Modulation of radiotherapy photon beam intensity using magnetic field.

International journal of cancer · 2001 · Mixed · Low evidence

← Research stream

MixedLow evidencePaper 3877

Study snapshot

PublicationInternational journal of cancer · 2001

Study typeengineering

Reported directionMixed

Evidence ratingLow

Abstract

The purpose of this study was to explore the potential advantages of using strong magnetic fields to increase tumor dose and to decrease normal tissue dose in radiation therapy. Strong magnetic fields are capable of altering the trajectories of charged particles. A magnetic field applied perpendicularly to the X-ray beam forces the secondary electrons and positrons to spiral and produces a dose peak. The same magnetic field also prevents the electrons and positrons from traveling downstream and produces a lower dose region distal to the dose peak. The locations of these high- and low-dose regions are potentially adjustable to enhance the dose to the target volume and decrease the dose to normal tissues. We studied this effect using the Monte Carlo simulation technique. The EGS4 code was used to simulate the effect produced by a coil magnet currently under construction. The coil magnet is designed to support up to 350 A operating current and 15 T peak field on windings. Dose calculations in a water phantom show that the transverse magnetic field produces significant dose effects along the beam direction of radiation therapy X-rays. Depending on the beam orientation, the radiation dose at different depths along the beam can be increased or reduced. This dose effect varies with photon energy, field size, magnetic field strength, and relative magnet/beam geometry. The off-axis beam profiles also show considerable skewness under the influence of the magnetic field. The magnetic field-induced dose shift may result in high dose regions outside the geometrical boundary of the initial radiation beam. We have demonstrated that current or near-term magnet technology is capable of producing significant dose enhancement and reduction in radiation therapy photon beams. This technology should be further developed to improve our ability to deliver higher doses to the tumor and lower doses to normal tissues in radiation therapy.

Machine Enhanced Logic

AI evidence extraction

Structured fields below were generated from the paper’s abstract and metadata to make the evidence easier to inspect. Automated extraction may be incomplete or incorrect; verify important details against the original paper.

Study typeengineering

Effect directionmixed

PopulationNot supplied

Sample sizeNot supplied

ExposureNot supplied

Evidence strengthLowConfidence: 74% · Peer reviewed: yes

Main findings

Using Monte Carlo simulations (EGS4) of a coil magnet (up to 350 A operating current; 15 T peak field on windings), a transverse magnetic field produced significant changes in dose along the beam direction for radiotherapy X-rays in a water phantom. Depending on beam orientation and parameters (photon energy, field size, magnetic field strength, and magnet/beam geometry), dose at different depths could be increased or reduced, and off-axis profiles showed skewness with possible high-dose regions outside the initial beam boundary.

Outcomes measured

Radiation dose distribution changes in a water phantom (dose peak and distal dose reduction)
Off-axis beam profile skewness
Potential dose shift outside geometric beam boundary

Limitations

Simulation study in a water phantom; no clinical or biological outcomes reported
Specific magnet design and geometry; generalizability to other systems not established in abstract
Quantitative effect sizes not provided in abstract

View raw extracted JSON

{
  "study_type": "engineering",
  "exposure": {
    "band": null,
    "source": "strong transverse magnetic field applied during radiotherapy photon (X-ray) beam delivery",
    "frequency_mhz": null,
    "sar_wkg": null,
    "duration": null
  },
  "population": null,
  "sample_size": null,
  "outcomes": [
    "Radiation dose distribution changes in a water phantom (dose peak and distal dose reduction)",
    "Off-axis beam profile skewness",
    "Potential dose shift outside geometric beam boundary"
  ],
  "main_findings": "Using Monte Carlo simulations (EGS4) of a coil magnet (up to 350 A operating current; 15 T peak field on windings), a transverse magnetic field produced significant changes in dose along the beam direction for radiotherapy X-rays in a water phantom. Depending on beam orientation and parameters (photon energy, field size, magnetic field strength, and magnet/beam geometry), dose at different depths could be increased or reduced, and off-axis profiles showed skewness with possible high-dose regions outside the initial beam boundary.",
  "effect_direction": "mixed",
  "limitations": [
    "Simulation study in a water phantom; no clinical or biological outcomes reported",
    "Specific magnet design and geometry; generalizability to other systems not established in abstract",
    "Quantitative effect sizes not provided in abstract"
  ],
  "evidence_strength": "low",
  "confidence": 0.74,
  "peer_reviewed_likely": "yes",
  "keywords": [
    "magnetic field",
    "radiotherapy",
    "photon beam",
    "X-ray",
    "secondary electrons",
    "positrons",
    "Monte Carlo simulation",
    "EGS4",
    "dose distribution",
    "water phantom",
    "15 T magnet"
  ],
  "suggested_hubs": [
    {
      "slug": "engineering-controls",
      "weight": 0.78,
      "reason": "Study models use of strong magnetic fields to modulate radiotherapy photon beam dose distribution (technology/physics application rather than health effects of environmental EMF)."
    }
  ]
}

AI can be wrong. Always verify against the paper.

AI-extracted fields are generated from the abstract and metadata and may be incomplete or incorrect. This material is for informational purposes and is not medical advice.

Identifiers and source

DOI: 10.1002/ijc.10352
PubMed: 11992397

Read the original paper →

Related papers

← Back to the Research Library