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Biomedical subjects

L K Harding

Publications and source records attributed to L K Harding.

At least 19 recordsLinked to original sources
PubMed1999

Radiation exposure of the families of outpatients treated with radioiodine (iodine-131) for hyperthyroidism.

Patients who receive radioiodine (iodine-131) treatment for hyperthyroidism (195-800 MBq) emit radiation and represent a potential hazard to other individuals. Critical groups amongst the public are fellow travellers on the patient's journey home from hospital and members of the patient's family, particularly young children. The dose which members of the public are allowed to receive as a result of a patient's treatment has been reduced in Europe following recently revised recommendations from ICRP. The annual public dose limit is 1 mSv, though adult members of the patient's family are allowed to receive higher doses, with the proviso that a limit of 5 mSv should not be exceeded over 5 years. Unless the doses received during out-patient administration of radioiodine can be demonstrated to comply with these new limits, hospitalisation of patients will be necessary. The radiation doses received by family members (35 adults and 87 children) of patients treated with radioiodine at five UK hospitals were measured using thermoluminescent dosimeters mounted in wrist bands. Families were given advice (according to current practice) from their treatment centre about limiting close contact with the patient for a period of time after treatment. Doses measured over 3-6 weeks were adjusted to give an estimate of values which might have been expected if the dosimeters had been worn indefinitely. Thirty-five passengers accompanying patients home after treatment also recorded the dose received during the journey using electronic (digital) personal dosimeters. For the "adjusted" doses to infinity, 97% of adults complied with a 5-mSv dose limit (range:0.2-5.8 mSv) and 89% of children with a 1-mSv limit (range: 0.2-7.2 mSv). However 6 of 17 children aged 3 years or less had an adjusted dose which exceeded this 1 mSv limit. The dose received by adults during travel was small in comparison with the total dose received. The median travel dose was 0.03 mSv for 1 h travel (range: 2 microSv-0.52 mSv for 1 h of travel time). These data suggest that hyperthyroid patients can continue to be treated with radioiodine on an out-patient basis, if given appropriate radiation protection advice. However, particular consideration needs to be given to children aged 3 years or younger. Admission to hospital is not warranted on radiation protection grounds.

Adolescent↗
PubMed1999

Aspects of fetal thyroid dose following iodine-131 administration during early stages of pregnancy in patients suffering from benign thyroid disorders.

Detrimental effects on the thyroid of the developing fetus as a result of iodine-131 treatment for thyrotoxicosis of the mother in the first trimester of pregnancy are discussed. Dose estimations under typical clinical circumstances yield a fetal thyroid dose of 100- 450 Sv. This dose may increase considerably if the blood concentration of (131)I in the mother remains high. Under such circumstances there may be fetal thyroid dysfunction, which can lead to severe abnormalities.

Abnormalities, Radiation-Induced↗
PubMed1999

Can reduced imaging times be used for scintimammography?

A reduction in acquisition times from 10 to 5 min for scintimammography does not reduce the diagnostic value of the study when imaging for detection of breast lesions. The test showed an overall sensitivity of 96%, specificity of 100% and accuracy of 98% for breast lesions visualized on both 5 and 10 min acquisitions. Even if lymph node detection is the primary concern of the study, longer scan times do not increase the sensitivity of the test (40% on both 5 and 10 min). Scintimammography is poor at detecting lymph nodes (sensitivity 40%, specificity 69-82%) and is not useful for assessing lymph node involvement. A reduction in imaging times appeared to be consistent on both camera systems tested, which have very different display outputs. This would indicate that other departments may be able to reduce times on their systems without affecting the quality of the study. The detection of breast lesions was also consistent between reporters.

Breast↗
PubMed1998

Radiation protection legislation.

Recent legislation which has been passed in Europe comprises the Basic Safety Standard (BSS) [1] and the Medical Exposure Directive (MED) [2]. These documents are the implementation of ICRP's report 60 [3], and ICRP publication 73 [4] expands ICRP60 for medical applications. The BSS repeals 80/836/EURATOM and 84/467/EURATOM amongst other EURATOM directives. The MED repeals 84/466/EURATOM, which is the patient protection directive. Member States (MS) are required to implement both the BSS and the MED by the 13 May 2000, and this is where input from individual members of the EANM is very important. Within every MS it is vital to ensure that the key points are debated properly, so that legislation in the countries of Europe is reasonable.

Breast Feeding↗
PubMed1998

Diagnostic nuclear medicine and risk for the fetus.

The possible detrimental effects on the developing embryo subsequent to irradiation are discussed. The doses to the embryo or fetus encountered for the most common procedures in diagnostic nuclear medicine are evaluated with respect to the threshold doses and the risks per cGy. The threshold dose for fatal and non-fatal malformations or other defects is, at the lowest estimate, 5-10 cGy. The dose which the embryo or fetus receives from diagnostic nuclear medicine is below 1 cGy. For the induction of fatal cancer and for genetic defects no threshold dose is assumed. The risk for the induction of cancer is 0.03%-0.05% per cGy. The risk for the induction of genetic defects is even lower (0.024%-0.099% per cGy). It is concluded that for common diagnostic nuclear medicine procedures the risk of detrimental effects on the embryo or fetus due to radiation is negligible. On the basis of present knowledge there are no radiation safety indications for abortus provocatus as a consequence of a diagnostic nuclear medicine study.

Abnormalities, Radiation-Induced↗
PubMed1998

Counting the cost of patients who do not attend nuclear medicine departments.

The mean rate of non-attendance at this hospital is 16%, with the Nuclear Medicine Department averaging 4%. Although only a small percentage, increasing demand for nuclear medicine studies has led to a need for greater efficiency to reduce financial losses. From April 1995 to March 1996, 104 patients did not attend over a range of 16 studies. We examined the types of study, patients and costs. The costs of wasted staff time, camera time and radiopharmaceutical ranged from pound sterling 24 (99Tc(m) thyroid) to pound sterling 470 (75Se cholesterol adrenal). This results in a loss equivalent to pound sterling 7258 over the year. There was no significant difference in non-attendance rates between different types of procedure, source and type of referral, or in the three age groups: children, working and retired population. Finally, we looked at cultural origins, segregating the groups into Asian and European origins based on surname. A significantly higher proportion of patients of Asian origin did not attend. This study has shown that it may be of benefit to target specific groups and tests. For example, at City Hospital, perhaps we should concentrate on our Asian community to ensure they understand fully what the study involves. It would also be worthwhile targeting the more expensive nuclear medicine studies.

Adolescent↗
PubMed1997

Are MIBI/tetrofosmin heart studies a potential radiation hazard to technologists?

The number of nuclear medicine studies is increasing and they are becoming more complex and time-consuming. In particular, this is true of myocardial perfusion investigations. We use a one-day protocol for these studies, utilizing 99Tc(m)-MIBI or 99Tc(m)-tetrofosmin with tomographic rest images (250 MBq) acquired in the morning and exercise images (750 MBq) approximately 4 h later after pharmacological stress. Imaging technologists are concerned about continual exposure to 1000 MBq 99Tc(m) per study. Radiation doses were measured during rest (1.0 microSv, n = 18), exercise (2.5 microSv, n = 18) and stress administration (2.0 microSv, n = 16), giving a total dose of 5.5 microSv per combined cardiac study. We have previously shown that the average dose per radionuclide study (excluding myocardial perfusion studies) is 1.5 microSv. Although 5.5 microSv is higher, a technologist is highly unlikely to exceed current dose limits. New EC legislation, however, is expected to reduce these limits, which may lead to more classified workers. Pregnant technologists should avoid, if possible, combined cardiac studies, especially if performing other nuclear medicine duties.

Adenosine↗
PubMed1997

Out-of-hours weekend scintigraphy: assessing/predicting the need.

We have assessed the potential impact of a regular half-day session on Saturday only, or Sunday only, and compared this with a whole weekend on-call service for lung scans. We predicted the effect of these services using the data gathered over 2 years (1992-94), looking at the results of lung scans and admission and discharge of patients. The on-call service in all three cases would be justified if resources from the savings on patient discharge and bed availability could be earmarked for the nuclear medicine service. The cost of introducing such an on-call service for the department would be Pounds 3000 per year per session at the weekend and up to Pounds 10,000 per year for a full weekend on-call service. The total cost to the hospital would be negligible.

Costs and Cost Analysis↗
PubMed1997

Radiation protection--lessons from the past.

This is a historical review of selected events in radiation protection of medical relevance since the discovery of X-rays. The report concentrates on the period 1895-1970. Key points were difficulty of measuring dose, rapid dissemination of the use of radiation for all sorts of illness, and regulation by professional bodies rather than by legislation. Both World Wars saw a huge expansion in the use of ionizing radiation, but the second war prevented international collaboration, which had begun formally in 1925. Early radiation deaths, and nuclear accidents have caused concerns about radiation safety, and although dose limits have been successively reduced, these concerns have not been overcome. Since the Second World War radiation safety has been subject to more and more legislation although professional bodies still have an important advisory role. Development of the main radiation safety committees both in the UK, US and internationally is described with emphasis on the particular role of the British Institute of Radiology.

History, 19th Century↗