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AIM There is increasing interest in using collimated gamma cameras for [75Se]tauroselcholic acid (SeHCAT) studies to image the distribution and to make use of the collimator pressure sensitive devices (PSD) for patient safety. However, the use of a collimator will substantially decrease the sensitivity of the gamma camera. The aim of this article is to enable departments to calculate the uncertainty of SeHCAT retention measurements so that the acquisition time can be optimised to perform a reliable SeHCAT study. METHOD We derive a mathematical equation from the first principles that can be used to calculate the uncertainty in SeHCAT retention measurements on the basis of Poisson counting statistics. The equation takes account of background subtraction, use of the geometric mean for anterior/posterior attenuation compensation and the day 7 to day 0 quotient calculation. RESULTS Uncertainties in SeHCAT retention measurement using an intrinsic (uncollimated) gamma camera counting for 100 s are very low, typically of the order 15 ± 0.1%. Uncertainties from collimated gamma camera counting significantly increase for the same 100 s counting duration: 15 ± 0.8% for slim patients and 15 ± 4% for obese patients. CONCLUSION The acquisition time must be increased for collimated gamma camera SeHCAT counting to achieve acceptable counting statistics for an acceptable total uncertainty in the SeHCAT retention measurement. For slim patients, a minimum counting time of 2 min is required. For larger patients, the acquisition time needs to be increased to 30 min and further increased to 50 min for obese patients.

AIM A recent audit has highlighted that there is a large variation in the way gastric emptying scintigraphy is performed, analysed and reported in the UK. In this study, we have established a comprehensive protocol on how to perform gastric emptying including normal ranges for two of the most widely used meals. A standardized scrambled egg sandwich was used as the main meal. Normal ranges were also established for oat porridge as an alternative gluten-free meal. We have calculated normal ranges for several functional parameters which may be used to assess gastric emptying. We hope that establishing a reliable normal range for these two simple and commonly used meals will encourage adoption of a universally accepted protocol for measurement of solid gastric emptying in the UK. METHOD A total of 42 volunteers (20 male, 22 female, age range 22-68) with no history of gastrointestinal symptoms or diabetes were studied. Each volunteer fasted overnight and consumed two meals with similar nutritional composition on two separate days: scrambled eggs with two slices of bread were consumed on one day and gluten-free porridge (40 g in 200 mL whole milk) was consumed on a different day. Each meal was radiolabelled with 10 MBq of Tc-DTPA. Simultaneous anterior-posterior 2-min static images were acquired with the patient standing between the gamma camera detectors. Images were acquired every 5 min over a 2 hour period, followed by a single image at 3 hour. The data were modelled using a power-exponential function that allowed measurements of gastric emptying functional parameters including lag time, half-emptying time (HET), peak emptying rate, time-to-peak emptying (TPE) and exponential half-life (EHL). Three-hour retention was also calculated. Paired t-tests were used to compare the two meals and two-sample t-tests were used to assess gender-related differences. Regression analysis was used to assess correlation of the functional parameters with age and body habitus (body surface area, BSA). RESULTS All gastric emptying functional parameters were significantly different between the two meals (P

TauroH-23-((75)Se)selena-25-homocholic acid (SeHCAT) retention has been used for the diagnosis of bile acid malabsorption since the early 1980s. Bile acid malabsorption has been increasingly recognized as an important cause of severe chronic diarroea with subsequent increase in the number of referrals for the SeHCAT test. In this study, we review and discuss the standard techniques for the measurement of SeHCAT retention and describe a simple and modified technique using a noncollimated whole-body scanner, suitable for most modern dual-headed cameras.

Objective Aspects of ileal pouch surgery remain controversial. The authors' single practice experience of 107 operations illustrates many of them. It was hoped that its study would contribute usefully to the debate. Patients and methods Details of all 107 restorative proctocolectomies carried out since the operation was started in Gloucester in 1984 until the study period ended have been kept prospectively. All patients had proctectomy by mesorectal dissection, and 106 had W pouch restoration. Four suffered functional failure requiring reversion to ileostomy and three patients have died. The remaining 99 were sent a questionnaire concerning pelvic visceral function and evidence of pouchitis. Records of all but one of the patients have been reviewed. Results Surgical morbidity was low with neither chronic pelvic sepsis, pouch related fistula, pouch haemorrhage nor pouch ischaemia. Mucosectomised patients had similar bowel control to the stapled group. The policy change from routine to selective protective ileostomy proved satisfactory. W pouch function was found to be comparable to that reported from major J pouch series, although anti-diarrhoeal usage was reduced, and was not influenced by either gender, age or time since surgery. Conclusion None of the following reasonably intuitive assumptions seem supported by our findings: that mesorectal excision necessarily poses a greater danger to pelvic visceral function than close rectal dissection, that the greater capacity of W pouches will be reflected in markedly less frequency, that mucosectomy would impair anal control, or that a defunctioning ileostomy is a mandatory precaution. Pouch frequency is less if wind can be passed separately; otherwise functional outcome seems determined by other, non-technical, factors.

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.

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 μSv-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.

Introduction Parastomal herniation is not uncommon and numerous surgical approaches to the problem have been employed including mesh reinforcement. Bowel wall erosion is a worrying potential complication of placing an edge of mesh around bowel. To reduce this possibility a simple modification is suggested. Method The polyproylene mesh repair is fashioned on the posterior rectus sheath. The required aperture for the bowel is marked appropriately on the mesh. Instead of simple removal of the marked circle, the aperture is fashioned by folding back and stitching in place the triangular flaps from the middle to form a rolled rather than sharp edge. Non-absorbable monofilament stitches reconstitute the mesh encirclement, and attach it laterally and medially to the aponeurotic tissue. A review of the case notes was conducted and each patient was contacted by a postal questionnaire. Results This technique has been used in 10 patients (7 end colostomies, 2 end ileostomies and 1 loop ileostomy) since 2000. Over a median follow-up period of 30 months (range 2 to 40 months) there have been no hernia recurrences, no infected meshes, no bowel damage attributable to the mesh and no troubles with stoma. The only complication encountered has been a segment of superficial wound breakdown in one patient. Conclusions This technique appears to offer a safe and reliable modification for mesh repair of parastomal herniation, in being designed to obviate the possibility of erosion of the stomal bowel wall by a sharp mesh edge but at the same time providing a sound herniorrhaphy by complete encirclement.

Background In this study, we have investigated the feasibility of a 180 degrees DaTSCAN brain SPECT acquisition. This technique has the advantage of being 'open view' for the patient and therefore more acceptable for claustrophobic patients. It also enables easier access for a technologist to hold the patient's head during acquisition to reduce movement in confused patients or in those with severe tremor. Methods In the first part of this study, we validated the practicality and image quality of a 180 degrees acquisition using a DaTSCAN Alderson head phantom with different camera configurations on GE Infinia and Philips AXIS gamma cameras. The effect on image quality of using half the acquisition time was also assessed. In the second part of the study, 50 sets of patient data were reprocessed by reconstructing half of the 360 degrees data to mimic a single-head 180 degrees acquisition. The 180 degrees images were then compared with 360 degrees images for the same patient using a visual score system. The effect of half-time 180 degrees data acquisition on quantification was also assessed using GE QuantiSPECT software. Results All phantom images from 180 degrees acquisitions contained some degree of distortion at the periphery, but clearly retain the presence of centrally positioned caudate and putamen; hence 180 degrees acquisitions were deemed to produce clinically useful diagnostic images. The shorter (half) acquisition time leads to noisier but acceptable images for all configurations. In the patient study, there was complete agreement between the two reporters with no clinical difference in the diagnostic accuracy between the 180 degrees and 360 degrees images. However, 6 of 50 180 degrees images were marked as poor quality but reportable, compared with 0 of 50 in 360 degrees images. Quantification gave consistently lower nuclei to background ratio values for 180 degrees compared with 360 degrees for normal and abnormal patients. Conclusion It is possible to obtain diagnostic DaTSCAN images using 180 degrees acquisition in difficult patients. The total length of the study may also be shortened by half using L-mode or V-mode camera head configuration.

The aim of this study was to measure the internal dose received by family members from ingestion of radioactive contamination after outpatient therapy.Advice was given to minimise transfer of radioiodine. Home visits were made approximately 2, 7 and 21 days after treatment to measure radioactivity in the thyroids of family members. A decay correction was applied to radioactivity detected assuming ingestion had occurred at the earlier contact time, either the day of treatment or the previous home visit. An effective half-life of 6 or 7 days was used depending on age. Thyroid activity was summed if activity was found at more than one visit in excess of the amount attributable to radioactive decay. Effective dose (ED) was calculated using ICRP72.Fifty-three adults and 92 children, median age 12 (range 4-17) years participated. Median administered activity was 576 (range 329-690) MBq (131)I. Thyroid activity ranged from 0 to 5.4 kBq in the adults with activity detected in 17. Maximum adult ED was 0.4 mSv. Thyroid activity ranged from 0 to 11.8 kBq in the children with activity detected in 26. The two highest values of 5.0 and 11.8 kBq occurred in children aged 5 and 14 years from different families. Eighty-five children had no activity or1 kBq detected. ED was0.2 mSv in 86 out of 92 children (93%). Previous published data showed 93% of children received an EDor=0.8 mSv from external irradiation.With advice, families of outpatients receiving radioiodine should be able to comply with statutory dose limits and constraints.

Lower radiopharmaceutical activities are used for myocardial perfusion scintigraphy (MPS) in the UK than in other countries. There is no evidence to suggest that higher activities improve imaging or clinical outcome.We undertook a multicentre study of the relationship between radiopharmaceutical activity and imaging outcome. Fifty-one patients with clinical referrals for MPS followed a 2-day protocol with an injection of 1,000 MBq (99m)Tc-tetrofosmin for each of the stress and rest images. ECG-gated acquisition was performed in three rotations occupying 25, 35 and 40% of a standard acquisition, and rotations were summed to simulate administered activities of 250, 400, 750 and 1,000 MBq. Each set of images was reported by an experienced physician who was blinded to all clinical information and to the simulated activity. Scores were assigned for image quality, low count, attenuation and reconstruction artefact, segmental tracer uptake, segmental and global defect classification, and confidence in the global classification. The images were reported twice to assess intra-observer variability.Positive relationships were found between administered activity and overall image quality, observer confidence and intra-observer agreement of uptake score, and a negative relationship was found with low-count artefact. For the majority of comparisons, there was no additional improvement with increasing activity from 750 to 1,000 MBq. Intra-observer agreement was found to be better in female patients and in those below average body mass index.We conclude that higher administered radiopharmaceutical activities lead to better quality images and improved surrogate parameters for clinical outcome, but that activities above 750 MBq may be unnecessary in average patients.

Irradiation of pregnant women either in the workplace or as a consequence of clinical diagnosis is often unavoidable. This paper reviews the issues relating to this topic. For clinical exposures the "missed period" rule is applied prior to most clinical studies. However normal physiological variations in the menstrual cycle may need to be understood. The possible effects of irradiation, both deterministic and stochastic, on the fetus are also described. The decision process in relation to irradiation of a pregnant or potentially pregnant patient is discussed in terms of the regulatory guidance. A different approach is needed for studies which clearly involve a low dose to the uterus compared with studies involving a high dose, including therapy. The issue of a pregnant or potentially pregnant worker in nuclear medicine is also considered. Restrictions on certain work activities may be necessary once pregnancy is declared. Other areas considered are biomedical research and also the potential for exposure of pregnant woman in the home or in the workplace as a consequence of others having a nuclear medicine study.

BackgroundThere is widespread antipathy to digital dilatation of the anus (DDA) for medically resistant anal fissure. A retrospective study was therefore undertaken to test the validity of the criticism of this technique.MethodsSome 273 patients who underwent DDA for fissure between November 1982 and July 1997 were sent a questionnaire and/or telephoned. Those with impaired control were offered investigation. In addition, routine clinic follow-up data were scrutinized in the 302 available notes of the 307 patients who had undergone DDA for fissure to determine its efficacy.ResultsSome 241 patients (88·3 per cent) were contacted successfully a median of 7·8 years after operation. Follow-up records showed the fissure to have healed in 89·1 per cent of 302 patients. No patient was rendered incontinent. Fifteen patients indicated persistently impaired control in the questionnaire, nine (3·8 per cent) as a result of the DDA and six preceding it. All 23 patients who had experienced either temporary or permanent impairment, whether or not pre-existing, were invited to attend for ultrasonography and manometric measurements, of whom 18 accepted. No sphincteric fragmentation was seen, and resting and squeeze pressures did not differ from normal.ConclusionA single DDA appears to heal 89 per cent of chronic anal fissures. Consequent impairment of control is infrequent and minor if the procedure is performed carefully and with the patient paralysed.

The low energy X-ray emissions of 123I lead to large variations in activity measurements using an ionisation chamber. A copper filter 0.5mm thick removes these X-rays but only reduces the 159 keV emissions by 14%. However the ionisation chamber needs to be recalibrated for the copper filter attenuation. We outline a simple method using a measurement made on 99Tcm to determine the change in sensitivity of the ionisation chamber using the copper filter. With the copper filter, the variation of activity measurements when 123I is in a syringe compared to those in a vial is reduced from 80% to 3%. The ratio of the manufacturers stated activity to measured activity was 102% and 111% for two manufacturers respectively.

This paper reviews the published data relating to the radiation hazards associated with nuclear medicine outpatients. It is discussed both in the context of the current UK advice as well as potential guidelines following the recommendations in ICRP 60. For diagnostic studies there is little need for restrictions. The main exceptions are for a prolonged journey home by public transport with high levels of 99Tcm and for the situation of an outpatient given 111In who has to look after a fretful infant. The main problem occurs following the administration of 131I therapy for thyrotoxicosis. The principal hazards are associated with external exposure; radiation doses from ingestion due to contamination are small. Restrictions should only be necessary for administered activities greater than 400 MBq (e.g. public transport, return to work, sleeping with partner). With such restrictions it is considered that 131I therapy for thyrotoxicosis can continue to be given on an outpatient basis.

Digital displays usually scale to the maximum pixel count. This means that images with hot areas, e.g. bladder activity on bone scans are inappropriately displayed. We have examined the pixel count distribution of the views of 30 normal bone studies. We have found that the pixel count for which 75% of the pixels of the image have that count or less (ignoring zero count pixels) is a stable parameter for each view of the bone study. The ratio of this parameter to the maximum was determined for the normal views. This ratio can be used to automatically derive the optimum maximum count value to set for an image with hot areas.

A patient satisfaction survey was carried out in a nuclear medicine department of a large acute hospital. Surveys were initially carried out by interview and postal techniques, with approximately 100 responders in each category. The responses to each question were not significantly different for the two types of survey, although overall there was a significantly larger number of dissatisfied responses in the postal survey (22%) compared with the interview study (12%). The postal survey was repeated after 1 year, thus completing the audit loop. A significant reduction in dissatisfied responses has occurred in those areas which had been addressed following the criticisms revealed by the first survey.

We have examined the implications of ICRP60 for nuclear medicine. Radiation doses to staff are currently low and reduction of the dose limits will have little impact. However, the proposed figures for the fetus may have implications for pregnant women where the workloads are high. With nursing staff on the ward, laboratory staff or indeed departmental porters there seems little problem. Radiation dose to the fingers is, however, a key factor, and ensuring that no further restrictions are placed on the proposed dose limits is important. The concept of constraints is becoming clearer but will need further thought, particularly with regard to exposure of the general public. The previous basis for declaring controlled and supervised areas has been abandoned, and the situation is now less clear. A most important area of debate will be the patient who is a controlled area, and great care will have to be taken to ensure that the number of patients in this category is not increased so that many more patients need to be kept in hospital. Exposure of the general public is also an issue and expanding the concept of medical exposure to include carers is an important development. This should prevent a number of unnecessary restrictions and adds weight to the point that two waiting rooms are not justified in nuclear medicine departments. ICRP recommendations will soon be incorporated into the legislation of member states and it is import for everyone to ensure that drafts are read carefully and that national proposals are not too restrictive.

We have examined the implications of ICRP60 for nuclear medicine. Radiation doses to staff are currently low and reduction of the dose limits will have little impact. However, the proposed figures for the fetus may have implications for pregnant women where the workloads are high. With nursing staff on the ward, laboratory staff or indeed departmental porters there seems little problem. Radiation dose to the fingers is, however, a key factor, and ensuring that no further restrictions are placed on the proposed dose limits is important. The concept of constraints is becoming clearer but will need further thought, particularly with regard to exposure of the general public. The previous basis for declaring controlled and supervised areas has been abandoned, and the situation is now less clear. A most important area of debate will be the patient who is a controlled area, and great care will have to be taken to ensure that the number of patients in this category is not increased so that many more patients need to be kept in hospital. Exposure of the general public is also an issue and expanding the concept of medical exposure to include carers is an important development. This should prevent a number of unnecessary restrictions and adds weight to the point that two waiting rooms are not justified in nuclear medicine departments. ICRP recommendations will soon be incorporated into the legislation of member states and it is import for everyone to ensure that drafts are read carefully and that national proposals are not too restrictive.

The ICRP has now recommended that the dose limit to the surface of the mother's abdomen during the declared term of pregnancy is reduced to 2 mSv. Direct measurements of the radiation dose to technologists carrying out a variety of imaging studies were made. The average dose ranged from 0.3 micro Sv for a liver scan to 5.3 micro Sv for a brain scan. Using national data for the frequency of nuclear medicine studies, a weighted average figure of 1.5 micro Sv per study was derived. A technologist could therefore perform approximately eight imaging studies per day during the declared term of her pregnancy and remain within the proposed limit. Generally, there should be no need to alter a technologist's duties during her pregnancy, and these findings should be helpful in allaying any anxiety.

Despite publication of the Approved Code of Practice and the Notes for Guidance, implementation of the UK Ionising Radiation Regulations has required local interpretation by nuclear medicine departments. One problem has been the lack of data upon which decisions can be based. In the last five years we and others have made a number of measurements of radiation doses to staff relating to nuclear medicine practice. This paper collates, summarizes and comments on this information. Where possible, results have been expressed in relation to the workload of an average nuclear medicine department.

The radiation dose to accompanying nurses, relatives and other patients in a nuclear medicine department waiting room was assessed at 5 min intervals by observing the seating arrangement. The total radiation dose to each person was calculated, using fixed values of dose rate per 100 MBq activity for radionuclides, and applying the inverse square law. Radioactive decay and attenuation effects due to intervening persons were also taken into account. The median radiation doses to accompanying nurses, relatives and other patients were 2.3, 2.0 and 0.2 microSv with maximum values of 17, 33 and 5 microSv respectively. In all cases, the radiation dose received by patients was less than 0.2% of the radiation dose resulting from their own investigation. Also, the maximum radiation dose received by an accompanying nurse or friend was less than 1% of their appropriate annual dose limit. Similar values were obtained with calculations based on a 15 min time interval. The radiation doses received by those in a nuclear medicine department waiting room are small, and separate waiting room facilities for radioactive patients are unnecessary.