Total scalp irradiation: A study comparing multiple types of bolus and VMAT optimization techniques

PURPOSE

To investigate bolus design and VMAT optimization settings for total scalp irradiation.

METHODS

Three silicone bolus designs (flat, hat, and custom) from .decimal were evaluated for adherence to five anthropomorphic head phantoms. Flat bolus was cut from a silicone sheet. Generic hat bolus resembles an elongated swim cap while custom bolus is manufactured by injecting silicone into a 3D printed mold. Bolus placement time was recorded. Air gaps between bolus and scalp were quantified on CT images. The dosimetric effect of air gaps on target coverage was evaluated in a treatment planning study where the scalp was planned to 60 Gy in 30 fractions. A noncoplanar VMAT technique based on gEUD penalties was investigated that explored the full range of gEUD alpha values to determine which settings achieve sufficient target coverage while minimizing brain dose. ANOVA and the t-test were used to evaluate statistically significant differences (threshold = 0.05).

RESULTS

The flat bolus took 32 ± 5.9 min to construct and place, which was significantly longer (p < 0.001) compared with 0.67 ± 0.2 min for the generic hat bolus or 0.53 ± 0.10 min for the custom bolus. The air gap volumes were 38 ± 9.3 cc, 32 ± 14 cc, and 17 ± 7.0 cc for the flat, hat, and custom boluses, respectively. While the air gap differences between the flat and custom boluses were significant (p = 0.011), there were no significant dosimetric differences in PTV coverage at V57Gy or V60Gy. In the VMAT optimization study, a gEUD alpha of 2 was found to minimize the mean brain dose.

CONCLUSIONS

Two challenging aspects of total scalp irradiation were investigated: bolus design and plan optimization. Results from this study show opportunities to shorten bolus fabrication time during simulation and create high quality treatment plans using a straightforward VMAT template with simple optimization settings.

Dosimetric study of whole-brain irradiation with high-energy photon beams for dose reduction to the scalp

OBJECTIVE

To evaluate the efficiency of high-energy photons for mitigating alopecia due to whole-brain irradiation (WBRT).

METHODS

Planning CT data from 10 patients who received WBRT were collected. We prepared 4 WBRT plans that used 6 or 15 MV photon beams, with or without use of a field-in-field (FiF) technique, and compared outcomes using a treatment planning system. The primary outcome was dose parameters to the scalp, including the mean dose, maximum dose, and dose received to 50% scalp(D50%). Secondary outcomes were minimum dose to the brain surface.

RESULTS

Using FiF, the mean doses were 24.4-26.0 and 22.4-24.1 Gy, and the maximum doses were 30.5-32.1 and 28.5-30.8 Gy for 6 and 15 MV photon beams, respectively. Without FiF, the mean doses were 24.6-26.9 and 22.6-24.5 Gy, and the maximum doses were 30.8-34.6 and 28.6-32.4 Gy for 6 and 15 MV photon beams. The 15 MV plan resulted in a lower scalp dose for each dose parameter (p < 0.001). Using FiF, the minimum doses to the brain surface for the 6 and 15 MV plans were 28.9 ± 0.440 and 29.0 ± 0.557 Gy, respectively (p = 0.70). Without FiF, the minimum doses to the brain surface for the 6 and 15 MV plans were 28.9 ± 0.456 and 29.0 ± 0.529, respectively (p = 0.66).

CONCLUSION

Compared with the 6 MV plan, the 15 MV plan achieved a lower scalp dose without impairing the brain surface dose.

ADVANCES IN KNOWLEDGE

High-energy photon WBRT may mitigate alopecia of patients who receiving WBRT.

Observations of tissue reactions following neuroradiology interventional procedures

A study has been undertaken over a period of eight years of tissue reactions in interventional radiology patients receiving cumulative air kerma values to their scalp above 3 Gy. Patients receiving doses to the scalp above this trigger level have been followed up to determine when effects occur and to provide reassurance if they do. The study has shown that hair thinning and hair loss are the more likely effects and may occur in 50% of patients at dose above 4.5 Gy.

Development and validation of a 3D-printed bolus cap for total scalp irradiation

PURPOSE

The goal of total scalp irradiation (TSI) is to deliver a uniform dose to the scalp, which requires the use of a bolus cap. Most current methods for fabricating bolus caps are laborious, yet still result in nonconformity and low reproducibility, which can lead to nonuniform irradiation of the scalp. We developed and validated patient-specific bolus caps for TSI using three-dimensional (3D) printing.

METHODS AND MATERIALS

3D-printing materials were radiologically analyzed to identify a material with properties suitable for use as a bolus cap. A Python script was developed within a commercial treatment planning system to automate the creation of a ready-to-print, patient-specific 3D bolus cap model. A bolus cap was printed for an anthropomorphic head phantom using a commercial vendor and a computed tomography simulation of the anthropomorphic head phantom and bolus cap was used to create a volumetric-modulated arc therapy TSI treatment plan. The planned treatment was delivered to the head phantom and dosimetric validation was performed using thermoluminescent dosimeters (TLD). The developed procedure was used to create a bolus cap for a clinical TSI patient, and in vivo TLD measurements were acquired for several fractions.

RESULTS

Agilus-60 was validated as a new 3D-printing material suitable for use as bolus. A 3D-printed Agilus-60 bolus cap had excellent conformality to the phantom scalp, with a maximum air gap of 4 mm. TLD measurements showed that the bolus cap generated a uniform dose to the scalp within a 2.7% standard deviation, and the delivered doses agreed with calculated doses to within 2.4% on average. The patient bolus was conformal and the average difference between TLD measured and planned doses was 5.3%.

CONCLUSIONS

We have developed a workflow to 3D-print highly conformal bolus caps for TSI and demonstrated these caps can reproducibly generate a uniform dose to the scalp.

Dosimetric comparison of surface mould HDR brachytherapy with VMAT

INTRODUCTION

The aim of this study was to investigate the dosimetric differences between surface mould high-dose-rate (HDR) brachytherapy and external beam volumetric-modulated arc therapy (VMAT) for two treatment sites.

METHODS

Previously treated HDR brachytherapy surface mould scalp (n = 4) and lower leg (n = 3) treatments were retrospectively analysed. The VMAT plans were optimised using an additional 3-mm setup margin on the clinical target volume (CTV) of the previously treated HDR plans. The HDR plans were calculated and normalised using the TG-43 formalism and recalculated with Acuros BV (AC).

RESULTS

On average, the mean brain and normal tissue doses were reduced by 44.8% and 27.4% for scalp and lower leg VMAT cases, respectively, when compared to AC calculated HDR plans. For VMAT plans, the average dose to a 1-mm thick skin structure deep to the target volume was not any lower than that in AC HDR plans. On average, the CTV coverage was 13.8% and 9.6% lower for scalp cases with AC dose calculation than with TG-43 and 8.3% and 5.3% lower for lower leg cases if 0- or 1-cm backscatter material was applied above the catheters, respectively.

CONCLUSIONS

VMAT is a feasible treatment option in the case of extensive skin malignancies of the scalp and lower leg. Uncertainties related to delivered dose with HDR brachytherapy when using the TG-43 dose calculation model or possible air gaps between the mould and skin favour the use of VMAT. The potential soft tissue deformation needs to be considered if VMAT is used.

Dosimetric comparison of three different treatment modalities for total scalp irradiation: the conventional lateral photon-electron technique, helical tomotherapy, and volumetric-modulated arc therapy

The aim of this study was to compare lateral photon-electron (LPE), helical tomotherapy (HT), and volumetric-modulated arc therapy (VMAT) plans for total scalp irradiation. We selected a single adult model case and compared the dosimetric results for the three plans. All plans mainly used 6-MV photon beams, and the prescription dose was 60 Gy in 30 fractions. First, we compared the LPE, HT and VMAT plans, with all plans including a 1-cm bolus. We also compared HT plans with and without the bolus. The conformity indices for LPE, HT and VMAT were 1.73, 1.35 and 1.49, respectively. The HT plan showed the best conformity and the LPE plan showed the worst. However, the plans had similar homogeneity indexes. The dose to the hippocampus was the highest in the VMAT plan, with a mean of 6.7 Gy, compared with 3.5 Gy in the LPE plan and 4.8 Gy in the HT plan. The doses to the optical structures were all within the clinically acceptable range. The beam-on time and monitor units were highest in the HT plan. The HT plans with and without a bolus showed similar target coverage and organ-at-risk (OAR) sparing. The HT plan showed the best target coverage and conformity, with low doses to the brain and hippocampus. This plan also had the advantage of not necessarily requiring a bolus. Although the VMAT plan showed better conformity than the LPE plan and acceptable OAR sparing, the dose to the hippocampus should be considered when high doses are prescribed.

Planning study of flattening filter free beams for volumetric modulated arc therapy in squamous cell carcinoma of the scalp

Purpose

Flattening filter free (FFF) beams show the potential for a higher dose rate and lower peripheral dose. We investigated the planning study of FFF beams with their role for volumetric modulated arc therapy (VMAT) in squamous cell carcinoma of the scalp.

Methods and Materials

One patient with squamous cell carcinoma which had involvement of entire scalp was subjected to VMAT using TrueBeam linear accelerator. As it was a rare skin malignancy, CT data of 7 patients with brain tumors were also included in this study, and their entire scalps were outlined as target volumes. Three VMAT plans were employed with RapidArc form: two half-field full-arcs VMAT using 6 MV standard beams (HFF-VMAT-FF), eight half-field quarter-arcs VMAT using 6 MV standard beams (HFQ-VMAT-FF), and HFQ-VMAT using FFF beams (HFQ-VMAT-FFF). Prescribed dose was 25×2 Gy (50 Gy). Plan quality and efficiency were assessed for all plans.

Results

There were no statistically significant differences among the three VMAT plans in target volume coverage, conformity, and homogeneity. For HFQ-VMAT-FF plans, there was a significant decrease by 12.6% in the mean dose to the brain compared with HFF-VMAT-FF. By the use of FFF beams, the mean dose to brain in HFQ-VMAT-FFF plans was further decreased by 7.4% compared with HFQ-VMAT-FF. Beam delivery times were similar for each technique.

Conclusions

The HFQ-VMAT-FF plans showed the superiority in dose distributions compared with HFF-VMAT-FF. HFQ-VMAT-FFF plans might provide further normal tissue sparing, particularly in the brain, showing their potential for radiation therapy in squamous cell carcinoma of the scalp.

The mass campaign to eradicate ringworm among the Jewish community in Eastern Europe, 1921-1938

Between the years 1921 and 1938, 27,600 children were irradiated during a mass campaign to eradicate ringworm among the Jewish community in East Europe. The ringworm campaign was the initiative of the American Jewish Joint Distribution Committee together with the Jewish health maintenance organization OZE (The Society for the Protection of Jewish Health). We describe this campaign that used x-rays to eradicate ringworm and its mission to enhance public health among Jewish communities in Eastern Europe during the period between the world wars. We discuss the concepts behind the campaign, the primary health agents that participated in it, and the latent medical ramifications that were found among children treated for ringworm, many years after treatment--pathologies that can be linked to the irradiation they received as children. Our research is based on historical archival materials in the United States, Europe, and Israel.

Temporary alopecia after embolization of an arteriovenous malformation

Alopecia after head and neck radiotherapy has been extensively reported in the literature. However, alopecia after endovascular procedures is seldom reported in the dermatological literature. Prolonged fluoroscopic imaging during these procedures may cause serious radiation injuries to the skin, such as dermatitis or alopecia. Radiation-induced temporary alopecia is a peculiar form of radiodermitis that occurs over the areas of the scalp that receive the highest doses of radiation. Although repopulation of alopecic patches occurs spontaneously without treatment, it is important to recognize this disorder to establish a correct diagnosis and inform patients about this transient side effect. We report a 44-year-old woman presenting with temporary alopecia after embolization of an arteriovenous malformation.

The treatment of extensive scalp lesions combining electrons with intensity-modulated photons

This study was to investigate the feasibility and potential benefits of combining electrons with intensity modulated photons (IMRT+e) for patients with extensive scalp lesions. A case of a patient with an extensive scalp lesion, in which the target volume covered the entire front half of the scalp, is presented. This approach incorporated the electron dose into the inverse treatment planning optimization. The resulting doses to the planning target volume (PTV) and relevant critical structures were compared. Thermoluminescent dosimeters (TLD), diodes, and GAFCHROMIC EBT films were used to verify the accuracy of the techniques. The IMRT+e plan produced a superior dose distribution to the patient as compared to the IMRT plan in terms of reduction of the dose to the brain with the same dose conformity and homogeneity in the target volumes. This study showed that IMRT+e is a viable treatment modality for extensive scalp lesions patients. It provides a feasible alternative to existing treatment techniques, resulting in improved homogeneity of dose to the PTV compared to conventional electron techniques and a decrease in dose to the brain compared to photon IMRT alone.

Malignant melanoma following scalp irradiation for tinea capitis

X-Rays were discovered by Roentgen in 1895 and were subsequently used in the treatment of many ailments. Numerous benign skin conditions including eczema and psoriasis have historically been treated with X-rays. During the 1930s and 1940s radiotherapy was introduced as an effective treatment for scalp ringworm (tinea capitis). Over the past few years radio-induced malignancies have been reported, with basal cell carcinoma predominating. We report a very rare case of a 64-year-old male with a 9.5mm Breslow thickness melanoma occurring over 50 years following irradiation. This case highlights the presence of another risk factor in the development of melanoma. With the increasing age of this irradiated population we may continue to see further evidence of the link between melanoma and skin irradiation.

Total scalp irradiation using helical tomotherapy

Homogeneous irradiation of the scalp poses technical and dosimetric challenges due to the extensive, superficial, curved treatment volume. Conventional treatments on a linear accelerator use multiple matched electron fields or a combination of electron and photon fields. Problems with these techniques include dose heterogeneity in the target due to varying source-to-skin distance (SSD) and angle of beam incidence, significant dose to the brain, and the potential for overdose or underdose at match lines between the fields. Linac-based intensity-modulated radiation therapy (IMRT) plans have similar problems. This work presents treatment plans for total scalp irradiation on a helical tomotherapy machine. Helical tomotherapy is well-suited for scalp irradiation because it has the ability to deliver beamlets that are tangential to the scalp at all points. Helical tomotherapy also avoids problems associated with field matching and use of more than one modality. Tomotherapy treatment plans were generated and are compared to plans for treatment of the same patient on a linac. The resulting tomotherapy plans show more homogeneous target dose and improved critical structure dose when compared to state-of-the-art linac techniques. Target equivalent uniform dose (EUD) for the best tomotherapy plan was slightly higher than for the linac plan, while the volume of brain tissue receiving over 30 Gy was reduced by two thirds. Furthermore, the tomotherapy plan can be more reliably delivered than linac treatments, because the patient is aligned prior to each treatment based on megavoltage computed tomography (MVCT).

Die Excimer-Laser-Therapie der Alopecia areata - Halbseitige Evaluation eines reprasentativen Areals. Excimer laser therapy of alopecia areata - side-by-side evaluation of a representative area

We report for the first time on hair regrowth in alopecia areata of the scalp achieved with the 308-nm xenon-chloride excimer laser in a prospective side-by-side trial. The alopecia areata had shown progression over a period of three years, and various treatments had not been effective. Out of a number of affected areas, one representative lesion was chosen; one half of it was treated, the other half remained untreated. After 27 sessions (200 - 4000 mJ/cm2, cumulative dose 52.6 J/cm2) over 3 months, only the treated area showed hair growth; which suggests that this was most probably not a spontaneous remission.

Prolactinoma and other head and neck tumors after scalp irradiation

Tumors of the thyroid and parathyroid glands may develop together or separately in patients who previously have been exposed to head and neck irradiation. Whether cranial irradiation confers an increased risk for pituitary adenoma remains unknown. We report the case of a 52-year-old woman who was treated during childhood for tinea capitis with scalp irradiation and later in life developed a prolactin-secreting tumor, a parathyroid adenoma, a benign thyroid lesion, and a basal cell carcinoma of the skin. She was treated successfully with bromocriptine and surgical removal of the parathyroid adenoma. Molecular analysis of the parathyroid tissue failed to demonstrate any abnormality of the multiple endocrine neoplasia Type 1 gene. This case report is the first to describe a prolactin-secreting tumor that developed in association with other endocrine neoplasia after head and neck irradiation. Our case suggests that multiple endocrine neoplasia may develop in a sporadic pattern after scalp irradiation.

Radiation-induced epilation due to couch transit dose for the Leksell gamma knife model C

PURPOSE

To determine the cause of epilation at the top of the head for 2 patients with acoustic neuromas after undergoing fractionated radiosurgery with the Leskell Gamma Knife model C. This epilation was unexpected, because the treatment planning program stated the dose at this location was <0.1 Gy.

METHODS AND MATERIALS

The radiation dose along a central axis, parallel to the couch, from the helmet's focus to the helmet cap was measured during couch transit.

RESULTS

Transit doses of 4.4 cGy/shot at 10 cm and 5.6 cGy/shot at distances >15 cm from the helmet's focus were measured. It was estimated that the 2 patients with epilation received approximately 6-7 Gy to the scalp. A shield was constructed and shown to reduce the transit dose by as much as 60%.

CONCLUSION

The design of the helmet allows the uncollimated beams to reach areas of the patient, superior to the target, just before and after couch docking with the housing. For treatment involving a large number of shots (i.e., fractionation), off-target doses < or = 8 Gy can result. For these cases, the transit dose should be considered and some form of additional shielding should be used.

Skin cancer after X-ray treatment for scalp ringworm

Some 2,224 children given X-ray therapy for tinea capitis (ringworm of the scalp) have been followed for up to 50 years to determine cancer incidence, along with a control group of 1,380 tinea capitis patients given only topical medications. The study found a relative risk (RR) of 3.6 (95% confidence interval, 2.3-5.9) for basal cell skin cancer (BCC) of the head and neck among irradiated Caucasians (124 irradiated cases and 21 control cases), in response to a scalp dose of about 4.8 Gy. No melanomas of the head and neck have been seen, and only a few squamous cell carcinomas. About 40% of irradiated cases have had multiple BCCs, for a total of 328 BCCs. Although 25% of both the irradiated and control groups are African-American, only 3 skin cancers have been seen among them, all in the irradiated group, indicating the importance of susceptibility to UV radiation as a cofactor. Light complexion, severe sunburning and North European ancestry were predictive of BCC risk in the irradiated group, but chronic sun exposure was not. Children irradiated at young ages had the highest BCC risk. The RR for BCC risk is approximately constant with time since exposure, suggesting that risk will probably last for a lifetime.

[Delayed cerebral radionecrosis following radiation therapy of cutaneous squamous cell carcinomas of the head]

INTRODUCTION

Three cases of cerebral radionecrosis occurring after radiation therapy for squamous cell carcinomas of the scalp are reported. This rare and poorly documented complication of radiotherapy is discussed.

CASE REPORTS

Three patients presenting with squamous cell carcinomas of the scalp were treated with surgery and radiotherapy for recurrent or incomplete resection of squamous cell carcinomas of the head. X-ray doses range were 50 to 60 Grays in 22 to 24 fractions. Cerebral radionecrotic lesions were diagnosed 6 months to 14 years after irradiation, and were inconstantly associated with clinical symptoms. The patients were treated with systemic steroids, which were of limited efficacy in one of our patients.

DISCUSSION

Little is known of cerebral radionecrosis following radiotherapy. This may be related to their rare occurrence and/or to the difficulties in establishing diagnosis. The delay of occurrence after radiotherapy can vary between a few months and several years, and the lesions are directly correlated with the doses and the fractionning of the X-rays. Intracerebral localization of the tumour is the main differential diagnosis. Localized and cystic forms of cerebral radionecrosis can be treated by surgery. Treatment otherwise relies on systemic steroids.

Thyroid cancer following scalp irradiation: a reanalysis accounting for uncertainty in dosimetry

In the 1940s and 1950s, over 20,000 children in Israel were treated for tinea capitis (scalp ringworm) by irradiation to induce epilation. Follow-up studies showed that the radiation exposure was associated with the development of malignant thyroid neoplasms. Despite this clear evidence of an effect, the magnitude of the dose-response relationship is much less clear because of probable errors in individual estimates of dose to the thyroid gland. Such errors have the potential to bias dose-response estimation, a potential that was not widely appreciated at the time of the original analyses. We revisit this issue, describing in detail how errors in dosimetry might occur, and we develop a new dose-response model that takes the uncertainties of the dosimetry into account. Our model for the uncertainty in dosimetry is a complex and new variant of the classical multiplicative Berkson error model, having components of classical multiplicative measurement error as well as missing data. Analysis of the tinea capitis data suggests that measurement error in the dosimetry has only a negligible effect on dose-response estimation and inference as well as on the modifying effect of age at exposure.

Tolerance of the normal canine brain to epithermal neutron irradiation in the presence of p-boronophenylalanine

Twelve normal dogs underwent brain irradiation in a mixed-radiation, mainly epithermal neutron field at the Brookhaven Medical Research Reactor following intravenous infusion of 950 mg of 10B-enriched BPA/kg as its fructose complex. The 5 x 10 cm irradiation aperture was centered over the left hemisphere. For a subgroup of dogs reported previously, we now present more detailed analyses including dose-volume relationships, longer follow-ups, MRIs, and histopathological observations. Peak doses (delivered to 1 cm3 of brain at the depth of maximum thermal neutron flux) ranged from 7.6 Gy (photon-equivalent dose: 11.8 Gy-Eq) to 11.6 Gy (17.5 Gy-Eq). The average dose to the brain ranged from 3.0 Gy (4.5 Gy-Eq) to 8.1 Gy (11.9 Gy-Eq) and to the left hemisphere, 6.6 Gy (10.1 Gy-Eq) to 10.0 Gy (15.0 Gy-Eq). Maximum tolerated 'threshold' doses were 6.7 Gy (9.8 Gy-Eq) to the whole brain and 8.2 Gy (12.3 Gy-Eq) to one hemisphere. The threshold peak brain dose was 9.5 Gy (14.3 Gy-Eq). At doses below threshold, some dogs developed subclinical MRI changes. Above threshold, all dogs developed dose-dependent MRI changes, neurological deficits, and focal brain necrosis.

A pilot study to assess the feasibility of prior scalp cooling with palliative whole brain radiotherapy

The objective of this work was to perform a feasibility study on the use of scalp cooling during palliative whole brain radiotherapy. Seven patients (1 male, 6 female) with good performance status underwent scalp cooling prior to and during radiotherapy for cerebral metastases. Five patients were prescribed 12 Gy in two fractions and two patients were prescribed 20 Gy in five fractions. Phantom thermoluminescent dosemeter (TLD) studies to assess the build-up effect from the scalp cap were performed. Seven out of eight patients that were offered scalp cooling completed treatment uneventfully. One patient reported discomfort on application of the scalp cap and continued treatment without scalp cooling. No patients reported other adverse effects from use of the cap during treatment or at follow-up. TLD studies demonstrated a 55-80% increase in dose to the scalp after application of the scalp cap. All patients experienced hair loss. Scalp cooling caps are well tolerated through a course of palliative whole brain radiotherapy. The scalp dose is significantly increased owing to a bolus effect from the scalp cap.

Advice on hair and scalp care during cranial radiotherapy: a prospective randomized trial

BACKGROUND

The advice on hair washing during brain irradiation is aimed at minimizing radiation induced skin toxicity. We performed a prospective randomized trial to assess the effect of advice on scalp care on the local skin reaction in patients undergoing cranial radiotherapy.

METHODS

One hundred and nine patients undergoing cranial radiotherapy were randomized into two groups. Patients in group 1 were advised not to wash hair during treatment and patients in group 2 to maintain normal pattern of hair washing. They were assessed weekly over a period of 10 weeks from the start of treatment. Symptoms of pain and itching were recorded using a modified RTOG/EORTC acute skin reaction scoring system and skin reaction was assessed clinically using erythema/desquamation score. The frequency of hair washing and the distress of changing the practice of normal hygiene were recorded on a diary card. Skin reaction scores were compared as a summary measure using area under the curve per week (AUC/week) and median scores, and the differences between groups were assessed by means of the t-test.

RESULTS

One hundred and nine patients commencing cranial radiotherapy according to standard protocol were randomized into the trial (group 1, 55 patients; group 2, 54 patients). Patients asked to restrict hair washing, washed at a lower average frequency. There were no significant differences between scores of skin reaction in the two groups for each of the variables measured.

CONCLUSIONS

The practice of normal hair washing is not associated with increased severity of adverse skin reaction. As a request to change the pattern of normal hygiene may cause distress, the current advice should be to maintain normal hair washing during cranial radiotherapy.

Malignant fibrous histiocytoma of the scalp. Multidisciplinary treatment

BACKGROUND

Malignant fibrous histiocytomas (MFH) are uncommon in the skin, and even less frequent on the scalp. On the scalp they are often very difficult to excise and it is even more difficult to close the resulting wound.

OBJECTIVE

To review all malignant fibrous histiocytomas diagnosed and treated in our Department during the past 6 years, and to describe the multidisciplinary procedure employed to treat one special case of aggressive malignant fibrous histiocytoma on the scalp that recurred twice.

RESULT

Malignant fibrous histiocytomas represent 0.01% of malignant cutaneous tumors in our area. The immediate results after a multidisciplinary treatment performed on a recurrent malignant fibrous histiocytoma located on the scalp were excellent, but recurrence was observed 6 months later. Two years later we have also treated another case of MFH on the scalp. The same surgical technique was performed, but the patient received high-dose-methotrexate-based neoadjuvant chemotherapy (HD-MTX). One year later, this patient is still alive and no signs of recurrence have been detected.

CONCLUSION

When malignant fibrous histiocytoma occurs on the scalp it must be treated immediately by means of an excision with a large peripheral edge of 2 cm from the visual or CAT limits of the lesion, since the first treatment must be definitive.

Structural and trace element changes in scalp hair of radiographers

Scalp hair samples were collected from medical radiographers and nonradiographers of matching age groups. Structural morphology of hair was studied by scanning electron microscopy, and the trace element profiles in hair were measured using neutron activation analysis. The structural damage to the hair follicles of the radiographers was quite obvious, and this may be a good qualitative indicator of radiation damage at low doses. The concentrations of aluminum (Al), potassium (K), and vanadium (V) in hair of the radiographers were significantly higher, whereas those of antimony (Sb) and magnesium (Mg) were significantly lower than those of nonradiographers. Some of our findings were quite consistent with those of others in determining the changes in trace element concentrations in irradiated tissue.

[Temporary roentgen epilation after embolization of a cerebral arteriovenous malformation]

A patient with a large left-sided arteriovenous malformation underwent superselective angiography and therapeutic embolization. Sixteen days later he presented with an acute anagen-dystrophic hair loss localized to the occipital and right parietal regions corresponding to the irradiated scalp area. The diagnosis of an acute radiation injury to the hair follicle from prolonged fluoroscopic imaging during the interventional neuroradiologic procedure was made. This reversible side effect occurs typically after single short-term exposures of 300-400 cGy. Above single doses of 1200 cGy, the epilation is permanent. Patients have to be informed about the possibility of this reversible complication, which must be distinguished from alopecia areata, postoperative ischemic pressure alopecia and drug toxicity.

Deep cerebral invasion by basal cell carcinoma of the scalp

We report recurrent basal cell carcinoma of the scalp with deep cerebral invasion in an 82-year-old man. Plain films and CT showed extensive, full thickness, skull destruction at the vertex. Gadolinium-enhanced MRI revealed neoplastic invasion of the meninges and left cerebral hemisphere, down to the lateral ventricle. We postulate that tumour extended into the brain along perivascular spaces of transcerebral vessels. This hypothesis is supported by the cleft-like contrast enhancement on MRI.

Effects of gamma irradiation on the transduction of dividing and nondividing cells in brain and muscle of rats by adeno-associated virus vectors

Vectors based on adeno-associated virus (AAV) are under investigation for use in gene therapy applications. Critical aspects of AAV vector biology remain undefined, in particular the intracellular events and activities mediating transduction and determining host cell permissiveness for transduction. Using cultured primary human fibroblasts, we previously showed that AAV vectors preferentially, but not exclusively, transduce cells in the S phase of the cell cycle, and that transduction can be markedly enhanced by pretreatment of target cells with physical and chemical agents that perturb DNA metabolism. In this study, we tested whether similar improvements in AAV vector performance might be achievable in vivo. The adult rat brain and overlying scalp muscle were selected for vector inoculation because of the presence of well-defined populations of dividing, quiescent, and post-mitotic cells, and gamma irradiation was chosen as a reproducible means of inducing DNA repair in these cells. We find that gamma irradiation markedly enhances the transduction of dividing cell populations in the pia-arachnoid and choroid epithelium within the central nervous system, and of mature nondividing muscle cells in the scalp, whereas gamma irradiation did not increase the basal transduction level of post-mitotic neurons in the hippocampus. These data confirm that replicative cellular DNA synthesis is not required for transduction by AAV vectors and show that the mitotic state of target cells is not necessarily predictive of responsiveness to transduction-enhancing treatments. Most importantly, these data demonstrate that target cells can be manipulated in vivo to render them more permissive for AAV vector transduction.

Laser hair transplantation. Tissue effects of laser parameters

BACKGROUND

Micro- and minigrafting have become increasingly popular in hair transplantation over the past decade, resulting in larger numbers of grafts per session and lengthy, potentially technically difficult procedures. The advent of very high energy pulsed carbon dioxide lasers as surgical instruments has led to the investigation of their use in hair transplantation, as bloodless surgery with tissue removal by vaporization has obvious advantages as far as surgical speed is concerned.

METHODS

A prospective study of eight patients comparing conventional micro- and minigrafting using 18- and 14-gauge needle punctures with dilators versus laser-vaporized donor sites with variation of laser parameters was conducted with monthly evaluation of healing and hair growth for 6 months. In addition, an in vitro histological study of laser vaporization recipient sites on excised scalp tissue was conducted to evaluate the residual thermal damage of various laser parameters.

RESULTS

The conventional micro- and minigrafts healed faster and resulted in better hair growth than the laser vaporization sites. The donor sites were judged to be comparable as far as healing, but more time consuming with the laser. The operative time for the laser recipient sites was 50% of that of the conventional sites.

CONCLUSIONS

The clinical results of laser hair transplantation are very dependent upon the laser parameters and technique used. Though operative time may be significantly reduced, the end result clinically is dependent on proper choices of pulse parameters and technique.

Intractable partial epilepsy following low-dose scalp irradiation in infancy

We report the development of intractable epilepsy in 3 patients treated with irradiation to "strawberry" scalp nevi in infancy. Low-dose radiation was used (12 and 13 Gy in 2 of the patients). The clinical evolution suggested a recognizable and distinctive postradiation syndrome. There was concordance between the site of radiation as shown by localized alopecia, the clinical features of the partial seizures, and electrographic abnormalities. The clinical picture was unlike delayed cerebral radiation necrosis of adulthood, which is not thought to occur at doses below 50 Gy, in 2-Gy fractions. Neurological deficits were not progressive and in 2 patients there was no evidence of parenchymal injury on cranial magnetic resonance imaging scanning. These differences suggest pathogenetic differences to cerebral radiation injury of adulthood, probably relating to the interaction between nervous system development, individual susceptibility, and the low doses of radiation employed.

[Benign meningioma following scalp irradiation in north African immigrants]

Many Jewish immigrants from North Africa in the late 1950s were treated with low-dose irradiation of the scalp for tinea capitis. In 2 such patients, a 47-year-old man and a 43-year-old woman, both with long histories of headaches and dizziness, meningiomas were found. There is a well-known correlation between low-dose irradiation of the scalp and development of meningioma. Therefore, in immigrants from North Africa with prolonged headaches and dizziness, there should be a careful history with regard to irradiation of the scalp and investigation to exclude meningioma.

Sarcomas subsequent to cranial irradiation

The development of sarcoma subsequent to cranial irradiation is a rare but serious and potentially fatal event. We describe seven patients who had undergone cranial irradiation (range, 1600-6000 cGy) to treat their primary disease and who developed sarcomas within the irradiated field. The median time from radiation therapy to the development of a sarcoma was 8 years (range, 4 to 15 yr). Fibrosarcomas developed in four patients, and malignant fibrous histiocytomas developed in three. Despite aggressive treatment, the prognosis was poor; the median survival from the diagnosis of sarcoma was 19 months. Sarcoma should be considered in the differential diagnosis of a new lesion or a lesion that progresses several years after radiation therapy.

Reconstruction of extensive scalp defects with rectus free flaps

This review represents the largest reported series involving reconstruction of complex scalp and calvarial defects with rectus abdominis free flaps. Sixteen patients presented with extensive (up to 300 cm2) scalp and calvarial defects requiring free tissue transfer for closure. All of the 11 patients who underwent a rectus abdominis free flap had a technically successful microvascular transfer. The defects encountered involved a wide spectrum of complexities including extensive multilaminar defects with exposed brain and dura, irradiated fields, and infection. In our institutions, the rectus abdominis muscle has evolved as a uniquely superior donor choice for restoring extensive scalp defects for several reasons: (1) accessibility, which eliminates intraoperative patient repositioning and allows for a simultaneous two-team approach; (2) minimal donor-site morbidity; (3) vascular reliability; and (4) the ability to supply abundant, easily contoured tissue.

Radiation-induced temporary epilation after a neuroradiologically guided embolization procedure

A 34-year-old woman underwent embolization of a left paraorbital arteriovenous malformation guided with a bi-plane x-ray system in two sessions separated by 3 days. Imaging included 110 minutes of fluoroscopy and 46 digital subtraction angiography acquisitions. Entrance skin dose rates were determined with measurements performed on a skull phantom. The maximum possible skin dose was estimated to be 6.6 Gy, which is consistent with the temporary epilation in the right occipital region of the skull reported by the patient approximately 5 weeks later.

Surgical management of radiated scalp in patients with recurrent glioma

Patients with malignant brain tumors requiring multiple craniotomies and external beam radiotherapy are at risk of scalp wound breakdown secondary to fibrosis and radiation damage. We present three cases to illustrate the nature of the problem and the surgical approaches to scalp repair. When a bicoronal incision has been used for the initial craniotomy, the plastic repair can be performed with a bipedicle visor scalp flap and split-thickness skin graft to cover the pericranium at the donor site. When a curvilinear (U-shaped or horseshoe) flap has been used for the initial craniotomy, a single-pedicle flap may be rotated to achieve closure without tension. In anticipation of the risk of scalp wound breakdown in patients with malignant brain tumors, the planning of the operative incision for the first craniotomy needs to take into account the long-term viability of the scalp. We recommend linear scalp incisions parallel to the arterial distribution instead of the traditional curvilinear (U-shaped or horseshoe) flaps; linear incisions are less likely to break down, and in the event of breakdown, linear wounds offer better therapeutic surgical options for plastic repair.

A radiation accident at an industrial accelerator facility

On 11 December 1991, a radiation overexposure occurred at an industrial radiation facility in Maryland. The radiation source was a 3-MV potential drop accelerator designed to produce high electron beam currents for materials-processing applications. This accelerator is capable of producing a 25 milliampere swept electron beam that is scanned over a width of 112.5 cm and which emerges from the accelerator vacuum system through a titanium double window assembly. During maintenance on the lower window pressure plate, an operator placed his hands, head, and feet in the beam. This was done with the filament voltage of the electron source turned "off," but with the full accelerating potential on the high voltage terminal. The operator's body, especially his extremities and head, were exposed to electron dark current. In an attempt to reconstruct the accident, radiochromic film and alanine measurements were made with the accelerator operated at two beam currents. Measured dose rates ranged from approximately 40 cGy s-1 inside the victim's shoe to 1,300 cGy s-1 at the hand position. Approximately 3 mo after the accident, it was necessary to amputate the four digits of the victim's right hand and most of the four digits of his left hand. Electron paramagnetic resonance spectrometry, which measures the concentration of radiation-induced paramagnetic centers in calcified tissues, was used to estimate the dose to the victim's extremities. A mean dose estimate of 55.0 +/- 3.5 Gy (95% confidence level) averaged over the mass of the bone was obtained for the victim's left middle finger (middle phalanx).

Microsurgical scalp and skull reconstruction using a serratus anterior myo-osseous flap

In reconstruction of large scalp and skull defects, the usefulness of microvascular free tissue transfer is manifest. We have performed 4 scalp and skull reconstructions by free serratus anterior osteomuscle flap transfer. The usefulness of serratus anterior osteomuscle flap for reconstruction of combined, extensive scalp and skull defects is emphasized.

Factors affecting the development of skin cancer after scalp irradiation

A nested case control study of persons who developed skin cancer after scalp irradiation in childhood revealed two risk factors for the appearance of radiation-induced skin cancer: (a) an apparently higher radiation dose delivered inadvertently, manifested by a higher prevalence of alopecia and radiation dermatitis (RR = 3.4; CI 1.3-8.8); (b) a more frequent exposure to the sun, manifested by summer sunbathing (RR = 2.6; CI 1.1-6.1). These findings may have certain implications with regard to the understanding of radiation-induced cancer, after low-dose radiation exposure, in general.