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Charged Particle Therapy with Mini-Segmented Beams.

Dilmanian FA, Eley JG, Rusek A, Krishnan S - Front Oncol (2015)

Bottom Line: In the case of interleaved carbon minibeams, which do not broaden much, two arrays of planar carbon minibeams that remain parallel at target depth, are aimed at the target from 90° angles and made to "interleave" at the target to produce a solid radiation field within the target.As a result, the surrounding tissues are exposed only to individual carbon minibeam arrays and are therefore spared.The resulting sparing of proximal normal tissue allows radiosurgical ablative treatments with smaller impact on the skin and shallow tissues.

View Article: PubMed Central - PubMed

Affiliation: Department of Radiation Oncology, Health Sciences Center, Stony Brook University , Stony Brook, NY , USA ; Department of Neurology, Health Sciences Center, Stony Brook University , Stony Brook, NY , USA ; Department of Radiology, Health Sciences Center, Stony Brook University , Stony Brook, NY , USA.

ABSTRACT
One of the fundamental attributes of proton therapy and carbon ion therapy is the ability of these charged particles to spare tissue distal to the targeted tumor. This significantly reduces normal tissue toxicity and has the potential to translate to a wider therapeutic index. Although, in general, particle therapy also reduces dose to the proximal tissues, particularly in the vicinity of the target, dose to the skin and to other very superficial tissues tends to be higher than that of megavoltage x-rays. The methods presented here, namely, "interleaved carbon minibeams" and "radiosurgery with arrays of proton and light ion minibeams," both utilize beams segmented into arrays of parallel "minibeams" of about 0.3 mm incident-beam size. These minibeam arrays spare tissues, as demonstrated by synchrotron x-ray experiments. An additional feature of particle minibeams is their gradual broadening due to multiple Coulomb scattering as they penetrate tissues. In the case of interleaved carbon minibeams, which do not broaden much, two arrays of planar carbon minibeams that remain parallel at target depth, are aimed at the target from 90° angles and made to "interleave" at the target to produce a solid radiation field within the target. As a result, the surrounding tissues are exposed only to individual carbon minibeam arrays and are therefore spared. The method was used in four-directional geometry at the NASA Space Radiation Laboratory to ablate a 6.5-mm target in a rabbit brain at a single exposure with 40 Gy physical absorbed dose. Contrast-enhanced magnetic resonance imaging and histology 6-month later showed very focal target necrosis with nearly no damage to the surrounding brain. As for minibeams of protons and light ions, for which the minibeam broadening is substantial, measurements at MD Anderson Cancer Center in Houston, TX, USA; and Monte Carlo simulations showed that the broadening minibeams will merge with their neighbors at a certain tissue depth to produce a solid beam to treat the target. The resulting sparing of proximal normal tissue allows radiosurgical ablative treatments with smaller impact on the skin and shallow tissues. This report describes these two methods and discusses their potential clinical applications.

No MeSH data available.


Related in: MedlinePlus

Proton pencil minibeams’ broadening for 109 MeV beam energy (circles: film measurements; x marks: the simulations in water).
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Figure 6: Proton pencil minibeams’ broadening for 109 MeV beam energy (circles: film measurements; x marks: the simulations in water).

Mentions: Figure 6 shows the measured minibeam broadening rate for 109-MeV proton pencil beams superimposed with the Monte Carlo simulations of the same minibeam width in water. The experimental minibeam width was defined as the full width at half-maximum of the beam’s image on the digitized film. The figure shows that the measured and the simulated 0.7-mm beam width for this beam energy are reached at 22 and 23.5 mm, respectively (19).


Charged Particle Therapy with Mini-Segmented Beams.

Dilmanian FA, Eley JG, Rusek A, Krishnan S - Front Oncol (2015)

Proton pencil minibeams’ broadening for 109 MeV beam energy (circles: film measurements; x marks: the simulations in water).
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4664668&req=5

Figure 6: Proton pencil minibeams’ broadening for 109 MeV beam energy (circles: film measurements; x marks: the simulations in water).
Mentions: Figure 6 shows the measured minibeam broadening rate for 109-MeV proton pencil beams superimposed with the Monte Carlo simulations of the same minibeam width in water. The experimental minibeam width was defined as the full width at half-maximum of the beam’s image on the digitized film. The figure shows that the measured and the simulated 0.7-mm beam width for this beam energy are reached at 22 and 23.5 mm, respectively (19).

Bottom Line: In the case of interleaved carbon minibeams, which do not broaden much, two arrays of planar carbon minibeams that remain parallel at target depth, are aimed at the target from 90° angles and made to "interleave" at the target to produce a solid radiation field within the target.As a result, the surrounding tissues are exposed only to individual carbon minibeam arrays and are therefore spared.The resulting sparing of proximal normal tissue allows radiosurgical ablative treatments with smaller impact on the skin and shallow tissues.

View Article: PubMed Central - PubMed

Affiliation: Department of Radiation Oncology, Health Sciences Center, Stony Brook University , Stony Brook, NY , USA ; Department of Neurology, Health Sciences Center, Stony Brook University , Stony Brook, NY , USA ; Department of Radiology, Health Sciences Center, Stony Brook University , Stony Brook, NY , USA.

ABSTRACT
One of the fundamental attributes of proton therapy and carbon ion therapy is the ability of these charged particles to spare tissue distal to the targeted tumor. This significantly reduces normal tissue toxicity and has the potential to translate to a wider therapeutic index. Although, in general, particle therapy also reduces dose to the proximal tissues, particularly in the vicinity of the target, dose to the skin and to other very superficial tissues tends to be higher than that of megavoltage x-rays. The methods presented here, namely, "interleaved carbon minibeams" and "radiosurgery with arrays of proton and light ion minibeams," both utilize beams segmented into arrays of parallel "minibeams" of about 0.3 mm incident-beam size. These minibeam arrays spare tissues, as demonstrated by synchrotron x-ray experiments. An additional feature of particle minibeams is their gradual broadening due to multiple Coulomb scattering as they penetrate tissues. In the case of interleaved carbon minibeams, which do not broaden much, two arrays of planar carbon minibeams that remain parallel at target depth, are aimed at the target from 90° angles and made to "interleave" at the target to produce a solid radiation field within the target. As a result, the surrounding tissues are exposed only to individual carbon minibeam arrays and are therefore spared. The method was used in four-directional geometry at the NASA Space Radiation Laboratory to ablate a 6.5-mm target in a rabbit brain at a single exposure with 40 Gy physical absorbed dose. Contrast-enhanced magnetic resonance imaging and histology 6-month later showed very focal target necrosis with nearly no damage to the surrounding brain. As for minibeams of protons and light ions, for which the minibeam broadening is substantial, measurements at MD Anderson Cancer Center in Houston, TX, USA; and Monte Carlo simulations showed that the broadening minibeams will merge with their neighbors at a certain tissue depth to produce a solid beam to treat the target. The resulting sparing of proximal normal tissue allows radiosurgical ablative treatments with smaller impact on the skin and shallow tissues. This report describes these two methods and discusses their potential clinical applications.

No MeSH data available.


Related in: MedlinePlus