Optimal number of beams for stereotactic body radiotherapy of lung and liver lesions

Liu, Ruiguo; Buatti, John M.; Howes, Terese L.; Dill, J.; Modrick, Joseph M.; Meeks, Sanford L.

doi:10.1016/j.ijrobp.2006.05.014

Cited by 44 publications

(26 citation statements)

References 30 publications

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“…25 In addition, in some tissues, such as lung and liver, that have low whole-organ dose tolerances, a higher number of beams may not be beneficial, since the limiting factor is whole-organ dose as opposed to dose to particular regions. 26 It is also worth noting that in some cases, it may be preferable to have an inhomogeneous dose. A particular structure may be so radiosensitive that it is preferable to avoid entirely delivering a beam from a certain angle, or an experimental protocol may require minimal dose to particular structures, so that they may serve as a control.…”

Section: Discussionmentioning

confidence: 99%

Investigation of the effects of treatment planning variables in small animal radiotherapy dose distributions

et al. 2010

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Purpose: Methods used for small animal radiation treatment have yet to achieve the same dose targeting as in clinical radiation therapy. Toward understanding how to better plan small animal radiation using a system recently developed for this purpose, the authors characterized dose distributions produced from conformal radiotherapy of small animals in a microCT scanner equipped with a variable-aperture collimator. Methods: Dose distributions delivered to a cylindrical solid water phantom were simulated using a Monte Carlo algorithm. Phase-space files for 120 kVp x-ray beams and collimator widths of 1-10 mm at isocenter were generated using BEAMnrc software, and dose distributions for evenly spaced beams numbered from 5 to 80 were generated in DOSXYZnrc for a variety of targets, including centered spherical targets in a range of sizes, spherical targets offset from centered by various distances, and various ellipsoidal targets. Dose distributions were analyzed using dose volume histograms. The dose delivered to a mouse bearing a spontaneous lung tumor was also simulated, and dose volume histograms were generated for the tumor, heart, left lung, right lung, and spinal cord. Results: Results indicated that for centered, symmetric targets, the number of beams required to achieve a smooth dose volume histogram decreased with increased target size. Dose distributions for noncentered, symmetric targets did not exhibit any significant loss of conformality with increasing offset from the phantom center, indicating sufficient beam penetration through the phantom for targeting superficial targets from all angles. Even with variable collimator widths, targeting of asymmetric targets was found to have less conformality than that of spherical targets. Irradiation of a mouse lung tumor with multiple beam widths was found to effectively deliver dose to the tumor volume while minimizing dose to other critical structures. Conclusions: Overall, this method of generating and analyzing dose distributions provides a quantitative method for developing practical guidelines for small animal radiotherapy treatment planning. Future work should address methods to improve conformality in asymmetric targets.

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Section: Discussionmentioning

confidence: 99%

Investigation of the effects of treatment planning variables in small animal radiotherapy dose distributions

et al. 2010

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“…Tumor volumes are also smaller. Hence, a small grid size (typically 2 mm) is recommended for dose calculation [1], and at least 5-9 noncoplanar or coplanar fields should be used for conventional treatment planning [35]. Small-size beam shaping devices may improve conformity of target dose distributions [1].…”

Section: Sbrt Techniquementioning

confidence: 99%

Consensus on Stereotactic Body Radiation Therapy for Small-Sized Hepatocellular Carcinoma at the 7th Asia-Pacific Primary Liver Cancer Expert Meeting

et al. 2017

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Background: Stereotactic body radiation therapy (SBRT) is an advanced technique of external beam radiation therapy that delivers large ablative doses of radiation. In the past decade, many cancer centers have adopted SBRT as one mode of radically treating small-sized hepatocellular carcinoma (HCC), based on encouraging clinical outcomes. SBRT thus seems reasonable as first-line treatment of inoperable HCC confined to the liver. However, most of the clinical studies to date have been retrospective in nature, with key issues still under investigation. Summary: The above-mentioned publications were subjected to scrutiny, fueling discussions at the 7th Asia-Pacific Primary Liver Cancer Expert (APPLE 2016) Meeting on various clinical variables, such as indications for SBRT, therapeutic outcomes, treatment-related toxicities, doses prescribed, and specific techniques. The consensus reached should be of interest to all professionals active in the treatment of HCC, especially radiation oncologists. Key Messages: SBRT is a safe and effective therapeutic option for patients with small-sized HCC, offering substantial local control, improved overall survival, and low toxicity.

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“…The objective function in (4) and the constraints in (2) and (3) form the MIP as the basis of our mathematical model. We emphasize that the neighbor cuts we discuss next can be added to any MIP formulation for BAO in radiation therapy treatment planning with any objective function or constraints.…”

Section: Mixed Integer Programming Treatment Planning Modelmentioning

confidence: 99%

“…Therefore finding the optimal solution to BAO requires an impractically long computation time, especially in case of IMRT. As a consequence, many heuristics have been developed to find "good" solutions to BAO (e.g., [2][3][4][5][6][7]. One heuristic which has sometimes been used is beam elimination, i.e., identifying and eliminating beams which are less likely to be among the optimal orientation.…”

Section: Introductionmentioning

confidence: 99%

MO‐A‐137‐03: Effective Heuristic Cuts for Beam Angle Optimization in Radiation Therapy

Yarmand

Craft

2013

Medical Physics

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2 AbstractPurpose: To improve the solution efficiency (i.e., reducing computation time while obtaining highquality treatment plans) for the beam angle optimization problem (BAO) in radiation therapy treatment planning. Methods:We formulate BAO as a mixed integer programming problem (MIP) whose solution gives the optimal beam orientation as well as optimal beam intensity map. We propose and investigate two novel heuristic approaches to reduce the computation time of the resultant MIP. One is a family of heuristic cuts based on the observation that the number of candidate beams is usually much larger than the number of beams used in the treatment plan, and therefore, it is less likely that "adjacent" beams are simultaneously used in the optimal treatment plan. The proposed cuts, referred to as "neighbor cuts", force the optimization system to choose one or a few beams from any set of adjacent beams. As a result, the search space and the computation time are reduced considerably. The second heuristic is a beam elimination scheme to eliminate beams with an insignificant contribution to deliver the dose to the tumor in the ideal plan in which all potential beams can be used simultaneously. Both heuristics can be added to any MIP formulation for BAO including the cases of coplanar/noncoplanar beams for intensity modulated radiation/proton therapy (IMRT and IMPT) and stereotactic body radiation therapy (SBRT). For the numerical experiments a clinical liver case (IMRT and SBRT) with 34 coplanar beams were considered. Results:We first solved the corresponding MIP without the heuristics and recorded the optimal solution and the computation time. Then we incorporated the heuristics into the MIP and resolved it. Our results show that both heuristics reduce the computation time considerably while obtaining high-quality treatment plans. Conclusion:This research incorporates two observations to improve the efficiency of the solution technique for BAO drastically: optimal beam configurations are typically a sparse set of well-spaced beams and optimal beams have a relatively large contribution to deliver the dose to the tumor in the ideal plan.3

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Optimal number of beams for stereotactic body radiotherapy of lung and liver lesions

Cited by 44 publications

References 30 publications

Investigation of the effects of treatment planning variables in small animal radiotherapy dose distributions

Investigation of the effects of treatment planning variables in small animal radiotherapy dose distributions

Consensus on Stereotactic Body Radiation Therapy for Small-Sized Hepatocellular Carcinoma at the 7th Asia-Pacific Primary Liver Cancer Expert Meeting

MO‐A‐137‐03: Effective Heuristic Cuts for Beam Angle Optimization in Radiation Therapy

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