A quantitative method to the analysis of <scp>MLC</scp> leaf position and speed based on <scp>EPID</scp> and <scp>EBT</scp>3 film for dynamic <scp>IMRT</scp> treatment with different types of <scp>MLC</scp>

Li, Yinghui; Chen, Lixin; Zhu, Jinhan; Wang, Bin; Liu, Xiaowei

doi:10.1002/acm2.12102

Cited by 17 publications

(25 citation statements)

References 24 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…Leaf transmission is an important factor that influences IMRT delivery. The transmission ratio of the Varian millennium120 MLC was measured to be 1.4% and 1.5% in the studies conducted by Li et al 14 and Yao et al 17 using different measurement methods. To reduce the transmission and leakage between the leaves, a collimator jaw is usually used in conventional accelerators.…”

Section: Discussionmentioning

confidence: 99%

“…The MLC is a critical component to provide an efficient means of shaping the treatment field 10. MLC properties with potential clinical effects, including the leaf width 11,12, transmission 13,14 and speed 14, have been extensively investigated. Lower MLC transmission may have advantages in organ at risk (OAR) sparing 13, and MLCs with very fast motion have been shown to reduce IMRT/VMAT delivery times 5.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Plan quality comparison for cervical carcinoma treated with Halcyon and Trilogy intensity-modulated radiotherapy

Li¹,

Chen²,

Jing-ci³

et al. 2019

J. Cancer

View full text Add to dashboard Cite

Purpose: Varian Halcyon is a novel machine with dual-layer leaves, single flattening filter free (FFF) energy and an enclosed bore. The purpose of this study was to compare the differences in dosimetry and plan parameters of intensity-modulated radiation therapy (IMRT) plans between the Halcyon and Trilogy accelerators. Methods and Materials: A total of 30 IMRT plans from cervical carcinoma patients were retrospectively analyzed on the Trilogy and Eclipse v13.5 treatment planning systems (TPSs). For each patient, a new plan based on Halcyon was created with the same planning parameters and optimization constraints using the Eclipse Version 15.1 TPS. To compare plan qualities, dosimetry parameters regarding planning target volume (PTV), organs at risk (OARs), monitor unit (MU) efficiency, segment size and treatment time were evaluated. Evaluation of the helical diode array system was performed with gamma-index analysis. Results: The dose distribution of the target volume of the Halcyon and Trilogy plans showed no significant difference (p > 0.05). The mean doses of rectum and both femoral heads for Halcyon plans were significantly reduced compared to those for Trilogy plans (p < 0.05). Compared to Trilogy, Halcyon increased the number of MUs from 1542.9±248.3 MU to 2514.9±328.2 MU (p = 0.00) and decreased the delivery time from 11.28±1.36 min to 3.26±0.26 min (p = 0.00). The average segment areas of Halcyon plans for proximal and distal multileaf collimators (MLCs) were 42.1 ± 31.2 cm 2 and 28.4 ± 23.7 cm 2 , respectively, and that of Trilogy plans was 27.3 ± 16.9 cm 2. The mean gamma index (3 mm/3%) results for the Halcyon and Trilogy plans were 99.41±0.26 and 99.76±0.32 (p > 0.05), respectively. Conclusions: All Halcyon treatment plans were recognized as clinically acceptable and had statistically better OAR sparing with higher delivery efficiency. The Halcyon system exhibited fast treatment delivery of IMRT with good dosimetric agreement using ArcCHECK.

show abstract

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Plan quality comparison for cervical carcinoma treated with Halcyon and Trilogy intensity-modulated radiotherapy

Li¹,

Chen²,

Jing-ci³

et al. 2019

J. Cancer

View full text Add to dashboard Cite

show abstract

“…[1][2][3] VMAT generates dose distributions using dynamic multi-leaf collimators and variable dose rates and gantry speeds. 4,5 By optimizing the dose distributions, the VMAT irradiation technique provides both a highly controlled dose to the target(s) and a reduction of the dose to normal tissue(s). 6 Cranial stereotactic radiosurgery (SRS) administered with a linear accelerator has been used with multiple isocenters to treat multiple brain metastases.…”

Section: Introductionmentioning

confidence: 99%

“…It produces a highly accurate three‐dimensional dose distribution with single or multi‐arc irradiation using a 360° gantry rotation 1–3 . VMAT generates dose distributions using dynamic multi‐leaf collimators and variable dose rates and gantry speeds 4,5 . By optimizing the dose distributions, the VMAT irradiation technique provides both a highly controlled dose to the target(s) and a reduction of the dose to normal tissue(s) 6 .…”

Section: Introductionmentioning

confidence: 99%

Effect of setup error in the single‐isocenter technique on stereotactic radiosurgery for multiple brain metastases

Nakano

Tanabe

Utsunomiya

et al. 2020

J Applied Clin Med Phys

View full text Add to dashboard Cite

In conventional stereotactic radiosurgery (SRS), treatment of multiple brain metastases using multiple isocenters is time-consuming resulting in long dose delivery times for patients. A single-isocenter technique has been developed which enables the simultaneous irradiation of multiple targets at one isocenter. This technique requires accurate positioning of the patient to ensure optimal dose coverage. We evaluated the effect of six degrees of freedom (6DoF) setup errors in patient setups on SRS dose distributions for multiple brain metastases using a single-isocenter technique. We used simulated spherical gross tumor volumes (GTVs) with diameters ranging from 1.0 to 3.0 cm. The distance from the isocenter to the target's center was varied from 0 to 15 cm. We created dose distributions so that each target was entirely covered by 100% of the prescribed dose. The target's position vectors were rotated from 0°-2.0°and translated from 0-1.0 mm with respect to the three axes in space. The reduction in dose coverage for the targets for each setup error was calculated and compared with zero setup error. The calculated margins for the GTV necessary to satisfy the tolerance values for loss of GTV coverage of 3% to 10% were defined as coverage-based margins. In addition, the maximum isocenter to target distance for different 6DoF setup errors was calculated to satisfy the tolerance values. The dose coverage reduction and coverage-based margins increased as the target diameter decreased, and the distance and 6DoF setup error increased. An increase in setup error when a single-isocenter technique is used may increase the risk of missing the tumor; this risk increases with increasing distance from the isocenter and decreasing tumor size.

show abstract

“…To achieve better than 1 mm accuracy and precision of MLC leaf positioning, routine MLC QA testing is recommended by TG-142 [11] to be performed weekly using visual inspection of matched segments and monthly quantitative testing using a special test pattern such as a picket fence test described by Losasso [3]. Different methods have been described in the literature for MLC QA to deliver IMRT/VMAT plans accurately [18,[23][24][25][26]. One of the used methods for MLCQA for IMRT/VMAT delivery was the twodimensional (2D) evaluation of either film or scanned image by visual inspection, which are subjective, timeconsuming, sensitive to external conditions, and a less accurate way to define MLC positioning errors [25].…”

Section: Discussionmentioning

confidence: 99%

Effect of Multileaf Collimator Leaf Position Error Determined by Picket Fence Test on Gamma Index Value in Patient-Specific Quality Assurance of Volumetric-Modulated Arc Therapy Plans

Ceylan

İnal

Şenol

et al. 2021

Cureus

View full text Add to dashboard Cite

Aim The correlation between the MLC QA (IBA Dosimetry, Germany) results of the picket fence test created with intentional errors and the patient's quality assurance (QA) evaluation was investigated to assess the impact of multileaf collimator (MLC) positioning error on patient QA. Materials and methods The picket fence, including error-free and intentional MLC errors, defined in Bank In, Bank Out, and Bank Both were analyzed using MLC QA. The QA of 15 plans consisting of stereotactic radiosurgery (SRS), stereotactic body radiotherapy (SBRT), and conventionally fractionated volumetric-modulated arc therapy (VMAT) acquired with electronic portal imaging devices (EPID) was evaluated in the presence of error-free and MLC errors. The QA of plans were analyzed with 2%/2 mm and 3%/3 mm criteria. Results The passing rates of the picket fence test were 97%, 92%, 91%, and 87% for error-free and intentional errors. The criterion of 3%/3 mm wasn’t able to detect an MLC error for either SRS/SBRT or conventionally fractionated VMAT. The criterion of 2%/2mm was more sensitive to detect MLC error for the conventionally fractionated VMAT than SRS/SBRT. While only two of SBRT plans had <90%, four of conventionally fractionated VMAT plans had a <90% passing rate. Conclusion We found that the systematic MLC positioning errors defined with picket fence have a smaller but measurable impact on SRS/SBRT than the VMAT plan for a conventionally fractionated and relatively complex plan such as head and neck and endometrium cases.

show abstract

A quantitative method to the analysis of MLC leaf position and speed based on EPID and EBT3 film for dynamic IMRT treatment with different types of MLC

Cited by 17 publications

References 24 publications

Plan quality comparison for cervical carcinoma treated with Halcyon and Trilogy intensity-modulated radiotherapy

Plan quality comparison for cervical carcinoma treated with Halcyon and Trilogy intensity-modulated radiotherapy

Effect of setup error in the single‐isocenter technique on stereotactic radiosurgery for multiple brain metastases

Effect of Multileaf Collimator Leaf Position Error Determined by Picket Fence Test on Gamma Index Value in Patient-Specific Quality Assurance of Volumetric-Modulated Arc Therapy Plans

Contact Info

Product

Resources

About