Effect of Headgroup Variation on the Self-Assembly of Cationic Surfactants with Sulfonatocalix[6]arene.

The effect of headgroup variation on the association of supramolecular amphiphiles composed of 4-sulfonatocalix[6]arene (SCX6) and cationic surfactant possessing tetradecyl substituent was studied in aqueous solutions at pH 7. When the surfactant contained hydrophilic trimethylammonium, pyridinium, or 1-methylimidazolium headgroup, highly reversible temperature-responsive nanoparticle-supramolecular micelle transformation could be attained at appropriately chosen component mixing ratios and NaCl concentrations. In these cases, the substantial negative molar heat capacity change (ΔCp) rendered nanoparticle formation strongly endothermic at low temperature, whereas the assembly to supramolecular micelle was always accompanied by enthalpy gain. The ΔCp values became less negative when the charge density and the hydrophilic character of the surfactant headgroup diminished. The association of the more hydrophobic 6-methoxyquinolinium and quinolinium surfactants with SCX6 did not lead to supramolecular micelle formation because the self-assembly into nanoparticles was highly exothermic.

Effect of Macrocycle Size on the Self-Assembly of Methylimidazolium Surfactant with Sulfonatocalix[n]arenes.

The effect of macrocycle size on the association of supramolecular amphiphiles composed of 4-sulfonatocalix[n]arene and 1-methyl-3-tetradecylimidazolium (C14mim+) was studied in aqueous solutions at pH 7. When the cavitand contained four sulfonatophenol units (SCX4), formation of spherical nanoparticles (NPs) was observed. By contrast, both supramolecular micelle (SM) and NP formation could be attained in the presence of NaCl when the larger, more flexible 4-sulfonatocalix[8]arene (SCX8) served as the host compound. The SCX8-promoted self-assembly into the SM was enthalpically more favorable than the NP production, but the molar heat capacity changes in the two processes barely differed. An addition of 50 mM NaCl significantly increased the enthalpy of C14mim+-SCX8 NP formation, thereby making the self-organization into the SM more favorable. The transformation of SM into NP at high temperatures was due to the substantial entropic contribution to the driving force behind the NP formation. The critical micelle concentration (cmc) and the local polarity in the headgroup domain were considerably lower for the SM compared with those of the conventional C14mim+Br- micelle.

Population based ranking of frameless CT-MRI registration methods.

BACKGROUND: Clinical practice often requires simultaneous information obtained by two different imaging modalities. Registration algorithms are commonly used for this purpose. Automated procedures are very helpful in cases when the same kind of registration has to be performed on images of a high number of subjects. Radiotherapists would prefer to use the best automated method to assist therapy planning, however there are not accepted procedures for ranking the different registration algorithms. PURPOSE: We were interested in developing a method to measure the population level performance of CT-MRI registration algorithms by a parameter of values in the [0,1] interval. MATERIALS AND METHODS: Pairs of CT and MRI images were collected from 1051 subjects. Results of an automated registration were corrected manually until a radiologist and a neurosurgeon expert both accepted the result as good. This way 1051 registered MRI images were produced by the same pair of experts to be used as gold standards for the evaluation of the performance of other registration algorithms. Pearson correlation coefficient, mutual information, normalized mutual information, Kullback-Leibler divergence, L1 norm and square L2 norm (dis)similarity measures were tested for sensitivity to indicate the extent of (dis)similarity of a pair of individual mismatched images. RESULTS: The square Hellinger distance proved suitable to grade the performance of registration algorithms at population level providing the developers with a valuable tool to rank algorithms. CONCLUSIONS: The developed procedure provides an objective method to find the registration algorithm performing the best on the population level out of newly constructed or available preselected ones.

Reversible Nanoparticle-Micelle Transformation of Ionic Liquid-Sulfonatocalix[6]arene Aggregates.

The effect of temperature and NaCl concentration variations on the self-assembly of 1-methyl-3-tetradecylimidazolium (C14mim(+)) and 4-sulfonatocalix[6]arene (SCX6) was studied by dynamic light scattering and isothermal calorimetric methods at pH 7. Inclusion complex formation promoted the self-assembly to spherical nanoparticles (NP), which transformed to supramolecular micelles (SM) in the presence of NaCl. Highly reversible, temperature-responsive behavior was observed, and the conditions of the NP-SM transition could be tuned by the alteration of C14mim(+):SCX6 mixing ratio and NaCl concentration. The association to SM was always exothermic with enthalpy independent of the amount of NaCl. In contrast, NPs were produced in endothermic process at low temperature, and the enthalpy change became less favorable upon increase in NaCl concentration. The NP formation was accompanied by negative molar heat capacity change, which further diminished when NaCl concentration was raised.

Effect of torsional isomerization and inclusion complex formation with cucurbit[7]uril on the fluorescence of 6-methoxy-1-methylquinolinium.

Inclusion of 6-methoxy-1-methylquinolinium (C1MQ) in the cavity of cucurbit[7]uril (CB7) was studied by absorption, fluorescence, NMR and isothermal calorimetric methods in aqueous solution at 298 K. The free C1MQ exhibited dual-exponential fluorescence decay kinetics due to the two torsional isomers differing in the orientation of the methoxy moiety relative to the heterocyclic ring. The enthalpy-driven encapsulation of the heterocycle in CB7 led to a very stable 1 : 1 complex with a binding constant of (2.0 ± 0.4) × 10(6) M(-1). The rate of C1MQ-CB7 complex dissociation was found to be comparable to the NMR timescale. Because the methoxy moiety is oriented outward from the host, its s-cis-s-trans isomerization is slightly affected by the confinement. Inclusion complex formation significantly slowed down the photoinduced electron transfer from I(-) and N3(-) to the singlet-excited C1MQ, but did not preclude the reaction because long distance electron transfer occurred through the wall of the CB7 macrocycle. Due to the large difference in the quenching rate constant for free and encapsulated forms, C1MQ is an excellent probe for the study of the inclusion of nonfluorescent compounds in CB7 in the presence of Cl(-) or Br(-).

4-Sulfonatocalix[6]arene-induced aggregation of ionic liquids.

The interaction of 4-sulfonatocalix[6]arene (SCX6) macrocycle with 1-alkyl-3-methylimidazolium type of ionic liquids possessing dodecyl, tetradecyl, or hexadecyl substituent was studied in aqueous solution at 298 K. Host-guest complexation promoted the spontaneous self-assembly into nanoparticles of 7:1 ionic liquid:SCX6 stoichiometry. Positively charged and stable nanoparticles were produced in solutions of 7-200-fold excess of ionic liquid as compared to the amount of SCX6. The negatively charged nanoparticles formed in solutions having 2-7 ionic liquid:SCX6 molar ratios evolved into larger species. The stability of the nanoparticles increased with the lengthening of aliphatic chain of the ionic liquid. Cryo-TEM experiments showed dense particles generally with spherical shape and multilayered structure, which has been confirmed by small-angle neutron scattering.

SU-E-T-111: Single Line Multi-Detector Scintillation Dosimetry: Demonstration of Feasibility.

PURPOSE: Obtain feasibility data on the use of multiple scintillators on a single optical line for dose measurements. METHODS: A CsI (Tl doped) crystal and a plastic (Rexon Inc, Rp-408) scintillator detectors, both transparent, were attached to the end of a fiberoptic line and connected to an Ocean Optics USB-2000 spectrometer. After baseline spectra, spectra with the two scintillators adjacent to each other and then separated by a 7.6 cm plexiglass spacer were obtained. Irradiations were performed using 6 MV X-ray beam from a Varian EX linear accelerator. Utilizing the baseline spectra the dose received by each scintillator were calculated from the measured spectral peaks of the linear scintillator assemblies. Linearity tests were performed by varying dose and the dose rate in a homogeneous radiation field covering both scintillators. Unequal doses were delivered to the scintillator by gradually closing the collimator from one direction, blocking one detector at a time. Doses to the scintillators were modulated by different amount of solid water placed over the two detectors, as well. RESULTS: Measured scintillation spectra agreed with the published spectra. The spectra did not change with depth in the phantom. The multi-scintillator system response was strictly linear between 1.67 and 40 MUs, (approx. 1.3 to 31 cGy) and dose rate independent between 100 to 600 MU/min. The profile curves obtained by closing the collimator agreed with qualitatively expected curves. Doses measured under different phantom thicknesses were in good agreement with ion chamber measurements on the same locations (+/- 3%). The linearity and dose rate independence allow absolute dose calibration for given beam energies and scintillator arrangement. CONCLUSIONS: Multi-probe scintillation dosimetry along a single optical fiber is possible in therapeutic irradiation conditions. This is feasible by using signals from multiple select scintillators with distinct spectroscopic responses arranged along an optical fiber.

Risk of chromosome abnormalities in the presence of bilateral or unilateral choroid plexus cysts.

OBJECTIVES: To evaluate the rate of chromosome abnormalities in cases of uni- and bilateral choroid plexus cysts (CPCs). METHODS: A total of 10,875 ultrasound (US) examinations were performed in the second trimester, and 435 cases with CPC (4%) were found. After genetic counseling, 45 patients decided not to undergo karyotyping. The authors performed a chromosome analysis in 390 cases of CPCs. RESULTS: The total risk of chromosome abnormalities was 3.59% (n = 14) and risk of trisomies was 2.05% (n = 8). Trisomy 18 was found in 6 cases (1.54%), trisomy 21 in 1 case (0.26%), and trisomy 9 in 1 case (0.26%). The risk of 45,X karyotype was 0.77% (n = 3). One case of 47,XXY karyotype and 2 cases with other chromosome abnormalities were found. In 212 unilateral cases there were 7 with chromosome abnormalities (3.3%). In 178 bilateral cases there were 7 with abnormal karyotypes (3.93%). The CPC was associated with additional fetal US anomalies (with or without polyhydramnios/oligohydramnios) in 112 cases; chromosome abnormalities were detected in 4 cases (3.57%). 66 cases were associated with polyhydramnios/oligohydramnios but not with other fetal US anomalies; 3 cases of abnormal karyotypes were found (4.55%). The CPC was isolated in 212 cases and 7 cases were associated with chromosome disorders (3.3%). CONCLUSIONS: US plays an important role in prenatal diagnostics. Further genetic counseling is recommended in cases with CPCs.

The role of perinatal autopsy in the management of pregnancies with major fetal trisomies.

We assessed the value of perinatal autopsy following mid-trimester termination of pregnancy due to major fetal trisomies. Singleton fetuses (n=305) that underwent prenatal sonography and karyotyping during the second trimester of pregnancy and that had trisomy 21, trisomy 18, or trisomy 13 constituted the study population. The findings of second trimester sonography and fetal autopsy were compared. Altogether, 611 separate major structural malformations were diagnosed during autopsy. Full agreement was achieved between sonography and autopsy in 35.8% of the malformations. The additional findings at autopsy (64.2%) involved mainly two organ systems: face, including ears and eyes, and extremities, including hands and feet. Some ultrasound findings were not confirmed at autopsy (n=49). Concordance rates between sonography and autopsy findings regarding soft markers were considerably high in cases of increased nuchal fold thickness and short femur/humerus. On the other hand, fetal autopsy was of limited value as far as hyperechoic bowel and echogenic intracardiac foci are concerned. Pathologic examination provides additional information regarding many fetuses with aneuploidy, and may indicate possible directions of sonographic screening for major chromosome aberrations. However, prenatal sonography and perinatal autopsy should be considered as complementary ways of increasing our knowledge about the possible features of fetal aneuploidies.

Hearing disturbances in hypertrophic cardiomyopathy. Is the sensorineural disorder neurogenic or myogenic?

BACKGROUND: In a previous study, we demonstrated that a hidden hearing defect is present in about 50% of patients with hypertrophic cardiomyopathy (HCM). Such defects were found significantly less frequently in age and clinical stage-matched patients with dilated cardiomyopathy (DCM), and were practically absent in patients with valvular aortic stenosis, and in patients taking beta-receptor blockers for different reasons (such as hypertension, ischemic heart disease, etc.). The hearing disturbances were first examined by means of brain-stem evoked response audiometry (BAEP). This method permitted only a rough differentiation between the origins of cochlear (myogenic) and retrocochlear (neurogenic) hearing disturbances, and did not allow us to establish their myogenic or neurogenic nature with certainty. AIMS: Our present aim was to determine whether the hearing disturbances present in HCM and DCM patients are myogenic or neurogenic in origin. METHODS: The neurogenic function of the inner ear was examined by BAEP as before, and the myogenic function by the distortion product otoacoustic emission technique. RESULTS: Myogenic abnormalities were found in 39/69 ears (57%) and neurogenic abnormalities in 19/69 (28%) ears among the HCM cases, as compared with 14/39 (36%) and 8/39 (21%) ears respectively among the DCM cases (p<0.005). Healthy controls displayed the lowest incidence of both types of hearing abnormalities. CONCLUSION: Our results lead us to conclude that myogenic lesions are more frequent than neurogenic lesions in patients with HCM. Both myogenic and neurogenic lesions are more frequent in HCM patients than in DCM patients or healthy controls. It may be hypothesized that abnormal sarcomeric proteins present in the muscular structures of the inner ear in HCM are possibly responsible for the hearing disorders in these patients, and that this is not merely a neurological defect.

Correlation of prenatal ultrasound diagnosis and pathologic findings in fetuses with trisomy 13.

OBJECTIVES: This study was conducted to compare the prenatal ultrasound findings and postmortem pathologic findings of fetuses with trisomy 13. METHODS: Of 22 150 fetal chromosome analyses, 28 fetuses with trisomy 13 were diagnosed between 1990 and 2004. Findings of second-trimester sonography and subsequent fetal autopsy were compared by organ system, and their correlation was assigned to one of three categories based on the degree of agreement. RESULTS: Of the total of 79 abnormalities that were found on autopsy, prenatal sonography showed 48 (60.8%). The agreement was more than 75% of all abnormalities of these systems: central nervous system (CNS) (76.5%), facial abnormalities (76.5%), urinary system (81.8%) and fetal hydrops (100%), whereas the sensitivity of sonography was lower in these organ systems: heart (53.3%), extremities (12.5%) and abdominal abnormalities (33.3%). In 39.2% of the cases, autopsy findings were not detected by sonography. These additional findings at autopsy involved mainly three organ systems: heart, face and extremities. Some ultrasound findings (n = 17) were not verified at autopsy; most of them were quantitative markers (mild ventriculomegaly, mild pyelectasis). CONCLUSION: Our results indicate that thorough sonographic examination of the fetal face (including ears) and extremities (including hands and feet) with an extensive use of fetal echocardiography may increase the sensitivity of prenatal sonography in detecting trisomy 13.

Trisomies and other chromosome abnormalities detected after positive sonographic findings.

OBJECTIVE: To evaluate the rate of trisomies and other chromosome abnormalities after positive ultrasound findings in thefirst and second trimester of pregnancy. STUDY DESIGN: The study investigated chromosome abnormalities detected in cases with prior abnormal ultrasoundfindings. During a 10-year period there were 1907 invasive interventions carried out with the purpose of chromosome analysis. The intervention was genetic amniocentesis in 1619 cases and chorionic villus sampling in 288. RESULTS: Karyotyping revealed 103 cases (5.4%) of chromosome abnormalities. Abnormalities with subcutaneous edema were examined: abnormal karyotype was found in 20% of cases with nonimmune hydrops, 48.1% of cases with cystic hygroma and 53.8% of cases with nonimmune hydrops and cystic hygroma together, 8.3% of cases with nuchal edema in the first trimester and 5.5% in the second trimester. The incidence of chromosome abnormalities in cases of cerebral anomalies was 6.3% of cases with ventricular dilatation, 3.6% of cases with choroid plexus cysts and 15.9% of cases with other cranial anomalies. Regarding abnormalities of the heart, isolated echogenic intracardiac focus and ventricular septal defects were not associated with chromosome abnormality, but, in conjunction with other positive ultrasound findings, the incidence of chromosome abnormalities was 7.9% and 26.7%, respectively. Other anomalies of the heart and large blood vessels showed an abnormal karyotype incidence of 18.2%. In cases of unilateral pyelectasis unassociated with other anomalies, the incidence of chromosome abnormalities was 1%. In cases of bilateral pyelectasis or pyelectasis associated with other anomalies, the incidence was 3%. In terms of anomalies of the abdominal wall and abdomen, the incidence of association with chromosome abnormalities was 9.5% in cases of omphalocele, 11.8% in cases of duodenal atresia and 5.7% in cases of echogenic bowel. In cases of short femur and humerus the rate of abnormal karyotypes was 16%. CONCLUSION: Ultrasound plays an important role in prenatal diagnosis. In cases of positive ultrasound findings, karyotyping is reasonable.

ALA (5-aminolevulinic acid)-induced protoporphyrin IX fluorescence in the endoscopic diagnostic and control of pharyngo-laryngeal cancer.

Photodynamic diagnosis is a modern method for the fluorescence imaging of superficial pharyngeal and laryngeal tumours. 5-aminolevulinic acid (ALA)-induced protoporphyrin IX fluorescence benefits the tumour selective accumulation of protoporphyrin; therefore, tumours can be differentiated from healthy tissue. ALA-induced fluorescence of laryngo-pharyngeal tumours and precancerous and benign lesions were evaluated by endoscopy. At the Department of Otorhinolaryngology, Head and Neck Surgery, Szeged, Hungary, 31 patients underwent ALA-induced protoporphyrin fluorescence imaging. After topical application of ALA, mesopharyngeal tumours were visualised by direct fluorescence endoscopy. Laryngeal and hypopharyngeal tumours were examined with a laryngomicroscope with the patients under general anaesthesia after inhalation of an ALA solution. Intensity of PPIX fluorescence was classified and compared with pathological findings. The examination of all 13 laryngeal and 12 pharyngeal tumours resulted in a middle or strong intensity of red fluorescence, but for one cancer, four precancerous and two benign lesions. Healthy tissues showed green autofluorescence. Margins of mesopharyngeal and vocal cord tumours were clearly outlined under fluorescent vision, giving a helpful contribution to diagnosis and therapy even in clinically non-visible tumours. Laryngomicroscopy combined with laser surgery also indicated PPIX fluorescence examination visualising margins of the tumour intermediately with the endoscope. The ALA-induced PPIX fluorescence imaging method revealed a sensitivity of 96%. This method is applicable for detecting early superficial tumours, margins of tumours and follow-up after surgery/radiation therapy in the laryngo-pharynx.

Neural response telemetry in cochlear implant users.

Programming of multichannel cochlear implants requires subjective responses to a series of sophisticated psychophysical percepts. It is often difficult for cochlear implant patients (especially young prelinguistically deaf children) to provide adequate responses for device fitting. However, the neural response telemetry (NRT) system renders possible the measurement of the compound action potential threshold. We performed NRT examinations in 27 cochlear implant users with Nucleus 24-channel cochlear implants. Measurements were obtained from five electrodes (3, 5, 10, 15, and 20) in each patient. Our goal was to look for correlation between behavioral subjective thresholds and compound action potentials. The action potentials could be elicited in 23 patients in all measured electrodes. The NRT threshold values were highly correlated with electrical threshold levels obtained through subjective responses. Our results suggest that the electrically elicited neural responses may yield very important information for device fitting in patients with cochlear implants.

Investigation of auditory brainstem function in diabetic patients.

We performed brainstem auditory evoked potential (BAEP) examinations in 15 patients with long-standing type 1 diabetes mellitus. We applied cardiovascular reflex tests for assessment of autonomic neuropathy. The aim of our investigation was to compare the BAEP results of this patient group with those of controls and to look for the possible correlation between alteration of the auditory brainstem function and cardiovascular autonomic neuropathy. Analysis of the latencies (waves I, II, III, and V) and the interpeak latencies (I-III and I-V) of BAEP revealed a significant difference between those of diabetics and those of healthy controls. The amplitudes of waves I, III, and V were definitely lower in comparison with amplitudes of healthy controls. We observed a positive correlation between the overall autonomic score and the latencies (waves III and V) and interpeak latencies (I-III, I-V). These data support the hypothesis that long-standing diabetes mellitus and diabetic neuropathy might be revealed as a cause of certain dysfunctions of the central auditory pathways.

Examination of nasopharyngeal and tracheal somatosensory evoked potential recordings in dogs.

OBJECTIVE: To investigate the value of nasopharyngeal and tracheal recordings of somatosensory evoked potentials (SSEP) in anesthetized dogs. ANIMALS: 10 healthy mixed-breed dogs (5 males and 5 females). PROCEDURE: Square-ware electrical stimuli (50 microseconds duration, 4Hz) were delivered through bipolar surface electrodes to the median nerve of the right forelimb with 7 to 12 mA constant current. The SSEP were recorded with soft electrodes placed on the epipharynx and dorsal wall of the trachea, respectively. Traditional scalp and neck recordings of SSEP were also performed, using SC-inserted needle electrodes. The potentials recorded dorsally and ventrally from the neuraxis were compared to assess the application of these signals for intraoperative neurophysiologic monitoring. RESULTS: Electrical stimulation of the median nerve resulted in multiphasic potentials recorded from all 4 recording sites. Latency and phase shifts were observed between the far-field potentials placed ventrally and dorsally from the neuraxis. CONCLUSIONS AND CLINICAL RELEVANCE: Potentials recorded with nasopharyngeal and tracheal electrodes are regarded suitable for intraoperative neurophysiologic monitoring in anesthized dogs.

Calculation of mean central dose in interstitial brachytherapy using Delaunay triangulation.

In 1997 the ICRU published Report 58 "Dose and Volume Specification for Reporting Interstitial Therapy" with the objective of addressing the problem of absorbed dose specification for reporting contemporary interstitial therapy. One of the concepts proposed in that report is "mean central dose." The fundamental goal of the mean central dose (MCD) calculation is to obtain a single, readily reportable and intercomparable value which is representative of dose in regions of the implant "where the dose gradient approximates a plateau." Delaunay triangulation (DT) is a method used in computational geometry to partition the space enclosed by the convex hull of a set of distinct points P into a set of nonoverlapping cells. In the three-dimensional case, each point of P becomes a vertex of a tetrahedron and the result of the DT is a set of tetrahedra. All treatment planning for interstitial brachytherapy inherently requires that the location of the radioactive sources, or dwell positions in the case of HDR, be known or digitized. These source locations may be regarded as a set of points representing the implanted volume. Delaunay triangulation of the source locations creates a set of tetrahedra without manual intervention. The geometric centers of these tetrahedra define a new set of points which lie "in between" the radioactive sources and which are distributed uniformly over the volume of the implant. The arithmetic mean of the dose at these centers is a three dimensional analog of the two-dimensional triangulation and inspection methods proposed for calculating MCD in ICRU 58. We demonstrate that DT can be successfully incorporated into a computerized treatment planning system and used to calculate the MCD.

Radiotherapy for carcinoma of the bladder: a review.

Carcinoma of the bladder (CaB) is a common and important tumor in North America and Western Europe. There has been a steady increase in the incidence of CaB during the past 25 years in both of these regions with a simultaneous decrease in the mortality rates. The decrease in mortality is primarily due to an earlier diagnosis and the availability of more effective therapeutic interventions resulting from major advances in surgery and a wide use of multimodality bladder preservation therapy.The use of radiotherapy in the management of muscle-invasive CaB has undergone a major evolution. External beam radiotherapy alone is used infrequently in carefully selected patients. The same applies to the use of preoperative irradiation. Brachytherapy alone or combined with external beam radiotherapy has been used successfully in Europe but is used infrequently in North America. External beam radiotherapy is an essential component of a multimodality therapy consisting of cytoreductive surgery via transurethral resection of a bladder tumor followed by a planned combination of radiotherapy and chemotherapy. The outcomes of this bladder preservation therapy are similar to those reported in a like patient population treated with radical cystectomy. The main benefit of conservatively treated patients is functioning bladder in about 50% of those receiving conservative therapy. Radiotherapy alone or in a combination with chemotherapy remains an important and effective palliative therapy for patients with recurrent and/or metastatic CaB. Current research efforts are directed toward a better identification of important pretreatment risk factors predicting failure thus helping in a more optimal selection of patients who would benefit most from radical cystectomy or from the application of bladder preservation therapy.

Application of radiosurgery principles to a target in the breast: a dosimetric study.

PURPOSE: To investigate the technical and physical feasibility of using a radiosurgery-like technique to irradiate a small target within the breast with a single fraction. MATERIAL AND METHODS: During diagnostic biopsy, a tantalum surgical clip is placed in the lesion identified at mammography. Transverse CT scans over the entire breast are obtained, as the patient lies prone on a special table that allows the breast to hang down. The clip is used as a reference point to define the isocenter of the radiation treatment. RESULTS: The clip is visible on port films taken with a 4 MV beam, allowing the isocenter to be set to its planned location. No movement of the hanging breast is visually detected. The possible beam directions are enclosed by a 220 degrees horizontal x 180 degrees vertical angular interval. Dosimetry of two "radiosurgical" examples, (A) seven fixed horizontal beams and (B) six 45 degrees arcs and a 90 degrees sagittal arc using a 4 MV x-ray beam with a 32 mm diameter collimator, are discussed. Both field arrangements produce adequate tumor coverage: the minimum target dose is 83% of the dose maximum in the fixed beam arrangement and 86% in the multiarc setup. In arrangement A the lung and other tissues external to the breast receive dose only from scattered radiation. In arrangement B the maximum lung dose is less than 5% of the dose to isocenter. CONCLUSION: From a dosimetric point of view both described techniques are feasible, and the radiosurgery-like treatment is executable.

Unresectable primary and recurrent head and neck tumors: effect of hyperthermia and carboplatin--preliminary experience.

PURPOSE: To perform a single-arm study to determine the effectiveness of and potential toxic reactions to local hyperthermia and systemic carboplatin (cis-diammine-1,1-cyclobutane dicarboxylate platinum II) for the treatment of advanced or recurrent squamous cell carcinomas of the head and neck. MATERIALS AND METHODS: Eight patients with squamous cell carcinoma of the head and neck and stage IV disease (N2 or N3 neck adenopathy) or recurrent local-regional disease and who were previously and definitively treated were included in the study. Thermochemotherapy was administered every 4 weeks. Recorded end points were tumor response, duration of response, incidence of distant metastases, survival, cause of death, and toxic reactions. RESULTS: One patient had a complete response to therapy, and two had a partial response. Five patients had no response or developed progressive disease during therapy. Six patients died after 4-13 months of progressive disease. Two long-term survivors received radiation therapy; one also underwent surgical resection for residual neck disease. Each thermochemotherapeutic session was well tolerated, with minimal discomfort. Toxic reactions included hypotension, vomiting, hyponatremia, anemia, thrombocytopenia, and infection at the site of administration. There were no life-threatening toxic reactions. CONCLUSION: The combined use of hyperthermia and carboplatin shows potential in the management of unresectable head and neck tumors and is safe and well tolerated. Further studies on thermochemotherapy are warranted to assess its potential.