AREA MONITORING DEVICES BY ZUBAIRUL ISLAM.pptxZubairUlIslam5
AREA MONITORING DEVICES BY ZUBAIRUL ISLAM
A Student Of Radiography.
Area Monitoring Devices is One of the Important in the Radiography.
• Area monitoring ( INTRODUCTION) • why we need Area monitoring •Area monitoring Devices
IONISATION CHAMBER
GM COUNTER
SCINTILLATION DETECTOR
AIM AND OBJECTIVE OF AREA MONITORING DEVICE
RADIATION MEASUREMENT
DEFECTORS
AREA MONITORING DEVICES BY ZUBAIRUL ISLAM.pptxZubairUlIslam5
AREA MONITORING DEVICES BY ZUBAIRUL ISLAM
A Student Of Radiography.
Area Monitoring Devices is One of the Important in the Radiography.
• Area monitoring ( INTRODUCTION) • why we need Area monitoring •Area monitoring Devices
IONISATION CHAMBER
GM COUNTER
SCINTILLATION DETECTOR
AIM AND OBJECTIVE OF AREA MONITORING DEVICE
RADIATION MEASUREMENT
DEFECTORS
Pharmaceutical Inorganic chemistry UNIT-V Radiopharmaceutical.pptx
Isotopes Types of decay
Alpha rays, which could barely penetrate a piece of paper
Beta rays, which could penetrate 3 mm of aluminium
Gamma rays, which could penetrate several centimetres of lead
Units of Radioactivity:
Measurement of Radioactivity
The measurement of nuclear radiation and detection is an important aspect in the identification of type of radiations (, , ) and to assay the radionuclide emitting the radiation, suitable detectors are required. The radiations are identified on the basis of their properties.
e.g. Ionization effect is measured in Ionization Chamber, Proportional Counter and Geiger Muller Counter.
The scintillation effect of radiation is measured using scintillation detector and the photographic effect is measured by Autoradiography.
Gas Filled Detectors:
Ionization Chamber:
Proportional Counters:
Geiger-Muller Counter
Properties of α, β, γ radiations
Half –life of Radioelement
Sodium Iodide (I131)
Handling and Storage of Radioactive Material:
Storage of Radioactive Substances –
Precautions For Handling Radioactive Substances
Labelling of Radioactive Substances
Pharmaceutical Application Of Radioactive Substances
Geiger–Müller Counter is a hand-held radiation survey instrument used in Radiation Dosimetry,Nuclear Physics,Experimental Physics & Radiological Protection.
gm counter .working principle of gm counter, construction, advantage and disadvantage of gm counter.
Scintillation counter, its history, solid and liquid scintillation, scintillation cocktail, photomultiplier tube, advantage, and disadvantage.
Complete detail about the Radiopharmaceutical, General Introduction, Radioactive substance, Radioactive rays like alpha, beta and gamma rays. All the Measurement method to determine the radioactivity of any element and widely used instrument Geiger Muller Counter. And some Radiopharmaceutical product used in many diagnosis , treatment such like sodium iodide solution & capsule, Rose Bengal I 131 and Application of Radiopharmaceuticals.
Professional air quality monitoring systems provide immediate, on-site data for analysis, compliance, and decision-making.
Monitor common gases, weather parameters, particulates.
Cancer cell metabolism: special Reference to Lactate PathwayAADYARAJPANDEY1
Normal Cell Metabolism:
Cellular respiration describes the series of steps that cells use to break down sugar and other chemicals to get the energy we need to function.
Energy is stored in the bonds of glucose and when glucose is broken down, much of that energy is released.
Cell utilize energy in the form of ATP.
The first step of respiration is called glycolysis. In a series of steps, glycolysis breaks glucose into two smaller molecules - a chemical called pyruvate. A small amount of ATP is formed during this process.
Most healthy cells continue the breakdown in a second process, called the Kreb's cycle. The Kreb's cycle allows cells to “burn” the pyruvates made in glycolysis to get more ATP.
The last step in the breakdown of glucose is called oxidative phosphorylation (Ox-Phos).
It takes place in specialized cell structures called mitochondria. This process produces a large amount of ATP. Importantly, cells need oxygen to complete oxidative phosphorylation.
If a cell completes only glycolysis, only 2 molecules of ATP are made per glucose. However, if the cell completes the entire respiration process (glycolysis - Kreb's - oxidative phosphorylation), about 36 molecules of ATP are created, giving it much more energy to use.
IN CANCER CELL:
Unlike healthy cells that "burn" the entire molecule of sugar to capture a large amount of energy as ATP, cancer cells are wasteful.
Cancer cells only partially break down sugar molecules. They overuse the first step of respiration, glycolysis. They frequently do not complete the second step, oxidative phosphorylation.
This results in only 2 molecules of ATP per each glucose molecule instead of the 36 or so ATPs healthy cells gain. As a result, cancer cells need to use a lot more sugar molecules to get enough energy to survive.
Unlike healthy cells that "burn" the entire molecule of sugar to capture a large amount of energy as ATP, cancer cells are wasteful.
Cancer cells only partially break down sugar molecules. They overuse the first step of respiration, glycolysis. They frequently do not complete the second step, oxidative phosphorylation.
This results in only 2 molecules of ATP per each glucose molecule instead of the 36 or so ATPs healthy cells gain. As a result, cancer cells need to use a lot more sugar molecules to get enough energy to survive.
introduction to WARBERG PHENOMENA:
WARBURG EFFECT Usually, cancer cells are highly glycolytic (glucose addiction) and take up more glucose than do normal cells from outside.
Otto Heinrich Warburg (; 8 October 1883 – 1 August 1970) In 1931 was awarded the Nobel Prize in Physiology for his "discovery of the nature and mode of action of the respiratory enzyme.
WARNBURG EFFECT : cancer cells under aerobic (well-oxygenated) conditions to metabolize glucose to lactate (aerobic glycolysis) is known as the Warburg effect. Warburg made the observation that tumor slices consume glucose and secrete lactate at a higher rate than normal tissues.
Introduction:
RNA interference (RNAi) or Post-Transcriptional Gene Silencing (PTGS) is an important biological process for modulating eukaryotic gene expression.
It is highly conserved process of posttranscriptional gene silencing by which double stranded RNA (dsRNA) causes sequence-specific degradation of mRNA sequences.
dsRNA-induced gene silencing (RNAi) is reported in a wide range of eukaryotes ranging from worms, insects, mammals and plants.
This process mediates resistance to both endogenous parasitic and exogenous pathogenic nucleic acids, and regulates the expression of protein-coding genes.
What are small ncRNAs?
micro RNA (miRNA)
short interfering RNA (siRNA)
Properties of small non-coding RNA:
Involved in silencing mRNA transcripts.
Called “small” because they are usually only about 21-24 nucleotides long.
Synthesized by first cutting up longer precursor sequences (like the 61nt one that Lee discovered).
Silence an mRNA by base pairing with some sequence on the mRNA.
Discovery of siRNA?
The first small RNA:
In 1993 Rosalind Lee (Victor Ambros lab) was studying a non- coding gene in C. elegans, lin-4, that was involved in silencing of another gene, lin-14, at the appropriate time in the
development of the worm C. elegans.
Two small transcripts of lin-4 (22nt and 61nt) were found to be complementary to a sequence in the 3' UTR of lin-14.
Because lin-4 encoded no protein, she deduced that it must be these transcripts that are causing the silencing by RNA-RNA interactions.
Types of RNAi ( non coding RNA)
MiRNA
Length (23-25 nt)
Trans acting
Binds with target MRNA in mismatch
Translation inhibition
Si RNA
Length 21 nt.
Cis acting
Bind with target Mrna in perfect complementary sequence
Piwi-RNA
Length ; 25 to 36 nt.
Expressed in Germ Cells
Regulates trnasposomes activity
MECHANISM OF RNAI:
First the double-stranded RNA teams up with a protein complex named Dicer, which cuts the long RNA into short pieces.
Then another protein complex called RISC (RNA-induced silencing complex) discards one of the two RNA strands.
The RISC-docked, single-stranded RNA then pairs with the homologous mRNA and destroys it.
THE RISC COMPLEX:
RISC is large(>500kD) RNA multi- protein Binding complex which triggers MRNA degradation in response to MRNA
Unwinding of double stranded Si RNA by ATP independent Helicase
Active component of RISC is Ago proteins( ENDONUCLEASE) which cleave target MRNA.
DICER: endonuclease (RNase Family III)
Argonaute: Central Component of the RNA-Induced Silencing Complex (RISC)
One strand of the dsRNA produced by Dicer is retained in the RISC complex in association with Argonaute
ARGONAUTE PROTEIN :
1.PAZ(PIWI/Argonaute/ Zwille)- Recognition of target MRNA
2.PIWI (p-element induced wimpy Testis)- breaks Phosphodiester bond of mRNA.)RNAse H activity.
MiRNA:
The Double-stranded RNAs are naturally produced in eukaryotic cells during development, and they have a key role in regulating gene expression .
THE IMPORTANCE OF MARTIAN ATMOSPHERE SAMPLE RETURN.Sérgio Sacani
The return of a sample of near-surface atmosphere from Mars would facilitate answers to several first-order science questions surrounding the formation and evolution of the planet. One of the important aspects of terrestrial planet formation in general is the role that primary atmospheres played in influencing the chemistry and structure of the planets and their antecedents. Studies of the martian atmosphere can be used to investigate the role of a primary atmosphere in its history. Atmosphere samples would also inform our understanding of the near-surface chemistry of the planet, and ultimately the prospects for life. High-precision isotopic analyses of constituent gases are needed to address these questions, requiring that the analyses are made on returned samples rather than in situ.
Richard's entangled aventures in wonderlandRichard Gill
Since the loophole-free Bell experiments of 2020 and the Nobel prizes in physics of 2022, critics of Bell's work have retreated to the fortress of super-determinism. Now, super-determinism is a derogatory word - it just means "determinism". Palmer, Hance and Hossenfelder argue that quantum mechanics and determinism are not incompatible, using a sophisticated mathematical construction based on a subtle thinning of allowed states and measurements in quantum mechanics, such that what is left appears to make Bell's argument fail, without altering the empirical predictions of quantum mechanics. I think however that it is a smoke screen, and the slogan "lost in math" comes to my mind. I will discuss some other recent disproofs of Bell's theorem using the language of causality based on causal graphs. Causal thinking is also central to law and justice. I will mention surprising connections to my work on serial killer nurse cases, in particular the Dutch case of Lucia de Berk and the current UK case of Lucy Letby.
A brief information about the SCOP protein database used in bioinformatics.
The Structural Classification of Proteins (SCOP) database is a comprehensive and authoritative resource for the structural and evolutionary relationships of proteins. It provides a detailed and curated classification of protein structures, grouping them into families, superfamilies, and folds based on their structural and sequence similarities.
3. Types of detectors (cont.)
• Detectors may also be classified by the type of information
produced:
– Detectors, such as Geiger-Mueller (GM) detectors, that indicate
the number of interactions occurring in the detector are called
counters
– Detectors that yield information about the energy
distribution of the incident radiation, such as NaI scintillation
detectors, are called spectrometers
– Detectors that indicate the net amount of energy deposited in
the detector by multiple interactions are called dosimeters
4. Types of gas-filled detectors
• Three types of gas-filled detectors in common use:
– Ionization chambers (continuous current output)
– Proportional counters (pulse current output)
– Geiger Muller counters (pulse current output)
• Type determined primarily by the voltage applied between the two
electrodes
• Ionization chambers have wider range of physical shape (parallel
plates, concentric cylinders, etc.)
• Proportional counters and GM counters must have thin wire anode
5. Gas-filled detectors
• A gas-filled detector consists of a volume of gas between two
electrodes, with an electrical potential difference (voltage) applied
between the electrodes
• Ionizing radiation produces ion pairs in the gas
• Positive ions (cations) attracted to negative electrode (cathode);
electrons or anions attracted to positive electrode (anode)
• In most detectors, cathode is the wall of the container that holds the
gas and anode is a wire inside the container
• The electrons make a meter needle deflect and, if a loudspeaker is
connected, you can hear a loud click every time particles are
detected.
8. Dead time
• In pulse mode detectors, two interactions must be separated by a
finite amount of time if they are to produce distinct signals
• This interval is called the dead time of the system
• If a second interaction occurs in this interval, its signal will be lost; if
it occurs close enough to the first interaction, it may distort the
signal from the first interaction
• GM counters have dead times ranging from tens to hundreds of
microseconds, most other systems have dead times of less than a
few microseconds
– Detector has longest dead time in GM counter systems
– In multichannel analyzer systems, the analog-to-digital converter
often has the longest dead time
9. Ionization chambers
• ionization chamber measures the charge from the number of
ion pairs created within a gas caused by incident radiation.
• Ion-pairs move towards opposte polarity electrodes, generating an
ionization current which is measured by an electrometer circuit.
• The chamber cannot discriminate between radiation types (beta or
gamma) and cannot produce an energy spectrum of radiation.
• Straight pleateu as there is no “multiplication” and also no
“recombination”.
10.
11. Ionization chambers
Applications
Nuclear industry
Used where a constant high dose rate is being measured as
they have a greater operating lifetime than standard GM tubes,
which suffer from gas break down
•Smoke detectors
Ionization chamber contains an alpha-emitter, producing
constant ion current. Smoke enters, disrupts this current
because ions strike smoke particles and are neutralized. This drop in
current triggers the alarm.
•Medical radiation measurement
Ionization chambers are used to ensure that the dose delivered
from a therapy unit
12. Ionization chambers
Advantages and Disadvantages:
•The advantages are good uniform response to gamma radiation and
accurate overall dose reading, capable of measuring very high
radiation rates, sustained high radiation levels do not degrade the fill
gas.
•The disadvantages are 1) low output requiring sophisticated
electrometer circuit and 2) operation and accuracy easily affected by
moisture.
13. Proportional counters
• Proportional counters operate at a slightly higher voltage, selected
such that discrete avalanches are generated. Each ion pair
produces a single avalanche so that an output current pulse is
generated which is proportional to the energy deposited by the
radiation. This is in the "proportional counting" region.
14. Proportional counters
Advantages and Disadvantages:
•The advantages are the ability to measure energy of radiation and
provide spectrographic information, discriminate between alpha and
beta particles, and that large area detectors can be constructed.
•The disadvantages are that anode wires delicate and can lose
efficiency in gas flow detectors due to deposition, the efficiency and
operation affected by ingress of oxygen into fill gas, and measurement
windows easily damaged in large area detectors.
15. Proportional counters
Applications
•Commonly used in standards laboratories, health physics laboratories, and for
physics research
•Seldom used in medical centers
•The wire chamber is a multi-electrode form of proportional counter used as a
research tool.
•The proportionality between the energy of the charged particle travelling
through the chamber and the total charge created makes proportional counters
useful for charged particle spectroscopy.
•Proportional counters are also useful for high energy photon detection, such
as gamma-rays, provided these can penetrate the entrance window. They are
also used for the detection of X-rays to below 1 Kev energy levels, using thin
walled tubes operating at or around atmospheric pressure.
•These are used extensively to check for radioactive contamination on
personnel, flat surfaces, tools and items of clothing.
17. GM counters
• consists of a GM tube, the sensing
• element, and processing electronics.
• Filled with an inert gas at Low
• pressure, and high voltage.
• each ion pair creates an avalanche,
• but by the emission of UV photons,
• multiple avalanches are created
• which spread along the anode wire.
• Ionization amplified within tube by Townsend Discharge Effect to
produce an easily measured detection pulse.
Ionization occurs mainly due to electrons emitted by the walls of
chamber by process of photoelectric effect when gamma rays enter
the chamber. In order to avoid this effect, 10% ethyl alcohol and
90% argon is added. Ethyl alcohol absorbs photons emitted by the
de-excitation of gas atoms. This is called adding Quenching gas.
18. This large pulse from tube makes
the G-M Counter relatively cheap.
Townsend Avalanche is a gas
ionization process where free
electrons are accelerated by an
electric field, collide with gas
molecules, and consequently free
additional electrons.
Those electrons are in turn
Accelerated and free additional
electrons.
The result is an avalanche
multiplication that permits electrical
conduction through the gas.
The discharge requires a source of
free electrons and a significant
electric Field.
20. Readout
Count per second
• Normally used when alpha or beta
particles are being detected
Absorbed dose
• Radiation dose rate, displayed in a unit such as the ”Sievert”
• Normally used for measuring gamma or X-ray dose rates
The readout can be analog or digital, modern
instruments are offering serial communications
with a host computer or network.
An option produces audible clicks
representing the number of ionization
events detected.
21. Advantages an Disadvantages OF GM
COUNTER
The advantages are that they are a
• cheap detector with a large variety of sizes and applications,
• large output signal is produced from tube
• can measure the overall gamma dose when using an energy
compensated tube.
The disadvantages are that it
• cannot measure the energy of the radiation (no spectrographic
information)
• Can not measure high radiation rates due to dead time
22. APPLICATIONS OF GM COUNTER
Particle Detection:-
• For alpha particles and low energy beta particles the "end-window" type of
G-M tube has to be used as these particles have a limited range even in
free air, and are easily stopped by a solid material. High energy beta
particles can also be detected by a thin-walled "windowless" G-M tube,
which has no end window.
Gamma and X-Ray Detection:-
• Geiger counters are widely used to detect gamma radiation, and for this the
windowless tube is used.
Neutron Detection:-
A variation of the Geiger tube is used to
measure neutrons, where the gas used is
Boron Trifluoride or Helium-3 and a plastic
moderator is used to slow the neutrons. This
creates an alpha particle inside the detector
and thus neutrons can be counted.
23. LIMITATIONS OF GEIGER-MULLER COUNTER
• The current pulses produced by the ionising events can derive a visual
display of count rate or radiation dose, and usually in the case of hand-
held instruments, an audio device producing clicks
There are two main limitations of the Geiger counter.
Because the output pulse from a Geiger-Müller tube is always the same
magnitude regardless of the energy of the incident radiation, the tube
cannot differentiate between radiation types.
A further limitation is the inability to measure high radiation rates due to
the "dead time" of the tube. This is an insensitive period after each
ionization of the gas during which any further incident radiation will not
result in a count, and the indicated rate is therefore lower than actual.
Editor's Notes
The diagram shows the relationship of the gaseous detection regions, using an experimental concept of applying a varying voltage to a cylindrical chamber which is subjected to ionizing radiation. Alpha and beta particles are plotted to demonstrate the effect of different ionizing energies, but the same principle extends to all forms of ionizing radiation.
The ion chamber and proportional regions can operate at atmospheric pressure, and their output varies with radiation energy. However in practice, the Geiger region is operated at a reduced pressure to allow operation at much lower voltages; otherwise impractically high voltages would be required. The Geiger region output does not differentiate radiation energies.
Each ion pair created deposits or removes a small electric charge to or from an electrode, such that the accumulated charge is proportional to the number of ion pairs created, and hence the radiation dose. This continual generation of charge produces an ionization current, which is a measure of the total ionizing dose entering the chamber. However, the chamber cannot discriminate between radiation types (beta or gamma) and cannot produce an energy spectrum of radiation.
Limited Proportional Region
The proportional behavior is lost in this region when applied pd is further increased than pd in region 3. The pulse heights are still related to the applied voltage but no longer proportional to initial ionizing intensity.
This region is not useful for measurement because ultraviolet photons maybe formed, new electrons may be formed when positive ions reach the cathode and space charge may distort the electric field.