🎯 Electrotherapy-II Exam Preparation — BPT 2nd Year

• 12 questions, attempt any 10
• Each = 8 marks
• Q1-Q6: Long answers (8 marks each)
• Q7-Q9: Short notes, 2 parts (2×4=8)
• Q10-Q12: Short notes, 4 parts (4×2=8)

📌 HIGH-PRIORITY LONG ANSWER QUESTIONS (8 marks each)

Q1. Production of LASER and its Physical Characteristics ⭐⭐⭐

1. Active Medium - can be gas (He-Ne), solid (Nd:YAG), semiconductor (GaAlAs diode laser)
2. Energy Source / Pumping - electrical discharge, flashlamp, or diode arrays excite atoms to higher energy state
3. Population Inversion - more atoms in excited state than ground state; achieved by pumping
4. Stimulated Emission - an incoming photon triggers an excited atom to release an identical photon (same phase, frequency, direction)
5. Optical Resonator / Cavity - two mirrors (one fully reflective, one partially reflective) amplify light by repeated reflection
6. Output - laser beam emitted through the partially reflective mirror

• Monochromaticity - single wavelength/colour
• Collimation - parallel rays, minimal divergence
• Coherence - all waves in same phase (spatial and temporal)
• High Intensity / Brightness - concentrated energy

• He-Ne laser: 632.8 nm (red, visible)
• GaAlAs / Diode laser: 780-900 nm (infrared)
• Nd:YAG: 1064 nm

Q2. Production of SWD + Method of Application + Circuit Diagram ⭐⭐⭐

• Frequency: 27.12 MHz, Wavelength: 11 metres

1. Mains supply → step-up transformer → rectifier
2. Oscillator tank circuit (inductor + capacitor) generates high-frequency oscillations
3. Patient circuit coupled to oscillator circuit
4. Produces high-frequency alternating current that heats deep tissues

• Primary/mains circuit
• Tank/oscillator circuit (LC circuit)
• Patient/output circuit
• Patient electrodes (capacitor or inductive coil)

• Dose I: No warmth (sub-thermal)
• Dose II: Mild warmth
• Dose III: Moderate warmth
• Dose IV: Strong warmth (just below pain threshold)

Q3. Indications, Contraindications of UVR, IRR, IFT ⭐⭐⭐

Q4. Production of IRR + Luminous and Non-Luminous ⭐⭐⭐

• Wavelength: 760 nm to 1 mm (beyond visible red)
• Subdivided: Near IR (760-1500 nm) and Far IR (1500 nm-1 mm)

• Generated by heating a material; all heated objects emit IR
• In physiotherapy, produced by purpose-built lamps

• Tungsten filament lamp / Radiant heat lamp
• Operates at ~2500-3000°C
• Emits visible red light + near IR
• Penetrates deeper (up to 10 mm into skin)
• Peak emission: ~1000 nm
• Requires warm-up time of ~5 minutes

• Carbon rod / nichrome wire coil heated to ~500-700°C
• No visible light emitted (dull red glow only)
• Emits far/long IR
• Penetrates more superficially (~1-2 mm)
• Peak emission: ~4000 nm
• Requires warm-up time of ~15 minutes
• More comfortable for patients (no glare)

Q5. Classification of UVR + All Generators ⭐⭐⭐

• UVA (Long Wave UV): 315-400 nm - least energetic; used in PUVA therapy; causes tanning
• UVB (Medium Wave UV): 280-315 nm - causes erythema and Vitamin D synthesis; most therapeutic
• UVC (Short Wave UV): 100-280 nm - most bactericidal; germicidal lamps

1. Hot Quartz Mercury Vapour Lamp (Kromayer lamp)

• Most used in physiotherapy
• Mercury vapour in quartz tube; emits UVA, UVB, UVC
• Water-cooled version: Kromayer lamp (contact treatment)
• Used for: local treatment, psoriasis, wounds

1. Cold Quartz (Low Pressure) Mercury Vapour Lamp

• Emits mainly UVC (253.7 nm)
• Bactericidal - used for wound/ulcer sterilization
• Cool-burning

1. Alpine Sun Lamp (AIR lamp)

• High-pressure mercury vapour in quartz tube
• Emits full spectrum UVR
• Used for general irradiation, vitamin D, psoriasis

1. Fluorescent Tube Lamps

• Emit specific bands (UVA for PUVA therapy)
• Used in phototherapy cabinets

1. Carbon Arc Lamp

• Older source; emits visible + UVR
• Largely obsolete

Q6. Production of Ultrasound + Indications + Contraindications ⭐⭐⭐

• Frequency: 0.5 - 3 MHz (1 MHz for deep tissues, 3 MHz for superficial)
• Longitudinal compression waves above audible range

1. Alternating electrical current applied to piezoelectric crystal (lead zirconate titanate / quartz)
2. Crystal rapidly expands and contracts (vibrates) in synchrony with AC frequency
3. Vibrations transmitted as acoustic/ultrasonic waves through coupling medium (gel) into tissue
4. Reverse piezoelectric effect = electrical → mechanical vibration

• Soft tissue injuries (sprains, strains, tendinopathies)
• Scar tissue/adhesions
• Plantar fasciitis, bursitis, epicondylitis
• Calcific deposits
• Wound healing
• Phonophoresis (drug delivery)
• Carpal tunnel syndrome
• Dupuytren's contracture

• Malignancy
• Over pregnant uterus
• Over cardiac pacemaker / heart area
• Thrombophlebitis / DVT
• Active infection / acute inflammation
• Over epiphyseal plates in children
• Over spinal cord after laminectomy
• Eyes, testes, brain

📌 SHORT NOTES (2 marks each) - VERY LIKELY TO REPEAT

Phonophoresis

Russian Current

• Developed by Yakov Kots (Soviet Union, 1970s)
• Medium-frequency sinusoidal AC: 2500 Hz carrier frequency
• Delivered in 50 bursts/second (50 Hz burst frequency)
• Each burst = 10 ms on, 10 ms off (50% duty cycle)
• Effect: Strong muscle contraction, muscle strengthening
• Training Protocol (Kots Protocol):
• 10-second stimulation, 50-second rest
• 10 contractions per session
• Used for strength training in athletes and rehabilitation

PSWD (Pulsed SWD) and MWD (Microwave Diathermy)

• SWD delivered in pulses; non-thermal effects predominate
• Mean power is low (no significant heating)
• Used for: oedema reduction, pain relief, wound healing
• Suitable for acute conditions (unlike continuous SWD)

• Frequency: 2450 MHz, Wavelength: 12.25 cm
• Heats tissues with high water content selectively
• Penetration: ~3-5 cm
• Applied via Director (antenna)
• Contraindicated: pacemakers, metallic implants, eyes, testes

Modes of IFT

• Two medium-frequency AC currents (e.g., 4000 Hz and 4001-4100 Hz) cross in tissue
• Produce a beat frequency (AMF = amplitude modulation frequency) of 1-100 Hz within tissues

1. Bipolar (2-pole): Interference within machine; simpler; smaller treatment area
2. Quadripolar (4-pole / true IFT): Two circuits cross in tissue; larger area; true interference
3. Vector (Swing pattern): Interference field rotates automatically; treats larger, irregular areas

• 0-10 Hz: Motor stimulation, muscle pump, oedema
• 80-100 Hz: Pain relief (acute); sensory stimulation
• 1-100 Hz sweep: General treatment

Sun Alpine Lamp

• High-pressure mercury vapour lamp in quartz envelope
• Emits full-spectrum UV (UVA + UVB + UVC) + visible light
• Used for: general UV irradiation, vitamin D production, psoriasis, eczema
• Requires MED (Minimal Erythema Dose) testing before use
• E2 erythema (first degree) is typical therapeutic response

Physical Characteristics of Laser (for short note)

• Monochromaticity - single wavelength
• Collimation - parallel non-diverging beam
• Coherence - all photons in phase (spatial + temporal)
• High intensity - concentration of energy in narrow beam

Frequency Sweep

• In IFT, instead of fixed AMF, the frequency automatically sweeps between two values
• Prevents accommodation (nerve adaptation to constant frequency)
• Example: sweep from 80-100 Hz; or 1-100 Hz
• Keeps treatment effective throughout session

Therapeutic Effects of SWD and Laser

• Increased local circulation
• Muscle relaxation
• Reduced pain (sedative effect)
• Accelerated tissue repair
• Reduced muscle spasm

• Biostimulation (cellular ATP production)
• Anti-inflammatory (reduces prostaglandins)
• Analgesic (endorphin release, nerve conduction alteration)
• Wound healing (fibroblast proliferation)
• Bactericidal (high power)

Cupping Therapy

• Traditional technique; uses glass/silicone cups
• Negative pressure created by heat or suction
• Dry cupping: suction only
• Wet cupping (Hijama): skin is nicked, blood drawn
• Sliding cupping: cup moved over oiled skin (like deep massage)
• Effects: increased circulation, myofascial release, pain relief
• Used in physiotherapy for: myofascial pain, trigger points, sports injuries

Pain Gate Theory

• Proposed by Melzack and Wall, 1965
• Mechanism: Large-diameter myelinated fibres (Aβ) activate inhibitory interneurons in substantia gelatinosa (lamina II of dorsal horn) → "gate" closes → blocks transmission of pain signals from small fibres (Aδ and C)
• TENS, IFT, and massage work via this mechanism
• High-frequency TENS (80-150 Hz) activates gate control
• Clinically: explains why rubbing an injury reduces pain

Coherence (Laser)

• All waves are in the same phase both spatially (across beam width) and temporally (over time)
• This property makes laser light fundamentally different from ordinary light
• Enables precise focusing and concentration of energy
• Responsible for laser's unique biological effects

Training Protocol of Russian Current

• Kots Protocol: 10 contractions/session
• Stimulation ON: 10 seconds, OFF: 50 seconds (1:5 duty cycle)
• Sessions: daily for 3-4 weeks
• Intensity: to 30-50% of maximal voluntary contraction
• Used: post-operative muscle wasting, athletic strength training, neurological rehab

Cable Method of SWD

• Insulated cable coiled around limb or body part
• Current flows through cable, generating oscillating magnetic field
• Induces eddy currents in tissues
• Heats tissues with high water/ion content (muscle)
• Used for: limb conditions (ankle, knee, elbow)

Dosages of SWD (Schliephake Scale)

Class 3 Laser

• Medium-power laser: 1-500 mW
• Class 3A: 1-5 mW; safe for skin, momentary eye exposure hazardous
• Class 3B: 5-500 mW; direct or specular reflection hazardous to eyes; therapeutic laser range
• Most physiotherapy lasers are Class 3B
• Safety: protective goggles mandatory, no direct eye exposure

Heliotherapy

• Use of sunlight for therapeutic purposes
• Natural source of UVR, IR, and visible light
• Indications: psoriasis, vitiligo, vitamin D deficiency, rickets, seasonal affective disorder
• Precautions: avoid peak UV hours (10 am - 4 pm), use graduated exposure (MED-based)
• Heliotherapy + sea bathing = Thalassotherapy

Therapeutic Effects of UVR

• Erythema production (first sign of reaction)
• Vitamin D synthesis (UVB converts 7-dehydrocholesterol → Vit D3)
• Bactericidal effect (UVC; denatures bacterial DNA)
• Pigmentation (tanning; UVA stimulates melanin)
• Antirachitic effect (prevents/treats rickets)
• Psychological effect (mood elevation)
• Wound healing (promotes fibroblast proliferation)

• E0: Suberythemal (no redness)
• E1: First degree (slight redness, fades in 24h)
• E2: Second degree (brighter, peeling, fades 48-72h)
• E3: Third degree (severe, blistering)
• E4: Fourth degree (severe blistering, systemic effects)

PUVA Therapy

• Psoralen + UVA photochemotherapy
• Psoralen (oral or topical) → photosensitizer; intercalates into DNA
• UVA (320-400 nm) activates psoralen → inhibits DNA synthesis in rapidly dividing cells
• Indications: psoriasis, vitiligo, mycosis fungoides, eczema
• Side effects: nausea (oral psoralen), phototoxicity, long-term skin cancer risk, cataracts (eye protection mandatory)

✅ EXAM STRATEGY SUMMARY

1. LASER production + characteristics
2. SWD production + application methods + circuit diagram
3. UVR classification + generators (Alpine sun lamp, Kromayer etc.)
4. Ultrasound production + indications + contraindications
5. IRR (luminous vs non-luminous)
6. IFT indications/contraindications OR modes

• PUVA, Heliotherapy, Class 3 laser
• Russian current + training protocol
• Pain gate theory
• Phonophoresis
• PSWD vs MWD
• Frequency sweep
• Cupping therapy
• Dosages of SWD, Cable method

Good luck tomorrow! 🌟 Cover at least 8-9 topics thoroughly - you only need to attempt 10 out of 12. Focus on the topics that appeared in Q1-Q6 of last year's paper as they are the highest-mark earners. Write neat diagrams wherever possible (LC circuit for SWD, LASER resonator cavity, IRR lamp diagrams) - they earn extra marks.