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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

Depth-dose distributions from 10 MV x-rays, proton beams, and carbon ion beams superimposed with each other for comparison.
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Figure 1: Depth-dose distributions from 10 MV x-rays, proton beams, and carbon ion beams superimposed with each other for comparison.

Mentions: Although the introduction of the megavoltage (MV) x-ray machines into radiation therapy, which occurred in the middle of the twentieth century, solved the problem of damage to the skin and other proximal tissues from low-energy orthovoltage x-rays the challenge to find better beams for radiation therapy did not go away. This is because the dose distribution produced in tissues from MV x-rays is far from ideal. As seen in Figure 1, they give unnecessary dose to the normal tissues surrounding the target both proximal and distal to the target. Furthermore, their lateral dose penumbra is very large. Although proton and carbon ion beams clearly produce a better dose confinement at the target because of their Bragg-Peak feature, they both lack the shallow-tissue-sparing effect of high-energy x-rays, which is considered a significant shortcoming.


Charged Particle Therapy with Mini-Segmented Beams.

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

Depth-dose distributions from 10 MV x-rays, proton beams, and carbon ion beams superimposed with each other for comparison.
© Copyright Policy
Related In: Results  -  Collection

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

Figure 1: Depth-dose distributions from 10 MV x-rays, proton beams, and carbon ion beams superimposed with each other for comparison.
Mentions: Although the introduction of the megavoltage (MV) x-ray machines into radiation therapy, which occurred in the middle of the twentieth century, solved the problem of damage to the skin and other proximal tissues from low-energy orthovoltage x-rays the challenge to find better beams for radiation therapy did not go away. This is because the dose distribution produced in tissues from MV x-rays is far from ideal. As seen in Figure 1, they give unnecessary dose to the normal tissues surrounding the target both proximal and distal to the target. Furthermore, their lateral dose penumbra is very large. Although proton and carbon ion beams clearly produce a better dose confinement at the target because of their Bragg-Peak feature, they both lack the shallow-tissue-sparing effect of high-energy x-rays, which is considered a significant shortcoming.

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