ABSTRACT
INTRODUCTION: Uterine artery embolization is performed in pre-menopausal women. Understanding the contribution of radiation dose at each stage of the procedure is important for potential dose reduction. The aim was to retrospectively analyse radiation dose on a per-procedural-stage basis, comparing digital subtraction angiography (DSA) and conventional roadmap (CRM). METHODS: Group A consisted of 50 patients where DSA was used for road mapping at all stages: (I) Aortogram, (II) Left internal iliac artery (IIA) DSA, (III) Left uterine artery (UA) DSA, (IV) Right IIA DSA and (V) Right UA DSA. Group B included 50 patients, where CRM was used for road mapping at stages (II) and (IV). RESULTS: For Group A, mean total dose-area product (DAP) was 39.7 Gy·cm2; mean DAP for each stage were (I) Aortogram = 3.4 Gy·cm2, (II) Left IIA DSA = 5.9 Gy·cm2, (III) Left UA DSA = 3.2 Gy·cm2, (IV) Right IIA DSA = 5.5 Gy·cm2 and (V) Right UA DSA = 3.0 Gy·cm2. For Group B, mean total DAP was 33.6 Gy·cm2, mean DAP for each stage were (I) Aortogram = 3.3 Gy·cm2, (II) Left IIA CRM = 1.5 Gy·cm2, (III) Left UA DSA = 3.3 Gy·cm2, (IV) Right IIA CRM = 1.5 Gy·cm2 and (V) Right UA DSA = 3.3 Gy·cm2. Fluoroscopy time was 10 and 9.4 min for Groups A and B, respectively. CONCLUSION: The highest road-mapping radiation dose contribution was from bilateral IIA DSA. The use of CRM, intermittent fluoroscopy and elimination of the aortogram is recommended to further reduce procedural radiation dose.
ABSTRACT
The free-surface Liquid-Lithium Target, recently developed at Soreq Applied Research Accelerator Facility (SARAF), was successfully used with a 1.9 MeV, 1.2 mA (2.3 kW) continuous-wave proton beam. Neutrons (~2 × 10(10) n/s having a peak energy of ~27 keV) from the (7)Li(p,n)(7)Be reaction were detected with a fission-chamber detector and by gold activation targets positioned in the forward direction. The setup is being used for nuclear astrophysics experiments to study neutron-induced reactions at stellar energies and to demonstrate the feasibility of accelerator-based boron neutron capture therapy.
ABSTRACT
In this report the effectiveness of low-energy alpha particles in the range 0.4 to 3.5 MeV for cell killing is investigated. Four cell lines of different nuclear dimensions (AG1522, C3H 10T1/2, CHO-10B, and HS-23) are studied. Monte Carlo simulations are carried out to interpret the experimental results. They are presented as a function of dose to the nucleus, the total track length of alpha particles in the nucleus, and other parameters. It is found that the effectiveness of alpha particles for cell killing decreases with decreasing alpha-particle energy. The maximum RBE value is found to extend to LET values as high as 180 keV/microns. Although the LET might be the same, the effectiveness of alpha particles for cell killing is higher in the ascending part of the Bragg curve compared to descending part of the Bragg curve. The terminal tracks of alpha particles are observed to be less effective for cell killing.
Subject(s)
Alpha Particles , Cell Survival/radiation effects , Animals , Cell Line , Cell Nucleus/ultrastructure , Cricetinae , Dose-Response Relationship, Radiation , Energy Transfer , Humans , Mice , Relative Biological EffectivenessABSTRACT
Three small parallel-plate ionization chambers were developed for measuring dose rates, of primarily low-energy alpha particles in the energy range 0.4-3.5 MeV, at a defined cell-Mylar interface. Spectral energy distributions of these alpha particles were also measured at the same position using a specially designed small-area silicon surface barrier detector. Dose rates were derived from the spectral distributions and compared with those derived from the ionization chambers. Different alpha-particle energies were obtained using a 144-MBq 238Pu collimated source and a variety of Mylar moderator foils of different thicknesses. These measurements, extended to mean alpha-particle energies as low as 0.4 MeV, will enable us to correlate radiobiological data with effects of alpha particles terminating in different regions of cell nuclei.
Subject(s)
Alpha Particles , Radiation DosageABSTRACT
Cell inactivation after exposure to collimated 3.5-MeV alpha particles in three hamster cell lines, V79, CHO-10B, and HS-23, one mouse cell line, C3H 10T1/2, and a human skin fibroblast cell line were studied. Several parameters were investigated for each cell line. Theoretical calculations were performed to find the distribution of energy deposited in the nuclear volume for each cell line. The mean number of alpha-particle traversals required to induce a lethal lesion varied between two for HS-23 cells and six for C3H 10T1/2 cells. The number of traversals per unit area and the total track length of alpha particles that inactivated a cell were found to be nearly constant for the hamster and mouse cell lines. These quantities were found to be lower for the human skin fibroblast cell line. The RBE values for all cell lines were found to be about 3.8 at 10% survival. Thus cell lines that are more sensitive to alpha radiation are also more sensitive to gamma radiation. The average number of alpha-particle traversals producing a single lethal lesion is greater than one. The passages of alpha particles through the cell nucleus that do not kill the cell may lead to carcinogenic effects.
Subject(s)
Alpha Particles , Cell Nucleus/radiation effects , Cell Survival/radiation effects , Animals , CHO Cells , Cricetinae , Humans , MiceABSTRACT
A 238Pu alpha-particle exposure apparatus was designed and constructed for use in radiobiological studies with cultured cell systems. The system provides a wide dynamic range of absorbed doses and a uniform radiation field. Average dose rate in air was measured with a small-volume ionization chamber. Estimates of dose rate at the cell surface were obtained from measurements taken with a silicon surface barrier detector. Particle fluence uniformity and fluence rate were measured using track etch procedures. The design and dosimetric characterization of the apparatus are discussed.
