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Biomedical subjects

P Cross

Publications and source records attributed to P Cross.

At least 19 recordsLinked to original sources
PubMed2003

Treatment of localized prostate cancer using a combination of high dose rate Iridium-192 brachytherapy and external beam irradiation: initial Australian experience.

Combination high dose rate brachytherapy (HDRB) and external beam radiation therapy is technically and clinically feasible as definitive treatment for localized prostate cancer. We report the first large Australian experience using this technique of radiation dose escalation in 82 patients with intermediate- and high-risk disease. With a median follow up of 3 years (156 weeks), complications were low and overall prostate-specific antigen progression-free survival was 91% using the American Society for Therapeutic Radiology and Oncology consensus definition. The delivery of hypofractionated radiation through the HDRB component shortens overall treatment time and is both biologically and logistically advantageous. As a radiation boost strategy, HDRB is easy to learn and could be introduced into most facilities with brachytherapy capability.

Adenocarcinoma↗
PubMed2002

An investigation into the source of low energy scattered radiation of significance in film dosimetry.

The nature of the background optical density on films exposed to orthovoltage x-rays and electron beams has been studied for correction purposes. A higher than expected background value can be demonstrated by comparing the film scanned beam profile with water phantom ionisation scans of the same beam. A range of 3-5% increased background in the penumbral tail, with energy dependence, has been shown experimentally. Testing the assumption that this increased background is due to Cerenkov radiation produced in the film, Filmstrips were interleaved in a solid water equivalent phantom and exposed to 300kV orthovoltage x-ray beams and 5MeV to 12MeV electron beams. The film stacks were made up of single or multiple bare filmstrips, multiple filmstrips interleaved with black paper, and multiple filmstrips interleaved with overhead transparency sheet. The experimental result demonstrated that visible light was not significantly responsible for an enhanced film optical density, but rather that this was due to scattered radiation, with a complex low energy spectrum, arising from the film silver halide emulsion or base. An improved background correction technique is developed which incorporates this unexpected background value as an added component in the correction applied to the measured optical density. The resulting profiles exhibit improved agreement between film and ionization chamber measurements in the penumbra and tail regions.

Artifacts↗
PubMed2002

Measurement of the neutron and gamma doses accumulated during commercial jet flights from sydney to several major destinations in the northern and southern hemispheres.

As recommended by the ICRP, the European Union (EU) agreed to abide by mandatory monitoring of radiation doses to crew during civil aviation flights operated by the airlines of the EU member states. A large number of measured and theoretically predicted values for the in-flight radiation doses of northern hemisphere flight routes are available. On the other hand very few data have been published for the southern hemisphere. This paper will present the results of Australian domestic and intemational return flight routes originating from Sydney. The paper also presents results of trans-hemisphere air traffic routes. Neutron and gamma doses were measured using superheated bubble dosemeters and semiconductor detectors respectively. Based on our measurements a method is suggested whereby aircrew may share their personal radiation burden by flight crew hemisphere exchange.

Aerospace Medicine↗
PubMed2002

Relative thermoluminescence efficiency of TLD-600 and TLD-700 dosemeters irradiated with 59.8 MeV per nucleon krypton-86 ions.

A batch of LiF thermoluminescence dosemeters (TLDs), each containing five TLD-600 and TLD-700 thermoluminescence dosemeter chips, was irradiated with 59.85 MeV per nucleon 86Kr20+ ions from the K1200 superconducting cyclotron at the National Superconducting Cyclotron Laboratory (NSCL). Michigan State University, USA. The average linear energy transfer of the accelerated 86Kr ions and the resulting dose imparted to the TLD chips were calculated to be 3343 keV.microm(-1) per ion and 1.68 Gy respectively. A similar batch of TLD chips was irradiated with 1.3 MeV gamma rays from a 60Co source to 1.0 Gy. The TLD chips were evaluated at a ramp heating rate of 10 degrees C.s(-1) to 400 degrees C using a hot-finger type TLD reader. The thermoluminescence efficiency of the TLD-600 and TLD-700 dosemeters, relative to 60Co gamma rays was calculated to be 0.0025 and 0.0027 respectively

Fluorides↗
PubMed2001

Incidence of AD in African-Americans, Caribbean Hispanics, and Caucasians in northern Manhattan.

OBJECTIVE: To compare the incidence rates for AD among elderly African-American, Caribbean Hispanic, and white individuals and to determine whether coincident cerebrovascular disease contributes to the inconsistency in reported differences among ethnic groups. METHODS: This was a population-based, longitudinal study over a 7-year period in the Washington Heights and Inwood communities of New York City. Annual incidence rates for AD were calculated and compared by ethnic group, and cumulative incidence adjusted for differences in education, diabetes, cardiovascular risk factors, and stroke was calculated. RESULTS: The age-specific incidence rate for probable and possible AD was 1.3% (95% CI, 0.8 to 1.7) per person-year between the ages of 65 and 74 years, 4.0% (95% CI, 3.2 to 4.8) per person-year between ages 75 and 84 years, and 7.9% (95% CI, 5.5 to 10.5) per person-year for ages 85 and older. Compared to white individuals, the cumulative incidence of AD to age 90 years was increased twofold among African-American and Caribbean Hispanic individuals. Adjustment for differences in number of years of education, illiteracy, or a history of stroke, hypertension, heart disease, or diabetes did not change the disproportionate risks among the three ethnic groups. CONCLUSION: The incidence rate for AD was significantly higher among African-American and Caribbean Hispanic elderly individuals compared white individuals. The presence of clinically apparent cardiovascular or cerebrovascular disease did not contribute to the increased risk of disease. Because the proportion of African-American and Caribbean Hispanic individuals reaching ages 65 and older in the United States is increasing more rapidly than the proportion of white individuals, it is imperative that this disparity in health among the elderly be understood.

Aged↗
PubMed2001

Process of and problems in changing a birth defects registry reporting system.

BACKGROUND: The New York State (NYS) Department of Health (DOH) Congenital Malformations Registry (CMR), which began operations in 1982, was developed after the Love Canal crisis. New York hospitals are mandated to report children under age 2 years in whom a congenital anomaly is diagnosed. The CMR has tried to maintain a quality birth defects registry by using identifiers; narrative for defects; and completeness and accuracy, balanced with timeliness. In recent years, the existence of the registry has been questioned, and the NYS DOH evaluated the CMR to streamline it and to reduce the reporting burden on the hospitals. METHODS: Because NYS hospitals were already required to submit hospital discharge data through the Statewide Planning and Research Cooperative System (SPARCS), the CMR used this system as an alternative method for reporting. RESULTS: The evaluation indicated that the CMR, SPARCS, and hospital systems needed to be modified. Modifications needed to maintain registry quality were the most difficult. CMR staff worked closely with hospital personnel on all modifications so they would understand the reasons for the modifications. The changes were more global than originally anticipated, involving large national software vendors. CONCLUSIONS: The transition is ongoing. Additional work will be needed to verify data quality. Some of the modification will affect national software vendors and may be useful for other birth defects registries.

Congenital Abnormalities↗
PubMed2001

Cervical cytology EQA--the Northern experience.

The experience of the Northern region using the 1995 draft National Gynaecological Cervical Cytology External Quality Assurance (EQA) Scheme is given. Over three rounds, 390 staff reporting Cervical Cytology took part, and using a cumulative non-numeric marking scheme, five participants were deemed "unacceptable" at the end of three rounds. A total of 3450 responses were given to the 40 test slides used, with an overall false-positive rate of 5.9% and a false-negative rate of 1.4%. Grading was assessed for pathologists, and many appeared to perform badly by accumulating discrepancies for non-clinically-significant grading differences. The problems of slide selection/staining and grading consistency/accuracy are highlighted. This EQA scheme serves its dual function of education and identifying poor performance. It must be seen as a viable EQA scheme, although other options must be considered, given advances in technology.

False Negative Reactions↗
PubMed2001

A framework for improving the quality of health information on the world-wide-web and bettering public (e-)health: the MedCERTAIN approach.

There has been considerable debate about the variable quality of health information on the world-wide-web and its impact on public health. While central authorities to regulate, control, censor, or centrally approve information, in-formation providers or websites are neither realistic nor desirable, public health professionals are interested in making systems available that direct patient streams to the best available information sources. National governments and medical societies have also recognized their responsibility to help users to identify "good quality" information sources. But what constitutes good quality, and how can such a system be implemented in a decentralized and democratic manner? This paper presents a model which combines aspects of consumer education, encouragement of best practices among information providers, self-labeling and external evaluations. The model is currently being implemented and evaluated in the MedCERTAIN project, funded by the European Union under the Action Plan for Safer Use of the Internet. The aim is to develop a technical and organisational infrastructure for a pilot system that allows consumers to access metainformation about web-sites and health information providers, including disclosure information from health providers and opinions of external evaluators. The paper explains the general conceptual framework of the model and presents preliminary experiences including results from an expert consensus meeting, where the framework was discussed.

Databases as Topic↗
PubMed2001

A metadata vocabulary for self- and third-party labeling of health web-sites: Health Information Disclosure, Description and Evaluation Language (HIDDEL).

We describe HIDDEL (Health Information Disclosure, Description and Evaluation Language), formerly known as medPICS (platform for Internet content selection in medicine), a metadata vocabulary designed to enhance transparency, trust and quality of health information on the web. The vocabulary may be used (1) by webmasters to self-describe their contents and policies; (2) by infomediaries (e.g. Healthfinder, NHS Direct/NeLH), e.g. third party evaluators, rating or portal services, to annotate other websites; (3) and by users, to describe their preferences. As an XML application it conforms to the W3C's RDF Specification. The metadata vocabulary is primarily intended to enable descriptions of whole health websites or health information providers. The vocabulary is designed to provide a computer-readable electronic "label" of a health website, telling users who is behind the website, how the website is sponsored, what the con-tent, aim and target audience is, how the information was compiled, what risks the service bears, or what people say about the resource. Client-software can "read" this label automatically, compare it to the user s own set of preferences and needs, and alert and advise users.

Information Services↗
PubMed2000

A clinical review of borderline glandular cells on cervical cytology.

OBJECTIVE: To review the diagnoses and diagnostic pathway of women presenting with borderline glandular cells on cervical cytology. To outline the basis of clinical approach of these women. DESIGN: Retrospective review. POPULATION: Forty-three women referred to the hospital department over a 32-month period. METHODS: Review of the casenotes for the demographic data, previous cervical cytology and/or histology report, indication for the smear resulting in borderline glandular cells, colposcopic findings, diagnostic and/or treatment procedures, final diagnosis and current status. RESULTS: The average age was 36.7 years. Twenty-four women (56%) had clinically significant lesions: seven women (16%) presented with cancers, of which one was endometrial in origin, and 17 (40%) with intraepithelial neoplasia (CIN and cervical glandular intraepithelial neoplasia (CGIN)). Sixty-seven percent of all clinically significant lesions were of squamous origin. Thirty-seven had histological diagnosis, while six went on to cytological surveillance. Colposcopy was the most significant predictor for clinically significant lesions (P < 0.05). Punch biopsies and loop excisions were diagnostic when based on abnormal colposcopic findings. Brush cytology was appropriate follow up for asymptomatic, premenopausal women with no colposcopic abnormality. In addition, endometrial sampling was recommended in the peri- and postmenopausal women. CONCLUSION: Borderline glandular cells have a high incidence of clinically significant lesions. Immediate referral for colposcopy and assessment is strongly recommended in women with two borderline glandular smears to avoid delays in potential cancer diagnosis.

Adult↗
PubMed2000

Dexamethasone for the prophylaxis of radiation-induced emesis: a National Cancer Institute of Canada Clinical Trials Group phase III study.

PURPOSE: To investigate the efficacy of dexamethasone as a prophylactic antiemetic for patients receiving fractionated radiotherapy to the upper abdomen in a randomized controlled trial. PATIENTS AND METHODS: One hundred fifty-four patients planned to receive fractionated radiotherapy to fields involving the upper abdomen (minimum total dose, 20 Gy; minimum number of fractions, five) were randomized to receive prophylactic dexamethasone (2 mg orally three times a day [tid], starting in the morning of first treatment and continuing until after their fifth treatment) or placebo. The primary end point of the study was the proportion of patients free from emesis during the study period. Secondary end points included a quality-of-life assessment using the core questionnaire of the European Organization for Research and Treatment of Cancer and side effects of dexamethasone therapy in this population of patients. RESULTS: Fifty-four (70%) out of 75 patients receiving dexamethasone had complete protection versus 37 (49%) out of 75 patients on placebo (P = .025). Most emetic episodes occurred during the initial phase of treatment. Although there was no difference in global quality of life between the two sets of patients, patients receiving dexamethasone had less nausea and vomiting and less loss of appetite but more insomnia. CONCLUSION: Dexamethasone 2 mg tid seems to be an effective prophylactic antiemetic in this situation. Side effects were acceptable, but there seemed to be no overall effect on global quality of life.

Abdomen↗
PubMed2000

Conservative surgery and radiation therapy for early stage breast cancer after previous mantle radiation for Hodgkin's disease.

There is an increased incidence of breast cancer in female patients who have previously undergone mantle radiation for Hodgkin's disease. Lumpectomy followed by breast irradiation is generally considered to be contraindicated in such patients owing to the high cumulative radiation dose to the breast. Mastectomy is therefore recommended as the preferred treatment option in these women. We report two cases of breast cancer occurring in women previously treated with mantle radiation for Hodgkin's disease. Both women declined mastectomy and requested breast-conserving treatment.

Adult↗
PubMed2000

MedCERTAIN: quality management, certification and rating of health information on the Net.

MedCERTAIN (MedPICS Certification and Rating of Trustworthy Health Information on the Net, http://www.medcertain.org/) is a recently launched international project funded under the European Union's (EU) "Action Plan for safer use of the Internet. It provides a technical infrastructure and a conceptual basis for an international system of "quality seals", ratings and self-labelling of Internet health information, with the final aim to establish a "trustmark" for networked health information. Digital "quality seals" are evaluative metadata (using standards such as PICS = Platform for Internet Content Selection, now being replaced by RDF/XML) assigned by trusted third-party raters. The project also enables and encourages self-labelling with descriptive meta-information by web authors. Together these measures will help consumers as well as professionals to identify high-quality information on the Internet. MedCERTAIN establishes a fully functional demonstrator for a self- and third-party rating system enabling consumers and professionals to filter harmful health information and to positively identify and select high quality information. We aim to provide a system which allows citizens to place greater trust in networked information, exemplified in the domain of health information, whilst also making a significant contribution for similar projects with different target domains. The project will demonstrate how PICS-based content rating and filtering technologies can automate and exploit value-adding resource description services. It further proposes standards for interoperability of rating services.

Databases as Topic↗
PubMed1999

Concurrent chemotherapy with hyperfractionated accelerated thoracic irradiation in stage III non-small cell lung cancer.

OBJECTIVES: We evaluated the effect of hyperfractionated accelerated radiotherapy combined with low dose radiosensitisers followed by standard dose chemotherapy in the treatment of unresectable stage III non small cell lung cancer (NSCLC). METHODS: Forty-seven patients received thoracic radiotherapy (1.5 bid x 5 days x 4 weeks) in combination with low dose daily (3-6 mg/m2) cisplatin +/- weekly vinblastine chemotherapy (step I), followed by three cycles of standard dose chemotherapy alone consisting of cisplatin (75-80 mg/m2) and vinblastine (8-16 mg/m2) given at 3-4 week intervals (step II). RESULTS: The overall response rate was 70% (21% CR). The progression free interval and the median survival duration were 10.4 months and 17.3 months, respectively. The 3 year survival rate was 21%. The site of first progression was local in 44%, distant in 41%, and simultaneous in 15% of patients. Levels of esophageal toxicity were significant but acceptable with the use of prophylactic therapy. Grade 3 or 4 esophageal toxicity was observed in 28 and 19% of patients during step I and II of the study, respectively. There were three deaths associated with esophageal toxicity. All occurred prior to the implementation of the prophylactic therapy for esophagitis. Acute pulmonary symptoms were reported in 25% of patients in step I, and pulmonary fibrosis, primarily asymptomatic, was observed in 51% of patients. Hematological toxicity was moderate. Two patients died of neutropenic sepsis/pneumonia. CONCLUSION: Concurrent chemotherapy and hyperfractionated accelerated radiotherapy followed by chemotherapy appears moderately effective in controlling tumour growth as measured by response rates and survival estimates. Toxicity is considerable but manageable and compatible with results from other combined modality studies.

Adult↗
PubMed1999

Description of a new motor re-education programme for the paretic lower limb aimed at improving the mobility of stroke patients.

OBJECTIVE: To describe and examine the feasibility of a new treatment approach for the paretic lower limb and to explore its effectiveness in one chronic hemiparetic stroke subject. DESIGN: Case report. The treatment was conducted three times per week over a period of six weeks. The mobility of the patient was assessed prior to the treatment, at the end of the treatment and at a six-week follow-up. SETTINGS: The study was carried out at the research centre of the Institut de réadaptation de Montréal. The treating therapist was an experienced rehabilitation professional as was the assessor, who worked at a different rehabilitation centre. INTERVENTIONS: The motor re-education programme was based on the use of a static dynamometer that measures the linear external forces produced at the ankle level. A computer program provided the subject with constant feedback on the direction and intensity of the applied force. In each treatment session, the subject was asked to produce several submaximal efforts in 16 specific directions. Both the intensity and the number of repetitions were gradually increased. OUTCOME MEASURES: In addition to force production measurements, three clinical assessments of mobility were used: the Timed 'Up and Go', the comfortable gait speed and a 2-minute walk test. RESULTS: The maximal static linear forces produced by the subject increased through the treatment for all directions of effort, but differences were observed amongst directions. During the treatment programme, the subject improved his performance at the three clinical assessments. Even if some of the functional gain was lost at the follow-up, the mobility was still considerably improved as compared to baseline values. CONCLUSION: This study demonstrated the applicability of the treatment programme to a stroke subject. The results seem very promising and encourage further investigation in order to assess more rigorously the effectiveness of this new approach.

Adult↗
PubMed1998

Prognostic factors derived from recursive partition analysis (RPA) of Radiation Therapy Oncology Group (RTOG) brain metastases trials applied to surgically resected and irradiated brain metastatic cases.

PURPOSE: (a) To identify the prognostic factors that determine survival after surgical resection and irradiation of tumors metastatic to brain. (b) To determine if the prognostic factors used in the recursive partition analysis (RPA) of brain metastases cases from Radiation Therapy Oncology Group (RTOG) studies into three distinct survival classes is applicable to surgically resected and irradiated patients. METHOD: The medical records of 125 patients who had surgical resection and radiotherapy for brain metastases from 1985 to 1997 were reviewed. The patients' disease and treatment related factors were analyzed to identify factors that independently determine survival after diagnosis of brain metastasis. The patients were also grouped into three classes using the RPA-derived prognostic parameters which are: age, performance status, state of the primary disease, and presence or absence of extracranial metastases. Class 1: patients < or = 65 years of age, Karnofsky performance status (KPS) of > or =70, with controlled primary disease and no extracranial metastases; Class 3: patients with KPS < 70. Patients who do not qualify for Class 1 or 3 are grouped as Class 2. The survival of these patients was determined from the time of diagnosis of brain metastases to the time of death. RESULTS: The median survival of the entire group was 9.5 months. The three classes of patients as grouped had median survivals of 14.8, 9.9, and 6.0 months respectively (p=0.0002). Age of < 65 years, KPS of > or = 70, controlled primary disease, absence of extracranial metastases, complete surgical resection of the brain lesion(s) were found to be independent prognostic factors for survival; the total dose of radiation was not. CONCLUSION: Based on the results of this study, the patients and disease characteristics have significant impact on the survival of patients with brain metastases treated with a combination of surgical resection and radiotherapy. These parameters could be used in selecting patients who would benefit most from such treatment.

Adult↗