Skip to main content
banner image
No data available.
Please log in to see this content.
You have no subscription access to this content.
No metrics data to plot.
The attempt to load metrics for this article has failed.
The attempt to plot a graph for these metrics has failed.
The full text of this article is not currently available.
/content/aapm/journal/medphys/40/2/10.1118/1.4773887
1.
1. G. A. Ezzell et al., “IMRT commissioning: Multiple institution planning and dosimetry comparisons, a report from AAPM Task Group 119,” Med. Phys. 36, 53595373 (2009).
http://dx.doi.org/10.1118/1.3238104
2.
2. D. A. Low et al., “A technique for the quantitative evaluation of dose distributions,” Med. Phys. 25, 656661 (1998).
http://dx.doi.org/10.1118/1.598248
3.
3. B. E. Nelms, H. Zhen, and W. A. Tomé, “Per-beam, planar IMRT QA passing rates do not predict clinically relevant patient dose errors,” Med. Phys. 38, 10371044 (2011).
http://dx.doi.org/10.1118/1.3544657
4.
4. H. Zhen, B. E. Nelms, and W. A. Tomé, “Moving from gamma passing rates to patient DVH-based QA metrics in pretreatment dose QA,” Med. Phys. 38, 54775489 (2011).
http://dx.doi.org/10.1118/1.3633904
5.
5. W. van Elmpt et al., “The next step in patient-specific QA: 3D dose verification of conformal and intensity-modulated RT based on EPID dosimetry and Monte Carlo dose calculations,” Radiother. Oncol. 86, 8692 (2008).
http://dx.doi.org/10.1016/j.radonc.2007.11.007
6.
6. T. Bortfeld et al., “Effects of intra-fraction motion on IMRT dose delivery: Statistical analysis and simulation,” Phys. Med. Biol. 47, 22032220 (2002).
http://dx.doi.org/10.1088/0031-9155/47/13/302
7.
7. E. D. Ehler, B. E. Nelms, and W. A. Tomé, “On the dose to a moving target while employing different IMRT delivery mechanisms,” Radiother. Oncol. 83, 4956 (2007).
http://dx.doi.org/10.1016/j.radonc.2007.02.007
8.
8. L. Court et al., “Evaluation of the interplay effect when using RapidArc to treat targets moving in the craniocaudal or right-left direction,” Med. Phys. 37, 411 (2010).
http://dx.doi.org/10.1118/1.3263614
9.
9. B. E. Nelms et al., “Quality assurance device for four-dimensional IMRT or SBRT and respiratory gating using patient-specific intrafraction motion kernels,” J. Appl. Clin. Med. Phys. 8, 152168 (2007).
http://dx.doi.org/10.1120/jacmp.v8i4.2683
10.
10. H. Norris, A. Thomas, and M. Oldham, “SU-C-213AB-06: Validation study of the accuracy of the transform method for clinically intuitive quality assurance,” Med. Phys. 39, 3599 (2012).
http://dx.doi.org/10.1118/1.4734611
11.
11. L. E. Court et al., “Use of a realistic breathing lung phantom to evaluate dose delivery errors,” Med. Phys. 37, 58505857 (2010).
http://dx.doi.org/10.1118/1.3496356
12.
12. S. Bharat et al., “Motion-compensated estimation of delivered dose during external beam radiation therapy: Implementation in Philips’ Pinnacle3 treatment planning system,” Med. Phys. 39, 437444 (2012).
http://dx.doi.org/10.1118/1.3670374
13.
13. B. Zhao et al., “Dosimetric effect of intrafraction tumor motion in phase gated lung stereotactic body radiotherapy,” Med. Phys. 39, 66296638 (2012).
http://dx.doi.org/10.1118/1.4757916
14.
14. M. H. Lin et al., “4D patient dose reconstruction using online measured EPID cine images for lung SBRT treatment validation,” Med. Phys. 39, 59495958 (2012).
http://dx.doi.org/10.1118/1.4748505
15.
15. B. E. Nelms et al., “VMAT QA: Measurement-guided 4D dose reconstruction on a patient,” Med. Phys. 39, 42284238 (2012).
http://dx.doi.org/10.1118/1.4729709
16.
16. A. J. Olch, “Evaluation of the accuracy of 3DVH software estimates of dose to virtual ion chamber and film in composite IMRT QA,” Med. Phys. 39, 8186 (2012).
http://dx.doi.org/10.1118/1.3666771
17.
17. J. Kozelka et al., “Optimizing the accuracy of a helical diode array dosimeter: A comprehensive calibration methodology coupled with a novel virtual inclinometer,” Med. Phys. 38, 50215032 (2011).
http://dx.doi.org/10.1118/1.3622823
18.
18. M. A. Admiraal, D. Schuring, and C. W. Hurkmans, “Dose calculations accounting for breathing motion in stereotactic lung radiotherapy based on 4D-CT and the internal target volume,” Radiother. Oncol. 86, 5560 (2008).
http://dx.doi.org/10.1016/j.radonc.2007.11.022
19.
19. T. D. Solberg et al., “Quality assurance of immobilization and target localization systems for frameless stereotactic cranial and extracranial hypofractionated radiotherapy,” Int. J. Radiat. Oncol., Biol., Phys. 71, S131S135 (2008).
http://dx.doi.org/10.1016/j.ijrobp.2007.05.097
20.
20. S. Pai et al., “TG-69: Radiographic film for megavoltage beam dosimetry,” Med. Phys. 34, 22282258 (2007).
http://dx.doi.org/10.1118/1.2736779
21.
21. B. Kanagaki et al., “A motion phantom study on helical tomotherapy: The dosimetric impacts of delivery technique and motion,” Phys. Med. Biol. 52, 243255 (2007).
http://dx.doi.org/10.1088/0031-9155/52/1/016
22.
22. Q. Liu, P. McDermott, and J. Burmeister, “Effect of respiratory motion on the delivery of breast radiotherapy using SMLC intensity modulation,” Med. Phys. 34, 347352 (2007).
http://dx.doi.org/10.1118/1.2405323
23.
23. E. Nioutsikou et al., “Quantifying the effect of respiratory motion on lung tumour dosimetry with the aid of a breathing phantom with deforming lungs,” Phys. Med. Biol. 51, 33593374 (2006).
http://dx.doi.org/10.1088/0031-9155/51/14/005
24.
24. C. Thilmann et al., “The influence of breathing motion on intensity modulated radiotherapy in the step-and-shoot technique: Phantom measurements for irradiation of superficial target volumes,” Phys. Med. Biol. 51, N117N126 (2006).
http://dx.doi.org/10.1088/0031-9155/51/6/N03
25.
25. Y. Y. Vinogradskiy et al., “Comparing the accuracy of four-dimensional photon dose calculations with three-dimensional calculations using moving and deforming phantoms,” Med. Phys. 36, 50005007 (2009).
http://dx.doi.org/10.1118/1.3238482
26.
26. C. Wu et al., “On using 3D γ-analysis for IMRT and VMAT pretreatment plan QA,” Med. Phys. 39, 30513060 (2012).
http://dx.doi.org/10.1118/1.4711755
27.
27. V. Gregoire and T. R. Mackie, “State of the art on dose prescription, reporting and recording in intensity-modulated radiation therapy (ICRU report No. 83),” Cancer Radiother. 15, 555559 (2011).
http://dx.doi.org/10.1016/j.canrad.2011.04.003
http://aip.metastore.ingenta.com/content/aapm/journal/medphys/40/2/10.1118/1.4773887
Loading
/content/aapm/journal/medphys/40/2/10.1118/1.4773887
Loading

Data & Media loading...

Loading

Article metrics loading...

/content/aapm/journal/medphys/40/2/10.1118/1.4773887
2013-01-15
2016-08-25

Abstract

Purpose:

To present a framework for measurement-guided VMAT dose reconstruction to moving patient voxels from a known motion kernel and the static phantom data, and to validate this perturbation-based approach with the proof-of-principle experiments.

Methods:

As described previously, the VMAT 3D dose to a static patient can be estimated by applying a phantom measurement-guided perturbation to the treatment planning system (TPS)-calculated dose grid. The fraction dose to any voxel in the presence of motion, assuming the motion kernel is known, can be derived in a similar fashion by applying a measurement-guided motion perturbation. The dose to the diodes in a helical phantom is recorded at 50 ms intervals and is transformed into a series of time-resolved high-density volumetric dose grids. A moving voxel is propagated through this 4D dose space and the fraction dose to that voxel in the phantom is accumulated. The ratio of this motion-perturbed, reconstructed dose to the TPS dose in the phantom serves as a perturbation factor, applied to the TPS fraction dose to the similarly situated voxel in the patient. This approach was validated by the ion chamber and film measurements on four phantoms of different shape and structure: homogeneous and inhomogeneous cylinders, a homogeneous cube, and an anthropomorphic thoracic phantom. A 2D motion stage was used to simulate the motion. The stage position was synchronized with the beam start time with the respiratory gating simulator. The motion patterns were designed such that the motion speed was in the upper range of the expected tumor motion (1–1.4 cm/s) and the range exceeded the normally observed limits (up to 5.7 cm). The conformal arc plans for X or Y motion (in the IEC 61217 coordinate system) consisted of manually created narrow (3 cm) rectangular strips moving in-phase (tracking) or phase-shifted by 90° (crossing) with respect to the phantom motion. The XY motion was tested with the computer-derived VMAT MLC sequences. For all phantoms and plans, time-resolved (10 Hz) ion chamber dose was collected. In addition, coronal (XY) films were exposed in the cube phantom to a VMAT beam with two different starting phases, and compared to the reconstructed motion-perturbed dose planes.

Results:

For the X or Y motions with the moving strip and geometrical phantoms, the maximum difference between perturbation-reconstructed and ion chamber doses did not exceed 1.9%, and the average for any motion pattern/starting phase did not exceed 1.3%. For the VMAT plans on the cubic and thoracic phantoms, one point exhibited a 3.5% error, while the remaining five were all within 1.1%. Across all the measurements (N = 22), the average disagreement was 0.5 ± 1.3% (1 SD). The films exhibited γ(3%/3 mm) passing rates ≥90%.

Conclusions

: The dose to an arbitrary moving voxel in a patient can be estimated with acceptable accuracy for a VMAT delivery, by performing a single QA measurement with a cylindrical phantom and applying two consecutive perturbations to the TPS-calculated patient dose. The first one accounts for the differences between the planned and delivered static doses, while the second one corrects for the motion.

Loading

Full text loading...

/deliver/fulltext/aapm/journal/medphys/40/2/1.4773887.html;jsessionid=21Ml0QGEBVQ6vIIg9reYNDIu.x-aip-live-02?itemId=/content/aapm/journal/medphys/40/2/10.1118/1.4773887&mimeType=html&fmt=ahah&containerItemId=content/aapm/journal/medphys
true
true

Access Key

  • FFree Content
  • OAOpen Access Content
  • SSubscribed Content
  • TFree Trial Content
752b84549af89a08dbdd7fdb8b9568b5 journal.articlezxybnytfddd
/content/realmedia?fmt=ahah&adPositionList=
&advertTargetUrl=//oascentral.aip.org/RealMedia/ads/&sitePageValue=online.medphys.org/40/2/10.1118/1.4773887&pageURL=http://scitation.aip.org/content/aapm/journal/medphys/40/2/10.1118/1.4773887'
Right1,Right2,Right3,