PRACTICAL GUIDELINES FOR PHOTOTHERAPY
1. ESSENTIAL INFORMATION FOR PHOTOTHERAPY Wavelength of UVA : 320-400 nm
UVB : 290-320 nm
Dosimetry :
Energy (joule) = Power (watt) x exposure time (second)
Fluence (J/cm²) = irradiance (W/cm²) x exposure time (sec)
Dosage (J/cm²)
Exposure Time (min) = --------------------------------------------------
0.06 x Irradiance (mW/cm²) Variation of irradiance :
Irradiance (power density) varies directly with power source and inversely with surface area (therefore inversely with the square of distance from the power source)
I1 x D1² = I2 x D2² (I=irradiance; D=distance)
D1² / T1 = D2² / T2 (T=exposure time)
Grading of erythema :
E0 No erythema
E1 Minimally perceptible erythema (faint pink)
E2 Marked erythema (red)
E3 Fiery red erythema with oedema
E4 Fiery red erythema with oedema and blistering
NB In pigmented patient, sometimes erythema and oedema may not be seen. Instead of these, patient may complain of hotness and tightness of skin.
Erythema is a limiting factor in phototherapy - E1 should not be exceeded. The onset of UVA-induced erythema has a delayed onset of 48 hours after exposure.
MPD (Minimal phototoxic dose) = The dose of PUVA required to produce a E1 reaction 48 hours after exposure.
MED (Minimal erythemogenic dose) = The dose of UVB required to produce a E1 reaction 24 hours after exposure.
Skin types :
I Always burn, never tan
II Always burn, but sometimes tan
III Sometimes burn, but always tan
IV Never burn, always tan
V Moderately pigmented people (Chinese, Indian)
VI Black people (West Indies, Africans)
2. PUVA
2.1 Indications
(i) Psoriasis
Mainly for plaque type
Relatively contraindicated for unstable, generalized pustular and erythrodermic psoriasis. Special cautions should be exercised if PUVA is being used in these conditions.
(ii) Mycosis fungoides (CTCL)
Patch stage and plaque stage
(iii) Vitiligo
Mainly for face
(iv) Others : severe atopic eczema, PLEVA, PLC etc.
2.2 Contraindications
(i) Pregnancy
(ii) Children < 12-year old
(iii) Photosensitivity
(iv) Severe cardiac, hepatic or renal diseases
(v) History of skin cancers
(vi) Aphakia or cataracts
(vii) Immunosuppressed patients (probably)
2.3 Factors for Consideration in Psoriasis
(i) Age & sex
(ii) Severity (>30% involvement - arbitrary)
(iii) Previous treatment for psoriasis
(iv) Concomitant medical illness
(v) Social & economic factors
2.4 Before Starting PUVA
(i) Consider indications & contraindications
(ii) Thoroughly inform the patient about the nature of therapy
Give the instruction sheet of PUVA to patient
(iii) Written consent
(iv) Routine blood screening (LFT, RFT, ANF)
(v) Body weight
2.5 Initiation of Treatment
(i) Starting dose of psoralen (body weight: 0.6 mg/kg) Body Weight Meladinine (Methoxsalen)
(Kg) (10mg/tablet)
<50 20mg
50-65 30mg
65-80 40mg
80-90 50mg
>90 60mg
(Take medication 2 hours before treatment with food) (ii) Starting dose of UVA (according to skin type or phototesting) Skin Type Dosage of UVA (J/cm²)
I 0.5
II 1.0
III 1.5
IV 2.0
V 2.5
VI 3.0
Phototesting : determine the Minimal phototoxic dose as the starting dose. (iii) Frequency of therapy: twice per week during clearing phase
(iv) Increment of dosage at each subsequent visit :
Initial : 0.5-1.0 J/cm² (depends on skin type and starting dose)
If no response after 10 treatments : 1.0-1.5 J/cm²
If still no response after 15 treatments : Increase dosage of methoxsalen
(v) Defaulter
(a) Miss one regularly scheduled treatment: dosage should not be increased, use the last dosage
(b) Miss more than one session : dosage should be reduced by 0.5 J/cm² per session missed (Minimum : starting dose)
(c) Default for more than two sessions : see MO before restart the treatment
(vi) Reaction (inform MO)
(a) If trace of erythema occurs, dosage should not be increased but the patient may be treated with previous exposure time.
(b) If more than trace of erythema occur, or patient complains of hotness and tightness, the areas affected should not be retreated until these subside.
(vii) When more than 95% clearance (flexible), the last dosage should be maintained, and a maintenance schedule should begin.
(viii) If no significant response or still not ready for maintenance treatment after 30 treatments, patient may be designated as treatment failure.
2.6 Frequency of Assessment by MO
Two weeks after initiation of treatment, then every four weeks during active phase. However, patient should be seen by doctor as soon as possible if any reaction occurs.
MO should specify the starting dosage, subsequent increment and frequency of therapy on the treatment sheet.
2.7 Maintenance Therapy
(i) The last clearance dose is maintained at once-weekly interval.
(ii) If clearing persists for 4 weeks, reduce the frequency to one exposure every 2 weeks (most patients need this frequency for maintenance).
(iii) If it persists for another 8 weeks, reduce to one exposure every month. If it persist for another 4 months, the treatment may be stopped.
(iv) If there is relapse during maintenance, treatment is increased to twice a week and UVA dose is increased by 0.5-1.5 J/cm² for each successive treatment. Maintenance is then given at a higher frequency than the one which did not work.
(v) During maintenance therapy, if erythema occurs as a result of decreasing pigmentation, the UVA dose should be decreased by 0.25 J/cm² per treatment until erythema is no longer present.
2.8 Sites for Special Consideration
(i) Extremities esp. legs do not respond as well as other areas, additional exposure time up to one fourth of the total may be given with shielding of the other sites.
(ii) Intertriginous areas, scrotum, perineum, pendulous breasts and abdomen are more sensitive to UV light. If necessary, they may be shielded with folded cloth for one third of the total exposure time until tanning occurs.
(iii) Hairy scalp does not benefit from PUVA therapy.
(iv) Face may be shielded with cloth after the first few exposures if it is not affected by psoriasis.
(v) Normal skin is more sensitive to UVA than psoriatic skin.
2.9 Precautions That Must Be Taken By Nursing Staff
(i) Before treatment
(a) a.ask whether the patient has taken psoralen
(b) check whether the patient has erythema
(c) check the correct exposure time
(ii) During treatment
(a) make sure that the patient is wearing the protective goggles
(b) make sure that accurate exposure time is given
(c) withhold treatment if patient complains of discomfort
(iii) After treatment
(a) Remind the patient to wear the sunglasses (Polarised grey - or green-tinted) for 8 hours after therapy (both indoor and outdoor), and shield from direct sunlight with sunscreen, suitable clothing, hat or umbrella.
(b) Check the next follow-up time.
(c) Calculate the cumulative dose given.
(iv) Maintenance of the PUVA machine
Check the irradiance of the machine with the UVA photometer every month. Inform the technician to change the fluorescent tubes at the recommended interval (For 3001 PUVA machine: after 1500-2000 hours) or when the irradiance drops. (new lamps: 10.5 mW/cm² at a distance of 21 cm; change lamps if output falls below 6 mW/cm²)
2.10 Complications
(i) Excessive erythema
Withhold PUVA therapy if more than E1 occurs
Treat as burns
(ii) Pruritus
Bland emollients and antihistamines
If severe and persistent, withhold the phototherapy
(iii) Nausea
(a) Always take methoxsalen with some food
(b) Mild nausea : take half the total dose of methoxsalen two and half hours and the remainder two hours before phototherapy
(c) Severe nausea : antiemetic half hour prior to ingestion of methoxsalen or decrease the dose of methoxsalen by 10 mg
(iv) Pigmentation
Reassure that it will fade as exposures become less frequent after the clearing phase
(v) Cataract
Preferably with ophthalmological examination annually
(vi) Premature ageing and potential carcinogenesis in skin
Cautious when the cumulative dose over 1500 J/cm²
3. PUVA IN VITILIGO
Essentially same as in psoriasis. Started the dose of UVA as that in type I skin with 0.5 J/cm², with each increment of 0.25 J/cm² and a frequency of two to three treatments per week. Try the PUVA for 3 months. If there is response, may continue up to one year.
In Social Hygiene Service, because of the shortage of manpower and PUVA machine, a modified regimen using Wood's lamp and topical psoralen has been used for years in vitiligo clinic. However, it is difficult to standardize the exposure time as different models of UV lamps are used and these lamps wear with time. It therefore depends much on the experience of individual therapist with that particular lamp.
3.1 Instrument and Specifications
(Used in YFS and SYP Dermatological Clinics)
Model B-100A Blak-ray Ultraviolet Lamp
Peak wavelength : 366nm
Minimal intensity : 1.020 mW/cm² at 15 inches
Radiation (measured with UVA photometer) :
at 6 inches is approx 6 mw/cm²
3.2 Patient Selection
Vitiligo on the face, avoid eyelids
3.3 Before Starting Topical PUVA for Vitiligo
(i) Explanation about the procedures and possible complications
(ii) Written consent
3.4 Dosimetry
(i) Start with 30 seconds at a distance of 6 inches
(ii) Frequency : twice per week
(iii) Increase 10 seconds each session until E1 occurs
(iv) Try three months' duration. Continue if there is response; stop if there is no response.
3.5 Procedures
(i) Apply topical meladinine 30 minutes before radiation. Apply a thin layer to the site of vitiligo only. Avoid the junction between the normal skin and vitiligo. Avoid application to eyelids.
Never dispense the topical meladinine to patient for home application.
(ii) Warm up the machine for 5 minutes before use.
(iii) Fix the required distance.
(iv) Treat with the required exposure time.
(v) Wash away the topical meladinine after treatment.
(vi) Leave the lamp on until all patients are treated, do not shift on and off frequently.
(vii) If the lamp is shifted off, wait for 5 minutes or more before restart.
3.6 Defaulter
(i) Miss one regularly scheduled treatment: dosage should not be increased, use the last dosage
(ii) Miss more than one session: dosage should be reduced by 10 seconds per session missed. (Minimum : starting dose)
(iii) Default for more than two sessions : see MO before restart the treatment
3.7 Precautions That Must Be Taken By Nursing Staff
(i) Before treatment
(a) check whether the patient has erythema
(b) check the correct exposure time
(ii) During treatment
(a) make sure that the patient is wearing the protective goggles
(b) make sure that accurate exposure time is given
(iii) After treatment
(a) Advise the patient to avoid sunlight for 2 days
Use broad-spectrum sunscreen (Coppertone 45, Sunsense, RV Paque etc.) both indoor and outdoor
(b) Check the next follow-up time
(iv) Maintenance of the machine
Check the irradiance of the machine with the UVA photometer every month. Inform the technician to change the bulb at the recommended interval or when the irradiance drops (minimal: 1.020 mW/cm² at 15 inches distance)
3.8 Frequency of Assessment by MO
(same as PUVA)
3.9 Complications of Topical PUVA
(i) Erythema
Local reaction with intense erythema with pain and blistering may occur (either due to over-exposure or photoallergic contact dermatitis). For large area of vitiligo on face, it is better to try the treatment on a small area first.
(ii) Photosensitivity
Photosensitivity of the skin can persist for 48-72 hours after application of topical psoralen.
(iii) Hyperpigmentation
Marked hyperpigmentation may occur at the site of treatment.
4. UVB PHOTOTHERPAY
4.1 Indications
(i) Psoriasis
(ii) PLEVA, PLC, PR
(iii) Uraemic pruritus
4.2 Regimens for Psoriasis (Chronic Plaque Type)
(i) Goeckerman regimen (Tar + UVB)
(ii) Ingram regimen (Dithranol + UVB)
(iii) UVB alone
4.3 Goeckerman Regimen
- Mainly for inpatient treatment
- Average duration of treatment: 28 days
- Monitor parameters: thickness, scaling and erythema
Procedures :
(i) Apply 3-10% Coal tar paste topically to the plaques (or whole body) bd.
(ii) Daily LPC (Liquor Pica Carbonis) bath. The coal tar paste should be washed away with liquid paraffin one hour before the UVB irradiation.
(iii) After the UVB therapy in Physiotherapy Department (QMH, QEH), reapply he coal tar.
Side-effects of coal tar :
(i) Messiness and staining of the clothes
(ii) Irritation of uninvolved skin
(iii) Folliculitis especially over flexures
4.4 Ingram regimen
- Mainly for inpatient treatment
- Average duration of treatment: 21 days
Procedures :
(i) Apply dithranol in Lassar paste (start with lowest concentration available: 0.25%) once daily to the plaques ONLY (Avoid the normal skin). The applied paste is then powdered (e.g. using Talcum powder) to harden the surface and prevent spreading to uninvolved skin. The treated areas are then enveloped in Tubegauze and left for 24 hours. Increase the concentration of dithranol if tolerated.
(ii) Daily LPC bath. The paste is removed with liquid paraffin one hour before the UVB irradiation.
(iii) After the UVB therapy in Physiotherapy Department, reapply the dithranol again.
Side-effects of dithranol :
(i) Brown staining of the skin (reversible)
(ii) Burning, which can be severe
(iii) Irritation (avoid applying to flexures, face and eyes)
4.5 UVB Therapy
(i) UVB machine: fluorescent bulbs with peak emission around 300 nm are commonly used
(ii) Dosimetry
Unlike the relatively standardised regimen in PUVA, the empirical starting dose and subsequent increment of UVB usually have to depend on the recommendations of the manufacturers of different UVB machine, and on the individual therapist's experience, taking account of the skin type of the patient.
Another more precise approach is to determine the patient's sensitivity by the phototesting. The aim is to achieve an erythema of E1. During the course of therapy, patient will develop various degree of tanning, which may require an increase of exposure dosage.
Starting dosage : 80% of the MED as determined by the phototesting or the starting dose as recommended by the manufacturer.
Subsequent increment : 1/8 (12.5%) of the last dosage
(iii) Frequency
Inpatient : 5 times per week (except Saturday & Sunday)
Outpatient : 3 times per week
(iv) Distance
Depend on different machine used. If the distance is changed during the treatment, the correct exposure time should be calculated accordingly. (See Page 2 - variation of irradiance)
(v) Maintenance
UVB phototherapy is mainly used as clearance schedules on intermittent basis. Effect from long term maintenance is unclear, if being given, most psoriatic patients require one to three exposures each week to maintain a clear state.
4.6 Complications
(similar to those of PUVA)
4.7 Machine and Specifications
(Used in YFS Dermatological Clinic)
Model : Hohensonne 3030
Irradiance : UVB : 3 mW/cm² at 75cm distance
(with two reflector units)
Irradiation time : 2.2 min for 1 J/cm² at 75 cm distance
Field size : UVB : 40 cm (16 in) x 110cm (44 in) at 75 cm
distance (with two reflector units)
4.8 Before Starting UVB Phototherapy
(i) Explanation about the procedures and possible complications
(ii) Written consent
(iii) Phototesting
4.9 Phototesting
(i) A template with holes of different size (approx 2 x 2 cm²) is covered to the back
(ii) Irradiate with different doses of UVB (10, 20, 30, 40 seconds) at a distance of 75 cm)
(iii) Read the result 24 hours later and determine the MED
4.10 Dosimetry
(i) Start with 80% of MED or 30 seconds (if phototesting has not been done) at a distance of 75 cm
(ii) Frequency : three times per week
(iii) Increase 1/8 (12.5%) of previous dosage each session, stop the increment if more than faint erythema occur
4.11 Procedures
(i) Fix the required distance (75 cm)
(ii) Select the UV switch and 2 reflector units
(iii) Turn main switch on
(iv) Set the required exposure time with the timeswitch
(v) After being swift off, the burner must be allowed to cool down at least for the set period before restart
(vi) The field size of irradiation should be considered (e.g. if the whole body is treated, the upper and lower parts have to be treated separately)
4.12 Defaulter
(i) Miss one regularly scheduled treatment : dosage should not be increased, use the last dosage
(ii) Miss more than one session: dosage should be reduced by 1/8 (12.5%) per session missed. (Minimum: starting dose)
(iii) Default for more than two sessions : see M.O. before restart the treatment
4.13 Precautions That Must Be Taken By Nursing Staff
(i) Before treatment
(a) check whether the patient has erythema
(b) check the correct exposure time
(ii) During treatment
make sure that the patient is wearing the protective goggles
(iii) After treatment
Check the next follow-up time
(iv) Maintenance of the machine
Inform the technician to change the bulb at the recommended interval (erythema-producing UV burner IQ 601KC should be renewed after approx 1000 switching operations).
4.14 Frequency of Assessment by MO
(same as PUVA)
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