Development of dose delivery verification by PET imaging of photonuclear reactions following high energy photon therapy

Janek, Sara; Svensson, Roger; Jonsson, Cathrine; Brahme, Anders

doi:10.1088/0031-9155/51/22/004

Cited by 35 publications

(23 citation statements)

References 23 publications

(16 reference statements)

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“…Also IGRT taking advantage of more reliable imaging techniques such us ultrasmall superparamagnetic iron oxide (USPIO) enhanced MRI to detect node involvement or FDG-PET to demonstrate tumour response during a radiotherapy course, can furthermore improve rectal cancer treatment. Future developments will probably involve the use of new PET tracers in order to identify new boost areas within the CTV and the use of PET to monitor the dose deposition during treatment [54] leading to the next radiotherapy frontier known as voxelintensity based IMRT or dose painting by numbers.…”

Section: Discussionmentioning

confidence: 99%

IGRT in rectal cancer

Ippolito

Mertens²,

Haustermans³

et al. 2008

Acta Oncologica

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Section: Discussionmentioning

confidence: 99%

IGRT in rectal cancer

Ippolito

Mertens²,

Haustermans³

et al. 2008

Acta Oncologica

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“…This is not only of interest for treatment planning but also for the level of induced positron activity in the body, which can be used for in vivo treatment planning and treatment verification using PET-CT imaging. 17,28,29 Due to a peak photonuclear cross section around 24 MeV(for carbon and oxygen) an intrinsic electron energy of 75 MeV would be ideal for PET-CT imaging since the effective photon energy is about 1=3 of the energy of the primary electrons with the additional advantage of a FWHM of the photon pencil beam of about 10 mm further improving the dose delivery modulation. This has the additional advantage that the narrow scanned pencil beam will be as small as around 10 mm and thus allow further improve dose delivery modulation.…”

Section: Discussionmentioning

confidence: 99%

“…31 This makes narrow high energy beam scanning very interesting not only from a physical, dosimetric, and technical point of view but also for PET-CT treatment verification and biologically adaptive therapy optimization. 16,17,26,28,29 …”

Section: Discussionmentioning

confidence: 99%

Fast IMRT with narrow high energy scanned photon beams

et al. 2011

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Purpose: Since the first publications on intensity modulated radiation therapy (IMRT) in the early 1980s almost all efforts have been focused on fairly time consuming dynamic or segmental multileaf collimation. With narrow fast scanned photon beams, the flexibility and accuracy in beam shaping increases, not least in combination with fast penumbra trimming multileaf collimators. Previously, experiments have been performed with full range targets, generating a broad bremsstrahlung beam, in combination with multileaf collimators or material compensators. In the present publication, the first measurements with fast narrow high energy (50 MV) scanned photon beams are presented indicating an interesting performance increase even though some of the hardware used were suboptimal. Methods: Inverse therapy planning was used to calculate optimal scanning patterns to generate dose distributions with interesting properties for fast IMRT. To fully utilize the dose distributional advantages with scanned beams, it is necessary to use narrow high energy beams from a thin bremsstrahlung target and a powerful purging magnet capable of deflecting the transmitted electron beam away from the generated photons onto a dedicated electron collector. During the present measurements the scanning system, purging magnet, and electron collimator in the treatment head of the MM50 racetrack accelerator was used with 3-6 mm thick bremsstrahlung targets of beryllium. The dose distributions were measured with diodes in water and with EDR2 film in PMMA. Monte Carlo simulations with GEANT4 were used to study the influence of the electrons transmitted through the target on the photon pencil beam kernel. Results: The full width at half-maximum (FWHM) of the scanned photon beam was 34 mm measured at isocenter, below 9.5 cm of water, 1 m from the 3 mm Be bremsstrahlung target. To generate a homogeneous dose distribution in a 10 Â 10 cm 2 field, the authors used a spot matrix of 100 equal intensity beam spots resulting in a uniformity of collimated 80%-20% penumbra of 9 mm at a primary electron energy of 50 MeV. For the more complex cardioid shaped dose distribution, they used 270 spots, which at a pulse repetition frequency of 200 Hz is completed every 1.36 s. Conclusions: The present measurements indicate that the use of narrow scanned photon beams is a flexible and fast method to deliver advanced intensity modulated beams. Fast scanned photon IMRT should, therefore, be a very interesting modality in the delivery of biologically optimized radiation therapy with the possibility for in vivo treatment verification with PET-CT imaging.

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“…Promising conclusions have already been obtained by means of Geant4 simulations [16] as well as by measuring the activity distributions after the irradiation with hard photons by a conventional PET scanner [17]- [19]. However, due to the time delay between irradiation and measurement for off-beam PET the number of positron emitters decreases resulting in worse statistics.…”

Section: Introductionmentioning

confidence: 99%

In-Beam and Off-Beam PET Measurements of Target Activation by Megavolt X-Ray Beams

Kunath

Kluge

Pawelke

et al. 2009

IEEE Trans. Nucl. Sci.

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In-beam positron emission tomography (in-beam PET) is a valuable in situ method for quality assurance in radiation therapy. It is well investigated for therapy with carbon ions and has been successfully implemented clinically at the Gesellschaft für Schwerionenforschung (GSI), Darmstadt, Germany. The extension of this efficient technique to other radiation treatment modalities may be worthwhile. For protons, 3 He, 7 Li, and 16 O the feasibility has already been experimentally shown.Furthermore, it seems to be feasible for the case of radiotherapy with high-energy photons, since positron emitters are generated by photons with energies above 20 MeV due to ( ) photo-nuclear reactions (predominantly 11 C and 15 O in tissue). In this regard, promising conclusions have been obtained by Geant4 simulations as well as by off-beam PET experiments using a conventional PET scanner. The next step was the installation of a small double head positron camera consisting of two bismuth germanate (BGO) block detectors at the irradiation site to measure the generated + activity distribution simultaneously to the irradiation. The relation between deposited dose and + activity density was quantified. The obtained results are presented and compared to that of off-beam PET experiments. Higher activities as well as an improved contrast between materials of different stoichiometry are achieved by measuring in-beam, showing the advantage of in-beam PET over off-beam PET. Thus, the application of in-beam PET to radiation therapy with high-energy photons can be useful for quality assurance, comprising monitoring of dose delivery, patient positioning and tumor response.Index Terms-Dose monitoring, high-energy photon therapy, positron emission tomography.

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Development of dose delivery verification by PET imaging of photonuclear reactions following high energy photon therapy

Cited by 35 publications

References 23 publications

IGRT in rectal cancer

IGRT in rectal cancer

Fast IMRT with narrow high energy scanned photon beams

In-Beam and Off-Beam PET Measurements of Target Activation by Megavolt X-Ray Beams

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