The influence of increment of gantry on VMAT plan quality for cervical cancer

Chen, Along; Li, Zhenghuan; Chen, Li; Lin, Mang; Li, Bin; Chen, Fei

doi:10.1080/16878507.2019.1707400

Cited by 6 publications

(11 citation statements)

References 19 publications

(19 reference statements)

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“…Two coplanar full arcs rotating in clockwise and anticlockwise directions were used. The segment width was set to 1.0 cm 15 and the increment of gantry was 30° 16 . All VMAT plans were designed to satisfy the dose constraints introduced by the RTOG 0418 for modulated radiotherapy 17 .…”

Section: Methodsmentioning

confidence: 99%

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Risk for second bladder and rectal malignancies from cervical cancer irradiation

Mazonakis

Lyraraki

Tolia

et al. 2021

J Applied Clin Med Phys

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The objective of this study was to estimate the risk of developing second malignancies to partially in-field organs from volumetric modulated arc therapy (VMAT) of cervical cancer and to compare the above risks with those from the conventional three-dimensional conformal radiotherapy (3D-CRT). Seventeen consecutive patients with uterine cervix carcinoma were selected. VMAT and 3D-CRT plans were generated with 6 and 10 MV photons, respectively. The prescribed tumor dose was 45 Gy given in 25 fractions. Differential dose-volume histogram data from the treatment plans were obtained for the partially in-field organs such as bladder and rectum. These data were used to estimate the patient-specific lifetime attributable risk (LAR) for bladder and rectal cancer induction with a non-linear model based on a mixture of plateau and bell-shaped dose-response relationships. The estimated risks per 10000 people were compared with the baseline risks for unexposed population.The patient-specific rectal cancer risk estimates from VMAT were significantly lower than those from 3D-CRT (P = 0.0144). The LARs for developing bladder malignancies from VMAT were significantly high compared to those from conventional irradiation (P = 0.0003). The mean difference between the patient-specific LARs for radiation-induced bladder and rectal malignancies as derived from 3D-CRT and VMAT plans was 6.6% and 2.0%, respectively. The average LAR for developing bladder and rectal malignant diseases due to VMAT was 9.2 × 10 -4 and 43.7 × 10 -4 , respectively. The corresponding risks following 3D-CRT were 8.6 × 10 -4 and 44.6 × 10 -4 . These average risks showed that pelvic irradiation increases the baseline probability for cancer induction by 12.6-19.1%. The differences in the second cancer risks associated with the VMAT and 3D-CRT for cervical cancer were found to be small. Both treatment techniques resulted in considerable increased probabilities for developing bladder and rectal malignancies relative to those of unirradiated population.

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Section: Methodsmentioning

confidence: 99%

“…The segment width was set to 1.0 cm 15 and the increment of gantry was 30°. 16 All VMAT plans were designed to satisfy the dose constraints introduced by the RTOG 0418 for modulated radiotherapy. 17 These constraints are summarized in Table 1.…”

Section: B | 3d-crt and Vmat Planningmentioning

confidence: 99%

Risk for second bladder and rectal malignancies from cervical cancer irradiation

Mazonakis

Lyraraki

Tolia

et al. 2021

J Applied Clin Med Phys

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“…Over the last decade, IMRT has been a major field of research in the treatment of nasopharyngeal carcinoma (NPC) owing to its dosimetric advantages ( Guo et al., 2021 ; Lee et al., 2012 ; Sayah et al., 2020 ). In automatic IMRT optimization, the quality and efficiency of plan are closely associated with a number of different parameters ( Pakela et al., 2020 ; Burmeister et al., 2004 ; Chen et al., 2020 ; Wang et al., 2018 ). The general approach for this technique is to broke up each beam into several beamlets, which are small units that can be modulated with the aid of a computer program.…”

Section: Introductionmentioning

confidence: 99%

Influence of beamlet width on dynamic IMRT plan quality in nasopharyngeal carcinoma

Jin

et al. 2022

PeerJ

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Objective This study aimed to identify the effects of beamlet width on dynamic intensity-modulated radiation therapy (IMRT) for nasopharyngeal carcinoma (NPC) and determine the optimal parameters for the most effective radiotherapy plan. Methods This study evaluated 20 patients with NPC were selected for dynamic IMRT. Only the beamlet width in the optimization parameters was changed (set to 2, 4, 6, 8, and 10 mm that were named BL02, BL04, BL06, BL08, and BL10, respectively) to optimize the results of the five groups of plans. Using the plan quality scoring system, the dose results of the planning target volumes (PTVs) and organs at risks (OARs) were analyzed objectively and comprehensively. The lower the quality score, the better the quality of the plan. The efficiency and accuracy of plan execution were evaluated using monitor units (MUs) and plan delivery time (PDT). Results The BL04 mm group had the lowest quality score for the targets and OARs (0.087), while the BL10 mm group had the highest total score (1.249). The BL04 mm group had the highest MUs (837 MUs) and longest PDT (358 s). However, the MUs range of each group plan was below 100 MUs, and the PDT range was within 30 s. In the BL02, BL04, BL06, BL08, and BL10 plans, <5 MUs segments accounted for 33%, 16%, 24%, 33%, and 40% of total segments, respectively, with which the lowest was in the BL04 mm group. Conclusion Smaller beamlet widths have not only reduced OARs dose while maintaining high dose coverage to the PTVs, but also lead to more MUs that would produce greater PDT. Considering the quality and efficiency of dynamic IMRT, the beamlet width value of the Monaco treatment planning system set to 4 mm would be optimal for NPC.

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“…An NPC IMRT plan usually includes hundreds of segments. The setting of the optimization parameters, such as gantry angle increment and minimum segment width, during planning affects the dose distribution and the delivery efficiency of the radiotherapy plan, thereby affecting plan quality (Chen et al, 2019;Wang et al, 2018). The number of control points in the IMRT plan determines the number of segments; an increase in the number of control points results in an increase in the number of segments and the degrees of freedom for plan modulation, thus improving plan quality.…”

Section: Introductionmentioning

confidence: 99%

Effect of the number of control points on the plan quality of intensity-modulated radiotherapy for nasopharyngeal carcinoma

Chen

et al. 2021

Journal of Radiation Research and Applied Sciences

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This study aimed to investigate the effect of the number of control points (CPs) on the plan quality, plan delivery efficiency, and gamma passing rate (GPR) of intensity-modulated radiotherapy (IMRT) for nasopharyngeal carcinoma (NPC). Twenty patients with NPC were selected. With all other optimization conditions unchanged, only the number of CPs in each field was changed and optimized to formulate four groups of IMRT plans (CP10, CP15, CP20, and CP25) for each case. An IMRT factor (IF) was used to evaluate the plan complexity, and the plan quality index (PQI) was employed to measure the plan quality. The MatriXX was used to measure each plan, and the plan delivery time (PDT) was recorded. The CP20 group had the lowest PQI (20.2%), while the CP10 group had the highest PQI (51.4%). The monitor unit (MU) values and PDTs gradually increased as the number of control points increased, while the MUs/segment significantly decreased. A negative correlation was observed between GPR and IF at the three commonly used criteria (R 2 = 0.39, 0.39, and 0.41, respectively). Considering the IMRT plan quality and the efficiency and accuracy of plan delivery, 20 CPs per field should be used in the IMRT planning for NPC.

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The influence of increment of gantry on VMAT plan quality for cervical cancer

Cited by 6 publications

References 19 publications

Risk for second bladder and rectal malignancies from cervical cancer irradiation

Risk for second bladder and rectal malignancies from cervical cancer irradiation

Influence of beamlet width on dynamic IMRT plan quality in nasopharyngeal carcinoma

Effect of the number of control points on the plan quality of intensity-modulated radiotherapy for nasopharyngeal carcinoma

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