Clinical study of relative biological effectiveness for cervical carcinoma treated by 252Cf neutrons and assessed by histological tumour eradication

Maruyama, Yosh; Feola, Jose M.; Wierzbicki, J.; Nagell, J.R. van; Powell, Deborah E.; Yoneda, J.

doi:10.1259/0007-1285-63-748-270

Cited by 14 publications

(6 citation statements)

References 24 publications

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“…252 Cf mainly decays ͑96.9%͒ through alpha emission to 248 Cm releasing He gas with only 3.1% of 252 Cf decays via spontaneous fission. Through this latter decay channel, 3.768 neutrons per fission are released for a total neutron yield of 2.314ϫ10 12 neutrons/g s. 4 The 252 Cf neutron energy spectrum may be fit to a Watt fission model with a most probable neutron energy of 0.7 MeV. As this energy spectrum is similar to that from a nuclear reactor, 252 Cf affords the opportunity for a compact and easily shieldable neutron source for both research and clinical applications.…”

Section: Introductionmentioning

confidence: 99%

“…Though RBE is a function of many factors, a value of 6 for low dose rate ͑LDR͒ irradiation with 252 Cf neutrons has been adopted for various tumor sites. 12 The dose distributions about 252 Cf sources may be measured and calculated in a number of ways. Monte Carlo modeling of 252 Cf was first performed by Krishnaswamy in 1971, and later confirmed experimentally in 1972 using paired chambers measuring sources fabricated at SRL.…”

Section: Introductionmentioning

confidence: 99%

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Clinical brachytherapy with neutron emitting sources and adherence to AAPM TG‐43 dosimetry protocol

et al. 1999

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Using Monte Carlo methods, neutron dosimetry for 252Cf Applicator Tube (AT) type medical sources available from Oak Ridge National Laboratory (ORNL) has for the first time been determined in terms of TG-43 formalism. This approach, as compared to previous "along-away" formalisms, demonstrates the relative angular independence of dose rate data, when the geometry factor has been removed. As the ORNL-made 252Cf AT type sources are considerably physically larger than most clinical sources used today, the radial dose function increases for radii less than 3.0 mm due to breakdown of the line source model. A comparison of the 252Cf neutron radial dose function with those for other medical sources revealed similarities with that from 137Cs. Differences with respect to previous 252Cf AT source neutron dosimetry data generally increased at increasing distances. This was attributed to differences in the various 252Cf AT source models and phantom compositions. The current status of 252Cf medical source fabrication and calibration procedures at ORNL is presented.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Clinical brachytherapy with neutron emitting sources and adherence to AAPM TG‐43 dosimetry protocol

et al. 1999

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“…Currently, the prevalence of RBE-weighting in the treatment planning process is not ubiquitous despite numerous suggestions in literature. 24,77,78,88,89,101,103,[114][115][116][117][118][119][120][121][122][123] Contrary to previous works, this study sought to determine how RBE changed as a function of distance from the source and the resulting impact on a treatment plan. In contradiction to 125 I, the RBE M of 192 Ir and 169 Yb was found to increase with distance away from the source by approximately 3% and 7%, respectively, at 8 cm (Figure 4.3).…”

Section: Discussionmentioning

confidence: 99%

Quantifying Radiobiological Variation in Cancer Radiotherapy Using Monte Carlo Simulation and Doped Plastic Scintillators

Nusrat¹

2021

Preprint

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This dissertation examines the extent to which radiobiological variations occur in photon radiotherapy, and then presents a novel methodology and detector prototype to measure this variation. In the first section, I examine the change in maximum RBE (RBEM) outside the primary field in open and composite 6 MV x-ray beams. This is done using Monte Carlo simulation and microdosimetric techniques. It was found that when comparing an open 10 10 cm2 6 MV beam to a composite 10 10 cm2 beam comprising one hundred 1x 1 cm2 beamlets, the out-of-field increase in RBE occurs much closer to the field edge in the composite case. This finding may have consequences for IMRT cases in which large amount of scattered radiation may be causing a higher than expected effective dose to organs at risk. In the second section, the maximum RBE variation is examined in the context of brachytherapy. The sources examined include 192Ir, 125I, and 169Yb. It was determined that maximum RBE of 125I relative to the source position did not vary significantly as distance from the source was increased, however, 192Ir and 169Yb were found to exhibit RBEM increases of 3.0% and 6.6% at a distance of 8 cm, respectively. Also, the impact of this variation on an HDR 192Ir prostate treatment plan was examined; it was found that RBEM hotspots of +3.6% occur at the treatment plan’s periphery. In the third part, the impact of lead doping on plastic scintillator response is quantified, a major step required for the development of the LET detector prototype. In this stage, 4 differently doped plastic scintillators were obtained, and measurements were conducted in low and medium LET beams. Using Geant4 Monte Carlo and the measured scintillator responses, the scintillator parameters: kB and L0 were determined as a function of dopant concentration and effective atomic number. Finally, the uniquely energy dependent scintillators were combined into a detector prototype used to measure the LET spectra produced by five low energy photon beams. These beams included four orthovoltage energies (100, 180, 250, and 300 kVp) along with an 192Ir HDR source. In this proof-of-principle work, the detector prototype and technique was found to accurately determine the LET spectra and the mean LET for all beams with the exception of the 100 kVp orthovoltage beam. Potential applications for the real-time LET detector prototype and technique described in this dissertation include LET measurement in radiotherapy, allowing for biologically optimized treatment plans improving patient care. This technique and prototype also has numerous applications in non-medical fields such as health physics, space travel dosimetry, and nuclear safety.

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“…[44] A RBE value of 6 for low dose rate (LDR) irradiation with 252 Cf neutrons has been adopted for various tumor sites based on the clinical data from the University of Kentucky trial. [45] The primary cell killing mechanism of fast neutrons is the recoiled protons from its elastic collision with water molecules. These recoiled protons ionize the water molecules along their paths.…”

Section: Neutron Brachytherapymentioning

confidence: 99%

Compact D-D/D-T neutron generators and their applications

Lou¹

2003

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Neutron generators based on the 2 H(d,n) 3 He and 3 H(d,n) 4 He fusion reactions are the most commonly available neutron sources. The applications of current commercial neutron generators are often limited by their low neutron yield and their short operational lifetime. A new generation of D-D/D-T fusion-based neutron generators has been designed at Lawrence Berkeley National Laboratory (LBNL) by using high current ion beams hitting on a self-loading target that has a large surface area to dissipate the heat load. This thesis describes the rationale behind the new designs and their potential applications. A survey of other neutron sources is presented to show their advantages and disadvantages compared to the fusion-based neutron generator. A prototype neutron facility was built at LBNL to test these neutron generators. High current ion beams were extracted from an RF-driven ion source to produce neutrons. With an average deuteron beam current of 24 mA and an energy of 100 keV, a neutron yield of >10 9 n/s has been obtained with a D-D coaxial neutron source.

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Clinical study of relative biological effectiveness for cervical carcinoma treated by 252Cf neutrons and assessed by histological tumour eradication

Cited by 14 publications

References 24 publications

Clinical brachytherapy with neutron emitting sources and adherence to AAPM TG‐43 dosimetry protocol

Clinical brachytherapy with neutron emitting sources and adherence to AAPM TG‐43 dosimetry protocol

Quantifying Radiobiological Variation in Cancer Radiotherapy Using Monte Carlo Simulation and Doped Plastic Scintillators

Compact D-D/D-T neutron generators and their applications

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