Dataset Information

Assessment of potential jaw-tracking advantage using control point sequences of VMAT planning.

ABSTRACT: This study aims to evaluate the potential jaw-tracking advantage using control point sequences of volume volumetric modulated arc therapy (VMAT) planning. VMAT plans for patients with prostate and head and neck (H&N) cancers were converted into new static arc (SA) plans. The SA plan consisted of a series of static fields at each control point of the VMAT plan. All other machine parameters of the SA plan were perfectly identical to those of the original VMAT plan. The jaw-tracking static arc (JTSA) plans were generated with fields that closed the jaws of each SA field into the multileaf collimators (MLCs) aperture. The dosimetric advantages of JTSA over SA were evaluated in terms of a dose-volume histogram (DVH) of organ at risk (OAR) after renormalizing both plans to make the same target coverage. Both plans were delivered to the MatriXX-based COMPASS system for 3D volume dose verification. The average jaw size reduction of the JTSA along the X direction was 3.1 ± 0.9 cm for prostate patients and 6.9 ± 1.9 cm for H&N patients. For prostate patients, the organs far from the target showed larger sparing (3.7%-8.1% on average) in JTSA than the organs adjacent to the target (1.1%-1.5%). For the H&N plans, the mean dose reductions for all organs ranged from 4.3% to 11.9%. The dose reductions were more significant in the dose regions of D80, D90, and D95 than the dose regions of D5, D10, and D20 for all patients. Likewise, the deliverability and reproducibility of jaw-tracking plan were validated. The measured dosimetric advantage of JTSA over SA coincided with the calculated one above.

SUBMITTER: Kim JI

PROVIDER: S-EPMC5875480 | biostudies-literature | 2014 Mar

REPOSITORIES: biostudies-literature

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Assessment of potential jaw-tracking advantage using control point sequences of VMAT planning.

Kim Jung-in JI Park Jong Min JM Park So-Yeon SY Choi Chang Heon CH Wu Hong-Gyun HG Ye Sung-Joon SJ

Journal of applied clinical medical physics 20140306 2

This study aims to evaluate the potential jaw-tracking advantage using control point sequences of volume volumetric modulated arc therapy (VMAT) planning. VMAT plans for patients with prostate and head and neck (H&N) cancers were converted into new static arc (SA) plans. The SA plan consisted of a series of static fields at each control point of the VMAT plan. All other machine parameters of the SA plan were perfectly identical to those of the original VMAT plan. The jaw-tracking static arc ...[more]

PMID: 24710450

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Project description:BackgroundThe newest release of the Eclipse (Varian) treatment planning system (TPS) includes an optimizing engine for Elekta volumetric-modulated arc therapy (VMAT) planning. The purpose of this study was to evaluate this new algorithm and to compare it to intensity-modulated radiation therapy (IMRT) for various disease sites by creating single- and double-arc VMAT plans.MethodsA total of 162 plans were evaluated in this study, including 38 endometrial, 57 head and neck, 12 brain, 10 breast and 45 prostate cancer cases. The real-life IMRT plans were developed during routine clinical cases using the TPS Eclipse. VMAT plans were generated using a preclinical version of Eclipse with tumor-region-specific optimizing templates without interference of the operator: with one full arc (1A) and with two full arcs (2A), and with partial arcs for breast and prostate with hip implant cases. All plans were evaluated based on target coverage, homogeneity and conformity. The organs at risk (OARs) were analyzed according to plan objectives, such as the mean and maximum doses. If one or more objectives were exceeded, the plan was considered clinically unacceptable, and a second VMAT plan was created by adapting the optimization penalties once.ResultsCompared to IMRT, single- and double-arc VMAT plans showed comparable or better results concerning the target coverage: the maximum dose in the target for 1A is the same as that for IMRT; for 2A, an average reduction of 1.3% over all plans was observed. The conformity showed a statistically significant improvement for both 1A (+3%) and 2A (+6%). The mean total body dose was statistically significant lower for the considered arc techniques (IMRT: 16.0 Gy, VMAT: 15.3 Gy, p < 0.001). However, the sparing of OARs shows individual behavior that depends strongly on the different tumor regions. A clear difference is found in the number of monitor units (MUs) per plan: VMAT shows a reduction of 31%.ConclusionThese findings demonstrate that based on optimizing templates with minimal interaction of the operator, the Eclipse TPS is able to achieve a plan quality for the Elekta VMAT delivery technique that is comparable to that of fixed-field IMRT. Plans with two arcs show better dose distributions than plans with one arc.

Project description:ObjectivesEye-tracking technology has emerged as a potentially useful learner assessment tool in several medical specialties. In the fields of general surgery and anesthesiology, it has been shown to reliably differentiate between different levels of expertise in procedural skills. In the field of radiology, it has been shown to be a valid assessment tool for diagnostic test interpretation. Current methods of competency assessment in point-of-care ultrasound (POCUS) remain a challenge, because they require significant direct observation time by an instructor. The purpose of this study was to determine if eye-tracking technology can accurately distinguish between novice and experts in the interpretation of POCUS clips, specifically of the focused assessment using sonography in trauma (FAST) scan.MethodsA convenience sample of medical students, residents, and emergency physicians from a single academic emergency department were invited to participate. Participants included both novices and experts in POCUS. Each participant completed a baseline questionnaire and viewed 16 video clips of a FAST ultrasound examination while their gaze patterns were recorded by a commercially available eye-tracking device. The primary outcome was total gaze time on the area of interest (AOI). Secondary outcomes included total time to fixation, mean number of fixations, and mean duration of first fixation on the AOI.ResultsFifteen novices and 15 experts completed this study. For total gaze time on the AOI, experts fixated their gaze significantly longer than novices (75.8 ± 16.2 seconds vs. 56.6 ± 12.8 seconds, p = 0.001). Similarly, experts were significantly faster to fixate on the AOI and had a higher fixation count on the AOI (8.5 ± 4.0 seconds vs. 15.1 ± 6.8 seconds, p = 0.003; and 170 ± 30 vs. 143 ± 28 seconds, p = 0.016). There were no differences on the mean duration of first fixation on the AOI (0.42 ± 0.12 seconds vs. 0.39 ± 0.09 seconds, p = 0.467).ConclusionEye-tracking technology shows the potential to differentiate between experts and novices by their gaze patterns on video clips of FAST examinations. The total gaze time on the AOI may be a useful metric to help in the assessment of competency in POCUS image interpretation. In addition, the evaluation of gaze patterns may help educators identify causes of interpretation errors. Future studies are needed to further validate these metrics in a larger cohort.

Project description:Postoperative/adjuvant radiotherapy of advanced gastric cancer involves a large planning target volume (PTV) with multi-concave shapes which presents a challenge for volumetric modulated arc therapy (VMAT) planning. This study investigates the advantages of automated VMAT planning for this site compared to manual VMAT planning by expert planners.For 20 gastric cancer patients in the postoperative/adjuvant setting, dual-arc VMAT plans were generated using fully automated multi-criterial treatment planning (autoVMAT), and compared to manually generated VMAT plans (manVMAT). Both automated and manual plans were created to deliver a median dose of 45 Gy to the PTV using identical planning and segmentation parameters. Plans were evaluated by two expert radiation oncologists for clinical acceptability. AutoVMAT and manVMAT plans were also compared based on dose-volume histogram (DVH) and predicted normal tissue complication probability (NTCP) analysis.Both manVMAT and autoVMAT plans were considered clinically acceptable. Target coverage was similar (manVMAT: 96.6?±?1.6%, autoVMAT: 97.4?±?1.0%, p?=?0.085). With autoVMAT, median kidney dose was reduced on average by >?25%; (for left kidney from 11.3?±?2.1 Gy to 8.9?±?3.5 Gy (p?=?0.002); for right kidney from 9.2?±?2.2 Gy to 6.1?±?1.3 Gy (p?<? 0.001)). Median dose to the liver was lower as well (18.8?±?2.3 Gy vs. 17.1?±?3.6 Gy, p?=?0.048). In addition, Dmax of the spinal cord was significantly reduced (38.3?±?3.7 Gy vs. 31.6?±?2.6 Gy, p?<? 0.001). Substantial improvements in dose conformity and integral dose were achieved with autoVMAT plans (4.2% and 9.1%, respectively; p?<? 0.001). Due to the better OAR sparing in the autoVMAT plans compared to manVMAT plans, the predicted NTCPs for the left and right kidney and the liver-PTV were significantly reduced by 11.3%, 12.8%, 7%, respectively (p???0.001). Delivery time and total number of monitor units were increased in autoVMAT plans (from 168?±?19 s to 207?±?26 s, p?=?0.006) and (from 781?±?168 MU to 1001?±?134 MU, p?=?0.003), respectively.For postoperative/adjuvant radiotherapy of advanced gastric cancer, involving a complex target shape, automated VMAT planning is feasible and can substantially reduce the dose to the kidneys and the liver, without compromising the target dose delivery.

Dataset Information

Assessment of potential jaw-tracking advantage using control point sequences of VMAT planning.

Publications

Assessment of potential jaw-tracking advantage using control point sequences of VMAT planning.

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