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Coleman AJ, Aneju GA, Freeman P, Fedele F. A model of the UV skin dose distribution in paediatric whole-body phototherapy. Phys Med Biol 2021; 66. [PMID: 34464950 DOI: 10.1088/1361-6560/ac2266] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2021] [Accepted: 08/31/2021] [Indexed: 11/11/2022]
Abstract
The radiance equation is applied in this study to model the ultraviolet (UV) radiation dose distribution over the skin in paediatric and adult patients treated in a whole-body phototherapy cabin. This approach extends a previously published model of UV radiation dose based on thermal radiation exchange between surfaces (Colemanet al2020Biomed. Phys. Eng. Express6055023). The new model makes it feasible to predict the distribution of UV irradiance over the head, trunk and legs in patients of varying height. The modelled irradiance distributions to directly lamp-facing skin surfaces agree to within 10% of those measured in simulated clinical paediatric treatments in a modern narrowband UVB treatment cabin. For a 10 year old (of height 1.36 m), for example, the model and the clinical measurements both show a UV radiation dose to the face that is around 25% more than that in an adult (of height 1.8 m). The dose to the crown of the head of a 10 year old is both predicted and measured to be more than double that of an adult. The automated dosimetry system, incorporated within the treatment cabin, is also predicted to overestimate irradiance to the body by between 10% and 25% in patients aged between 10 and 4 years (height 1.36-1.0 m). The value of the model and its implications for paediatric whole-body UV treatment in adult-size whole-body treatment cabins are considered.
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Affiliation(s)
- A J Coleman
- Medical Physics Department, Guy's and St Thomas' NHS Foundation Trust, London, United Kingdom
| | - G A Aneju
- Medical Physics Department, Guy's and St Thomas' NHS Foundation Trust, London, United Kingdom
| | - P Freeman
- Medical Physics Department, Guy's and St Thomas' NHS Foundation Trust, London, United Kingdom
| | - F Fedele
- Medical Physics Department, Guy's and St Thomas' NHS Foundation Trust, London, United Kingdom
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Coleman AJ, Aneju GA, Freeman P, Fedele F. A thermal radiation exchange model of whole-body UV phototherapy. Biomed Phys Eng Express 2020; 6:055023. [PMID: 33444254 DOI: 10.1088/2057-1976/abac1d] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
A novel model of the skin dose in whole-body UV phototherapy treatment cabins is presented. The model is based on an analysis of the thermal radiation exchange between two surfaces, in this case the UV source and the patient. It is shown to allow analytical treatment of the multiple internal reflections in a treatment cabin that account for around 40% of the skin irradiance. The model provides predictions of the absolute irradiance at the skin and shielding factors in seven different UVA and NB-UVB cabins that are within 6% of those measured using a calibrated radiometer and within 12% for all nine cabins. The model predicts reducing skin irradiances with increasingly patient size, a trend demonstrated in clinical measurements. The exact sensitivity to patient size in automated cabin dosimetry systems, however, varies with in-built sensor positioning. The potential to extend the use of the model to investigate improved design of automated dosimetry systems is discussed.
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Affiliation(s)
- A J Coleman
- Medical Physics Department, Guy's and St Thomas' NHS Foundation Trust, London, United Kingdom
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Moseley H, Allan D, Amatiello H, Coleman A, du Peloux Menagé H, Edwards C, Exton L, Ferguson J, Garibaldinos T, Martin C, Mohd Mustapa M, McHenry P, Griffiths M, Buckley D, Nasr I, Swale V, Duarte Williamson C, Leslie T, Mallon E, Towers K, Saunders C, Brain A. Guidelines on the measurement of ultraviolet radiation levels in ultraviolet phototherapy: report issued by the British Association of Dermatologists and British Photodermatology Group 2015. Br J Dermatol 2015; 173:333-50. [DOI: 10.1111/bjd.13937] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/17/2015] [Indexed: 11/26/2022]
Affiliation(s)
- H. Moseley
- The Photobiology Unit Ninewells Hospital and Medical School Dundee DD1 9SY U.K
| | - D. Allan
- The Christie NHS Foundation Trust and University of Manchester Manchester Academic Health Science Centre Wilmslow Road Manchester M20 4BX U.K
| | - H. Amatiello
- Radiation Physics and Protection Group Churchill Hospital Old Road Headington Oxford OX3 7LJ U.K
| | - A. Coleman
- Guy's and St Thomas' NHS Foundation Trust St Thomas' Hospital Westminster Bridge Road London SE1 7EH U.K
| | - H. du Peloux Menagé
- Guy's and St Thomas' NHS Foundation Trust St Thomas' Hospital Westminster Bridge Road London SE1 7EH U.K
- Lewisham and Greenwich NHS Trust High Street London SE13 6LH U.K
| | - C. Edwards
- Royal Gwent Hospital Cardiff Road Newport NP20 2UB U.K
| | - L.S. Exton
- British Association of Dermatologists Willan House, 4 Fitzroy Square London W1T 5HQ U.K
| | - J. Ferguson
- The Photobiology Unit Ninewells Hospital and Medical School Dundee DD1 9SY U.K
| | - T. Garibaldinos
- Guy's and St Thomas' NHS Foundation Trust St Thomas' Hospital Westminster Bridge Road London SE1 7EH U.K
| | - C. Martin
- Department of Clinical Physics and Bio‐Engineering University of Glasgow Glasgow G12 8QQ U.K
| | - M.F. Mohd Mustapa
- British Association of Dermatologists Willan House, 4 Fitzroy Square London W1T 5HQ U.K
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Narbutt J, Pawlaczyk M, Sysa-Jędrzejowska A, Krzyścin JW, Sobolewski P, Rajewska-Więch B, Lesiak A. System for monitoring UV radiation level in phototherapy cabins in Poland. Arch Med Sci 2014; 10:1244-54. [PMID: 25624865 PMCID: PMC4296080 DOI: 10.5114/aoms.2014.47834] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/27/2012] [Revised: 07/30/2012] [Accepted: 10/10/2012] [Indexed: 12/05/2022] Open
Abstract
INTRODUCTION Ultraviolet phototherapy (UVP) is widely used in dermatological practice for the treatment of various skin diseases. Numerous studies support its beneficial curing effectiveness; however, overexposure to ultraviolet radiation can cause adverse health effects, such as sunburn reaction, erythema response, cataract, skin aging, etc. For these reasons, it is of special importance to monitor performance of UVP cabins using a calibration system to evaluate the UV doses incident upon the patient. MATERIAL AND METHODS A mechanized cabin control system (CCS) is proposed. It consists of radiometers with a wide and narrow field of view to estimate the body irradiation and to identify malfunctioning cabin tubes. Quality control and quality assurance procedures are developed to keep high accuracy of the calibration procedure. The CCS has been used in the examination of two different types of UVP cabins routinely working in Poland. RESULTS It allows precise calculation of UV doses and spatial variability of UV radiance inside the cabin, thus providing uncertainties of the doses assigned by medical staff. The CCS could potentially serve as a primary standard for monitoring various UVP cabins working in Poland. CONCLUSIONS The methodology developed to quantify UV doses in UVP cabins may be easily extended to any UV radiation source.
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Affiliation(s)
- Joanna Narbutt
- Department of Dermatology, Medical University of Lodz, Lodz, Poland
| | - Mariola Pawlaczyk
- Department of Biology and Environmental Study, Poznan University of Medical Sciences, Poznan, Poland
| | | | | | - Piotr Sobolewski
- Institute of Geophysics, Polish Academy of Sciences, Warsaw, Poland
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Grimes DR. A computational simulation of reflector and tube effects in ultraviolet phototherapy. Phys Med Biol 2012; 57:6661-70. [DOI: 10.1088/0031-9155/57/20/6661] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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Grimes DR, Martin CJ, Phanco G. Investigations of cabin design in UV phototherapy. Med Phys 2012; 39:3019-25. [DOI: 10.1118/1.4711812] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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Grimes DR, Robbins C, Martin CJ, Phanco G, O'Hare NJ. Reflection modeling in ultraviolet phototherapy. Med Phys 2011; 38:4312-20. [DOI: 10.1118/1.3600694] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
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Grimes DR, Robbins C, O'Hare NJ. Dose modeling in ultraviolet phototherapy. Med Phys 2010; 37:5251-7. [DOI: 10.1118/1.3484093] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
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Schneider LA, Wlaschek M, Dissemond J, Scharffetter-Kochanek K. Examples for the importance of radiophysical measurements in clinical phototherapy. J Dtsch Dermatol Ges 2007; 5:384-9. [PMID: 17451382 DOI: 10.1111/j.1610-0387.2007.06281.x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
BACKGROUND Optimal UV therapy requires regular surveillance of the variables that influence therapeutic success. In daily practice, phototherapy equipment is often operated with an attitude of "autocontrol." This implies that thorough control measurements of the emission spectra and calibration of UV fluences are not routinely performed. For both quality control and patient safety, it is essential to regularly check whether a UV source is providing the right target spectrum with the correct dose to the skin. METHODS We have exemplarily taken three UV sources currently used in clinical practice and performed radiophysical measurements, i. e. determined emission spectra, radiation output and correctness of dose calculation. RESULTS All three sources revealed either a largely inhomogeneous distribution pattern of radiation intensity, variation of radiation intensity over time or insufficient filtering of the UV lamp emission spectrum. Furthermore the dose calculation procedures had to be revised because of significant differences between the estimated and the administered UV doses. CONCLUSIONS Radiophysical measurement of all UV-equipment in clinical use is a simple and effective way to improve the safety and reliability of phototherapy. Such measurements help to uncover technical flaws in radiation sources and prevent unnecessary side effects and UV exposure risks for the patient.
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Diffey B. The contribution of medical physics to the development of psoralen photochemotherapy (PUVA) in the UK: a personal reminiscence. Phys Med Biol 2006; 51:R229-44. [PMID: 16790905 DOI: 10.1088/0031-9155/51/13/r14] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Psoralen photochemotherapy (PUVA) is the combined treatment of skin disorders with a photosensitizing drug (Psoralen) and UltraViolet A radiation. The introduction of PUVA therapy has arguably been the most important development in dermatology over the past 30 years and from the first days of the treatment being introduced in the UK, British medical physicists were an integral part of the effort to establish it. Medical physicists have contributed to this development in a number of ways, from designing irradiation units in the early days of the technique, through to collaborating with dermatologists in prosecuting clinical and experimental studies aimed at improving patient outcomes. That the dose of UVA radiation is administered quantitatively, and not qualitatively, has probably been the single most important contribution made by several medical physicists over this period. However, despite concerns that were expressed almost 30 years ago about the accuracy with which UVA doses are administered to patients, the medical physics community still has some way to go before we can be satisfied that statements about UVA irradiance and dose can be made with confidence.
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Affiliation(s)
- Brian Diffey
- Regional Medical Physics Department, Newcastle General Hospital, Newcastle upon Tyne NE4 6BE, UK.
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Martin CJ, Clouting H, Aitken A. A study of the correction factor for ultraviolet phototherapy dose measurements made by the indirect method. Br J Dermatol 2003; 149:1227-31. [PMID: 14674901 DOI: 10.1111/j.1365-2133.2003.05507.x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
BACKGROUND Optimization of ultraviolet (UV) phototherapy for treatment of psoriasis and other skin conditions requires accurate dosimetry. One factor involved in whole body treatments is the correction that needs to be applied to radiometer measurements of irradiance made remotely without a person in the phototherapy cabin. OBJECTIVES To evaluate the correction factor for cabins of different design and to consider whether different factors should be used for different phototherapy cabins and radiometers. METHODS An automated UV dosimetry system capable of recording irradiances at positions around the circumference of a circle equating to a human trunk has been developed. The system has been combined with a phantom to derive values for the ratio between irradiance measurements made by the direct method with a person in a cabin, and indirect measurements recorded remotely. In addition, values for the ratio in UVA cabins have been derived from comparisons between measurements made directly by persons in a cabin and indirect measurements. RESULTS Variations in direct to indirect ratio (DIR) with cabin type were less than between individual sets of measurements. The mean DIR obtained for cabins with TL01 lamps was 0.85 +/- 0.02, while that for UVA cabins was 0.80 +/- 0.05. The DIR for dual lamp (TL01/UVA) cabins, when TL01 lamps were illuminated, was higher (0.92). CONCLUSIONS The DIR should be applied to any measurements made using radiometers without a person or equivalent phantom in a cabin. It is proposed that standard values are appropriate for groups of cabins with a single type of lamp and similar reflectors.
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Affiliation(s)
- C J Martin
- Health Physics, Department of Clinical Physics and Bio-Engineering, Gartnavel Royal Infirmary, Glasgow G12 OXH, Scotland, U.K.
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Taylor DK, Anstey AV, Coleman AJ, Diffey BL, Farr PM, Ferguson J, Ibbotson S, Langmack K, Lloyd JJ, McCann P, Martin CJ, Menagé HDP, Moseley H, Murphy G, Pye SD, Rhodes LE, Rogers S. Guidelines for dosimetry and calibration in ultraviolet radiation therapy: a report of a British Photodermatology Group workshop. Br J Dermatol 2002; 146:755-63. [PMID: 12000370 DOI: 10.1046/j.1365-2133.2002.04740.x] [Citation(s) in RCA: 56] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
This report examines the dosimetry of ultraviolet (UV) radiation applied to dermatological treatments, and considers the definition of the radiation quantities and their measurement. Guidelines are offered for preferred measurement techniques and standard methods of dosimetry. The recommendations have been graded according to the American Joint Committee on Cancer classification of strength of recommendation and quality of evidence (summarized in Appendix 5).
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Affiliation(s)
- D K Taylor
- Medical Physics Department, Gloucestershire Royal Hospital, Great Western Road, Gloucester, GL1 3NN, UK.
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Currie GD, Evans AL, Smith D, Martin CJ, McCalman S, Bilsland D. An automated dosimetry system for testing whole-body ultraviolet phototherapy cabinets. Phys Med Biol 2001; 46:333-46. [PMID: 11229718 DOI: 10.1088/0031-9155/46/2/305] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
A new technique is described for automated ultraviolet dosimetry within whole-body phototherapy cabinets. A dual-head detector system has been designed, permitting simultaneous assessment of irradiance levels and radiant intensities from individual lamps. One detector is used in combination with a diffuser/filter system for the measurement of irradiance and the other is mounted at the end of a slit collimator to provide a measurement which can be related to the radiant intensities of the individual lamps. These quantities are derived from 800 separate measurements made during rotation of the detector head around a 360 degrees circle at a fixed height and position within the cabinet under remote computer software control. The device has advantages compared with standard techniques, enabling measurements to be made without the need for a person to be present in the cabinet. A full set of measurements is made with minimal switching of the power supply to the lamps. This simplifies the assessment and reduces the uncertainty from variation in output after the lamps are switched on. Variations in irradiance with orientation for the smaller phototherapy cabinets are clearly demonstrated. Plots of data from the collimated detector show peaks corresponding to the lamps and the surrounding reflectors. The plots enable failed lamps to be detected and peak values can be related to radiant intensities of individual lamps.
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Affiliation(s)
- G D Currie
- Department of Clinical Physics and Bio-engineering, North Glasgow University Hospital NHS Trusts, UK
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Martin CJ, Pye SD. A study of the directional response of ultraviolet radiometers: II. Implications for ultraviolet phototherapy derived from computer simulations. Phys Med Biol 2000; 45:2713-29. [PMID: 11008967 DOI: 10.1088/0031-9155/45/9/320] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
A theoretical model has been used to simulate irradiances for ultraviolet (UV) phototherapy cabinets and other sources. The accuracy of the simulation results has been checked by comparison with experimental measurements. The simulations have been used to study the influence of different factors on UV phototherapy exposure and to develop recommendations for the operation and calibration of phototherapy cabinets. Many radiometers used in the evaluation of skin doses have input optics with directional responses that are not proportional to the cosine of the angle of incidence for the UV radiation. Data on radiometer directional responses have been incorporated into the simulations, which show that the poor directional responses for some radiometers currently in use will give errors of 20-50% in the assessment of irradiance. The influence of lamp source geometries employed for radiometer calibration has been investigated. UV phototherapy dosimetry commonly uses a spectroradiometer and a radiometer in the transfer of irradiance calibrations from a small standard UV lamp to a large-area source with a different UV spectrum. Recommendations are given on the range of acceptability for radiometer directional responses and a method is described for determining whether these are fulfilled. Recommendations are made on the techniques that should be used for calibration.
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Affiliation(s)
- C J Martin
- Department of Clinical Physics and Bio-Engineering, North Glasgow University Hospitals NHS Trust, Western Infirmary, UK
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Abstract
A phantom was developed as a reproducible means of measuring the irradiance in an occupied ultraviolet cabin, by placing the phantom, or replica person, in the cabin, obviating the need for human exposure. The contributions to the patient irradiance measured in the cabin were investigated, looking in particular at the effect of the reflectors. Radiation undergoing single reflection was seen to contribute to a greater extent than multiple reflections. Placing an object in the cabin reduces the measured irradiance due to the blocking of multiple reflections, but variation in the exact shape and size of the object has less effect, which is useful as patients are of all shapes and sizes and a representative phantom was to be developed. The phantom was made of expanded polystyrene blocks with an embedded probe. Measurements were made to verify the equivalence of human and phantom cabin occupancy. It was found that the irradiance measured with the phantom in the cabin lies within the values measured with human occupancy.
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Affiliation(s)
- C A Fulljames
- Medical Physics Department, Gloucestershire Royal Hospital, Gloucester GL1 3NN, UK.
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Coleman AJ, Collins M, Saunders JE. Traceable calibration of ultraviolet meters used with broadband, extended sources. Phys Med Biol 2000; 45:185-96. [PMID: 10661591 DOI: 10.1088/0031-9155/45/1/313] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
A calibration system has been developed to provide increased accuracy in the measurement of the irradiance responsivity appropriate for UV meters used with broadband, extended sources of the type employed in phototherapy. The single wavelength responsivity of the test meter is obtained in the wavelength range 250-400 nm by intercomparison with a transfer standard meter in a narrow, monochromatic beam. Traceability to primary standard irradiance scales is provided via the National Measurement System with a best uncertainty of 7% (at 95% confidence). The effective responsivity of the test meter, when used with broadband extended sources, is calculated using the measured spectral and angular response of the meter and tabulated data on the spectral and spatial characteristics of the source radiance. The uncertainty in the effective responsivity, independent of the source variability, is estimated to be 10% (at 95% confidence). The advantages of this calibration system over existing approaches are discussed.
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Affiliation(s)
- A J Coleman
- Medical Physics Directorate, St Thomas' Hospital, London, UK
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Martin CJ, Currie GD, Pye SD. The importance of radiometer angular response for ultraviolet phototherapy dosimetry. Phys Med Biol 1999; 44:843-55. [PMID: 10232800 DOI: 10.1088/0031-9155/44/4/003] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
The influence of the angular response of radiometer probes on measurements of irradiance in ultraviolet phototherapy has been studied. Irradiance measurements were made using nine ultraviolet (UV) radiometers employed by phototherapy centres in Scotland and Northern Ireland, and compared with measurements made using two spectroradiometers. The light sources used were UVB TL01 fluorescent lamps, arranged in different geometries. Irradiances within TL01 whole body treatment cabinets were assessed based on a comparison with one of the spectroradiometers. The results show variations of 50% in cabinet irradiance measurements made by different radiometers, even when they were calibrated using the same source geometry and spectroradiometer. Differences in radiometer probe design and construction lead to an under- or over-response at angles of incidence greater than zero. Angular responses of different probes were assessed using banks of fluorescent lamps. The differences found are large enough to account for the variations in measurements of cabinet irradiance. The variations in irradiance measurements are significant in terms of planning and monitoring patient exposure during TL01 phototherapy. Accurate dosimetry can only be achieved if radiometer probes have a good cosine response and recommendations are made for better calibration techniques.
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Affiliation(s)
- C J Martin
- Department of Clinical Physics and Bio-Engineering, West Glasgow Hospitals University NHS Trust, UK
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