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VMAT

Rx: 18Gy/1fx mets + 15Gy/1fx resection cavity

Many vastly differing size and shape metastasis and resection target

 

Beams
DVH
Metrics

Name (ID): Brain Mets, 4 mets, CT-MR (VSS 06)
Plan or PlanSum ID: HA10m1rc

Structure ID Structure Code Patient Structure DVH Objective Evaluator Variation Priority Met Achieved
4GyBrain_noPTV   BRAIN-GTV V4Gy[cc]         195.18 cc
9GyBrain_noPTV   BRAIN-GTV V9Gy[cc]         35.51 cc
18GyBrain_noPTV   BRAIN-GTV V18Gy[cc]         0.62 cc
Brain_noPTV   BRAIN-GTV Mean[Gy]         3.066 Gy
GTV1   GTV1 V15Gy[%] >=99     Goal 99.68 %
GTV1   GTV1 Max[%]         113.8 %
GTV1   GTV1 Max[Gy]         20.486 Gy
GTV1   GTV1 Min[Gy]         14.033 Gy
GTV1   GTV1 Volume[cc]         19.82 cc
GTV2   GTV2 V100%[%] >=99     Goal 99.66 %
GTV2   GTV2 Max[%]         137.8 %
GTV2   GTV2 Max[Gy]         24.800 Gy
GTV2   GTV2 Min[Gy]         17.083 Gy
GTV2   GTV2 Volume[cc]         3.82 cc
GTV3   GTV3 V100%[%] >=99     Goal 99.71 %
GTV3   GTV3 Max[%]         140.1 %
GTV3   GTV3 Max[Gy]         25.219 Gy
GTV3   GTV3 Min[Gy]         17.601 Gy
GTV3   GTV3 Volume[cc]         0.24 cc
GTV5   GTV5 V100%[%] >=99     Goal 99.54 %
GTV5   GTV5 Max[%]         131.8 %
GTV5   GTV5 Max[Gy]         23.717 Gy
GTV5   GTV5 Min[Gy]         17.339 Gy
GTV5   GTV5 Volume[cc]         0.10 cc
GTV6   GTV6 V100%[%] >=99     Goal >99% (low sampling coverage)
GTV6   GTV6 Max[%]         118.8 %
GTV6   GTV6 Max[Gy]         21.379 Gy
GTV6   GTV6 Min[Gy]         17.749 Gy
GTV6   GTV6 Volume[cc]         0.03 cc
GTV7   GTV7 V100%[%] >=99     Goal 99.66 %
GTV7   GTV7 Max[%]         132.0 %
GTV7   GTV7 Max[Gy]         23.764 Gy
GTV7   GTV7 Min[Gy]         17.422 Gy
GTV7   GTV7 Volume[cc]         0.14 cc
GTV8   GTV8 V100%[%] >=99     Goal >99% (low sampling coverage)
GTV8   GTV8 Max[%]         125.1 %
GTV8   GTV8 Max[Gy]         22.520 Gy
GTV8   GTV8 Min[Gy]         17.592 Gy
GTV8   GTV8 Volume[cc]         0.08 cc
GTV9   GTV9 V100%[%] >=99     Goal >99% (low sampling coverage)
GTV9   GTV9 Max[%]         126.2 %
GTV9   GTV9 Max[Gy]         22.711 Gy
GTV9   GTV9 Min[Gy]         17.767 Gy
GTV9   GTV9 Volume[cc]         0.05 cc
GTV10   GTV10 V100%[%] >=99     Goal >99% (low sampling coverage)
GTV10   GTV10 Max[%]         121.9 %
GTV10   GTV10 Max[Gy]         21.933 Gy
GTV10   GTV10 Min[Gy]         17.469 Gy
GTV10   GTV10 Volume[cc]         0.04 cc
GTV11   GTV11 V100%[%] >=99     Goal 99.57 %
GTV11   GTV11 Max[%]         130.6 %
GTV11   GTV11 Max[Gy]         23.508 Gy
GTV11   GTV11 Min[Gy]         17.414 Gy
GTV11   GTV11 Volume[cc]         0.10 cc
GTV12   GTV12 V100%[%] >=99     Goal >99% (low sampling coverage)
GTV12   GTV12 Max[%]         128.4 %
GTV12   GTV12 Max[Gy]         23.118 Gy
GTV12   GTV12 Min[Gy]         18.188 Gy
GTV12   GTV12 Volume[cc]         0.04 cc
Brainstem   BRAINSTEM Max[Gy]         3.907 Gy
Chiasm   CHIASM Max[Gy]         4.785 Gy
Optic_Nrv_L   OPTIC_NRV_L Max[Gy]         3.955 Gy
Optic_Nrv_R   OPTIC_NRV_R Max[Gy]         2.391 Gy
Globe_L   GLOBE_L Max[Gy]         3.175 Gy
Globe_R   GLOBE_R Max[Gy]         1.977 Gy
Technical Plan Comments

HyperArc was utilized for this case which means it used a very simplified workflow for planning and delivery.  First the immobilization device is added as a structure model to the patient.  Then, creating a new HyperArc plan walks the user through the process of placing the isocenter of the predefined HyperArc beam set and identifying the target structures and their desired Rx dose.  At that point the Photon Optimizer can be launched automatically which includes preset lower objectives for each target with 100 priority and the HyperArc exclusive SRS NTO (also with 100 priority) which is tuned specifically to enforce a sharp dose falloff and prevent dose bridging of multiple adjacent disparate targets.

Eclipse 15.5+ also features the Automatic Lower Dose Objective (ALDO) which, when enabled in the Photon Optimizer, in the background automatically adjusts dose/priority to keep dose converge on targets near 98%.  Enabling ALDO thereby balances dose received by each target prescribed to the same dose level during optimization.

The plan presented here was created with minimal user interaction during optimization.  ALDO was enabled which did keep target coverage similar during optimization.  However, after final dose calculation there were minor differences in target coverage between some of the most extreme sized targets.  The offsets between requested and resulting calculated doses were noted and the optimizer was restarted with offsets added to the requested target doses.  The offsets were as follows: GTV1-resection 16.2Gy(from 15Gy), GTV2 19Gy, GTV3 18.5Gy, GTV8 18.5Gy, GTV9 18.5Gy, all other optimization objectives were left at their default values (18Gy) with no change made to any priority (all were 100).

Utilizing the ALDO feature resulted in significant time savings as most targets were equally covered after the first optimization and only a single additional optimization was required to create dose offsets in the optimizer for some of the most extreme large and small targets.  The Photon Optimizer calculation option Convergence Mode was set to Extended.

Links

Review 3rd party software generated full treatment plan report

PDF

                              

Download full DICOM CT, struct, plan and dose file         

ZIP        

Any reference to a "plan study" are simply what the organizers call each case and may not be a "study" in the FDA sense as they may not have been published in a peer reviewed journal.
Varian does not provide medical advice and these are illustrative examples only.
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