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Biomedical subjects

G Luxton

Publications and source records attributed to G Luxton.

At least 55 records · Page 3Linked to original sources
PubMed1989

Interstitial microwave hyperthermia combined with iridium-192 radiotherapy for recurrent tumors.

From 1985 through 1987, 44 tumors in 39 patients with recurrent cancer were treated with interstitial microwave hyperthermia (HT) combined with interstitial 192Ir radiotherapy (RT). All patients had unresectable and previously treated tumors (mean RT dose 57.6 Gy). Diagnoses were squamous cell carcinoma in 27 (62%), adenocarcinoma in 11 (25%), melanoma in 5 (11%), and soft tissue sarcoma in 1 (2%) site. Interstitial RT dose was from 25 to 50 Gy (mean 38.3 Gy). The first HT session was scheduled immediately before the loading of 192Ir, and the second was scheduled following its removal. Each session lasted 45-60 min at therapeutic temperature (42.5 degrees C). Complete response (CR) was obtained in 28 (64%) sites and partial response (PR) in 15 (34%) sites. None of the CR patients had local recurrence. Tumor volume was the most important factor influencing CR (p less than 0.001). The treated site, radiation dose, and thermal dose were not significant factors for CR (p = 0.03). The overall median survival was 39 weeks, with a 2-year survival of 22%. The treatment was well tolerated, with two patients developing focal skin necrosis.

Actuarial Analysis↗
PubMed1989

Deep regional hyperthermia of the liver. A clinical study of 49 patients.

From 1981 to 1986, six medical centers participated in feasibility studies of radiofrequency deep regional hyperthermia (HT) in the treatment of hepatic metastases. A total of 49 patients, 32 men and 17 women, were treated with an annular phased array. Colon was the primary site in 74% of the patients, and adenocarcinoma was the diagnosis in 80%. More than one half of the patients had been treated previously. This included chemotherapy (CT) in 17 patients and radiotherapy (RT) in 10 patients, with a mean RT dose of 24 Gy. Upper abdominal pain was the dominant presenting symptom in 53% of patients. In the study, treatment was administered as follows: 14 (28%) patients received HT alone, 17 (35%) received HT + RT, 14 (28%) received HT + CT, and 4 (8%) received HT + RT + CT. A total of 157 HT treatments was administered at a mean frequency of 55 MHz and a mean power of 780 watts. The number of HT sessions ranged from 1 to 8, with a mean of 3.2 treatments per patient. Temperature was monitored continuously throughout each treatment session. The treatment aim was to reach and maintain a temperature of 42.5 degrees C for 30 min. In practice, owing to the difficulty in reaching this temperature, an equivalent (lower) temperature from 40 to 42 degrees C was used, extending the duration of treatment sessions to 45-60 min. Thermal dose was defined as the number of minutes at 42.5 degrees C or its equivalent. In 21 (43%) patients, a temperature less than 40 degrees C was obtained and thermal dose = 0. Thermal dose was less than or equal to 50 in 17 (35%) patients, greater than 50 less than or equal to 100 in 7 (14%), and greater than 100 in 4 (8%). RT was given at a daily dose of 1.8 Gy to a total of less than 20 Gy in 14 patients, greater than 20 less than or equal to 30 Gy in 6, and greater than 30 Gy in 1. CT consisted of 5-Fluorouracil by way of Hepatic Artery Infusion (HAI) in 9 patients, i.v. cisplatin in 5, and doxorubicin HAI in 3. Objective tumor regression (CR + PR) was seen in 6 (12%) patients. An additional 10 (20%) patients had less than 50% greater than 25% tumor regression, and 10 (20%) had complete or partial pain relief. The median duration of CR and PR was 26 weeks.(ABSTRACT TRUNCATED AT 400 WORDS)

Adult↗
PubMed1989

Surgical therapy and radiotherapy for carcinoma of the esophagus. Treatment results in 195 patients.

Between 1963 and 1986, 195 patients with carcinoma of the esophagus were seen in the Department of Radiation Oncology at the University of Southern California School of Medicine. Of these 195 patients, 137 had unresectable or inoperable tumors and received radiotherapy. A combination of radiotherapy and surgical therapy was used in 46 patients, 9 patients were treated with surgery alone, and three with chemotherapy alone. Among the nonsurgical patients, 13 scored less than 50 on the Karnofsky scale, 25 had distant metastases, and 69 lost more than 10% of their body weight. The majority (94%) had squamous cell carcinoma and a few (6%) had adenocarcinoma. Fifty percent had middle esophageal lesions, 30% had lower lesions, and 20% had upper esophageal lesions. Stage I was diagnosed in 13%, II in 27%, III in 29%, and IV in 27%; the disease was not staged in 5%. The 5-year actuarial survival rate for all patients was 4% (median 32 weeks). The 5-year survival rate of the 46 patients with combination therapy was 18%, and it was 2% for the remaining 149 patients (p less than 0.001). These figures are independent of stage of disease. The 2-year survival rate by stage was as follows: I, 25%; II, 21%; III, 5%; and IV, 0% (p less than 0.001). Complete response was obtained in 18% and partial response in 41%. Complete response was dependent on the tumor stage. It was 40% for stage I disease, 23% for stage II, 11% for stage III, and 6% for stage IV disease. Similarly, a larger percentage (39%) of the 46 patients with combination surgical/radiation therapy had a complete response than of patients treated by either radiotherapy alone (n = 137, 12%) or surgery alone (n = 9, 11%). Complete response and initial performance status were important factors influencing survival (p less than 0.001). Surgery with adjuvant irradiation offered a better survival rate than radiotherapy or surgery used as single modalities. Treatment results for patients with advanced carcinoma of the esophagus remain poor.

Adult↗
PubMed1988

Interstitial radiotherapy combined with interstitial hyperthermia in the management of recurrent tumors.

During a 2-year period 31 sites in 27 patients with recurrent, previously treated tumors received a combination of interstitial 192Ir radiation (RT) with microwave hyperthermia (HT). Head and neck sites were treated most frequently (48%), with breast and vagina each representing about 20% of sites. Complete response (CR) with no local recurrence was obtained in 61%, partial response (PR) in 11 (36%), and one (3%) had less than 50% tumor regression. Of these patients, nine had no evidence of tumor following HT-RT therapy, 8/18 in the CR group and 1/11 in the PR group. Significant factors influencing CR were: radiation dose, tumor volume and duration of tumor control following the initial therapy (p less than 0.02). Treated site, histology and thermal dose were not significant factors influencing tumor regression. Complications of significance developed in one patient who had local skin necrosis. Interstitial HT-RT combination provides an effective palliative therapy for recurrent and/or persistent tumors. Randomized trials are necessary to assess the effectiveness of this combination as a component part of primary management of selected tumors.

Brachytherapy↗
PubMed1988

Dosimetric calculations and measurements of gold plaque ophthalmic irradiators using iridium-192 and iodine-125 seeds.

The dosimetry of ophthalmic plaques designed to hold iridium-192 or iodine-125 seeds is investigated experimentally and by means of a computer model. A phantom for thermoluminescent dosimetry (TLD) which permits measurements to within 2 mm of the plaque surface is described. TLD data are compared with model calculations that take into account the active length of the seeds, anisotropy of dose distribution from single seeds, and scatter within the phantom. An isotropic point source calculational model is accurate for clinical calculations, particularly at depths greater than 5 mm. Relative central axis dose measurements for 125I in a gold plaque are also in agreement with the model. Comparisons of 192Ir, 125I and 60Co plaques are presented. The relative advantages of using these isotopes in eye plaques are discussed.

Brachytherapy↗
PubMed1988

Treatment of carcinoma of the skin with bone and/or cartilage involvement.

From 1956 to 1978, 23 patients with stage T4 carcinoma of the skin of the head and neck were treated with radiotherapy (RT). There were nine patients with cancer of the skin of the nose, eight with tumors of the pinna, and six with lesions of the eyelids. Basal cell carcinoma (BCC) was seen in 61%, squamous cell carcinoma (SCC) in 26%, and 13% of patients had tumors with BCC and SCC features. The majority of patients had large tumors. Less than one-third of patients had smaller lesions, whereas three patients had intermediate-size tumors (greater than 2 cm to less than or equal to 5 cm). Of the 23 patients treated, nine had prior surgical therapy and recurrent or persistent tumor. The remaining 14 patients had no prior therapy. RT was given up to an average total dose of 55 Gy. The 5-year actuarial tumor control rate was 80%. Of the 23 patients treated, four had recurrent tumors. There were no recurrences among the 14 BCC patients, whereas there were four recurrences among the nine SCC and mixed histology patients. Of the four patients who had tumor recurrence, one was salvaged by subsequent radical surgery and three died of their tumor. No serious complications were observed in this group of 23 patients. There was no cartilage, bone, or soft-tissue necrosis noted. RT is a good treatment option and it may be treatment of choice in patients with BCC and SCC of the skin with cartilage or bone involvement. It provides an excellent chance of tumor control, good cosmesis, preservation of function, and a low incidence of complications.

Adult↗
PubMed1988

External beam and intraluminal radiotherapy in the treatment of carcinoma of the esophagus.

During a 10-year period, 46 patients with unresectable or inoperable carcinoma of the esophagus were treated with teletherapy-brachytherapy combination at the University of Southern California School of Medicine. Stage distribution was as follows: stage I, 5 (11%) patients; stage II, 23 (50%) patients; stage III, six (13%) patients; and stage IV, 12 (26%) patients. Thirteen patients were treated for recurrent disease, including 11 patients initially treated with teletherapy and two who had had surgical resection. Radiotherapy was given by teletherapy in 33 and brachytherapy in all 46 patients. An average tumor dose was 50 Gy with teletherapy and 20 Gy per application with brachytherapy. There were 25 patients who had more than one brachytherapy application. The 5-year actuarial survival rate for 28 patients with stage I or II disease was 12%, with a median of 13 months. This compared with no 5-year survivals and a median survival of 10 months for the 18 patients with stage III or IV disease. Failure at the primary site was seen in 16 (35%) patients. Complete response was seen in 20%, partial response in 76%, and no response in 4%. Treatment was well tolerated. Complications included esophageal stenosis in two patients and tracheoesophageal fistula in one. Teletherapy-brachytherapy combination is an effective treatment in the management of unresectable or inoperable carcinoma of the esophagus.

Adenocarcinoma↗
PubMed1987

Treatment results and patterns of failure in 646 patients with carcinoma of the eyelids, pinna, and nose.

From 1956 to 1978, 646 patients were treated with radiotherapy for carcinoma of the nose (350 patients, 54 percent), eyelids (159 patients, 25 percent), pinna (93 patients, 14 percent), and skin adjacent to the lip (44 patients, 7 percent). The histologic distribution was 72 percent basal cell carcinoma, 18 percent squamous cell carcinoma, and 10 percent mixed basal and squamous cell features. Tumors less than 2 cm in diameter were found in 602 patients (93 percent), whereas 44 patients (7 percent) had larger tumors. Tumor involvement of cartilage and bone was seen in 23 patients at the time of diagnosis. The 5, 10, and 20 year control rates were 99 percent, 98 percent, and 98 percent, respectively, for 502 tumors less than 2 cm in diameter. This compared favorably with control rates of 92 percent at 5 years and 79 percent at 10 years for tumors from 2 to 5 cm in diameter and 60 percent at 5 years and 53 percent at 8 years for 12 patients with massive tumors (p less than 0.0001). The histologic characteristics of the lesion had a strong influence on tumor control (p less than 0.02). Of the patients with cartilage or bone invasion, tumor was controlled in 19 (83 percent). Of these 19 patients, 11 had no evidence of disease for 3 years or more. Of all 646 patients treated, failure was seen in 60 (9 percent). It correlated well with the size of the lesion, being 7 percent for tumors of less than 2 cm and 50 percent for tumors of greater than 5 cm. Of the 60 patients in whom treatment failed, 48 (80 percent) had prior definitive therapy. Radiotherapy was an efficient modality to control operative failures; however, it was not as efficient at control in patients in whom previous radiotherapy failed. Operation was the treatment of choice to salvage patients in whom radiotherapy failed. Of the patients in whom retreatment failed, 10 were known to have died from skin cancer, and an additional 6 patients were presumed to have died from the cancer. This study has demonstrated a good control rate and good cosmetic results for small tumors of the eyelids, pinna, and nose. In addition, a good control rate was obtained in patients with cartilage and bone involvement. Treatment of massive tumors should involve planned operative resection with adjuvant radiotherapy.

Adult↗
PubMed1987

Carcinoma of the lip and selected sites of head and neck skin. A clinical study of 896 patients.

During a period of over 20 years, 896 patients were treated with radiation in Wadsworth Medical Center, Los Angeles, for carcinoma of the lip and selected sites of skin of the head and neck. Basal cell carcinoma (BCC) was found in 467 (52%) patients, squamous cell carcinoma (SCC) in 362 (40%), and the remaining 67 (8%) had tumors with mixed basal and squamous cell features. BCC was the most common tumor (72%) among the 646 skin cancer patients while SCC predominated (99%) among the 250 lip cancer patients. Tumor control correlated well with the size of the lesion, p less than 0.0001. Histology of the lesion also had a significant (p = 0.021) influence on the tumor control rate, which was the highest among the BCC patients when compared with SCC or mixed cell patients. This study has again demonstrated the effectiveness of radiotherapy in controlling small and intermediate size epithelial tumors of the skin and lip. Additionally, irradiation, if administered properly, results in excellent cosmesis and a low incidence of treatment complications. Severe complications of radiotherapy reported in the literature took place at the beginning of this century and are no longer pertinent in the practice of modern radiation oncology. Larger lesions remain a challenge to radiation or surgical dermato-oncologists. A lack of tumor control in such lesions frequently results in a death of patient.

Adult↗
PubMed1987

Interstitial radiobrachytherapy of malignant cerebral neoplasms: rationale, methodology, prospects.

The local use of radionuclides in the management of neoplastic processes was initially considered over 80 yr ago and has enjoyed increasing enthusiasm in the treatment of somatic and central nervous system tumours during the past 30 yr. The marriage of complex neuroimaging techniques and modern stereotactic devices has markedly enhanced the technical precision of interstitial radiobrachytherapy of malignant cerebral neoplasms. In applying these techniques, it is imperative to achieve an optimal placement of radionuclide sources in order to develop a geometrically homogenous, controlled distribution of radiation. Critical considerations include determination of tumour volume and contour, and development of a homogenous dose rate (dependent upon multiple sources at varying intensity) that will not only effect tumour cell kill but do this without excessive production of radionecrosis which necessitates craniotomy because of mass. Using the Brown-Roberts-Wells (BRW) stereotactic guidance system and an image-defined, volumetrically determined target, implants of multiple iridium 192(192Ir) sources were used to establish appropriate isodose envelopes. A methodology for achieving the described objectives is detailed as it applies to a variety of malignant intracerebral neoplasms (glioblastoma multiforme, malignant astrocytoma, malignant mixed glioma, primary cerebral lymphoma, metastatic carcinoma and malignant pineal region tumours). Technical realization of precision implantation relying upon imaging data may be acheived with this method with satisfactory responses that are dependent upon histological tumour type and the morphology of the tumour distribution as related to the image. Early and late complications related to the surgical technique and radionuclide applications were less than 5%. Although encouraging, these techniques require further definition and greater data accrual before uniform application outside major medical centres can be justified. It is anticipated that improvement in results with intrinsic gliomas and other invasive neoplasms will be realized with further definition of tumour boundaries by tract biopsy techniques and concurrent utilization of hyperthermia and brain protective methods.

Brachytherapy↗
PubMed1977

Initial performance of the Stanford Medical pion generator.

A novel, cylindrical geometry, superconducting pion channel has been constructed at Stanford. It can simultaneously deliver up to 60 radially converging pion beams of the same mean momentum but with individually variable momentum spread (0.0-4.3%). Virtually no tuning of the pion beam is required Preliminary tests have demonstrated many of the performance characteristics which facilitate the treatment of selected human tumors.

Cold Temperature↗
PubMedDate not supplied

Interstitial thermoradiotherapy for recurrent head and neck cancer.

From 1985 to 1987, 22 head and neck sites in 20 patients with recurrent tumors were treated with interstitial thermoradiotherapy (ITRT). The sites treated were 15 neck (68%), four tongue (18%), two parotid (9%), and one buccal mucosa (4%). Squamous cell carcinoma was diagnosed in 21 sites and adenocarcinoma in the other. All patients had prior radiotherapy (RT), including 15 who underwent a combination of RT and surgery. Interstitial RT with iridium 192 (mean dose, 40 Gy) was combined with interstitial microwave hyperthermia (mean thermal dose, 90 units). Complete response (CR) was obtained in 15 (68%) sites and partial response (PR) in seven (32%) sites. There were no local recurrences in the 15 CR patients during a period of observation of up to 30 months. Of the seven PR patients, one had radical neck dissection and is free of tumor after 28 months. Tumor volume was an important factor influencing CR (P less than .001), whereas RT and thermal dose were not (P = .3). Of the 20 patients treated, 19 experienced major subjective benefit. Serious complications occurred in two patients: one had localized soft tissue necrosis, the other had aspiration pneumonia. ITRT was well-tolerated by patients despite prior aggressive therapy. High objective response rate and low toxicity demonstrate the value of this treatment combination in the management of patients with postradiation recurrence of head and neck tumors.

Aged↗
PubMedDate not supplied

Characteristics of the high-energy photon beam of a 25-MeV accelerator.

The CGR Saturne 25 is an isocentrically mounted standing wave medical linear accelerator that produces dual-energy photon beams and a scanned electron beam with six selectable energies between 4 and 25 MeV. The highest energy photon beam is nominally referred to as 23 MV. For this beam the mean energy of the accelerated electron beam on the 1.3 radiation length (4 mm) tungsten x-ray target is found to be approximately 21 MeV, with the energy acceptance stated to be +/- 5%. The electron beam traverses a 270 degrees bending magnet upstream of the x-ray production target. The resulting bremsstrahlung beam passes through a combination steel and lead flattening filter, 4-cm maximum thickness. Dosimetric data for the 23-MV beam are presented with respect to rectangular field output factor, depth of maximum dose as a function of field size, surface and buildup dose, central axis percent depth dose, tissue-phantom ratios, beam profile, applicability of inverse square, and block transmission. Some data are also presented on the effect of different flattening filter designs on apparent beam energy.

Electrons↗