Factors influencing the degree of erythematous skin reactions in humans

Skin erythema assessment techniques

Skin erythema may present owing to many causes. One of the common causes is prolonged exposure to sunrays. Other than sun exposure, skin erythema is an accompanying sign of dermatologic diseases, such as psoriasis and acne. Quantifying skin erythema in patients enables the dermatologist to assess the patient's skin health. Quantitative assessment of skin erythema has been the focus of several studies. The clinical standard for erythema evaluation is visual assessment; however, this standard has some deficiencies. For instance, visual assessment is subjective and ineffectual for precise color information exchange. To overcome these limitations, in the past three decades various methodologies have been developed in an attempt to achieve objective erythema assessments, such as diffuse reflectance spectroscopy and both optical and nonoptical systems. This review considers the studies published during the past three decades and discusses the performance, the mathematical tactics for computation, and the limited capabilities of erythema assessment techniques for cutaneous diseases. The achievements and limitations of the current techniques in erythema assessment are presented. The advantages and development trends of optical and nonoptical methods are presented to make the reader aware of the present technological advances and their potential for dermatological disease research.

Factors Influencing the Severity of Acute Radiation-Induced Skin and Mucosal Toxicity in Head and Neck Cancer

Background and purpose

Radiotherapy is a crucial part of cancer therapy armamentarium, but it is associated with skin and mucosal toxicity in a substantial proportion of patients with head and neck cancer. Its extent, however, depends on several patient-related and treatment-related factors. In-depth knowledge of these is prudent for better patient management.

Aim

The aim of this study is to assess the factors influencing the severity of acute radiation-induced skin and mucosal toxicity in patients with head and neck cancer receiving external beam radiotherapy.

Materials and methods

This longitudinal observational study included all patients receiving curative external beam radiotherapy for head and neck cancer aged 18 years or above from January 2018 to December 2018. Patient-related and treatment-related characteristics including age, gender, type, staging and site of cancer, history of smoking and diabetes, surface area exposed, and concurrent chemotherapy were compared in patients experiencing severe and non-severe acute skin and mucosal toxicity using the Radiation Therapy Oncology Group (RTOG) scoring system.

Results

Higher age (p = 0.002), TNM stage IV (p = 0.023), and concurrent administration of chemotherapy (p = 0.002) were statistically associated with severe acute radiation-induced skin and mucosa toxicity, whereas gender, surface area irradiated, history of smoking, and diabetes did not show such an association.

Conclusion

Older patients with TNM stage IV malignancy receiving concurrent chemotherapy are at a high risk of developing skin and mucosal toxicity that might interfere with the treatment protocol and warrant hospitalization, compromising their quality of life.

Hyperspectral imaging assessment for radiotherapy induced skin-erythema: Pilot study

Skin cancer (SC) is a widely spread disease in the USA, Canada, and Australia. Skin cancer patients may be treated by many different techniques including radiation therapy. However, radiation therapy has side effects, which may range from skin erythema to skin necrosis. As erythema is the early evidence of exposure to radiation, monitoring erythema is important to prevent more severe reactions. Visual assessment (VA) is the gold standard for evaluating erythema. Nevertheless, VA is not ideal, since it depends on the observer's experience and skills. Digital photography and hyperspectral imaging (HSI) are optical techniques that provide an opportunity for objective assessment of erythema. Erythema indices were computed from the spectral data using Dawson's technique. The Dawson relative erythema index proved to be highly correlated (97.1 %) with clinical visual assessment scores. In addition, on the 7th session of radiation therapy, the relative erythema index differentiates with 99 % significance between irradiated and non-radiated skin regions. In this study, HSI is compared to digital photography for skin erythema statistical classification.

Skin erythema and pigmentation: a review of optical assessment techniques

BACKGROUND

Skin erythema may present due to many causes. One of the common causes is prolonged exposure to sun rays. Other than sun exposure, skin erythema is an accompanying sign of dermatological diseases such as acne, psoriasis, melasma, post inflammatory hyperpigmentation, fever, as well as exposure to specific electromagnetic wave bands.

METHODS

Quantifying skin erythema in patients enables the dermatologist to assess the patient's skin health. Therefore, quantitative assessment of skin erythema was the target of several studies. The clinical standard for erythema evaluation is visual assessment. However, the former standard has some imperfections. For instance, it is subjective, and unqualified for precise color information exchange. To overcome these shortcomings, the past three decades witnessed various methodologies that aimed to achieve erythema objective assessment, such as diffuse reflectance spectroscopy (DRS), and both optical and non-optical systems.

DISCUSSION

This review article reports on the studies published in the past three decades where the performance, the mathematical tactics for computation, and the capabilities of erythema assessment techniques for cutaneous diseases are discussed. In particular, the achievements and limitations of the current techniques in erythema assessment are presented.

CONCLUSION

The profits and development trends of optical and non-optical methods are displayed to provide the researcher with awareness into the present technological advances and its potential for dermatological diseases research.

Changes in skin microcirculation during radiation therapy for breast cancer

BACKGROUND

The majority of breast cancer patients who receive radiation treatment are affected by acute radiation-induced skin changes. The assessment of these changes is usually done by subjective methods, which complicates the comparison between different treatments or patient groups. This study investigates the feasibility of new robust methods for monitoring skin microcirculation to objectively assess and quantify acute skin reactions during radiation treatment.

MATERIAL AND METHODS

Laser Doppler flowmetry, laser speckle contrast imaging, and polarized light spectroscopy imaging were used to measure radiation-induced changes in microvascular perfusion and red blood cell concentration (RBC) in the skin of 15 patients undergoing adjuvant radiation therapy for breast cancer. Measurements were made before treatment, once a week during treatment, and directly after the last fraction.

RESULTS

In the treated breast, perfusion and RBC concentration were increased after 1-5 fractions (2.66-13.3 Gy) compared to baseline. The largest effects were seen in the areola and the medial area. No changes in perfusion and RBC concentration were seen in the untreated breast. In contrast, Radiation Therapy Oncology Group (RTOG) scores were increased only after 2 weeks of treatment, which demonstrates the potential of the proposed methods for early assessment of skin changes. Also, there was a moderate to good correlation between the perfusion (r = 0.52) and RBC concentration (r = 0.59) and the RTOG score given a week later.

CONCLUSION

We conclude that radiation-induced microvascular changes in the skin can be objectively measured using novel camera-based techniques before visual changes in the skin are apparent. Objective measurement of microvascular changes in the skin may be valuable in the comparison of skin reactions between different radiation treatments and possibly in predicting acute skin effects at an earlier stage.

Mitochondrial Superoxide Increases Age-Associated Susceptibility of Human Dermal Fibroblasts to Radiation and Chemotherapy

Elderly cancer patients treated with ionizing radiation (IR) or chemotherapy experience more frequent and greater normal tissue toxicity relative to younger patients. The current study demonstrates that exponentially growing fibroblasts from elderly (old) male donor subjects (70, 72, and 78 years) are significantly more sensitive to clonogenic killing mediated by platinum-based chemotherapy and IR (∼70%-80% killing) relative to young fibroblasts (5 months and 1 year; ∼10%-20% killing) and adult fibroblasts (20 years old; ∼10%-30% killing). Old fibroblasts also displayed significantly increased (2-4-fold) steady-state levels of O₂^•-, O₂ consumption, and mitochondrial membrane potential as well as significantly decreased (40%-50%) electron transport chain (ETC) complex I, II, IV, V, and aconitase (70%) activities, decreased ATP levels, and significantly altered mitochondrial structure. Following adenoviral-mediated overexpression of SOD2 activity (5-7-fold), mitochondrial ETC activity and aconitase activity were restored, demonstrating a role for mitochondrial O₂^•- in these effects. Old fibroblasts also demonstrated elevated levels of endogenous DNA damage that were increased following treatment with IR and chemotherapy. Most importantly, treatment with the small-molecule, superoxide dismutase mimetic (GC4419; 0.25 μmol/L) significantly mitigated the increased sensitivity of old fibroblasts to IR and chemotherapy and partially restored mitochondrial function without affecting IR or chemotherapy-induced cancer cell killing. These results support the hypothesis that age-associated increased O₂^•- and resulting DNA damage mediate the increased susceptibility of old fibroblasts to IR and chemotherapy that can be mitigated by GC4419. Cancer Res; 77(18); 5054-67. ©2017 AACR.

Early biomarker for radiation-induced wounds: day one post-irradiation assessment using hemoglobin concentration measured from diffuse optical reflectance spectroscopy

Normal tissue radiation toxicities are evaluated subjectively and cannot predict the development of severe side-effects. Using a hand-held diffuse reflectance optical spectroscopy probe, we measured optical parameters in mouse skin 1-4 days after irradiation. Using a radiation toxicity model and a therapeutic mitigator described previously [BMC Cancer14, 614 (2014)], we found that hemoglobin (Hb) levels increased sharply 24 h after irradiation only in the irradiated group without the mitigator. This group also had the largest peak wound areas after 14 days. We conclude that increased Hb one day after skin irradiation predicts the severity of the subsequent irradiation-induced wound.

Endothelial perturbations and therapeutic strategies in normal tissue radiation damage

Most cancer patients are treated with radiotherapy, but the treatment can also damage the surrounding normal tissue. Radiotherapy side-effects diminish patients’ quality of life, yet effective biological interventions for normal tissue damage are lacking. Protecting microvascular endothelial cells from the effects of irradiation is emerging as a targeted damage-reduction strategy. We illustrate the concept of the microvasculature as a mediator of overall normal tissue radiation toxicity through cell death, vascular inflammation (hemodynamic and molecular changes) and a change in functional capacity. Endothelial cell targeted therapies that protect against such endothelial cell perturbations and the development of acute normal tissue damage are mostly under preclinical development. Since acute radiation toxicity is a common clinical problem in cutaneous, gastrointestinal and mucosal tissues, we also focus on damage in these tissues.

Vasculotide, an Angiopoietin-1 mimetic, reduces acute skin ionizing radiation damage in a preclinical mouse model

Background

Most cancer patients are treated with radiotherapy, but the treatment can also damage the surrounding normal tissue. Acute skin damage from cancer radiotherapy diminishes patients’ quality of life, yet effective biological interventions for this damage are lacking. Protecting microvascular endothelial cells from irradiation-induced perturbations is emerging as a targeted damage-reduction strategy. Since Angiopoetin-1 signaling through the Tie2 receptor on endothelial cells opposes microvascular perturbations in other disease contexts, we used a preclinical Angiopoietin-1 mimic called Vasculotide to investigate its effect on skin radiation toxicity using a preclinical model.

Methods

Athymic mice were treated intraperitoneally with saline or Vasculotide and their flank skin was irradiated with a single large dose of ionizing radiation. Acute cutaneous damage and wound healing were evaluated by clinical skin grading, histology and immunostaining. Diffuse reflectance optical spectroscopy, myeloperoxidase-dependent bioluminescence imaging of neutrophils and a serum cytokine array were used to assess inflammation. Microvascular endothelial cell response to radiation was tested with in vitro clonogenic and Matrigel tubule formation assays. Tumour xenograft growth delay experiments were also performed. Appreciable differences between treatment groups were assessed mainly using parametric and non-parametric statistical tests comparing areas under curves, followed by post-hoc comparisons.

Results

In vivo, different schedules of Vasculotide treatment reduced the size of the irradiation-induced wound. Although skin damage scores remained similar on individual days, Vasculotide administered post irradiation resulted in less skin damage overall. Vasculotide alleviated irradiation-induced inflammation in the form of reduced levels of oxygenated hemoglobin, myeloperoxidase bioluminescence and chemokine MIP-2. Surprisingly, Vasculotide-treated animals also had higher microvascular endothelial cell density in wound granulation tissue. In vitro, Vasculotide enhanced the survival and function of irradiated endothelial cells.

Conclusions

Vasculotide administration reduces acute skin radiation damage in mice, and may do so by affecting several biological processes. This radiation protection approach may have clinical impact for cancer radiotherapy patients by reducing the severity of their acute skin radiation damage.

Electronic supplementary material

The online version of this article (doi:10.1186/1471-2407-14-614) contains supplementary material, which is available to authorized users.

Skin tumorigenic potential of benzanthrone: prevention by ascorbic acid

Benzanthrone (BA) exposed occupational workers have been found to exhibit toxicological manifestations in the skin, thus it is quite likely that long term exposure may lead to skin tumorigenicity. Thus, attempts were made to elucidate the tumor initiating and promoting potentials of pure (PBA) and commercial benzanthrone (CBA). Additionally, the preventive role of ascorbic acid (AsA) was also assessed. PBA showed tumor initiating activity while CBA demonstrated tumor initiating as well as promoting activities in two-stage mouse skin tumor protocol. Further, prior treatment of AsA to PBA and CBA followed by twice weekly application of 12-o-tetradecanoyl phorbal myristate acetate (TPA) resulted into delayed onset of tumor formation and similarly single application of 7,12-dimethylbenz [α] anthracene (DMBA) followed by twice weekly application of AsA and CBA showed an increase in the latency period. Thus, AsA showed a protective effect against CBA promoted skin tumor. Furthermore, the topical application of CBA significantly increased the levels of xenobiotic enzymes. The animals topically treated with AsA along with topical application of CBA, restored all the impairment observed in enzyme activities. Thus, this study suggested that AsA can be useful in preventing PBA and CBA induced skin tumorigenicity.

In vivo verification of superficial dose for head and neck treatments using intensity-modulated techniques

Skin dose is one of the key issues for clinical dosimetry in radiation therapy. Currently planning computer systems are unable to accurately predict dose in the buildup region, leaving ambiguity as to the dose levels actually received by the patient's skin during radiotherapy. This is one of the prime reasons why in vivo measurements are necessary to estimate the dose in the buildup region. A newly developed metal-oxide-semiconductor-field-effect-transistor (MOSFET) detector designed specifically for dose measurements in rapidly changing dose gradients was introduced for accurate in vivo skin dosimetry. The feasibility of this detector for skin dose measurements was verified in comparison with plane parallel ionization chamber and radiochromic films. The accuracy of a commercial treatment planning system (TPS) in skin dose calculations for intensity-modulated radiation therapy treatment of nasopharyngeal carcinoma was evaluated using MOSFET detectors in an anthropomorphic phantom as well as on the patients. Results show that this newly developed MOSFET detector can provide a minimal but highly reproducible intrinsic buildup of 7 mg cm(-2) corresponding to the requirements of personal surface dose equivalent Hp (0.07). The reproducibility of the MOSFET response, in high sensitivity mode, is found to be better than 2% at the phantom surface for the doses normally delivered to the patients. The MOSFET detector agrees well with the Attix chamber and the EBT Gafchromic film in terms of surface and buildup region dose measurements, even for oblique incident beams. While the dose difference between MOSFET measurements and TPS calculations is within measurement uncertainty for the depths equal to or greater than 0.5 cm, an overestimation of up to 8.5% was found for the surface dose calculations in the anthropomorphic phantom study. In vivo skin dose measurements reveal that the dose difference between the MOSFET results and the TPS calculations was on average -7.2%, ranging from -4.3% to -9.2%. The newly designed MOSFET detector encapsulated into a thin water protective film has a minimal reproducible intrinsic buildup recommended for skin dosimetry. This feature makes it very suitable for routine IMRT QA and accurate in vivo skin dosimetry.

Evaluation of the Sinmed Mastercouch® as replacement for a standard couch

BACKGROUND AND PURPOSE

Introducing into practice a new carbon-fibre couch necessitates its evaluation with regard to the present clinical situation.

MATERIALS AND METHODS

In this study, a geometric and dosimetric evaluation has been made for the Sinmed Mastercouch as a replacement for the Elekta C-arm couch with Mylar-tennis racket combination. Geometrically, feasible gantry angles with regard to collision and beam intersection were discriminated as function of isocentric table rotation for 10 treatment isocentres. Dosimetrically, the build-up distortion and attenuation by the aforementioned tabletops and a carbon-fibre tabletop of an Elekta Precise simulator was measured. Finally, the clinical implications of these influences were assessed for a 3-field prostate treatment in three configurations: Mastercouch, C-arm couch and no-intersection situation.

RESULTS

With regard to collision, the largest advantages are observed for the Mastercouch with the Omega-shaped treatment module compared to the C-arm couch for isocentres located in the upper part of the body, thanks to its shape and the absence of any metal. Dosimetrically, one has to take into account the build-up loss and attenuation by beam intersection with Mastercouch and the carbon-fibre edges of the tennis racket (C-arm couch). The clinical relevance of these dosimetric aspects depends on the dose delivered by the compromised beams.

Does aqueous or sucralfate cream affect the severity of erythematous radiation skin reactions? A randomised controlled trial

BACKGROUND AND PURPOSE

Evidence on which to base decisions about the management of radiation skin reactions is lacking. The purpose of this study was to investigate whether sucralfate or aqueous cream reduced acute skin toxicity during radiotherapy to the head and neck, breast or anorectal area (phase A), and to evaluate the effect of hydrogels and dry dressings on moist desquamation (phase B). This paper presents the results of phase A.

PATIENTS AND METHODS

Three hundred and fifty seven patients were randomised to apply aqueous cream, sucralfate cream or no cream to the irradiated area from day one of radical radiotherapy treatment. All patients were instructed to wash using unperfumed soap. Acute skin toxicity was measured using a modified radiation therapy oncology group (RTOG) score, reflectance spectrophotometry, patient diary card and dermatology life quality index (DLQI). A cost minimisation approach was used to compare the costs of each skin care approach.

RESULTS

No consistent differences were found in the severity of skin reactions or levels of discomfort suffered by patients in each of the randomised groups. Patients with a higher body mass index, who smoked, received concomitant chemotherapy, boost or bolus during treatment were more likely to develop skin reactions.

CONCLUSIONS

There is no evidence to support the prophylactic application of either of the creams tested for the prevention of radiation skin reactions. Our results show that it is possible to predict which patients are at greatest risk of skin reactions. We suggest that known risk factors should be incorporated into future study protocols.

Quantitative assessment of skin erythema due to radiotherapy—evaluation of different measurements

BACKGROUND AND PURPOSE

Visual assessment is the most common clinical investigation of skin reactions in radiotherapy. Due to the unquantitative and subjective nature of this method additional non-invasive methods are needed for more accurate evaluation of the visible acute adverse skin reactions due to radiotherapy. The purpose of this study was to evaluate a new objective measure with regard to reliability and validity and compare it with an established objective measure and a visual assessment.

PATIENTS AND METHODS

A sample of 53 consecutive patients commencing curative tangential radiation therapy to the breast parenchyma were included in the study. The skin area of the treated breast was divided into five sections and assessed individually at 0, 24 and 50 Gy. The RTOG scoring system was used for the visual assessment of the skin reactions. The first objective measure included reflectance spectrometry (DermaSpectrometer) measures at fixed points within the treatment area. For the second objective measure digital images (Camera) were taken with a system using a digital camera and software. The images were analyzed using the Adobe Photoshop 5.0 software program.

RESULTS

The results provided significant evidence of the test-retest reliability of the camera. The correlation between the objective measures proved to be significant as the treatment progressed.

CONCLUSIONS

The results suggest that the camera may be used in a reliable and valid way to measure skin erythema due to radiotherapy.

Personal characteristics, therapy modalities and individual DNA repair capacity as predictive factors of acute skin toxicity in an unselected cohort of breast cancer patients receiving radiotherapy

BACKGROUND AND PURPOSE

Intrinsic and extrinsic factors can affect the occurrence of side effects of radiotherapy. The influence of therapy modalities, personal characteristics and individual DNA repair capacity on the risk of acute skin toxicity was thus evaluated.

MATERIALS AND METHODS

In a prospective study of 478 female breast cancer patients receiving adjuvant radiotherapy of the breast after breast-conserving surgery, acute skin toxicity was documented systematically using a modified version of the common toxicity criteria. Prognostic personal and treatment characteristics were identified for the entire cohort. Individual DNA repair capacity was determined in a subgroup of 113 patients with alkaline comet assay using phytohemagglutinin stimulated lymphocytes. Using proportional hazards analysis to account for cumulative biologically effective radiation dose, the hazard for the development of acute skin reactions (moist desquamation) associated with DNA repair capacity was modeled.

RESULTS

Of the 478 participants, 84 presented with acute reactions by the end of treatment. Higher body mass index was significantly associated with an increased risk for acute reactions (hazard ratio=1.09 per 1 kg/m(2)), adjusted for treating hospital and photon beam quality. The comet assay parameters examined, including background DNA damage in non-irradiated cells, DNA damage induced by 5 Gy, and DNA repair capacity, were not significantly associated with risk of acute skin toxicity.

CONCLUSIONS

Higher BMI is predictive of acute skin toxicity, however, individual repair parameters as determined by the alkaline comet assay are not informative enough. More comprehensive analyses including late effects of radiotherapy and repair kinetics optimized for different radiation-induced DNA lesions are warranted.

Determinants of skin sensitivity to solar irradiation

BACKGROUND

Acute effects of UV irradiation include UV-induced erythema. Sunlight plays an important role in the development of skin cancer. Several predictive factors of UV-induced erythema could also be predictive for skin cancer.

OBJECTIVE

Our objective was to quantitatively assess phenotypical and nutritional determinants of sensitivity to UV irradiation, as assessed by the minimal erythema dose (MED).

DESIGN

We conducted a cross-sectional study among 335 volunteers. Sensitivity to UV irradiation was established through assessment of the MED. Phenotypical determinants, including skin melanin content, hair color and iris color were determined by skin reflectance spectrometry, a subjective questionnaire and an objective classification system, respectively. Furthermore, dietary exposure was measured by carotenoids, vitamin C, retinol and alpha-tocopherol in serum.

RESULTS

Male subjects were found to be more sensitive to UV irradiation; that is, the MED was significantly lower compared to female subjects. Skin melanin content, which was positively associated with iris color in both sexes and with hair color in men, was the main phenotypical determinant of sensitivity to UV irradiation. No associations were found between serum carotenoids and MED in the total study group. Vitamin C was inversely associated with MED. However, associations between carotenoids concentrations and MED showed a positive trend in subjects with melanin values above and a negative trend in subjects below the median after adjustment for gender and total cholesterol.

CONCLUSIONS

Skin melanin content and gender are important determinants of sensitivity to UV irradiation. No relation was found between serum carotenoids and MED in the total study group. The inverse association between vitamin C and MED was against our hypothesis. For the modifying effect of melanin on the association between carotenoids and MED, we do not have a clear biological explanation.

Single dose irradiation response of pig skin: a comparison of brachytherapy using a single, high dose rate iridium-192 stepping source with 200 kV X-rays

An experimental brachytherapy model has been developed to study acute and late normal tissue reactions as a tool to examine the effects of clinically relevant multifractionation schedules. Pig skin was used as a model since its morphology, structure, cell kinetics and radiation-induced responses are similar to human skin. Brachytherapy was performed using a microSelectron high dose rate (HDR) afterloading machine with a single stepping source and a custom-made template. In this study the acute epidermal reactions of erythema and moist desquamation and the late dermal reactions of dusky mauve erythema and necrosis were evaluated after single doses of irradiation over a follow-up period of 16 weeks. The major aims of this work were: (a) to compare the effects of iridium-192 (192Ir) irradiation with effects after X-irradiation; (b) to compare the skin reactions in Yorkshire and Large White pigs; and (c) to standardize the methodology. For 192Ir irradiation with 100% isodose at the skin surface, the 95% isodose was estimated at the basal membrane, while the 80% isodose covered the dermal fat layers. After HDR 192Ir irradiation of Yorkshire pig skin the ED50 values (95% isodose) for moderate/severe erythema and moist desquamation were 24.8 Gy and 31.9 Gy, respectively. The associated mean latent period (+/- SD) was 39 +/- 7 days for both skin reactions. Late skin responses of dusky mauve erythema and dermal necrosis were characterized by ED50 values (80% isodose) of 16.3 Gy and 19.5 Gy, with latent periods of 58 +/- 7 days and 76 +/- 12 days, respectively. After X-irradiation, the incidence of the various skin reactions and their latent periods were similar. Acute and late reactions were well separated in time. The occurrence of skin reactions and the incidence of effects were comparable in Yorkshire and Large White pigs for both X-irradiation and HDR 192Ir brachytherapy. This pig skin model is feasible for future studies on clinically relevant multifractionation schedules in a brachytherapy setting.

Do inflammatory processes contribute to radiation induced erythema observed in the skin of humans?

BACKGROUND

Two prospective trials were designed to determine whether there may be a role for inflammatory mediators in human skin erythema at both high and low doses per fraction and for 'out of field' effects.

METHODS

Trial 1. Effects of topical indomethacin (1%) and hydrocortisone (1%) applied before and during radiotherapy were compared for erythema induced by 20 Gy in four fractions (n = 26, 6 MV). Trial 2. Effects of topical hydrocortisone (1 %) applied before and during radiotherapy and no medication were compared for erythema induced by 1, 3, 5 and 7 Gy in five fractions (n = 21, 120 kV). Erythema was measured using reflectance spectrophotometry (RFS) and laser Doppler (LD) on a weekly basis.

RESULTS

Trial 1. A bi-phasic reaction time course was suggested in two-thirds of the cases. The first phase did not appear to be influenced by hydrocortisone cream but the second was significantly attenuated. Indomethacin had no effect on either reaction phase. Erythema measured several centimetres outside of the field was reduced by hydrocortisone but not by indomethacin. Trial 2. Trial 2 confirmed the presence of measurable erythema, invisible to the eye, that coincided in its time course to the first phase of erythema noted in trial 1. This reaction was more intense than predicted by the LQ formula and was non-significantly attenuated by topical hydrocortisone. RFS readings proved to be less subject to inter- and intra-patient variations than the LD unit used.

CONCLUSION

Inflammatory responses may play a role in the mediation of the erythematous response to radiation in human skin. Further studies are warranted.

The effect of carbon fibre inserts on the build-up and attenuation of high energy photon beams

BACKGROUND AND PURPOSE

The use of new materials in radiotherapy requires an investigation of the effects of these materials on the relevant beam parameters. The high strength and low density of carbon fibre suggest an excellent material for table inserts with minimal attenuation, without changing the skin sparing effect in the build-up zone.

MATERIALS AND METHODS

In this paper three different carbon fibre plates and two conventionally table top materials are studied in Co-60, 6 MV and 23 MV photon beams.

RESULTS AND CONCLUSIONS

From depth dose measurements it is clear that the dose in the build-up zone is influenced in the qualities of the beams. The mutual differences for the three carbon plates are minimal. For Co-60 the depth of the maximum dose is decreased by carbon from 5 to 2 mm and the surface dose is increased from 18 to 76%. For 6 and 23 MV the surface dose is increased from 21 to 52% and 20 to 32%, respectively, as well as the dose in the build-up region. A transmission of 99% was measured for two carbon plates out of three in Co-60 and for one out of three in 6 MV.

Normal variation in cutaneous blood content and red blood cell velocity in humans

This study was designed to determine normal variations in cutaneous blood content, red blood cell content and skin thickness in healthy human volunteers. The blood content (BC) of human skin and the velocity of red blood cells (RBV) has been comprehensively mapped over 30 anatomical sites in 28 volunteers between the age of 7 and 77 years using reflectance spectrophotometry (RFS) and laser Doppler (LD) techniques respectively. Total skin thickness, which may have a relationship with blood content, has been mapped at the same anatomical sites in six of the volunteers using two-dimensional array, 12 MHz ultrasound equipment. The major determinant of BC and RBV was found to be anatomical site. Regardless of age, gender or prior sun exposure, anatomical sites above the waist produced higher readings than below. BC and RBV were found to be dependent on age and gender at most sites with higher readings being observed in males and younger volunteers. The largest difference was seen in males under 55 years whose RFS readings above the waist were significantly higher than in older males or females of any age. Heavy prior sun exposure and skin thickness could not be demonstrated to impact on either RFS or LD readings independently of the effects of anatomical site, gender or age. In general, RFS and LD readings paralleled one another and correlated linearly at most anatomical sites. While RFS readings tended to decrease in the cranio-caudal direction, LD readings were relatively uniform across the body except for the head and groin where they were higher, and the abdomen where they were lower. The site-to-site variations in RFS readings observed in this study correspond well to capillary density variations noted in previous studies.

Response of human hair cortical cells to fractionated radiotherapy

Hair cortical cell counting (HCCC) represents a non-invasive, in-vivo measure of cell kill in the human integument. Sixty-six patients undergoing conventionally fractionated, external beam radiotherapy for early stage carcinoma of the prostate had groin hair samples counted. This technique is a sensitive and reproducible measure of radiation effect and may have applicability as an in-vivo prediction tool or in the field of biological dosimetry. A repopulative follicular response occurring at 3-4 weeks may explain flattening of the dose response curve.

Fractionated high-dose-rate and pulsed-dose-rate brachytherapy: first clinical experience in squamous cell carcinoma of the tonsillar fossa and soft palate

PURPOSE

Fractionated high-dose-rate (fr.HDR) and pulsed-dose-rate (PDR) brachytherapy (BT) regimens, which simulate classical continuous low-dose-rate (LDR) interstitial radiation therapy (IRT) schedules, have been developed for clinical use. This article reports the initial results using these novel schedules in squamous cell carcinoma (SCC) of the tonsillar fossa (TF) and/or soft palate (SP).

METHODS AND MATERIALS

Between 1990 and 1994, 38 patients with TF and SP tumors (5 T1, 22 T2, 10 T3, and 1 T4) were treated by fr.HDR or PDR brachytherapy, either alone or in combination with external irradiation (ERT). Half of the patients were treated with fr.HDR, which entailed twice-daily fractions of > or = 3 Gy. The other 19 patients were administered PDR, which consisted of pulses of < or = 2 Gy delivered 4-8 times/day. The median cumulative dose of IRT +/- ERT series was 66 Gy (range 55-73). The results in these patients treated by brachytherapy were compared to 72 patients with similar tumors treated in our institute with curative intent, using ERT alone. The median cumulative dose of ERT-only series was 70 Gy (range 40-77).

RESULTS

Excellent locoregional control was achieved with the use of IRT +/- ERT, with only 13% (5 of 38) developing local failure, and salvage surgery being possible in three of the latter (60%). Neither BT scheme (fr.HDR vs. PDR) nor tumor site (TF vs. SP) significantly influenced local control rates. The type and severity of the side effects observed are comparable to those reported in the literature for LDR-IRT. These results contrast sharply with our ERT-only series, in which 39% of patients (28 of 72) developed local failure, with surgical salvage being possible only in three patients (11%). Taking the data set of 110 patients, in a univariate analysis IRT, T stage, N stage, overall treatment time (OTT), and BEDcor10 (biological effective dose with a correction for the OTT) were significant prognostic factors for local relapse-free survival (LRFS) and overall survival (OS) at 3 years. Using Cox proportional hazard analysis, only T stage and BEDcor10 remained significant for LRFS (p < 0.001 and 0.008, respectively), as well as for OS (p < 0.001 and 0.003, respectively). With regard to the current (IRT) and historical (ERT) series, for the LRFS at 3 years, dose-response relationships were established, significant, however, only for the BEDcor10 (p = 0.03).

CONCLUSION

The 3-year LRFS of approximately 90% for TF and SP tumors reported here is comparable with the best results in the literature, particularly given the fact that 30% of the patients (11 of 38) presented with T3/4 tumors. When compared with our historical (ERT-only) controls, the patients treated with IRT had superior local control. A dose-response relationship was established for the BEDcor10.

Underprediction of human skin erythema at low doses per fraction by the linear quadratic model

BACKGROUND AND PURPOSE

The erythematous response of human skin to radiotherapy has proven useful for testing the predictions of the linear quadratic (LQ) model in terms of fractionation sensitivity and repair half time. No formal investigation of the response of human skin to doses less than 2 Gy per fraction has occurred. This study aims to test the validity of the LQ model for human skin at doses ranging from 0.4 to 5.2 Gy per fraction.

MATERIALS AND METHODS

Complete erythema reaction profiles were obtained using reflectance spectrophotometry in two patient populations: 65 patients treated palliatively with 5, 10, 12 and 20 daily treatment fractions (varying thicknesses of bolus, various body sites) and 52 patients undergoing prostatic irradiation for localised carcinoma of the prostate (no bolus, 30-32 fractions).

RESULTS AND CONCLUSIONS

Gender, age, site and prior sun exposure influence pre- and post-treatment erythema values independently of dose administered. Out-of-field effects were also noted. The linear quadratic model significantly underpredicted peak erythema values at doses less than 1.5 Gy per fraction. This suggests that either the conventional linear quadratic model does not apply for low doses per fraction in human skin or that erythema is not exclusively initiated by radiation damage to the basal layer. The data are potentially explained by an induced repair model.