scholarly journals Multifunctional ionization chamber and its electronic path for use on the medical accelerator "Prometeus"

2020 ◽  
Vol 23 (3) ◽  
pp. 229-240
Author(s):  
V. V. Siksin
Keyword(s):  
Proton Therapy ◽  
Ionization Chamber ◽  
Accurate Determination ◽  
Absorbed Dose ◽  
Incident Beam ◽  
Operating Mode ◽  
Therapy Session ◽  
Proton Accelerator ◽  
High Dose ◽  
Scanning Beam

The article describes the proposed new multifunctional ionization chamber (MIC) designed to measure dose profiles when the medical accelerator "Prometheus" is operating in the scanning "pencil beam" mode. A digital image acquisition detector (DIDE) with a tissue-equivalent water phantom is used to calibrate the accelerator before a radiation therapy session. The application of the CPPI on the beam of a proton accelerator operating in the mode of beam splitting into spots with a scanning beam is considered. The CDPI detector allows for a few accelerator pulses in on-line mode to see how the energy release of each spot is distributed over the area of the irradiated target, which is the actual calibration of the accelerator before the proton therapy session. During the proton therapy session, it is planned to install the MIC directly in front of the patient. The MIC chamber contains two ionization chambers operating simultaneously — a pad chamber (PC) operating on gas or "warm liquid" and a strip ionization chamber operating only on gas (SC). At the accelerator "Prometheus" it is proposed to use a MIC, which will be used in the mode of operation by the method of active scanning with a "pencil" proton beam. The use of the MIC operation is intended to control the density of the beam intensity during the irradiation of the "target" in the patient during the proton therapy session. In case of violation of the planned operating mode of the accelerator and the beam goes beyond the parameters preset before the session, the deviation detection control system (SDMS) will turn off the accelerator. The device of the readout electronics (SE) of the MIC and SKOO cameras is described. This proposed detector, including the MIC and SKOO camera and the reading electronics serving it, will improve the quality of the therapeutic beam supply, due to the accurate determination of the absorbed dose density supplied by the scanning beam to each spot of the irradiated target, and therefore the generated high dose distribution field will correspond to the irradiated volume of the patient and will increase the safety and control of patient exposure to the target. The PC included in the MIC is designed on a "warm liquid" (or gas) and is a high-precision ionization chamber with coordinate sensitivity over the width of the irradiated target. The SC included in the MIC operates on gas and controls the direction of the incident beam to a given spot in the target. A version of the charge-sensitive preamplifier (QCD) and the SE system designed for experimental verification of the MIC prototype has been developed. The SCOO circuit working in conjunction with the MIC camera allows you to control the predetermined parameters of the irradiation of the patient's target boundaries and turns off the accelerator if these parameters deviate from the initially specified ones.

scholarly journals “Warm liquid” detector for measuring dose profiles from ionizing radiation

2020 ◽  
Vol 22 (3) ◽  
pp. 228-236
Author(s):  
V. V. Siksin
Keyword(s):  
Proton Beam ◽  
Proton Therapy ◽  
Dose Distribution ◽  
Bragg Peak ◽  
Beam Width ◽  
Great Accuracy ◽  
Therapy Session ◽  
High Dose ◽  
Water Phantom ◽  
Accuracy Measure

The use of “warm liquid” tetramethylsilane (TMS) in ionization chambers for measuring dose profiles in water phantoms to prepare the accelerator for a proton therapy session is relevant. One of the promising areas of radiation therapy is proton therapy. To increase the conformality of proton therapy, it is important to know exactly the dose distributions from the energy release of the proton beam in the water phantom before conducting a proton therapy session. A television-type detector (TTD), which measures the profiles of the Bragg peak by the depth of the beam in the water phantom, helps to increase the accuracy of the dose distribution knowledge. To accurately determine the profile of the Bragg peak by the beam width in the water phantom, an additional method is proposed that will allow TTD to quickly determine the profile by the width of the Bragg peak in on-line mode. This prefix to the TTD will improve the quality of summing up the therapeutic beam-thanks to accurate knowledge of the profile by width, and therefore the formed high-dose distribution field will correspond to the irradiated volume in the patient and will increase the conformality of irradiation. The additional prefix to the TTD is designed on an organosilicon “warm liquid” and represents a high-precision ionization chamber with coordinate sensitivity along the width of the water phantom. The fully developed technology for obtaining “warm liquid” TMS allows creating both microdosimeters for proton therapy and detectors for measuring “dose profiles” in water phantoms during accelerator calibration. The considered prefix to the TTD detector - the calibrator meter of the dose field (KIDP) - can also be used independently of the TTD and with great accuracy measure the dose profiles of the Bragg peak in the water phantom, both in depth and width. KIDP can also be used to measure the outputs of secondary “instantaneous” neutrons and gamma quanta emitted from the water phantom orthogonally to the direction of the proton beam.

Fast calibration of CBED patterns for quantitative analysis

1993 ◽  
Vol 51 ◽  
pp. 674-675
Author(s):  
M.A. Gribelyuk ◽  
M. Rühle
Keyword(s):  
Reciprocal Lattice ◽  
Accurate Determination ◽  
Incident Beam ◽  
Crystal Thickness ◽  
Structure Model ◽  
Beam Direction ◽  
Transmitted Beam ◽  
Reciprocal Vector ◽  
On Line

A new method is suggested for the accurate determination of the incident beam direction K, crystal thickness t and the coordinates of the basic reciprocal lattice vectors V1 and V2 (Fig. 1) of the ZOLZ plans in pixels of the digitized 2-D CBED pattern. For a given structure model and some estimated values Vest and Kest of some point O in the CBED pattern a set of line scans AkBk is chosen so that all the scans are located within CBED disks.The points on line scans AkBk are conjugate to those on A0B0 since they are shifted by the reciprocal vector gk with respect to each other. As many conjugate scans are considered as CBED disks fall into the energy filtered region of the experimental pattern. Electron intensities of the transmitted beam I0 and diffracted beams Igk for all points on conjugate scans are found as a function of crystal thickness t on the basis of the full dynamical calculation.

scholarly journals Commissioning of a clinical pencil beam scanning proton therapy unit for ultra‐high dose rates (FLASH)

2021 ◽  
Author(s):  
Konrad P. Nesteruk ◽  
Michele Togno ◽  
Martin Grossmann ◽  
Anthony J. Lomax ◽  
Damien C. Weber ◽  
...  
Keyword(s):  
Proton Therapy ◽  
High Dose ◽  
Pencil Beam ◽  
Beam Scanning ◽  
Dose Rates ◽  
Pencil Beam Scanning

scholarly journals Magnetic Resonance Imaging during Proton Therapy Irradiation Allows for the Early Response Assessment of Pediatric Chordoma

Diagnostics ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 1117
Author(s):  
Sabina Vennarini ◽  
Dante Amelio ◽  
Stefano Lorentini ◽  
Giovanna Stefania Colafati ◽  
Antonella Cacchione ◽  
...  
Keyword(s):  
Magnetic Resonance Imaging ◽  
Magnetic Resonance ◽  
Proton Therapy ◽  
Treatment Plan ◽  
Surgical Excision ◽  
Response Assessment ◽  
Early Response ◽  
High Dose ◽  
Resonance Imaging ◽  
Early Response Assessment

Chordoma in pediatric patients is very rare. Proton therapy has become a gold standard in the treatment of these neoplasms, as high dose escalation can be achieved regarding the target while maximizing the sparing of the healthy tissues near the tumor. The aim of the work was to assess the evolution of morphological sequences during treatment using T1/T2-weighted magnetic resonance imaging (MRI) for the early response assessment of a classic chordoma of the skull base in a pediatric patient who had undergone surgical excision. Our results demonstrated a significant quantitative reduction in the residual nodule component adhered to the medullary bulb junction, with an almost complete recovery of normal anatomy at the end of the irradiation treatment. This was mainly shown in the T2-weighted MRI. On the other hand, the classic component of the lesion was predominantly present and located around the tooth of the axis. The occipital condyles were morphologically and dimensionally stable for the entire irradiation period. In conclusion, the application of this type of monitoring methodology, which is unusual during the administration of a proton treatment for chordoma, highlighted the unexpected early response of the disease. At the same time, it allowed the continuous assessment of the reliability of the treatment plan.

Meyer-Neldel Rule on thermal stability parameters (trap depth and frequency factor) of luminescence signals in quartz

2021 ◽  
Author(s):  
Zuzanna Kabacińska ◽  
Alida Timar-Gabor ◽  
Benny Guralnik
Keyword(s):  
Activation Energy ◽  
Thermal Stability ◽  
Hydrogen Diffusion ◽  
Dose Range ◽  
Accurate Determination ◽  
Frequency Factor ◽  
Proton Conduction ◽  
High Dose ◽  
Compensation Law ◽  
Thermal Stability Of

<p>Thermally activated processes can be described mathematically by the Arrhenius equation. The Meyer-Neldel Rule (MNR), or compensation law, linearly relates the pre-exponent term to the logarithm of the excitation enthalpy for processes that are thermally driven in an Arrhenian manner. This empirical rule was observed in many areas of materials science, in physics, chemistry, and biology. In geosciences it was found to uphold in hydrogen diffusion (Jones 2014a) and proton conduction (Jones 2014b) in minerals.</p><p>Trapped charge dating methods that use electron spin resonance (ESR) or optically or thermally stimulated luminescence (OSL and TL) are based on the dose-dependent accumulation of defects in minerals such as quartz and feldspar. The thermal stability of these defects in the age range investigated is a major prerequisite for accurate dating, while the accurate determination of the values of the trap depths and frequency factors play a major role in thermochronometry applications. </p><p>The correlation of kinetic parameters for diffusion has been very recently established for irradiated oxides (Kotomin et al. 2018). A correlation between the activation energy and the frequency factor that satisfied the Meyer–Neldel rule was reported when the thermal stability of [AlO<sub>4</sub>/h<sup>+</sup>]<sup>0</sup> and [TiO<sub>4</sub>/M<sup>+</sup>]<sup>0</sup> ESR signals in quartz was studied as function of dose (Benzid and Timar-Gabor 2020). Here we compiled the optically stimulated luminescence (OSL) data published so far in this regard, and investigated experimentally the thermal stability of OSL signals for doses ranging from 10 to 10000 Gy in sedimentary quartz samples. We report a linear relationship between the natural logarithm of the preexponent term (the frequency factor) and the activation energy E, corresponding to a Meyer-Neldel energy of 45 meV, and a deviation from first order kinetics in the high dose range accompanied by an apparent decrease in thermal stability. The implications of these observations and the atomic and physical mechanisms are currently studied.</p><p> </p><p><strong>References</strong></p><p>Benzid, K., Timar Gabor, A. 2020. The compensation effect (Meyer–Neldel rule) on [AlO<sub>4</sub>/h<sup>+</sup>]<sup>0</sup> and [TiO<sub>4</sub>/M<sup>+</sup>]<sup>0</sup> paramagnetic centers in irradiated sedimentary quartz. <em>AIP Advance</em>s 10, 075114.</p><p>Kotomin, E., Kuzovkov, V., Popov, A. I., Maier, J., and Vila, R. 2018. Anomalous kinetics of diffusion-controlled defect annealing in irradiated ionic solids. <em>J. Phys. Chem. A</em> 122(1), 28–32</p><p>Jones, A. G. (2014a), Compensation of the Meyer-Neldel Compensation Law for H diffusion in minerals, <em>Geochem. Geophys. Geosyst.</em>, 15, 2616–2631</p><p>Jones, A. G. (2014b), Reconciling different equations for proton conduction using the Meyer-Neldel compensation rule, <em>Geochem. Geophys. Geosyst</em>., 15, 337–349</p>

Minimal Acute Toxicities Following High-Dose Proton Therapy for Spinal Tumors

2014 ◽  
Vol 90 (1) ◽  
pp. S301
Author(s):  
J. Jefferis ◽  
W. Hartsell ◽  
J. Chang ◽  
V. Gondi
Keyword(s):  
Proton Therapy ◽  
Spinal Tumors ◽  
High Dose

scholarly journals Novel Hybrid Scattering- and Scanning-Beam Proton Therapy Approach

2016 ◽  
Vol 3 (1) ◽  
pp. 37-50 ◽  
Author(s):  
Shengpeng Jiang ◽  
Jingqian Wang ◽  
Heng Li ◽  
Li Liao ◽  
Yupeng Li ◽  
...  
Keyword(s):  
Proton Therapy ◽  
Therapy Approach ◽  
Scanning Beam ◽  
Beam Proton

scholarly journals Spectrophotometric Study of ?-Irradiated PM-355

2009 ◽  
Vol 6 (3) ◽  
pp. 584-589
Author(s):  
Baghdad Science Journal
Keyword(s):  
Absorption Spectra ◽  
Calibration Curve ◽  
Linear Relation ◽  
Response Curve ◽  
Energy Gap ◽  
Linear Part ◽  
Absorbed Dose ◽  
Spectrophotometric Study ◽  
High Dose ◽  
Radiation Induced

The aim of the present work is concerned with the effect of ?-irradiation on PM-355 with absorbed dose of (30-160Mrad) range. This polymer is evaluated spectrophotometrically for use as high dose dosimeters. The absorption spectra of irradiated samples showed radiation induced absorption changes. There is an increment in absorption proportional with absorbed dose. This increment is attributed to interfaces traps which, are formed by irradiation. Calibration curve was drawn .The linear relation was found in calibration curve, and dosimeter range was determined from the linear part. The linearity in response curve suggested that PM-355 could be used as dosimeter within (30-160Mrad) rang. Energy gap shift was used as a second tool to determine the dosimeter range. It was found that PM-355 energy gap systematically decreasing with absorbed dose, and it could be used as a second tool to determine the dosimeter range.

scholarly journals Quality assurance evaluation of spot scanning beam proton therapy with an anthropomorphic prostate phantom

2013 ◽  
Vol 86 (1031) ◽  
pp. 20130390 ◽  
Author(s):  
K Iqbal ◽  
M Gillin ◽  
P A Summers ◽  
S Dhanesar ◽  
K A Gifford ◽  
...  
Keyword(s):  
Quality Assurance ◽  
Proton Therapy ◽  
Scanning Beam ◽  
Spot Scanning ◽  
Beam Proton
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