Field size effect of radiation quality in carbon therapy using passive method

Journal Article · Sun Mar 15 04:00:00 EDT 2009 · Medical Physics

DOI:https://doi.org/10.1118/1.3077490· OSTI ID:22098463

Nose, H.; Kase, Y.; Matsufuji, N.; Kanai, T. ^[1]

---

1. Advanced Applied Science Department, Research Laboratory, IHI Corporation, 1 Shin-Nakahara-Cho, Isogo-Ku, Yokohama 235-8501 (Japan)

The authors have investigated the dependency of radiation quality and absorbed dose on radiation field size in therapeutic carbon beams. The field size of the broad beam, formed using the passive technique, was controlled from 20 to 100 mm per side with a multileaf collimator. The absorbed dose and radiation quality on the beam center were evaluated at several depths in a water phantom using microdosimetric technique in experiments and Monte Carlo simulations. With an increase in the field size, the radiation quality was reduced, although the absorbed dose grew at the center of the field. This indicates that the dose and radiation quality at the center of the broad beam are influenced by particles from the off-center region via large-angle scattering and that such particles have relatively low radiation quality and mainly consist of fragment particles. Because such a tendency appeared to be more remarkable in the deeper region of the water phantom, it is likely that fragment particles that are born in a water phantom have a marked role in determining the field size effect.

• OSTI ID: 22098463
• Journal Information: Medical Physics, Journal Name: Medical Physics Journal Issue: 3 Vol. 36; ISSN 0094-2405; ISSN MPHYA6
• Country of Publication: United States
• Language: English

Related Subjects

61 RADIATION PROTECTION AND DOSIMETRY
62 RADIOLOGY AND NUCLEAR MEDICINE
CARBON
COMPUTERIZED SIMULATION
MICRODOSIMETRY
MONTE CARLO METHOD
PHANTOMS
RADIATION QUALITY
RADIOTHERAPY
SCATTERING
WATER