We will develop treatment planning procedures for determining dose to soft tissue adjacent to bone when irradiated by photon beams in the energy range of 60CO to 24 MV.
Our aim i s to improve dosimetric accuracy near bone-tissue interfaces and thereby gain a favorable therapeutic ratio in cancer treatment. Since the current calculation methods are incapable of providing accurate dosimetry near tissue interfaces of different atomic number, errors of the order of 10 to 20% are possible in clinical dosimetry. Our goal is to reduce this dosimetric uncertainty to within 5%. We consider this improvement in dosimetric accuracy to be significant in radiotherapy in terms of control of the disease and treatment complications. We will use three complementary approaches to develop the appropriate algorithms: a) an analytic method which will separately calculate the kerma distribution and the absorbed dose distribution. the latter will be calculated by our analytic model which describes the transport of electrons across and interface between different media. b) experimental investigations and model verification using suitable phantoms and dosimetry methods; and c) Monte Carlo calculations to verify and supplement the analytic model and the experimental data. Our algorithms for interface dosimetry will be incorporated into a commercial treatment planning system. The sofeware will be readily exportable to other radiotherapy facilities having access to CT scanners and low-cost minicomputers.

Agency
National Institute of Health (NIH)
Institute
National Cancer Institute (NCI)
Type
Research Project (R01)
Project #
5R01CA043748-03
Application #
3186067
Study Section
Radiation Study Section (RAD)
Project Start
1986-12-01
Project End
1990-11-30
Budget Start
1988-12-01
Budget End
1990-11-30
Support Year
3
Fiscal Year
1989
Total Cost
Indirect Cost
Name
University of Minnesota Twin Cities
Department
Type
Schools of Medicine
DUNS #
168559177
City
Minneapolis
State
MN
Country
United States
Zip Code
55455
Gerbi, B J; Khan, F M (1997) Plane-parallel ionization chamber response in the buildup region of obliquely incident photon beams. Med Phys 24:873-8
Das, I J; Kase, K R; Meigooni, A S et al. (1990) Validity of transition-zone dosimetry at high atomic number interfaces in megavoltage photon beams. Med Phys 17:10-6
Gerbi, B J; Khan, F M (1990) Measurement of dose in the buildup region using fixed-separation plane-parallel ionization chambers. Med Phys 17:17-26
Gerbi, B J; Khan, F M; Deibel, F C et al. (1989) Total skin electron arc irradiation using a reclined patient position. Int J Radiat Oncol Biol Phys 17:397-404
Das, I J; Kahn, F M (1989) Backscatter dose perturbation at high atomic number interfaces in megavoltage photon beams. Med Phys 16:367-75
Das, I J; Khan, F M; Gerbi, B J (1988) Interface dose perturbation as a measure of megavoltage photon beam energy. Med Phys 15:78-81
Das, I J (1987) An empirical method for beta-ray dosimetry at a homogeneous plane interface. Phys Med Biol 32:1609-13
Gerbi, B J; Meigooni, A S; Khan, F M (1987) Dose buildup for obliquely incident photon beams. Med Phys 14:393-9
Werner, B L; Das, I J; Khan, F M et al. (1987) Dose perturbations at interfaces in photon beams. Med Phys 14:585-95