Effect of head phantom size on [sup 10]B and [sup 1]H[[ital n],[gamma]][sup 2]H dose distributions for a broad field accelerator epithermal neutron source for BNCT

Journal Article · Mon Mar 01 04:00:00 EST 1993 · Medical Physics; (United States)

DOI:https://doi.org/10.1118/1.597131· OSTI ID:6617580

Gupta, N ^[1]; Niemkiewicz, J ^[2]; Blue, T E ^[1]; Gahbauer, R ^[3]; Qu, T X ^[1]

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1. Nuclear Engineering Program, Ohio State University, 1079 Robinson Laboratory, 206 W. 18th Avenue, Columbus, Ohio 43210 (United States)
2. Department of Radiation Oncology, Riverside Methodist Hospitals, 3535 Olentangy River Road, Columbus, Ohio 43214 (United States)
3. Department of Radiation Oncology, Ohio State University, Arthur James Cancer Hospital, 090A, 300 W. 10th Avenue, Columbus, Ohio 43210 (United States)

The effect of head phantom size on the [sup 10]B and [sup 1]H[[ital n],[gamma]][sup 2]H dose distributions for a broad epithermal neutron radiation field generated by an accelerator-based epithermal neutron source for boron neutron capture therapy (BNCT) have been studied. Also two techniques for calculating the absorbed gamma dose from a measured gamma-ray source distribution are compared: a Monte Carlo technique, which is well accepted in the BNCT community, and a Point Kernel technique. The count-rate distribution in the central plane of three rectangular parallelopiped head water phantoms irradiated with an epithermal neutron field was measured with a boron trifluoride (BF[sub 3]) detector. This epithermal neutron field was produced at the Ohio State University Van de Graaff Accelerator Facility. The [sup 10]B absorbed dose and the gamma-ray source have the same distribution in the head phantom as the BF[sub 3] count-rate distribution. The absorbed gamma dose from the measured source distribution was calculated using MCNP, a Monte Carlo code, and QAD[minus]CGGP, a Point Kernel code. The most pronounced effect of phantom size on [sup 10]B absorbed dose was on the dose rate at the depth of maximum dose, [ital d][sub max]. An increase in dose rate at [ital d][sub max] was observed with a decrease in phantom size, the dose rate in the smallest phantom being larger by a factor of 1.4 than the dose rate in the largest phantom. Also, [ital d][sub max] for the phantoms shifted deeper with a decrease in phantom dimensions. The shift between the largest and the smallest phantoms was 6 mm. Finally, the smaller phantoms had lower entrance [sup 10]B dose as a percent of the dose at [ital d][sub max], or better skin sparing. Our calculations for the gamma dose show that a Point Kernel technique can be used to calculate the dose distribution as accurately as a Monte Carlo technique, in much shorter computation times.

• DOE Contract Number: FG02-89ER60872
• OSTI ID: 6617580
• Journal Information: Medical Physics; (United States), Journal Name: Medical Physics; (United States) Vol. 20:2; ISSN 0094-2405; ISSN MPHYA6
• Country of Publication: United States
• Language: English

Related Subjects

560101* -- Biomedical Sciences
Applied Studies-- Radiation Effects-- Dosimetry & Monitoring-- (1992-)
61 RADIATION PROTECTION AND DOSIMETRY
BARYONS
BODY
BODY AREAS
CALCULATION METHODS
DOSIMETRY
ELEMENTARY PARTICLES
EPITHERMAL NEUTRONS
FERMIONS
HADRONS
HEAD
MEDICINE
MOCKUP
MONTE CARLO METHOD
NEUTRON CAPTURE THERAPY
NEUTRON DOSIMETRY
NEUTRON THERAPY
NEUTRONS
NUCLEAR MEDICINE
NUCLEONS
PHANTOMS
RADIATION DOSE DISTRIBUTIONS
RADIOLOGY
RADIOTHERAPY
STRUCTURAL MODELS
THERAPY