverage, target overdose, beam on time (BOT) and mean lung dose. Materials and Methods: Ten patients who underwent high-dose TBI were taken for this study. For each patient, 35 dose plans were created by different combination of pitch and MF. The optimal pitch and MF were deduced using scatter plot and regression methodology based on target coverage, HI, target volume receiving 103%(V 103% ), 105%(V 105% ) and 107% (V 107% ) of the prescription dose and BOT. Using these optimal pitch and MF, the final dose plan was made and the planning aim and achieved dose was compared using two tailed student’s t-test. Radiochromic films and ionization chambers were used to measure the delivered dose using anthropomorphic phantom on various points for the head and pelvis regions to verify the skin flash margin and its effect on skin dose. Results: The optimal pitch and MF value were 0.287 and 2.4 respectively. Based on optimal pitch and MF, the mean BOT was 1692 seconds with optimal inhomogeneity (7.4%). For target, D95 and D98 were 97.09% (range:94.7-99.6%, p=0.002) and 93.9% (range:91.5-94.4%,p=0.007) respectively, and mean D2 was within 107% with SD of ±1.22% (p=0.04). The mean of PTV receiving V 103 , V105 and V107 was 24.48% (range=7.7-36.6%, p=0.03), 5.76% (range=1.4-12.1%, SD=±3.3%), 1.93% (range=0.1-4.6%, p=0.008) respectively. Our measurements show that the flash margin did not increase the skin dose. Conclusion: In our study, the optimal combination of pitch value of 0.287 and MF value of 2.4 provided acceptable plans for all patients planned for TBI in HT. The flash margin can provide adequate coverage during patient position uncertainty without increasing the skin dose.

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“…14,15 Van Gestel et al and Meyer et al 18 examined the changes of the MF, jaw width, and pitch in oropharyngeal cancer and extremity sarcoma treatment plans, respectively. [16][17][18] Ryczkowski et al 19 reported a phantom test that showed that the MF affected the treatment plan quality and performance time. The resulting treatment plan showed no statistically significant difference from the initial treatment plan when the MF in the initial treatment plan was within the 6.0 to 1.8 range.…”

Section: Introductionmentioning

confidence: 99%

“…In the case of complex treatment plans, it has been proposed that the responsible provider should start from a high MF, achieve a favorable conformal plan, and then reduce the MF until the dose quality is at a level that is not clinically tolerable. 14,15 Van Gestel et al and Meyer et al 18 examined the changes of the MF, jaw width, and pitch in oropharyngeal cancer and extremity sarcoma treatment plans, respectively. [16][17][18] Ryczkowski et al 19 reported a phantom test that showed that the MF affected the treatment plan quality and performance time.…”

Section: Introductionmentioning

confidence: 99%

Influence of Modulation Factor on Treatment Plan Quality and Irradiation Time in Hippocampus-Sparing Whole-Brain Radiotherapy Using Tomotherapy

Ishibashi

Kurosaki

Miura

et al. 2021

Technol Cancer Res Treat

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Objectives: Hippocampus-sparing whole-brain radiotherapy (HS-WBRT) using tomotherapy is known to provide a better dose distribution than volumetric-modulated arc therapy but requires an extended irradiation time. The present study aimed to investigate whether irradiation time can be shortened by reducing the modulation factor (MF) without losing the target dose distribution. Methods: Using six tilted computed tomography images in the head area, the planning target volume (PTV) and hippocampal doses, and the irradiation time was investigated with a jaw width of 1 cm, a pitch of 0.200, and the MF changed from 3.0 to 2.6, 2.2, 1.8, and 1.4. Results: No significant changes in the PTV or hippocampus were found with MF in the range from 3.0 to 1.8, but marked deterioration was found with that of 1.4. The irradiation time showed a linear relationship with the MF within the range from 3.0 to 1.8, with 1334, 1158, 986, and 817 s at modulation factors of 3.0, 2.6, 2.2, and 1.8, respectively. However, when the MF was 1.4, the irradiation time was 808 s. Conclusions: When HS-WBRT is performed with a tilted body position and a jaw width of 1 cm, with a MF of 1.8, a favorable balance between dose parameters and irradiation time is achieved, whereas with a MF of 1.4, the quality of the radiotherapy plan deteriorates, and the irradiation time is approximately the same as that with a MF of 1.8.

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The optimal tomotherapy treatment planning parameters for extremity soft tissue sarcomas

Cited by 6 publications

References 20 publications

Comprehensive clinical evaluation of TomoEQA for patient-specific pre-treatment quality assurance in helical tomotherapy

Comprehensive clinical evaluation of TomoEQA for patient-specific pre-treatment quality assurance in helical tomotherapy

Optimal Combination of Pitch, Modulation Factor and Dosimetric Considerations in Treatment Planning for Total Body Irradiation Using Helical Tomotherapy

Influence of Modulation Factor on Treatment Plan Quality and Irradiation Time in Hippocampus-Sparing Whole-Brain Radiotherapy Using Tomotherapy

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