2025 question paper

Radiological Equipment

26 questions

Q1(a). What kind of electromagnetic radiation is used in diagnostic imaging to view bones? (i) Gamma rays (ii) UV rays (iii) X-rays (iv) IR rays20252m
Unit 1: Science Behind Radiological Equipment
What kind of electromagnetic radiation is used in diagnostic imaging to view bones?
(i) Gamma rays
(ii) UV rays
(iii) X-rays
(iv) IR rays

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Answer

Correct option: (iii) X-rays

X-rays are high-energy electromagnetic radiation used in diagnostic radiography. They penetrate tissues differently and produce image contrast, particularly making bones clearly visible.
Q1(b). Who discovered X-rays? (i) Wilhelm Röntgen (ii) Marie Curie (iii) Henri Becquerel (iv) Ernest Rutherford20252m
Unit 1: Science Behind Radiological Equipment
Who discovered X-rays?
(i) Wilhelm Röntgen
(ii) Marie Curie
(iii) Henri Becquerel
(iv) Ernest Rutherford

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Answer

Correct option: (i) Wilhelm Röntgen

Wilhelm Conrad Röntgen discovered X-rays in 1895 while experimenting with cathode-ray tubes. He observed that an unknown penetrating radiation could produce images of internal structures, famously obtaining an image of his wife's hand.
Q1(c). Ultrasonography employs what type of waves? (i) Neutrino (ii) Electromagnetic (iii) Mechanical (iv) Gravitational20252m
Unit 2: Operation and Analysis of Imaging Equipment
Ultrasonography employs what type of waves?
(i) Neutrino
(ii) Electromagnetic
(iii) Mechanical
(iv) Gravitational

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Answer

Correct option: (iii) Mechanical

Ultrasound uses high-frequency mechanical sound waves, not electromagnetic radiation. These waves require a material medium to propagate.
Q1(d). The Doppler effect in ultrasound is used to measure: (i) Bone density (ii) Tumor size (iii) Blood flow velocity (iv) Magnetic field strength20252m
Unit 2: Operation and Analysis of Imaging Equipment
The Doppler effect in ultrasound is used to measure:
(i) Bone density
(ii) Tumor size
(iii) Blood flow velocity
(iv) Magnetic field strength

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Answer

Correct option: (iii) Blood flow velocity

The Doppler effect measures the frequency shift produced when ultrasound reflects from moving blood cells. The shift is related to the velocity and direction of blood flow, so Doppler ultrasound is widely used in vascular and cardiac imaging.
Q1(e). Which imaging modality uses ionizing radiation? (i) X-ray (ii) MRI (iii) Gamma camera (iv) CT-scan20252m
Unit 2: Operation and Analysis of Imaging Equipment
Which imaging modality uses ionizing radiation?
(i) X-ray
(ii) MRI
(iii) Gamma camera
(iv) CT-scan

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Answer

Correct options: (i) X-ray and (iv) CT-scan

Both conventional X-ray imaging and CT use ionizing X-ray radiation. MRI and ultrasound do not use ionizing radiation.

Exam note: If the paper expects only one option, CT-scan may be intended depending on the original wording, but scientifically both X-ray and CT are ionizing-radiation modalities.
Q1(f). MRI uses what kind of waves/energy to generate images? (i) [unclear in source] (ii) [unclear in source] (iii) Radiofrequency waves (iv) Ultraviolet20252m
Unit 2: Operation and Analysis of Imaging Equipment
MRI uses what kind of waves/energy to generate images?
(i) [unclear in source]
(ii) [unclear in source]
(iii) Radiofrequency waves
(iv) Ultraviolet

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Answer

Correct option: (iii) Radiofrequency waves

MRI uses a strong static magnetic field together with radiofrequency (RF) electromagnetic pulses to excite hydrogen nuclei. The detected RF signals are processed to form images.
Q1(g). What is used to detect gamma rays in nuclear medicine? (i) [unclear in source] (ii) [unclear in source] (iii) CT-Scan (iv) MRI20252m
Unit 2: Operation and Analysis of Imaging Equipment
What is used to detect gamma rays in nuclear medicine?
(i) [unclear in source]
(ii) [unclear in source]
(iii) CT-Scan
(iv) MRI

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Answer

Answer: Gamma camera / scintillation detector

In nuclear medicine, gamma photons are detected using a gamma camera, whose detector system commonly uses a scintillation crystal such as NaI(Tl) coupled to photodetectors. The detector converts gamma-ray energy into electrical signals for image formation.

The OCR of the paper has lost some answer choices, but CT and MRI do not directly detect gamma rays.
Q1(h). Which is most penetrating among electron beam, gamma photons, and X-ray photons? (i) X-rays (ii) Alpha rays (iii) Gamma rays (iv) Sound waves20252m
Unit 1: Science Behind Radiological Equipment
Which is most penetrating among electron beam, gamma photons, and X-ray photons?
(i) X-rays
(ii) Alpha rays
(iii) Gamma rays
(iv) Sound waves

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Answer

Correct option: (iii) Gamma rays

Among the listed radiation types, gamma photons are highly penetrating electromagnetic radiation because of their high photon energy and lack of electric charge. Their penetration also depends on photon energy and material thickness/density.
Q1(i). The unit used for measuring the effective dose of radiation is: (i) RAD (ii) Gray (iii) REM (iv) Sievert20252m
Unit 1: Science Behind Radiological Equipment
The unit used for measuring the effective dose of radiation is:
(i) RAD
(ii) Gray
(iii) REM
(iv) Sievert

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Answer

Correct option: (iv) Sievert

The sievert (Sv) is the SI unit of equivalent dose and effective dose, accounting for radiation type and biological sensitivity. The gray (Gy) measures absorbed dose.
Q1(j). Which radiation has higher energy? (i) X-rays (ii) Alpha emission (iii) Gamma rays (iv) Beta emission20252m
Unit 1: Science Behind Radiological Equipment
Which radiation has higher energy?
(i) X-rays
(ii) Alpha emission
(iii) Gamma rays
(iv) Beta emission

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Answer

Correct option: (iii) Gamma rays

Gamma rays are electromagnetic photons and can have very high energies. In radiological physics, photon energy is related to frequency by $E=hf$ , so higher-frequency photons have higher energy. The actual energy ranges of X-rays and gamma rays can overlap; the distinction is primarily based on origin rather than an absolute energy boundary.
Q2(a). What is a pulse height analyser in imaging using a gamma camera?20257m
Unit 2: Operation and Analysis of Imaging Equipment
What is a pulse height analyser in imaging using a gamma camera?

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Pulse Height Analyser in a Gamma Camera

Definition

A Pulse Height Analyser (PHA) is an electronic energy-discrimination system used in nuclear medicine to select detector pulses corresponding to a desired range of gamma-photon energies.

Need for PHA

A gamma camera receives useful photons as well as scattered photons. Compton-scattered photons have lower energies than the original photopeak. If these scattered events are accepted, image contrast and spatial accuracy decrease.

Working

Gamma Photon ↓ Collimator ↓ Scintillation Crystal ↓ Photomultiplier Tubes ↓ Position + Energy Signals ↓ Pulse Height Analyser ↓ Accept / Reject ↓ Image Computer

A gamma photon enters through the collimator.

The scintillation crystal converts the gamma photon into visible light.

Photomultiplier tubes or solid-state photodetectors convert the light into electrical pulses.

Pulse amplitude is approximately related to deposited photon energy.

The PHA compares the pulse height with a selected energy window around the photopeak.

Pulses inside the window are accepted for image formation; others are rejected.

Energy Window

For a radionuclide with a known photopeak energy $E_0$ , a window may be selected around $E_0$ , for example:

$E_0 \pm \Delta E$

The exact window is chosen according to the radionuclide and camera protocol.

Importance

Rejects a large fraction of scattered photons.

Improves image contrast.

Improves quantitative accuracy.

Helps isolate the desired photopeak.

Conclusion

The PHA acts as an energy filter in a gamma-camera system, accepting pulses within the selected energy range and rejecting unwanted radiation.
Q2(b). How do X-rays interact with living tissues? Describe.20257m
Unit 1: Science Behind Radiological Equipment
How do X-rays interact with living tissues? Describe.

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How X-rays Interact with Living Tissues

X-rays are ionizing photons. When they pass through the body, they may be absorbed, scattered, or transmitted. The relative amount depends on photon energy, tissue composition and thickness.

1. Photoelectric Effect

An X-ray photon transfers most or all of its energy to a bound electron and ejects it from the atom. The resulting vacancy can produce characteristic X-rays or Auger electrons.

The photoelectric effect is more important at lower diagnostic photon energies and in materials with higher atomic number. It contributes strongly to bone contrast.

2. Compton Scattering

The incident photon collides with a loosely bound electron, transfers part of its energy to the electron and changes direction with lower energy.

Compton scattering:

Produces scattered radiation.

Reduces image contrast.

Contributes to radiation dose outside the primary beam.

3. Coherent Scattering

The photon changes direction without significant energy transfer or ionization. Its contribution in diagnostic imaging is comparatively small.

4. Transmission

Some photons pass through the body without interaction and reach the detector. These transmitted photons form a major part of the useful image signal.

Tissue Attenuation

As X-rays pass through tissue, intensity decreases approximately according to:

$I=I_0e^{-\mu x}$

where $I_0$ is incident intensity, $\mu$ is the linear attenuation coefficient and $x$ is tissue thickness.

Different tissues have different attenuation coefficients, producing image contrast.

Biological Effects

Ionization can damage cellular molecules, including DNA. Effects may be deterministic/tissue reactions at sufficiently high doses or stochastic risks, such as increased cancer probability, associated with radiation exposure.

Conclusion

X-ray imaging depends on differential attenuation caused mainly by photoelectric absorption and Compton scattering in the diagnostic-energy range. The differences in attenuation between tissues allow internal structures to be visualized.
Q3(a). Explain the operation of the rotating X-ray tube using a neat and labelled diagram.20257m
Unit 1: Science Behind Radiological Equipment
Explain the operation of the rotating X-ray tube using a neat and labelled diagram.

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Worked Solution
Rotating-Anode X-ray Tube: Operation

Construction

A rotating-anode X-ray tube contains:

Cathode: filament and focusing cup.

Anode/target: rotating disc containing a target material such as tungsten-rhenium.

Rotor: rotates the anode inside the evacuated tube.

Stator: external electromagnetic coils drive the rotor.

Vacuum envelope: allows electrons to travel with minimal gas interaction.

Labelled Schematic

Rotating Anode / Target ↻ ┌─────────────────┐ │ Tungsten Target│ └───────┬─────────┘ │ Electron beam → ● X-rays → Window → Patient │ Rotor │ Cathode Anode Filament → e− e− e− →→→→→ (+) (-) Stator outside tube

Working

The filament is heated by a current and releases electrons through thermionic emission.

A high potential difference accelerates electrons from cathode to anode.

The focusing cup directs the electron beam toward the focal track.

Electrons strike the tungsten target at high speed.

Their rapid deceleration produces bremsstrahlung X-rays; characteristic radiation is also produced.

Most electron energy becomes heat, so the anode rotates to distribute heat over a larger focal track.

X-rays leave through the tube window and are shaped by collimation for imaging.

Why Rotate the Anode?

A stationary target would concentrate heat at one small area. Rotation spreads heat over a circular focal track, allowing higher tube loading while maintaining a small effective focal spot.

Advantages

Better heat dissipation.

Higher tube current/loading capability.

Longer target life.

Suitable for CT and high-duty diagnostic systems.

Conclusion

A rotating-anode X-ray tube converts electron kinetic energy into X-rays while distributing the large amount of generated heat over a rotating target track.

Q3(b). Describe different generations of CT-scan machine.20257m

Unit 2: Operation and Analysis of Imaging Equipment

Describe different generations of CT-scan machine.

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Worked Solution

Generations of CT Scanners

CT scanners evolved through several generations to improve speed, coverage, image quality and practicality.

Generation	Beam	Detector arrangement	Main feature
1st	Pencil beam	Single/few detectors	Translate-rotate; very slow
2nd	Narrow fan beam	Multiple detectors	Faster than 1st generation
3rd	Wide fan beam	Curved detector array	Rotate-rotate; common modern basis
4th	Wide fan beam	Fixed 360° detector ring	Rotating X-ray tube only
5th	Electron beam	Stationary target/anode arrangement	Very rapid cardiac imaging historically

1. First Generation

Used a narrow pencil beam and a single detector or very small detector array. The tube and detector translated across the patient and then rotated slightly. Many measurements were required, making scanning slow.

2. Second Generation

Used a narrow fan beam and multiple detectors. The increased number of detectors reduced the number of translation steps and shortened scan time.

3. Third Generation

Uses a broad fan beam with the X-ray tube and detector array rotating together around the patient. This design became the basis of most conventional modern CT systems.

4. Fourth Generation

Uses a stationary ring of detectors surrounding the patient while the X-ray tube rotates inside the ring. It can provide rapid acquisition but has different cost, calibration and dose considerations.

5. Fifth Generation

Electron-beam CT used an electron beam steered onto a stationary target ring to generate X-rays without mechanically rotating the X-ray tube. It was designed especially for very rapid imaging such as cardiac applications.

Modern CT

Modern scanners commonly use rotating gantries, multi-row detector arrays and helical/spiral scanning. Continuous rotation with slip-ring technology permits rapid volumetric acquisition, followed by computer reconstruction into cross-sectional and 3D images.

Conclusion

The progression from first to later generations primarily improved scan speed, detector coverage, spatial/temporal performance and clinical applicability.

Q4(a). What are the different modes in ultrasonography? Why is B-mode preferred?20257m
Unit 2: Operation and Analysis of Imaging Equipment
What are the different modes in ultrasonography? Why is B-mode preferred?

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Ultrasonography Modes and Preference for B-Mode

Ultrasound systems display returning echoes in different modes depending on how echo information is represented.

Major Modes

1. A-Mode (Amplitude Mode)

Displays echo amplitude as spikes against depth. It is mainly used in specialized applications such as ophthalmic measurements.

2. B-Mode (Brightness Mode)

Converts echo strength into brightness at the corresponding spatial location. Multiple scan lines form a two-dimensional grayscale image.

3. M-Mode (Motion Mode)

Displays movement of structures along a selected ultrasound line as a function of time. It is especially useful for cardiac valve and wall motion.

4. Doppler Mode

Uses frequency shifts caused by moving blood cells to estimate flow direction and velocity.

Common forms include spectral Doppler, color Doppler and power Doppler.

Why B-Mode is Preferred

B-mode is widely preferred for general diagnostic ultrasound because it provides a real-time two-dimensional anatomical image.

Advantages:

Good visualization of anatomy.

Real-time imaging.

Grayscale representation is easy to interpret.

No ionizing radiation.

Suitable for abdomen, obstetrics, thyroid, breast and many other examinations.

Can be combined with Doppler for simultaneous structural and flow assessment.

Conclusion

Although A-, M- and Doppler modes have specialized uses, B-mode is the principal general-purpose mode because it provides real-time anatomical imaging.
Q4(b). How do you image the cardiac system using ultrasonography?20257m
Unit 2: Operation and Analysis of Imaging Equipment
How do you image the cardiac system using ultrasonography?

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Worked Solution
Cardiac Imaging Using Ultrasonography

Cardiac ultrasound is called echocardiography. It uses a transducer to send and receive ultrasound waves and produces real-time images of the heart.

Basic Arrangement

Ultrasound Probe ↓ Chest Wall ↓ Heart Structures ↓ Reflected Echoes ↓ Probe ↓ Beamformer / Processor ↓ B-mode + Doppler Image

Procedure

The patient is positioned, commonly in a left lateral decubitus position for transthoracic imaging.

Acoustic gel is applied to remove air between the probe and skin.

A phased-array transducer is placed at standard acoustic windows such as parasternal, apical, subcostal and suprasternal positions.

Short ultrasound pulses are transmitted into the chest.

Echoes from myocardium, valves and blood interfaces return to the probe.

B-mode creates real-time anatomical images.

M-mode can measure rapid valve and wall motion along a selected line.

Doppler measures blood-flow velocity and direction.

Color Doppler maps flow over the anatomical image.

Important Measurements

Echocardiography can assess:

Chamber size.

Wall thickness and motion.

Valve structure and function.

Blood-flow velocity.

Ventricular function and ejection fraction.

Abnormal flow such as regurgitation or stenosis.

Advantages

Real-time imaging.

No ionizing radiation.

Portable and relatively inexpensive.

Can assess both anatomy and blood flow.

Useful for repeated examinations.

Limitations

Image quality can be reduced by obesity, lung air, ribs and other acoustic barriers. Operator skill and correct acoustic windows are important.

Conclusion

Echocardiography combines B-mode, M-mode and Doppler techniques to evaluate cardiac anatomy, motion and blood flow in real time.
Q5(a). Explain the working principle of a gamma camera with the help of a schematic diagram.20257m
Unit 2: Operation and Analysis of Imaging Equipment
Explain the working principle of a gamma camera with the help of a schematic diagram.

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Worked Solution
Gamma Camera: Working Principle

A gamma camera detects gamma photons emitted by a radiopharmaceutical inside the patient and produces a two-dimensional distribution image.

Schematic

Patient / Radiopharmaceutical ↓ Gamma photons Collimator ↓ NaI(Tl) Scintillation Crystal ↓ Light Photomultiplier Tubes ↓ Position + Energy Circuits ↓ Pulse Height Analyser ↓ Computer / Image Processor ↓ Gamma Image

Construction

Main components are:

Collimator – accepts photons traveling in selected directions and determines spatial localization.

Scintillation crystal – commonly sodium iodide activated with thallium, NaI(Tl), converts gamma photons into visible light.

Photodetectors – traditionally photomultiplier tubes convert light into electrical signals.

Positioning electronics – estimate the interaction position.

Pulse Height Analyser – selects photons in an appropriate energy window and rejects many scattered events.

Computer – converts accepted events into an image.

Working

A radiopharmaceutical accumulates in the organ of interest.

The radionuclide emits gamma photons.

The collimator allows selected photon trajectories to reach the detector.

The crystal produces flashes of light when gamma photons interact.

Photodetectors convert the light into electrical pulses.

The system estimates the position and energy of each event.

The PHA accepts events within the selected energy window.

Accepted events are accumulated to form the image.

Applications

Bone scans.

Thyroid imaging.

Renal imaging.

Cardiac perfusion studies.

Hepatobiliary studies.

Conclusion

A gamma camera converts the spatial distribution of emitted gamma radiation into an image using collimation, scintillation, photodetection, energy selection and computer processing.
Q5(b). Explain the construction of the ultrasonic probe.20257m
Unit 2: Operation and Analysis of Imaging Equipment
Explain the construction of the ultrasonic probe.

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Worked Solution
Construction of an Ultrasonic Probe

An ultrasonic probe (transducer) converts electrical energy into ultrasound and returning ultrasound echoes back into electrical signals.

Basic Construction

Probe Face ┌──────────────────┐ │ Acoustic Lens │ ├──────────────────┤ │ Matching Layer │ ├──────────────────┤ │ Piezoelectric │ │ Crystal / Array │ ├──────────────────┤ │ Backing / Damping│ ├──────────────────┤ │ Electrodes │ └────────┬─────────┘ │ Cable

Main Components

1. Piezoelectric Element

Usually made from a piezoelectric ceramic or other piezoelectric material. It converts electrical pulses into mechanical vibrations and converts returning echoes back into electrical signals.

2. Electrodes

Electrodes apply the excitation voltage and collect the electrical signal generated by received echoes.

3. Matching Layer

The acoustic impedance of the piezoelectric element is much higher than that of soft tissue. A matching layer reduces acoustic reflection at the probe-tissue interface and improves energy transmission.

4. Backing/Damping Material

The backing absorbs backward-directed acoustic energy and shortens the pulse duration. This improves axial resolution and controls ringing.

5. Acoustic Lens

The lens focuses the ultrasound beam and protects the probe face.

6. Housing and Cable

The housing mechanically supports the components, while the cable carries electrical excitation and received signals to the ultrasound system.

Working

The scanner applies a short electrical pulse to the piezoelectric element.

The element expands and contracts because of the piezoelectric effect, producing ultrasound.

The acoustic lens/matching layers transmit the sound efficiently into tissue.

Echoes return from tissue boundaries.

The piezoelectric element converts the echoes into electrical signals.

The scanner amplifies and processes these signals to form the image.

Array Probes

Modern probes often contain many small elements. Electronic beam steering and focusing can produce rapid scanning without mechanically moving the probe.

Conclusion

The probe's piezoelectric element, electrodes, matching layer, backing material, acoustic lens and housing work together to transmit and receive diagnostic ultrasound.
Q6(a). Define exposure dose. How do you measure the radiation dose?20257m
Unit 1: Science Behind Radiological Equipment
Define exposure dose. How do you measure the radiation dose?

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Worked Solution
Exposure Dose and Radiation Dose Measurement

Exposure Dose

Exposure describes the ionization produced by X-rays or gamma rays in air. It is historically expressed using units such as roentgen (R). Modern radiation protection practice generally uses absorbed, equivalent and effective dose quantities rather than exposure alone.

Important Dose Quantities

1. Absorbed Dose

Energy deposited per unit mass:

$D=\frac{d\bar{\epsilon}}{dm}$

SI unit: gray (Gy), where $1\,Gy=1\,J/kg$ .

2. Equivalent Dose

Accounts for the radiation type using a radiation weighting factor:

$H_T=\sum_R w_R D_{T,R}$

Unit: sievert (Sv).

3. Effective Dose

Accounts for different tissue sensitivities:

$E=\sum_T w_T H_T$

Unit: sievert (Sv).

How Radiation Dose is Measured

Different instruments are used according to the application:

Ionization chambers: accurate measurement of exposure/air kerma and output of X-ray equipment.

Geiger-Müller counters: radiation detection and survey applications.

Scintillation detectors: convert radiation into light and electrical pulses.

Semiconductor detectors: compact, sensitive detectors used in dosimetry and spectroscopy.

Personal dosimeters: monitor occupational exposure over time.

Thermoluminescent dosimeters (TLDs): store radiation energy and release light when heated during readout.

OSL dosimeters: use optically stimulated luminescence for dose readout.

X-ray Equipment Output

In diagnostic radiology, output can be measured using an ionization chamber or solid-state dosimeter. Patient dose may be estimated/measured using quantities such as entrance-surface air kerma or dose-area product, depending on the procedure.

Conclusion

Radiation dose measurement quantifies radiation exposure so that equipment performance can be controlled and patient and occupational doses can be kept appropriately low under the ALARA principle.
Q6(b). Explain the construction and operation of any one personal dosimeter.20257m
Unit 1: Science Behind Radiological Equipment
Explain the construction and operation of any one personal dosimeter.

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Worked Solution
Personal Dosimeter: TLD

A Thermoluminescent Dosimeter (TLD) is a personal dosimeter used to monitor occupational exposure to ionizing radiation.

Construction

A typical TLD badge contains:

One or more thermoluminescent detector elements, such as lithium fluoride (LiF).

Filters made from materials such as plastic, aluminium or copper to help distinguish radiation energy/type.

A holder or badge containing the detector.

Identification and protective casing.

Working Principle

When ionizing radiation strikes the TLD material, electrons are raised to higher-energy states and become trapped at defect sites in the crystal lattice.

During readout:

The TLD element is heated in a controlled reader.

Trapped electrons return to lower-energy states.

Light is emitted during this process.

A photodetector measures the emitted light.

The light output is related to the absorbed radiation dose after calibration.

Radiation Exposure ↓ TLD Crystal ↓ Energy stored in traps ↓ Controlled Heating ↓ Thermoluminescence ↓ Photodetector ↓ Dose Calculation

Advantages

Small and lightweight.

Good sensitivity.

Passive and requires no battery during exposure.

Can measure accumulated occupational dose.

Available in reusable formats after readout.

Limitations

The TLD does not provide an immediate real-time reading during exposure. It requires a reader for dose evaluation and must be properly calibrated.

Applications

TLDs are worn by radiographers, radiologists, nuclear-medicine workers and other personnel who may be occupationally exposed to ionizing radiation.

Conclusion

A TLD records radiation exposure by storing energy in crystal traps and releasing it as light during controlled heating; the emitted light is used to estimate personal dose.

Q7(a). What are the differences between CyberKnife and Gamma Knife?20257m

Unit 4: Integrate AI and Robotics into Radiological Systems II

What are the differences between CyberKnife and Gamma Knife?

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Worked Solution

CyberKnife vs Gamma Knife

Both systems provide stereotactic radiosurgery/radiotherapy, but their radiation sources, delivery mechanisms and clinical flexibility differ.

Feature	CyberKnife	Gamma Knife
Radiation source	Compact linear accelerator producing X-rays	Multiple sealed radioactive Cobalt-60 sources producing gamma rays
Delivery	Robotic arm moves the radiation source around the patient	Many fixed gamma beams converge on a target
Beam direction	Many dynamically selected angles	Fixed source geometry
Image guidance	Integrated image guidance and tracking	Uses stereotactic localization; modern systems may incorporate image guidance
Patient motion	Can track/correct for certain motion depending on system and site	Traditionally requires rigid/stereotactic immobilization; modern workflows vary
Typical use	Intracranial and selected extracranial lesions	Primarily intracranial lesions
Flexibility	Highly flexible beam positioning	Highly precise fixed geometry
Radiation source replacement	No radioactive cobalt source replacement; linac maintenance required	Requires management/replacement of radioactive sources according to system and regulations

CyberKnife

CyberKnife uses a small linear accelerator mounted on a robotic arm. The robot directs X-ray beams from many angles while image guidance helps localize the target.

Gamma Knife

Gamma Knife uses multiple Cobalt-60 sources arranged around the patient. Their gamma beams are focused on a target so that the target receives a high dose while surrounding tissue receives substantially less dose.

Conclusion

CyberKnife = robotic linac-based, flexible image-guided delivery.

Gamma Knife = multi-source Cobalt-60 stereotactic gamma-ray treatment, mainly for intracranial targets.

Q7(b). Elaborate on the common issues in radiological equipment.20257m
Unit 5: Maintenance and Troubleshooting of Radiological Devices
Elaborate on the common issues in radiological equipment.

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Worked Solution
Common Issues in Radiological Equipment

Radiological systems are complex combinations of high-voltage electronics, X-ray sources, detectors, mechanical components, computers and safety systems. Common faults can affect image quality, dose, availability and safety.

1. X-ray Tube Problems

Filament failure.

Anode overheating.

Focal-spot degradation.

Vacuum deterioration.

Unusual rotor noise.

Symptoms: low output, unstable exposure, artifacts or tube errors.

2. Detector Problems

Detector calibration errors, damaged detector elements, dead pixels or electronic noise can cause image artifacts and non-uniformity.

3. Power Supply Faults

High-voltage generator instability can produce incorrect tube voltage/current and inconsistent image exposure.

4. Mechanical Problems

Gantries, tables, tube stands and positioning mechanisms may develop alignment errors, vibration or movement faults.

5. Software and Communication Problems

Problems may occur in reconstruction software, workstation computers, DICOM networking, storage or PACS communication.

6. Image-Quality Problems

Typical artifacts include:

Excessive noise.

Poor contrast.

Motion artifacts.

Ring artifacts in CT.

Detector artifacts.

Geometric distortion.

7. Calibration Errors

Incorrect calibration can produce inaccurate measurements, non-uniform images or incorrect dose/output. Regular quality-control testing is therefore essential.

8. Ultrasound-Specific Issues

Probe cable damage, broken elements, poor acoustic coupling and probe surface damage can produce missing lines, reduced sensitivity or artifacts.

9. Radiation-Safety Problems

Interlocks, warning lights, shielding, exposure controls and monitoring systems must function correctly. Any safety-system fault should be addressed before clinical operation according to applicable procedures.

Preventive Maintenance

Scheduled inspection and cleaning.

Calibration and quality-control tests.

Cooling-system checks.

Detector and tube performance checks.

Electrical safety testing.

Software/database backups.

Maintenance documentation.

Conclusion

Common radiological-equipment problems involve tube, detector, power, mechanical, software, calibration, image-quality and safety systems. Preventive maintenance and documented quality control reduce failures and help maintain safe, consistent imaging.

Q8(a). What is the difference between supervised and unsupervised learning? Elaborate with an example.20257m

Unit 3: Integrate AI and Robotics into Radiological Systems I

What is the difference between supervised and unsupervised learning? Elaborate with an example.

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Worked Solution

Supervised vs Unsupervised Learning

Machine learning methods differ mainly in whether training data contains known target labels.

Feature	Supervised Learning	Unsupervised Learning
Training data	Labeled	Unlabeled
Goal	Learn mapping from input to target	Discover structure/patterns
Common tasks	Classification, regression	Clustering, dimensionality reduction
Example in radiology	Tumor vs non-tumor classification	Grouping scans into similar patterns

Supervised Learning

The model is trained using examples where the desired output is known.

For radiology, a dataset may contain CT/MRI images labeled tumor or no tumor. A neural network learns features associated with the labels and can then predict the class of a new image.

Examples:

CNN for tumor detection.
Fracture classification.
Disease-risk prediction.

Unsupervised Learning

The model receives data without predefined labels and attempts to discover structure in the dataset.

For example, clustering could group medical images according to similarities in image features without being told the diagnostic category beforehand.

Examples:

K-means clustering.
Hierarchical clustering.
Principal Component Analysis (PCA) for dimensionality reduction.

Example

Suppose 10,000 chest X-rays are available.

If each image is labeled pneumonia / normal, training a classifier is supervised learning.
If no labels are provided and an algorithm groups images according to similarity, it is unsupervised learning.

Conclusion

Supervised learning learns from labeled examples, whereas unsupervised learning discovers patterns in unlabeled data. Both can support medical-imaging research, but clinical deployment requires appropriate validation and human oversight.

Q8(b). How do you use robotics in radiology? Explain.20257m
Unit 4: Integrate AI and Robotics into Radiological Systems II
How do you use robotics in radiology? Explain.

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Robotics in Radiology

Robotics can improve precision, repeatability and access to difficult anatomical targets. In radiology, robots can assist image-guided procedures, positioning, biopsy and radiation treatment.

Major Applications

1. Robotic-Assisted Biopsy

A robot can position a needle along a planned trajectory based on CT, MRI or ultrasound images. The operator remains responsible for planning and clinical supervision.

Medical Image → Target Planning → Robot Positioning → Needle Guidance ↑ ↓ └────────────── Image Verification ────────────┘

2. Robotic Radiation Therapy

Systems such as CyberKnife use robotic positioning of a compact linear accelerator to deliver radiation from multiple angles while image guidance helps localize the target.

3. Patient/Imaging-System Positioning

Robotic mechanisms can assist positioning of patients or imaging components, improving repeatability and workflow.

4. Image-Guided Intervention

Robotic systems can integrate imaging data with navigation and motion control for minimally invasive procedures.

5. Tele-Radiology Support

Robotics can assist remote or semi-automated positioning and procedure support, although communication, safety and regulatory requirements must be carefully addressed.

Advantages

High positional precision.

Repeatable movements.

Ability to operate in constrained trajectories.

Reduced physical workload for clinicians.

Integration with image guidance.

Potentially improved targeting consistency.

Limitations and Safety

High system cost.

Complex calibration.

Need for reliable image-to-robot registration.

Mechanical/electrical failure risks.

Cybersecurity and network risks.

Requires trained clinical operators and appropriate safety interlocks.

Conclusion

Robotics in radiology combines medical imaging, navigation, motion control and clinical expertise to improve precision in procedures such as biopsies and radiation treatment. The robot assists the clinician; it does not replace clinical responsibility.
Q9(a). Write a short note on Robotic-assisted surgeries.20257m
Unit 4: Integrate AI and Robotics into Radiological Systems II
Write a short note on Robotic-assisted surgeries.

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Robotic-Assisted Surgeries

Robotic-assisted surgery uses computer-controlled robotic instruments operated by a surgeon to perform precise surgical movements. The robot is an assistive system; the surgeon remains responsible for clinical decisions and control.

Basic System

Surgeon Console ↓ Control Computer ↓ Robotic Manipulator ↓ Surgical Instruments ↓ Patient ↑ 3D Camera / Imaging Feedback

Working

The surgeon views the operative field through an imaging system.

Hand movements and commands at the console are translated into controlled instrument movements.

Robotic joints provide precise positioning and allow instruments to move through constrained surgical paths.

Depending on the system, tremor filtering and motion scaling can improve control.

The surgeon continuously monitors the procedure.

Advantages

High precision and repeatability.

Tremor reduction.

Small and controlled instrument movements.

Improved visualization in systems providing 3D magnified views.

Can facilitate minimally invasive procedures.

Potentially smaller incisions and reduced tissue trauma in suitable procedures.

Limitations

High acquisition and maintenance cost.

Specialized training required.

Complex equipment and setup.

Possible mechanical/software failures.

Lack of true autonomous decision-making in conventional surgical robots.

Applications

Robotic assistance is used in selected procedures in areas such as urology, gynecology, general surgery and cardiothoracic surgery. Image-guided robotic systems may also support biopsy and other minimally invasive interventions.

Conclusion

Robotic-assisted surgery combines surgeon expertise, medical imaging, computer control and precise robotic instruments to improve control during suitable surgical procedures.
Q9(b). Write a short note on AI in radiology.20257m
Unit 3: Integrate AI and Robotics into Radiological Systems I
Write a short note on AI in radiology.

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AI in Radiology

Artificial Intelligence (AI) in radiology refers to the use of machine-learning and deep-learning algorithms to assist with image interpretation, workflow, measurement, reporting and clinical decision support.

Major AI Techniques

Machine Learning

Models learn patterns from data to perform tasks such as classification or prediction.

Deep Learning

Deep neural networks, especially convolutional neural networks (CNNs) and related architectures, can learn image features directly from medical images.

Applications

1. Tumor Detection

AI can identify suspicious regions in CT, MRI or other images and provide candidate lesion locations.

2. Fracture Identification

Algorithms can flag radiographs that may contain fractures for further review.

3. Image Segmentation

AI can outline organs, tumors or other structures to support measurements and treatment planning.

4. Image Reconstruction and Enhancement

AI methods can help reduce noise or accelerate reconstruction in selected imaging workflows while maintaining useful image quality.

5. Workflow Prioritization

AI can flag potentially urgent studies so they can receive appropriate attention sooner.

6. Quantitative Analysis

Automated measurements such as lesion size, organ volume or imaging biomarkers can improve consistency.

Basic Workflow

Medical Image ↓ Pre-processing ↓ AI / Deep Learning Model ↓ Detection / Classification / Segmentation ↓ Radiologist Review ↓ Clinical Decision

Advantages

Rapid analysis of large datasets.

Assistance with repetitive measurements.

Potentially improved consistency.

Workflow support and prioritization.

Quantitative image analysis.

Challenges

Need for representative, high-quality training data.

Dataset bias and differences between hospitals/scanners.

False positives and false negatives.

Explainability and validation.

Patient privacy and cybersecurity.

Regulatory and clinical responsibility.

Conclusion

AI is best viewed as a clinical decision-support tool that can augment radiologists rather than automatically replace them. Safe deployment requires rigorous validation, monitoring and appropriate human oversight.

Radiological Equipment

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Pulse Height Analyser in a Gamma Camera

Definition

Need for PHA

Working

Energy Window

Importance

Conclusion

How X-rays Interact with Living Tissues

1. Photoelectric Effect

2. Compton Scattering

3. Coherent Scattering

4. Transmission

Tissue Attenuation

Biological Effects

Conclusion

Rotating-Anode X-ray Tube: Operation

Construction

Labelled Schematic

Working

Why Rotate the Anode?

Advantages

Conclusion

Generations of CT Scanners

1. First Generation

2. Second Generation

3. Third Generation

4. Fourth Generation

5. Fifth Generation

Modern CT

Conclusion

Ultrasonography Modes and Preference for B-Mode

Major Modes

1. A-Mode (Amplitude Mode)

2. B-Mode (Brightness Mode)

3. M-Mode (Motion Mode)

4. Doppler Mode

Why B-Mode is Preferred

Conclusion

Cardiac Imaging Using Ultrasonography

Basic Arrangement

Procedure

Important Measurements

Advantages

Limitations

Conclusion

Gamma Camera: Working Principle

Schematic

Construction

Working

Applications

Conclusion

Construction of an Ultrasonic Probe

Basic Construction

Main Components

1. Piezoelectric Element

2. Electrodes

3. Matching Layer

4. Backing/Damping Material

5. Acoustic Lens

6. Housing and Cable

Working

Array Probes

Conclusion

Exposure Dose and Radiation Dose Measurement

Exposure Dose

Important Dose Quantities

1. Absorbed Dose

2. Equivalent Dose

3. Effective Dose