A Hairy Situation: Laser Hair Removal after Oral Reconstruction.

OBJECTIVES: To present a case series of 4 patients who underwent postoperative hair removal using the long-pulsed Alexandrite or Nd:YAG laser following intraoral cutaneous flap reconstruction. METHODS: Patients underwent epilation in dermatology clinic with long-pulsed Alexandrite or Nd:YAG lasers, spaced 8 weeks apart, until hair removal was achieved. RESULTS: All patients achieved improvement in hair removal regardless of initial flap donor site with significant improvement in quality of life and minimal side effects. CONCLUSIONS: The long-pulsed Alexandrite and Nd:YAG represent safe and effective treatment options to improve patient quality of life following intraoral flap repair following excision of malignancy.

Accelerator driven neutron source design via beryllium target and 208Pb moderator for boron neutron capture therapy in alternative treatment strategy by Monte Carlo method.

AIMS: The reactor has increased its area of application into medicine especially boron neutron capture therapy (BNCT); however, accelerator-driven neutron sources can be used for therapy purposes. The present study aimed to discuss an alternative method in BNCT functions by a small cyclotron with low current protons based on Karaj cyclotron in Iran. MATERIALS AND METHODS: An epithermal neutron spectrum generator was simulated with 30 MeV proton energy for BNCT purposes. A low current of 300 µA of the proton beam in spallation target concept via 9Be target was accomplished to model neutron spectrum using 208Pb moderator around the target. The graphite reflector and dual layer collimator were planned to prevent and collimate the neutrons produced from proton interactions. Neutron yield per proton, energy distribution, flux, and dose components in the simulated head phantom were estimated by MCNPX code. RESULTS: The neutron beam quality was investigated by diverse filters thicknesses. The maximum epithermal flux transpired using Fluental, Fe, Li, and Bi filters with thicknesses of 7.4, 3, 0.5, and 4 cm, respectively; as well as the epithermal to thermal neutron flux ratio was 161. Results demonstrated that the induced neutrons from a low energy and low current proton may be effective in tumor therapy using 208Pb moderator with average lethargy and also graphite reflector with low absorption cross section to keep the generated neutrons. CONCLUSIONS: Combination of spallation-based BNCT and proton therapy can be especially effective, if a high beam intensity cyclotron becomes available.

Computational assessment of deep-seated tumor treatment capability of the 9Be(d,n)10B reaction for accelerator-based boron neutron capture therapy (AB-BNCT).

The 9Be(d,n)10B reaction was studied as an epithermal neutron source for brain tumor treatment through Boron Neutron Capture Therapy (BNCT). In BNCT, neutrons are classified according to their energies as thermal (<0.5 eV), epithermal (from 0.5 eV to 10 keV) or fast (>10 keV). For deep-seated tumors epithermal neutrons are needed. Since a fraction of the neutrons produced by this reaction are quite fast (up to 5-6 MeV, even for low-bombarding energies), an efficient beam shaping design is required. This task was carried out (1) by selecting the combinations of bombarding energy and target thickness that minimize the highest-energy neutron production; and (2) by the appropriate choice of the Beam Shaping Assembly (BSA) geometry, for each of the combinations found in (1). The BSA geometry was determined as the configuration that maximized the dose deliverable to the tumor in a 1 h treatment, within the constraints imposed by the healthy tissue dose adopted tolerance. Doses were calculated through the MCNP code. The highest dose deliverable to the tumor was found for an 8 µm target and a deuteron beam of 1.45 MeV. Tumor weighted doses ≥40 Gy can be delivered up to about 5 cm in depth, with a maximum value of 51 Gy at a depth of about 2 cm. This dose performance can be improved by relaxing the treatment time constraint and splitting the treatment into two 1-h sessions. These good treatment capabilities strengthen the prospects for a potential use of this reaction in BNCT.

Optimizing normal tissue sparing in ion therapy using calculated isoeffective dose for ion selection.

PURPOSE: To investigate how the selection of ion type affects the calculated isoeffective dose to the surrounding normal tissue as a function of both normal tissue and target tissue α/ß ratios. METHODS AND MATERIALS: A microdosimetric biologic dose model was incorporated into a Geant4 simulation of parallel opposed beams of protons, helium, lithium, beryllium, carbon, and neon ions. The beams were constructed to give a homogeneous isoeffective dose to a volume in the center of a water phantom for target tissues covering a range of cobalt equivalent α/ß ratios of 1-20 Gy. Concomitant normal tissue isoeffective doses in the plateau of the ion beam were then compared for different ions across the range of normal tissue and target tissue radiosensitivities for a fixed isoeffective dose to the target tissue. RESULTS: The ion type yielding the optimal normal tissue sparing was highly dependent on the α/ß ratio of both the normal and the target tissue. For carbon ions, the calculated isoeffective dose to normal tissue at a 5-cm depth varied by almost a factor of 5, depending on the α/ß ratios of the normal and target tissue. This ranges from a factor of 2 less than the isoeffective dose of a similar proton treatment to a factor of 2 greater. CONCLUSIONS: No single ion is optimal for all treatment scenarios. The heavier ions are superior in cases in which the α/ß ratio of the target tissue is low and the α/ß ratio of normal tissue is high, and protons are superior in the opposite circumstances. Lithium and beryllium appear to offer dose advantages similar to carbon, with a considerably lower normal tissue dose when the α/ß ratio in the target tissue is high and the α/ß ratio in the normal tissue is low.

Applicability of the 9Be(d,n)10B reaction to AB-BNCT skin and deep tumor treatment.

In the range of low bombarding energies (less than about 1.5 MeV) the (9)Be(d,n)(10)B reaction produces neutron spectra that can be moderated depending on the choice of the target thickness and the deuteron bombarding energy. In this work, a Monte Carlo simulation study to determine the capability of this reaction to deliver enough dose to efficiently control both skin and deep seated tumors has been performed by means of MCNP calculations using eight optimized (9)Be targets.

Laser depilation and hygiene: preventing recurrent pilonidal sinus disease.

BACKGROUND: Pilonidal sinus disease of the natal cleft is a painful and debilitating condition which often recurs despite multiple surgical undertakings. We describe the long pulsed alexandrite laser for hair depilation and the role of personal hygiene, which is often overlooked when treating this disease, as an adjunct to preventing recurrent pilonidal sinus disease. METHODS: A review of 14 patients who underwent laser hair depilation in the natal cleft following pilonidal sinus surgery. The majority of patients had recurrent disease and had undergone numerous surgical procedures (range 1-5, mean 2.07) All patients were given advice regarding meticulous personal hygiene at the time of consultation. RESULTS: 12 patients received the full course of treatment (three treatments, 6-weekly) followed by 'top-up' treatments as required (mean number of treatments 3.9). None of the patients developed recurrent disease at 1-year follow up and, to date, none have required further surgery. CONCLUSION: Laser hair depilation is a useful adjunct in preventing the recurrence of pilonidal sinus disease and should be offered routinely to all patients. This coupled with patient education regarding personal hygiene reduces the risk of developing recurrent pilonidal sinus disease.

Comparison study of a Q-switched alexandrite laser delivered with versus without compression in the treatment of dermal pigmented lesions.

BACKGROUND: The Q-switched laser is the treatment of choice when attempting to improve dermal pigmented lesions. However, purpura and dyspigmentation are frequently observed after treatment. OBJECTIVE: To compare the efficacy and complications of the Q-switched alexandrite laser when delivered with versus without compression in the treatment of dermal pigmented lesions. METHODS: Ten patients with dermal lesions were enrolled in the study. Each patient had a lesion treated with the Q-switched alexandrite laser delivered with compression. Each patient also had a lesion treated with the Q-switched alexandrite laser delivered without compression with the same fluence and spot size. The patients were evaluated for efficacy and treatment-related side effects. RESULTS: There was no significant difference in efficacy, but purpura and dyspigmentation were more likely when pigmented lesions were treated without compression. CONCLUSION: Purpura from Q-switched laser treatment in darkly pigmented skin is due to mechanical injury of blood vessels. It is well known that pressure 'diascopy' eliminates blood from cutaneous vessels by coapting the vessel lumen. In this study, we used pressure applied by a glass window on the Q-switched laser handpiece to remove cutaneous blood during laser exposure, making it possible to reduce purpura and dyspigmentation.

Treatment of 153 Japanese patients with Q-switched alexandrite laser.

We have recently used Q-switched alexandrite laser for the treatment of various kinds of pigmented skin lesions. We retrospectively compared therapeutic outcomes of 153 Japanese patients who consulted our department. This approach was not very efficient for nevus spilus/café-au-lait spots, which seemed laser-resistant, especially when the pigmentation had appeared after 1 year of age, was treated after 5 years of age, was located on the face, was oval with a smooth border, and the patient was male. This approach was equally effective for senile lentigo, nevus of Ota, and Mongolian spots, but less effective for acquired bilateral nevus of Ota-like macules. Some patients with sacral Mongolian spots or those with light-colored, senile lentigo developed severe post-inflammatory hyperpigmentation after treatment. As a whole, good therapeutic outcome was achieved after multiple treatment sessions. However, the use of other lasers or other treatment modalities should be considered to treat nevus spilus/café-au-lait spots.

Characteristics of BDE dependent on 10B concentration for accelerator-based BNCT using near-threshold 7Li(p,n)7Be direct neutrons.

The characteristics boron-dose enhancer (BDE) was evaluated as to the dependence on the (10)B concentration for BNCT using near-threshold (7)Li(p,n)(7)Be direct neutrons. The treatable protocol depth (TPD) was utilized as an evaluation index. MCNP-4B calculations were performed for near-threshold (7)Li(p,n)(7)Be at a proton energy of 1.900MeV and for a polyethylene BDE. Consequently, the TPD was increased by increasing T/N ratio, i.e., the ratio of the (10)B concentration in the tumor ((10)B(Tumor)) to that in the normal tissue ((10)B(Normal)), and by increasing (10)B(Tumor) and (10)B(Normal) for constant T/N ratio. It has been found that the BDE becomes unnecessary from the viewpoint of increasing the TPD, when (10)B(Tumor) is over a certain level.

Optimization parameters for BDE in BNCT using near threshold 7Li(p,n)7Be direct neutrons.

The dose contribution of (10)B(n,alpha)(7)Li reaction in BNCT using near threshold (7)Li(p,n)(7)Be direct neutrons can be increased through the use of materials referred to as boron-dose enhancers (BDE). In this paper, possible BDE optimization criteria were determined from the characteristics of candidate BDE materials namely (C(2)H(4))(n), (C(2)H(3)F)(n), (C(2)H(2)F(2))(n), (C(2)HF(3))(n), (C(2)D(4))(n), (C(2)F(4))(n), beryllium metal, graphite, D(2)O and (7)LiF. The treatable protocol depth (TPD) was used as the assessment index for evaluating the effect of these materials on the dose distribution in a medium undergoing BNCT using near threshold (7)Li(p,n)(7)Be direct neutrons. The maximum TPD (TPD(max)) did not exhibit an explicit dependence on material type as evidenced by its small range and arbitrary variations. The dependence of TPD on BDE thickness was influenced by the BDE material used as indicated by the sharply peaked TPD versus BDE thickness curves for materials with hydrogen compared to the broader curves obtained for those without hydrogen. The BDE thickness required to achieve TPD(max) (BDE(TPD(max))) were also found to be thinner for materials with hydrogen. The TPD(max), the dependence of TPD on BDE thickness, and the BDE(TPD(max)) were established as appropriate BDE optimization parameters. Based on these criteria and other practical considerations, the suitable choice as BDE among the candidate materials considered in this study for treatments involving tumors located at shallow depths would be (C(2)H(4))(n) while beryllium metal was judged as more appropriate for treatment of deep-seated tumors.

Treatment of exogenous ochronosis with a Q-switched alexandrite (755 nm) laser.

BACKGROUND: Exogenous ochronosis is a cutaneous disorder characterized by blue-black or slate-gray hyperpigmentation resulting from the prolonged use of certain topical agents, most commonly hydroquinones. It is notoriously difficult to treat. OBJECTIVE: To report the effectiveness of a quality-switched (QS) 755-nm alexandrite laser in treating hydroquinone-induced exogenous ochronosis. METHODS: Hydroquinone-induced exogenous ochronosis in two patients was treated with a QS alexandrite laser. The first patient received six treatments (average fluence=7.8 J/cm(2)) at 2-month intervals. The second patient received four treatments (average fluence=6.9 J/cm(2)) at 4-month intervals. Biopsies of lesional skin were obtained before and after laser treatment for histologic evaluation. RESULTS: Significant lightening of the pigmented skin areas was achieved in both patients without scarring or textural changes. Decreased dermal pigmentation was observed on histologic examination of treated skin specimens. CONCLUSION: The QS alexandrite laser can effectively treat exogenous ochronosis without untoward side effects.

Effect of Q-switched Alexandrite laser irradiation on epidermal melanocytes in treatment of Nevus of Ota.

OBJECTIVE: To investigate injury to epidermal melanocyte by Q-switched Alexandrite laser. METHODS: Multiple biopsies were performed on 5 patients with nevus of Ota from before irradiation to 1 year after irradiation. Fourteen specimens were obtained for light microscopy, and 17 for transmission electron microscopy. RESULTS: Melanosomes in epidermal melanocytes were both smaller in size and fewer in number than those in dermal melanocytes. Immediately after irradiation, focal extracellular vacuoles of the basal layer could be observed under light microscopy. Most epidermal melanocytes underwent mild or moderate injury in the form of vacuolated melanosomes, swollen mitochondria, dilation of endoplasmic reticulum, and expansion of extracellular space, retaining intact cell membranes. Normal structures were restored 5 months to 1 year after irradiation, with no depigmentation or hyperpigmentation as seen by light microscopy. CONCLUSION: Injury of melanosomes in epidermal melanocytes is reversible.

Use of the alexandrite laser for treatment of seborrheic keratoses.

BACKGROUND: Seborrheic karatoses are benign lesions that are easily irritated and often cosmetically objectionable. Liquid nitrogen cryotherapy and other surgical methods are useful in treating these lesions, but are difficult to tolerate in patients who have large numbers of lesions requiring treatment. The alexandrite laser was used in one patient to quickly and efficiently destroy hundreds of seborrheic keratoses. The treatment was tolerable and excellent cosmetic results were achieved.

Treatment of minocycline-induced cutaneous pigmentation with the Q-switched Alexandrite laser and a review of the literature.

Cutaneous pigmentation associated with minocycline ingestion is an unusual adverse effect for which few treatments have been described. Within the past few years, treatment with different Q-switched lasers has been reported in the literature. The purpose of this therapeutic intervention was to determine whether the Q-switched Alexandrite laser could clinically and histologically improve pigmentation associated with minocycline ingestion. A patient with type II minocycline pigmentation was treated with the Q-switched Alexandrite (755 nm) laser and then evaluated clinically and histologically to determine the outcome of this intervention. Treatment with the Q-switched Alexandrite (755 nm) laser provided excellent clinical and histologic clearing of minocycline pigmentation. One year after completion of laser treatment, the skin has remained clinically clear with no recurrence. The Q-switched Alexandrite laser (755 nm) should be considered for treatment of type II minocycline pigmentation.

An in vivo trial comparing the clinical efficacy and complications of Q-switched 755 nm alexandrite and Q-switched 1064 nm Nd:YAG lasers in the treatment of nevus of Ota.

BACKGROUND: Q-switched 755 nm alexandrite (QS alex) and Q-switched 1064 nm Nd:YAG lasers are effective in the treatment of nevus of Ota. Our previous in vivo study indicated that patients better tolerate QS alex than QS 1064 nm Nd:YAG laser. However, in terms of clinical efficacy and long-term complications, the study did not indicate which laser is superior. Although both machines may appear to be similar in effectiveness, the low number of treatment sessions may contribute to this apparent lack of difference. OBJECTIVE: The aim of this study was to compare the clinical efficacy and complications of QS 755 nm alex and QS 1064 nm Nd:YAG lasers in the treatment of nevus of Ota after three or more treatment sessions. METHOD: Forty patients were recruited for this study and all had received three or more laser treatment sessions with an interval of at least 2 months between each. Half of the lesion was treated with QS alex and the other half with QS 1064 nm Nd:YAG laser. The degree of lightening was assessed subjectively by the patient using a visual analog scale and objectively by two independent clinicians. Patients were called back to be examined for evidence of complications. RESULTS: In terms of subjective degree of lightening, QS 1064 nm Nd:YAG laser was found to be significantly more efficacious than QS alex (P = 0.018). Both clinicians also found QS 1064 nm Nd:YAG laser to be more effective, but statistical significance was only detected in one, not both of their scores (P = 0.005 and 0.414 for observers 1 and 2, respectively). More patients that received QS Alex developed complications (4 for QS alex and 2 for QS Nd:YAG), but the difference was not statistically significant. CONCLUSION: QS 1064 nm Nd:YAG laser appears to be more effective than QS alex in the lightening of nevus of Ota after three or more laser treatment sessions. However, the majority (55%) of the patients reported no differences in results between the two lasers, and only one of the two observers noted statistically significant improvement of QS 1064 nm Nd:YAG over QS alex.

Measurements of low-energy (d,n) reactions for BNCT. Boron Neutron Capture Therapy.

Neutron yields and energy spectra have been measured for various deuteron-induced reactions at low energy. Neutrons of energy > 100 keV emitted in the 9Be(d,n)10B, 12C(d,n)13N, and 13C(d,n)14N reactions at Ed= 1.5 MeV were detected at five angles by means of liquid scintillator detectors. While low-energy neutrons were observed in all studied reactions, only 13C(d,n)14N is characterized by a relatively large yield with spectral features potentially interesting for an accelerator-based neutron source for BNCT.

Potencialidade do elemento tóxico berílio, usado em prótese dentárias / Potentiality of the toxic element beryllium, used in dental prosthesis

Neste trabalho, foi estudado o efeito do berílio sobre a microestrutura e a temperatura de fusäo em ligas Ni-Cr-Mo-Co e suas propriedades de corrosäo. O estudo consistiu na obtençäo das diversas ligas através de fusäo sob vácuo, seguidas de forjamento em condiçöes industriais. Após o forjamento, as ligas foram tratadas termicamente em diversas temperaturas e resfriadas em água, ar e forno. Nas ligas Ni-Cr-Mo-Co, a presença do Be altera a microestrutura, proporcionando a formaçäo de fases intermetálicas. Foi constatado que, nas ligas estudadas, o Be abaixa a temperatura de fusäo e as torna susceptíveis à corrosäo por pite

Radiosensitivity variations in human tumor cell lines exposed in vitro to p(66)/Be neutrons or 60Co gamma-rays.

BACKGROUND: Neutron therapy should be beneficial to patients with tumor types which are resistant to photons but relatively sensitive to high-LET radiation. In this work the potential therapeutic gain of a clinical neutron beam is evaluated by quantifying the variations in radiosensitivity of different cell lines to neutrons and photons. MATERIAL AND METHODS: Different cell lines were exposed in vitro to p(66)/Be neutrons or 60Co gamma-rays. Micronuclei frequencies in binucleated cells and surviving fractions were determined for each cell type. RESULTS: Following exposure to either 1 or 1.5 Gy neutrons, micronuclei frequencies were significantly correlated with that observed for 2 Gy photons. A weak but significant correlation between the variation in neutron RBE values, determined from survival curve inactivation parameters and the mean inactivation doses for photon exposures, was also established. CONCLUSION: It is concluded that although neutron and photon sensitivities are related, the use of this high energy neutron source may constitute a potential therapeutic gain for tumor types that can be identified as very resistant to photons. Considering that a definitive oxygen gain factor has been established for this neutron beam the observed therapeutic gain is expected to be further enhanced in tumors where hypoxia protects cells from conventional radiation damage.

Biological intercomparisons of neutron beams used for radiotherapy generated by p(+)-->Be in hospital-based cyclotrons.

The new generation of hospital-based neutron therapy facilities involve cyclotrons using protons on beryllium. The spectrum of neutrons produced includes a large and variable proportion of low-energy neutrons that are poorly penetrating but biologically effective. Cells cultured in vitro were used to compare the three US facilities at Seattle, M.D. Anderson and UCLA, together with the UK facility at Clatterbridge. Cyclotrons were compared within a given experiment on the same day using cells from a common suspension. Among the three US facilities, the relative potency factor at a depth of 25 mm differs by about 11%, with Seattle the least and UCLA the most biologically effective. Clatterbridge was compared directly with M.D. Anderson and found to be less effective by about 5%; it has a slightly lower biological effectiveness than any of the US facilities. There is evidence for an increased biological effectiveness in the build-up region, which reduces the effective skin sparing potential. There is not much difference in build-up between the three US facilities. Using the proton-on-beryllium neutron production process results in a wide spectrum of neutrons with a large but variable low-energy component. The biological effectiveness of the beam depends on target design and thickness as well as the design of the collimating system. Consequently the biological effectiveness of neutron beams generated by this process must be assessed on an individual basis. It cannot be assumed that because cyclotrons have similar accelerating energies that the relative biological effectiveness will be the same.