Feasibility of prostate robotic radiation therapy on conventional C-arm linacs

Dong, Peng; Nguyen, Dan; Ruan, Dan; King, Christopher R.; Long, Tammy M.; Romeijn, Edwin; Low, Daniel A.; Kupelian, Patrick A.; Steinberg, Michael; Yang, Yingli; Sheng, Ke

doi:10.1016/j.prro.2013.10.009

Cited by 41 publications

(51 citation statements)

References 25 publications

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“…However, the off-plane dose is low and less of a concern in prostate treatment. This is consistent with previous studies comparing VMAT to 4π for a different prostate stereotactic body radiotherapy patient cohort [17]. Putting all three modalities together, one may make the observation that IMPT excels at reducing the maximal point dose to surrounding normal organs, reducing the low dose spillage and achieving a more homogeneous target dose.…”

Section: Discussionsupporting

confidence: 89%

Treatment planning comparison of IMPT, VMAT and 4π radiotherapy for prostate cases

et al. 2017

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BackgroundIntensity-modulated proton therapy (IMPT), non-coplanar 4π intensity-modulated radiation therapy (IMRT), and volumetric-modulated arc therapy (VMAT) represent the most advanced treatment methods based on heavy ion and X-rays, respectively. Here we compare their performance for prostate cancer treatment.MethodsTen prostate patients were planned using IMPT with robustness optimization, VMAT, and 4π to an initial dose of 54 Gy to a clinical target volume (CTV) that encompassed the prostate and seminal vesicles, then a boost prescription dose of 25.2 Gy to the prostate for a total dose of 79.2 Gy. The IMPT plans utilized two coplanar, oblique scanning beams 10° posterior of the lateral beam positions. Range uncertainties were taken into consideration in the IMPT plans. VMAT plans used two full, coplanar arcs to ensure sufficient PTV coverage. 4π plans were created by inversely selecting and optimizing 30 beams from 1162 candidate non-coplanar beams using a greedy column generation algorithm. CTV doses, bladder and rectum dose volumes (V40, V45, V60, V65, V70, V75, and V80), R100, R50, R10, and CTV homogeneity index (D95/D5) were evaluated.ResultsCompared to IMPT, 4π resulted in lower anterior rectal wall mean dose as well as lower rectum V40, V45, V60, V65, V70, and V75. Due to the opposing beam arrangement, IMPT resulted in significantly (p < 0.05) greater femoral head doses. However, IMPT plans had significantly lower bladder, rectum, and anterior rectal wall max dose. IMPT doses were also significantly more homogeneous than 4π and VMAT doses.ConclusionCompared to the VMAT and 4π plans, IMPT treatment plans are superior in CTV homogeneity and maximum point organ-at-risk (OAR) doses with the exception of femur heads. IMPT is inferior in rectum and bladder volumes receiving intermediate to high doses, particularly to the 4π plans, but significantly reduced low dose spillage and integral dose, which are correlated to secondary cancer for patients with expected long survival. The dosimetric benefits of 4π plans over VMAT are consistent with the previous publication.

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Section: Discussionsupporting

confidence: 89%

Treatment planning comparison of IMPT, VMAT and 4π radiotherapy for prostate cases

et al. 2017

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“…The use of additional 4π space in radiotherapy has been shown to deliver highly conformal plans with a reduction in high dose spillage for lung, liver, prostate, and brain plans . The additional beam entrance angles and improved conformality allows for more normal tissue sparing, which allows for reduced treatment‐related toxicity, furthers opportunity for re‐irradiation, and may enable dose escalation where warranted.…”

Section: Discussionmentioning

confidence: 99%

Lateral head flexion as a noncoplanar solution for ring gantry stereotactic radiosurgery

et al. 2019

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Purpose Ring gantry radiotherapy devices are often limited to deliver beams in the axial plane, severely limiting beam entrance angles and rendering noncoplanar beam delivery impossible. However, a ring gantry geometry greatly simplifies delivery machines and increases the efficiency of treatment with the potential to decrease the overall costs of radiotherapy. This study explores the use of lateral head flexion in order to increase beam entrance angles and extend the available solid angle space for a ring gantry stereotactic radiosurgery (SRS) application. Materials and methods A 1.5 T magnetic resonance imaging scanner was used to scan seven healthy volunteers at three different head positions: a neutral position, a left lateral flexion position and a right lateral flexion position. The lateral flexion scans were co‐registered to the neutral head position scan using rigid registration and extracting the rotational transformation. The head pitch, roll, and yaw were computed for each registration to evaluate the natural range of motion for all volunteers. A ring gantry plan geometry was used to generate two sets of single fraction SRS plans (21 Gy): one coplanar set for head neutral scans, and a three‐arc plan set using the head neutral and lateral head flexion scans. The conformity index (CI), intermediate dose fall‐off (R50), low dose spillage (R10), and gradient measure (GM) were used to evaluate both sets of plans. The treatment plans were generated for a ring‐gantry linear accelerator (linac) (Varian Halcyon 2.0) as well as radiosurgery linac (Varian Edge) for comparison. Results The average pitch, yaw, and roll for the lateral head flexion scans were 4.1° ± 4.7°, 16.9° ± 3.7°, and 2.5° ± 4.9° for the right flexion and 4.9° ± 4.3°, 14.0° ± 3.7° and 2.8° ± 5.4° for left flexion. When comparing the head flexion technique with a fully coplanar geometry, the ring gantry plans showed an average improvement in CI of 7.3% (1.46 ± 0.25 vs 1.36 ± 0.28), a decrease of 13% in R50 (5.46 ± 1.14 vs 4.78 ± 1.12), a decrease of 32% in R10 (85.7 ± 20.3 vs 58.2 ± 15.1), and a decrease of 7.8% in GM (0.53 ± 0.05 vs 0.49 ± 0.04). The Edge plans showed an average improvement in CI of 3.0% (1.49 ± 0.26 vs 1.45 ± 0.25), a decrease of 6.8% in R50 (5.19 ± 1.03 vs 4.82 ± 0.83), a decrease of 29% in R10 (84.1 ± 16.3 vs 59.9 ± 12.5), and a decrease of 5.0% in GM (0.50 ± 0.04 vs 0.47 ± 0.03). Conclusion Lateral head flexion was shown to increase beam entrance angles considerably improving plan conformity and normal tissue sparing in this pilot study of seven sets of plans. Rigid registrations demonstrated each lateral flexion to be analogous to a 15° couch kick. The head flexion technique outlined here was shown to be a feasible solution for SRS treatments being delivered on ring gantry devices.

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“…One of the techniques that challenge this perception is the 4 π approach, which involves the use of multiple noncoplanar beams using robotic couch and gantry on modern C‐arm linear accelerators. The studies from the University of California (Los Angeles, UCLA) have elegantly described this technique and have demonstrated significant sparing of OAR and discussed the potential for dose escalation in patients of lung, liver, prostate, HNC, and brain tumors 9, 10, 11, 12, 13…”

Section: Discussionmentioning

confidence: 99%

“…More recently, some groups explored the possibility to deliver SF‐IMRT with conventional c‐arm linear accelerators using most of the 4 π space, i.e., making extensive use of noncoplanar beam arrangements and creating complex delivery trajectories for the couch‐gantry‐collimator system around the patient 10, 11, 12, 13, 14, 15. These investigators focused on stereotactic irradiation in the brain, lungs, and prostate and have shown that significantly sharper dose gradients can be achieved with this approach.…”

Section: Introductionmentioning

confidence: 99%

Multi‐isocentric 4π volumetric‐modulated arc therapy approach for head and neck cancer

Subramanian

Subramani

Chilukuri

et al. 2017

J Applied Clin Med Phys

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ObjectivesTo explore the feasibility of multi‐isocentric 4π volumetric‐modulated arc therapy (MI4π‐VMAT) for the complex targets of head and neck cancers.MethodsTwenty‐five previously treated patients of HNC underwent re‐planning to improve the dose distributions with either coplanar VMAT technique (CP‐VMAT) or noncoplanar MI4π‐VMAT plans. The latter, involving 3–6 noncoplanar arcs and 2–3 isocenters were re‐optimized using the same priorities and objectives. Dosimetric comparison on standard metrics from dose‐volume histograms was performed to appraise relative merits of the two techniques. Pretreatment quality assurance was performed with IMRT phantoms to assess deliverability and accuracy of the MI4π‐VMAT plans. The gamma agreement index (GAI) analysis with criteria of 3 mm distance to agreement (DTA) and 3% dose difference (DD) was applied.Results CP‐VMAT and MI4π‐VMAT plans achieved the same degree of coverage for all target volumes related to near‐to‐minimum and near‐to‐maximum doses. MI4π‐VΜΑΤ plans resulted in an improved sparing of organs at risk. The average mean dose reduction to the parotids, larynx, oral cavity, and pharyngeal muscles were 3 Gy, 4 Gy, 5 Gy, and 4.3 Gy, respectively. The average maximum dose reduction to the brain stem, spinal cord, and oral cavity was 6.0 Gy, 3.8 Gy, and 2.4 Gy. Pretreatment QA results showed that plans can be reliably delivered with mean gamma agreement index of 97.0 ± 1.1%.Conclusions MI4π‐VMAT plans allowed to decrease the dose‐volume‐metrics for relevant OAR and results are reliable from a dosimetric standpoint. Early clinical experience has begun and future studies will report treatment outcome.

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Feasibility of prostate robotic radiation therapy on conventional C-arm linacs

Cited by 41 publications

References 25 publications

Treatment planning comparison of IMPT, VMAT and 4π radiotherapy for prostate cases

Treatment planning comparison of IMPT, VMAT and 4π radiotherapy for prostate cases

Lateral head flexion as a noncoplanar solution for ring gantry stereotactic radiosurgery

Multi‐isocentric 4π volumetric‐modulated arc therapy approach for head and neck cancer

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