"In radiation therapy, trajectory-based delivery involves the dynamic motion of linear accelerator components combined with continuous arc radiation delivery. The increased complexity of the delivery may yield dosimetric advantages, but the delivery technique has not seen clinical implementation. The purpose of this thesis work is to provide support for clinical implementation of trajectory-based treatment delivery, through the application of novel trajectories, implementation of a trajectory-based optimization algorithm, and verification of the treatment delivery accuracy under dynamic conditions.The initial study in this thesis applied translational couch trajectories to reduce the effective source-to-axis distance (SAD), with potential benefits due to the decreased projected size of the multileaf collimator and an increased effective dose rate. A noncoplanar trajectory was applied to patients presented with cranial targets, and treatment plans were optimized at shortened and standard SAD. Through comparisons to clinical treatment plans, the shortened SAD treatment plans yielded a fraction size dependent decrease in the treatment delivery time due to the increased effective dose rate. The noncoplanar trajectories yielded comparable plan quality to the clinical deliveries.The next study focused on the novel implementation of a trajectory optimization algorithm for concurrent gantry and couch rotation. The optimization algorithm implemented uses the column generation approach to simultaneously determine the trajectory path during volumetric modulated arc therapy optimization (simTr-VMAT). With comparisons to coplanar VMAT plans and to randomly generated trajectories that represent the solution space for the optimization problem, the simTr-VMAT optimization methodology was validated.The complex trajectory paths resulting from the simTr-VMAT optimizations were observed as a potential source of dose delivery inaccuracy. A trajectory smoothing procedure was implemented, and the base and smoothed treatment plans were delivered on the TrueBeam linear accelerator. The trajectory smoothing retained the treatment plan quality of the base trajectories. The delivery accuracy was largely within combined standard uncertainty. A systematic difference between measurement and calculation was observed that requires further investigation. The smoothed trajectory plans yielded improved agreement with measurement compared to the base trajectory plans.The final study investigated the gantry-couch rotation angle coordinate system. Trajectory optimizations were performed under a cartesian and spherical coordinate system for seven patient cases, using a overlap score map approach. The arclength between adjacent control points showed less variation for cases where the cartesian trajectory included arc segments with couch-only rotations. The objective function value was improved for 4 out of 7 patient cases for the spherical trajectories, but limitations of two-step trajectory optimization approaches were observed.Through the research presented in this thesis, clinical advantages of trajectory-based delivery were demonstrated, as well as the importance of trajectory smoothing to improve the accuracy of dose delivery. This work helps to pave the way towards the clinical implementation of trajectory-based treatment delivery"--

Radiotherapy treatment planning optimization employs metrics for the quantification of plan quality indicators based on a set of input desired criteria by the planner. Patient-specificity in current practice is limited to the customization and refinement of input optimization criteria to contextualize relative urgency. The arc geometry and machine trajectory in radiotherapy planning can create additional opportunities for optimization on a patient-specific basis. This work proposes novel technologies capable of leveraging new degrees of freedom in the domain of radiotherapy to improve radiotherapy plan quality. A series of four manuscripts form the basis for this thesis. The first manuscript, "Overlap Guided Fixed Patient Support Positioning Optimization for Cranial SRT", is an investigation into the optimization of couch rotation angle in the standard cranial stereotactic VMAT template to reduce the presence of overlap of sensitive structures with the targeted tissues in the aperture of the radiation beam. The second manuscript, "Dynamic Collimator Trajectory Algorithm for Multiple Metastases Dynamic Conformal Arc Treatment Planning", demonstrates a novel method of reducing the presence of uncollimated non-target anatomy from the aperture of the radiation beam and increases the efficacy of collimation by optimizing the rotation angles of the multi-leaf collimator. Additionally, it proposes the use of dynamically updated collimator angle throughout delivery to maximize the capacity of this optimization. The third manuscript, "Intra-Arc Binary Collimation Algorithm for the Optimization of Stereotactic Radiotherapy Treatment of Multiple Metastases with Multiple Prescriptions", demonstrates a novel method of aperture design in multiple metastases cranial radiosurgery which maximizes the presence of conformal aperture to increase the efficiency of monitor units, while regularly shielding targets completely to modulate dose to meet target prescription and healthy tissues sparing. Finally, the fourth manuscript, "CODA: Combined Optimization of Dynamic Axes", is the first investigation into the synergistic optimization of the rotation angle of the collimator, the rotation angle of the treatment couch, and the rotation angle of the gantry to accomplish the objectives of normal tissue sparing and treatment efficiency using a novel organization of cost function and trajectory design. These manuscripts form the basis for automated optimization of linear accelerator trajectories in cranial radiosurgery. Their implementation can result in significant increases in plan quality when compared to state of the art conventional treatment planning. The introduction of these additional forms of optimization can be used to mitigate the effects of inter-planner variation in plan quality by automating the steps performed in expert-planning.

Non-coplanar VMAT has the potential to treat tumors that are located in close proximity of critical organs or that are partially surrounded by normal tissues. The use of dynamic couch-gantry trajectories offers an opportunity for more precise and accurate delivery of radiation during cancer treatments.Despite the improvements that have been seen in non-coplanar VMAT, challenges still persist.In this thesis, we present a methodology for the determination of collision free couch-gantry orientations. This methodology is proposed to avoid the possibility of a collision during the motion of the couch and gantry during treatment.We propose an algorithm based on simulated annealing for non-coplanar VMAT treatment planning. This algorithm is used to select the best possible beam orientations for the accurate delivery of the prescribed dose.We also propose a RRT inspired algorithm for generating the trajectory for the non-coplanarVMAT plan delivery. The algorithm is proposed to solve the problem of the addition of intermediate beam orientations observed in beam selection methods.From the results of studies on the proposed methods, improvements to collision detection, global optimization and trajectory generation for non-coplanar VMAT treatment planning were observed. These improvements include a better dosimetry with respect to reductions in mean dose to the organs-at-risk and a more efficient delivery trajectory.Our studies indicate that there exists a reasonable trade-off between treatment plan quality and plan deliverability if the dosimetry of the VMAT treatment plan is continuously monitored during trajectory generation.

This book presents the proceedings of the IUPESM World Biomedical Engineering and Medical Physics, a tri-annual high-level policy meeting dedicated exclusively to furthering the role of biomedical engineering and medical physics in medicine. The book offers papers about emerging issues related to the development and sustainability of the role and impact of medical physicists and biomedical engineers in medicine and healthcare. It provides a unique and important forum to secure a coordinated, multileveled global response to the need, demand and importance of creating and supporting strong academic and clinical teams of biomedical engineers and medical physicists for the benefit of human health.

"The Varian TrueBeam STx linear accelerator features a developer's mode in which treatment plans can be programmed that include patient couch motion during radiation delivery. The combination of synchronous couch/gantry trajectories with Varian volumetric modulated arc therapy (VMAT) optimizations, called RapidArc, can result in a treatment technique that has been designated Virtual Isocenter RapidArc (VIRA). Prior to its implementation, the accuracy of dose calculations in the Varian Eclipse treatment planning system, on which the RapidArc optimization depends, must be validated, as well as the positional accuracy of the TrueBeam patient couch. The dose calculation accuracy was evaluated extrinsically through the delivery of clinical dynamic multileaf collimator (DMLC) intensity modulated radiotherapy (IMRT) treatment plans as a function of source-to-surface distance (SSD) and measurement with ionization chamber and Gafchromic EBT3 film. Parameters intrinsic to dose calculations in Eclipse, the dosimetric leaf gap (DLG) and leaf transmission (LT), were also investigated for their dependence on SSD. The positional accuracy of the treatment couch was assessed through the generation of treatment plans with static couch/gantry, static couch/rotating gantry, and synchronous couch and gantry motion, with measurement of the real-time ionization chamber current positioned in a cylindrical phantom during radiation delivery. The relative agreement of ionization chamber measurements to Eclipse dose calculations for DMLC IMRT treatment plans decreased by 1.5±0.3% over SSDs in the range of 85 cm to 135 cm (less than 1.0% deviation from standard clinical reference conditions of 100 cm SSD). Gafchromic EBT3 film measurements were consistent with ionization chamber results, though noise in the film data at low doses resulted in large uncertainties. Measurements of DLG were independent of SSD, following corrections for geometric projection. LT showed a dependence on SSD of 0.09±0.02% over the SSD range investigated. The ionization chamber current measurements for synchronous couch and gantry rotation, analogous to the proposed VIRA technique, indicated a maximum deviation of 0.2 cm relative to treatment isocenter, equal to the deviation observed for the rotating gantry/static couch treatment, analogous to conventional VMAT delivery. These results indicate that the Varian TrueBeam and Eclipse maintain the necessary positional and dosimetric accuracy required for VMAT treatments involving dynamic couch trajectories." --

Offering comprehensive coverage of the clinical, physical, and technical aspects of radiation treatment planning, Khan’s Treatment Planning in Radiation Oncology, Fifth Edition, provides a team approach to this complex field. Drs. Paul W. Sperduto and John P. Gibbons are joined by expert contributing authors who focus on the application of physical and clinical concepts to solve treatment planning problems—helping you provide effective, state-of-the-art care for cancer patients. This unique, well-regarded text has been updated throughout to reflect the most current practices in today’s radiation oncology treatment.