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INTRODUCTIONAccording to the National Cancer Institute, Glioblastomas multiforme (GBM)

account for approximately 52% of all primary brain tumors, which occur in the range of 45 to 70 years of age (AANS, 2015). Recent clinical history shows that the development of GBM treatment plans can be labor intensive and complex due to the abundance of organs at risk (OARs) present in the treatment vicinity. Volumetric Modulated Arc Therapy (VMAT) is a modern external beam radiation modality that generally delivers optimal radiation treatment plans. Nonetheless, the medical industry continues to innovate techniques that can reduce the planning time and maintain the quality of the treatment plans. Recently, Philips released an auto-plan feature within Pinnacle’s treatment planning software (TPS) that claims to provide clinically acceptable treatment plans at a faster rate versus manually crafted plans. Therefore, the objective of this research is to provide a dosimetric comparison between VMAT auto-plan versus VMAT manual plan for Glioblastoma cases.

METHODS & MATERIALS

RESULTS RESULTS (CONTINUED)

DISCUSSION

CONCLUSIONS

REFERENCES

With the vast diversity in experience among dosimetrists, manually crafted plans range between sub-optimal to nearly perfect depending on who constructs the plan. Despite the fact that this study highlighted the comparison of auto-plans solely generated by the TPS versus manually crafted plans, it is recognized that in a clinical setting the combination of both planning techniques is applied in order to produce optimal plans. A major benefit of auto-planning is the elimination of sub-optimal plans due to inexperience. With one optimization using auto-planning, a plan that requires minor adjustments is usually produced. By increasing the quality of plans produced with the auto-plan technique, the quality of care patients receive is increased, and their likelihood of radiation toxicity and side effects are decreased.

Isaac D. ValdezEmail address: IDVALDEZ@MDANDERSON.ORG

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Figure 1. Demonstrates the planning time difference between auto and manual plans.

Figure 2. Illustrates the OARs max dose percent difference between auto and manual plans.

Figure 3. Illustrates the OARs mean dose percent difference between auto and manual plans.

Figure 4. Depicts the brain V30 Gy percent difference between auto and manual plans.

Figure 5. Is a visual manual vs. auto-plan trail comparison from one of the plans studied. The left two quadrants show the axial and sagittal planes of the VMAT manual plan and the right two quadrants show the auto-plan views.

CONTACT INFORMATION

1. American Association of Neurological Surgeons, "Glioblastoma Multiforme", Glioblastoma Multiforme, October 2015, www.aans.org (31 March 2017)

2. Dunlop et al., Brain-Sparing Methods for IMRT of Head and Neck Cancer. Plos ONE. 10, 1-13, (2015)3. V. Feygelman et al., Initial evaluation of automated treatment planning software. Journal of Applied Clinical

Medical Physics. 17, 331-3466. (2016)4. Y. Jeong et al., A dosimetric comparison of volumetric modulated arc therapy (VMAT) and non-coplanar intensity

modulated radiotherapy (IMRT) for nasal cavity and paranasal sinus cancer. Radiation Oncolog, 9, 193. (2014)5. J. Krayenbuehl et al., Evaluation of an automated knowledge based treatment planning system for head and

neck. Radiation Oncology. 10, 226-234. (2015)6. E. Schreibmann et al., Automated population-based planning for whole brain radiation therapy. Journal of Applied

Clinical Medical Physics. 15, 76-86. (2015)7. D. Teguh et al., Clinical Validation of Atlas-Based Auto-Segmentation of Multiple Target Volumes and Normal

Tissue (Swallowing/Mastication) Structures in the Head and Neck. International Journal of Radiation Oncology, Biology, Physics. 81. 950-957. (2011)

8. J.P. Tol et al., Automatic interactive optimization for volumetric modulated arc therapy planning. Radiation Oncology (London, England). 10, 75-87. (2015)

9. Xhaferllari et al., Automated IMRT planning with regional optimization using planning scripts. Journal of Applied Clinical Medical Physics. 14, 176-191. (2013)

10. H. Yang et al., Comparison of three-dimensional conformal radiation therapy, intensity-modulated radiation therapy, and volumetric-modulated arc therapy in the treatment of cervical esophageal carcinoma. Diseases of the Esophagus. 30, 1-8. (2016)

A Dosimetric Comparison on the Efficiency of Philips Pinnacle’s 9.10v Auto-Plan Algorithm: Comparison of VMAT Manual Plan vs. VMAT Auto-Plan in the Treatment of Glioblastomas

Isaac D. Valdez, B.S., Sheeda H. Vo, Antonio Martinez Jr, B.S., Brody L. Barker, R.T.(R)., M. Fernanda Gomez, Shirly J. Kuruvila, B.S., CMD.The University of Texas MD Anderson Cancer Center School of Health Professions – Houston, Tx

Auto vs. Manual Planning Time

Organs At Risk Max Dose Auto vs. Manual Plans

Organs At Risk Mean Dose Auto vs. Manual Plans

Brain V30 Auto vs Manual Plans

Patient & Tumor Information

• Twelve patients diagnosed with GBM were retrospectively studied.• GTV size ranged from 36.68 cc to 205.3 cc.• Tumor location were multi-regionally located in the brain.

Volumes Considered

• GTV• PTV = GTV + 2.5 cm • Boost PTV = GTV + 0.5 cm

Organs at Risk Toxicity Constraints

Planning Process Details

• TPS: Philips Pinnacle 9.10v• Plans were re-optimized twice (manual and auto-plan)• VMAT smart arc was utilized

– Two full arcs – Start & Stop angles: 182° clockwise and 178° counter clockwise

• Collimator angles– 10° and 350° respectively in order to minimize MLC leakage

Planning Goals

Data Collection & Analysis

• For all plans, the start of the timer began after the planner loaded the initial plan scan and it ended after the planner met the goals.

• All of the data was analyzed by an average of percent difference calculation.

Organs Dose ConstraintsLenses • 150 – 500 cGyOptic Nerves • Max dose ≤ 54 GyOptic Chiasm • Max dose ≤ 54 GyBrainstem • Max dose ≤ 54 Gy

• If Boost PTV is very close, per RTOG, 60 Gy ≤ 0.01cc,V55 ≤ 0.5cc, V30 ≤ 33%

BrainBrain – (GTV, chiasm, brainstem)

• Mean dose of 30 Gy • V30 ≤ 50 Gy• Keep 30 Gy conformal around the target

Cochleae • Max dose ≤ 45 Gy• Mean ≤ 30 Gy

Pituitary Gland • Mean dose < 40 Gy Eyes • Max dose ≤ 40 Gy

• Mean dose ≤ 30 Gy

Objectives ParametersGTV • 100% coverageBoost PTV • 100% coveragePTV • ≥ 95 % coverage OARs • Meet toxicity levels & ALARA without jeopardizing

target coverage

• The planning time on auto-plans was on average 24.6% faster than manual plans.• Both methods achieved 100% of GTV coverage.• Target dose conformality & low dose control was improved by 4.2% in auto-plan.• Most OAR max and mean dose tolerances were on average superior in manual

plans.

• The auto-plan algorithm was able to meet the OARs dose constraints and reduce planning time by an average of 24.6%.

• Manual plans maintained the ability to further tailor the dose contamination to the critical structures.

• As a standalone technique, the auto-plan algorithm was not adequate enough as it did not ensure maximum sparing of OARs.

• As technological advancements aim to automate the radiation treatment planning process, it is of utmost importance to actively continue to investigate the efficiency and reliability of such practices.