An assessment of the radiation dose received by staff using fluoroscopic equipment

Measurement of occupational doses of ionising radiation to the lens of the eyes of interventional radiologists

Currently, there exists no standardised method for monitoring radiation doses to the eye lens. This investigation aimed to determine the optimum method for monitoring the eye doses for interventional radiologists. Three interventional radiologists were issued with a series of dosimeters to wear during their routine work. These dosimeters were worn at defined positions on the body and the absorbed dose to each position was measured. It was confirmed that the dose received to the thyroid collar followed an apparently well-defined relationship to the dose recorded on the forehead, which is representative of the dose to the lens of the eye. It was also confirmed that, as hypothesised, the dose to the left eye was universally greater than to the right, although by varying factors. It was concluded that the use of dosimeters attached to the inside arms of protective eyewear is the optimum solution for eye lens dosimetry. It was also concluded that, when used with a dose conversion factor which corroborates existing literature, dosimeters attached to the outside of a thyroid collar yield sufficiently accurate results for use in routine dosimetry programmes.

FRACTURES OF THE DISTAL EXTREMITY OF THE TIBIA TREATED WITH INTRAMEDULLARY NAIL OR BRIDGE PLATE: COMPARISON OF RADIATION EXPOSURE DURATION BETWEEN THE TWO METHODS

Objective: To compare the duration of exposure to radiation among patients with fractures of the distal third of the tibia treated with an intramedullary nail or with a bridge plate. Methods: Intramedullary nails were used for 33 fractures, and bridge plates were used for 41 fractures. In the nail group, according to the AO classification, 14 patients had type A fractures, 15 had type B and four had type C. Twelve patients had closed fractures and 21 had open fractures. In the plate group, 10 patients had type A fractures, 22 had type B and nine had type C. Twenty-seven patients had closed fractures and 14 had open fractures. Results: There was a significant difference in the duration of exposure to radiation between the patients treated using a nail and those treated using a plate (p = 0.0001). The group treated using a nail had significantly greater exposure to radiation than did the group treated using a plate. Comparing the type of fracture (A, B or C), it was observed that there was no significant difference in the duration of exposure to radiation between the nail technique (p = 0.19) and the plate technique (p = 0.80). Conclusion: Fractures of the distal third of the tibia treated with an intramedullary nail present significantly greater exposure to radiation than do fractures treated with a bridge plate, independent of the fracture type.

Endoscope-guided pneumatic dilation for treatment of esophageal achalasia

Pneumatic dilation (PD) is considered to be the first line nonsurgical therapy for achalasia. The principle of the procedure is to weaken the lower esophageal sphincter by tearing its muscle fibers by generating radial force. The endoscope-guided procedure is done without fluoroscopic control. Clinicians usually use a low-compliance balloon such as Rigiflex dilator to perform endoscope-guided PD for the treatment of esophageal achalasia. It has the advantage of determining mucosal injury during the dilation process, so that a repeat endoscopy is not needed to assess the mucosal tearing. Previous studies have shown that endoscope-guided PD is an efficient and safe nonsurgical therapy with results that compare well with other treatment modalities. Although the results may be promising, long-term follow-up is required in the near future.

Clinical remission in endoscope-guided pneumatic dilation for the treatment of esophageal achalasia: 7-year follow-up results of a prospective investigation

BACKGROUND AND AIMS

Prospective, long-term reports and predictors of outcome of endoscope-guided pneumatic dilation are lacking in the literature. The aim of this prospective 7-year follow-up study is to report the efficacy of endoscope-guided pneumatic dilation and determine the possible confounding factors related to remission.

METHODS

Between January 1998 and June 2004, 32 patients were enrolled. Each patient was treated with endoscope-guided pneumatic dilation and followed-up at regular intervals for a median of 4.5 years. Remission was determined with the use of a structured interview and a previously described symptom score. Cumulative remission rate was analyzed by using the Kaplan-Meier method with assessment of symptom scores between grades before and after PD at 6 weeks, 6 months, 1 year, and then every year after. Possible confounding factors related to the remissions were analyzed by Cox's proportional hazard model.

RESULTS

Complete follow-up until August 2007 was obtained in 100% of all patients. Cumulative remissions were 1 year (86.7%), 2 years (86.7%), 3 years (80.0%), 4 years (76.5%), 5 years (72.9%), 6 years (61.7%), and 7 years (61.7%), respectively. Age is a relevant confounding factor to the remissions showing a worse outcome for those under 45 (p = 0.046). One esophageal perforation occurred (3.3%).

CONCLUSIONS

Endoscope-guided PD itself is safe and modestly effective for up to 7 years investigations in current study. Older patients (>45 years) have favorable overall clinical remissions.

Measurement of the dose of radiation to the surgeon during surgery to the foot and ankle

We carried out a prospective study over a period of 12 months to measure the exposure to radiation of the hands of a dedicated foot and ankle surgeon. A thermoluminescent dosimeter ring (TLD) was used to measure the cumulative dose of radiation. Fluoroscopy was used in operations on the foot and ankle. The total screening time was 3028 s, with a mean time per procedure of 37.4 s (0.6 to 197). This correlated positively with the number of procedures performed (r = 0.92, p < 0.001), and with the dose of radiation in both the left (r = 0.85, p = 0.0005) and right TLDs (r = 0.59, p = 0.419). There was no significant difference in the dose of radiation between the two hands (t-test, p = 0.62). The total dose to the right TLD over the 12 months was 2.4 millisieverts.

This is a simple and convenient method for evaluating the exposure of a single surgeon to radiation. The radiation detected was well below the annual dose limit set by the International Commission on Radiological Protection.

Radiation protection for your hands

A prospective clinical trial was performed to assess the suitability of a new type of sterilisable, user-friendly radiation protection glove. In a preliminary trial, we showed that the dominant hand of the primary operating orthopaedic surgeon receives the highest dose of radiation. During a 4-month period, 98 procedures were done requiring the use of an image intensifier. The doses of radiation to the dominant hand of the operating surgeon were reduced to less than the doses of radiation to the non-dominant hand. The glove was sterilisable, user-friendly and accepted by the majority of surgeons. It offers greater than 90% attenuation of X-rays and is superior to all other scatter gloves on the market.

A study of the distribution of dose across the hands of interventional radiologists and cardiologists

The magnitude and distribution of doses across the hands of interventional radiologists and cardiologists have been studied. The aims were to determine the region of highest dose, investigate variations in dose distribution, and propose an effective method for dose monitoring. Doses have been measured using sets of up to 18 thermoluminescent dosemeters (TLDs) for 183 single procedures. Important factors influencing the dose to the hand are the type of procedure, particularly the access route, the X-ray equipment used, and the experience of the operator. Radiologists performing percutaneous procedures received the highest doses, because of the proximity of their hands to the X-ray tube. The majority of procedures involve a combination of twisting and prodding actions, and the relative proportions of each determine the parts of the fingers which receive a higher dose. For most interventional radiology and cardiology procedures the bases of the ring and little fingers receive the highest dose. However, during percutaneous procedures the tips of the middle and ring fingers could receive doses which were 20-30% higher than this. For radiologists and cardiologists with a mixed workload, monitoring using TLD rings located at the base of the little or the ring fingers on either hand should provide a reasonable estimate of dose to the most exposed area. Monitoring is recommended for operators who may receive over 50 mSv to their hands per year, and should be considered for operators carrying out therapeutic procedures involving patient dose-area products over 500 Gy cm2 per month.

Radiation doses to the legs of radiologists performing interventional procedures: are they a cause for concern?

The purpose of this study was to ascertain the magnitude and distribution of doses to the legs of radiologists when performing interventional procedures. LiF:Mg,Ti TLD100 chips were used to measure simultaneously doses to the lower limbs and, for comparison, the hands during 100 interventional procedures. Results show leg dose was dependent upon type and complexity of procedure, equipment used and whether lead protection was available. Where no lead protection was used, the doses to the lower limbs were frequently similar to or higher than those received by the hands. The mean dose to the legs ranged from 0.19 mSv to 2.61 mSv per procedure, compared with 0.04 mSv to 1.25 mSv to the hands. During transjugular intrahepatic portosystemic shunt and embolisation procedures the leg dose could be as much as 2-3 times greater than that to the hands. When lead protection was used, the dose to the legs was reduced significantly to 0.02 mSv to 0.5 mSv per procedure. A clear linear relationship was shown between the dose-area product (DAP) reading and the dose to the feet of the radiologist. As a "rule of thumb", a DAP reading of 100 Gy cm(2) will give a dose of 1 mSv to the legs, if no lead protection was used, dropping to approximately 0.02 mSv if lead protection was present. This study demonstrates that the dose to the legs of radiologists can be higher than that to the hands when no lead protection is used. The inclusion of a lead screen to protect the legs is an effective method of dose reduction when performing interventional procedures.

Radiation exposure to the spine surgeon during fluoroscopically assisted pedicle screw insertion

STUDY DESIGN

In vitro study to determine occupational radiation exposure during lumbar fluoroscopy.

OBJECTIVES

To assess radiation exposure to the spine surgeon during fluoroscopically assisted thoracolumbar pedicle screw placement.

SUMMARY OF BACKGROUND DATA

Occupational radiation exposure during a variety of fluoroscopically assisted musculoskeletal procedures has been previously evaluated. No prior study has assessed fluoroscopy-related radiation exposure to the spine surgeon.

METHODS

Bilateral pedicle screw placement (T11-S1) was performed in six cadavers using lateral fluoroscopic imaging. Radiation dose rates to the surgeon's neck, torso, and dominant hand were measured with dosimeter badges and thermolucent dosimeter (TLD) rings. Radiation levels were also quantified at various distances from the dorsal lumbar surface using an ion chamber radiation survey meter.

RESULTS

The mean dose rate to the neck was 8.3 mrem/min. The dose rate to the torso was greatest when the surgeon was positioned ipsilateral to the beam source (53.3 mrem/min, compared with 2.2 mrem/min on the contralateral side). The average hand dose rate was 58.2 mrem/min. A significant increase in hand dose rate was associated with placement of screws ipsilateral to the beam source (P = 0.0005) and larger specimens (P = 0.0007). Radiation levels significantly decreased as distance from the beam source and dorsal body surface increased. The greatest levels of radiation were noted on the side where the primary radiograph beam entered the cadaver.

CONCLUSION

Fluoroscopically assisted thoracolumbar pedicle screw placement exposes the spine surgeon to significantly greater radiation levels than other, nonspinal musculoskeletal procedures that involve the use of a fluoroscope. In fact, dose rates are up to 10-12 times greater. Spine surgeons performing fluoroscopically assisted thoracolumbar procedures should monitor their annual radiation exposure. Measures to reduce radiation exposure and surgeon awareness of high-exposure body and hand positions are certainly called for.

Radiation exposure to medical staff in interventional and cardiac radiology

The aim of this work has been to determine typical occupational dose levels in interventional radiology and cardiology installations and to relate doses to patient and occupational dosimetry through the dose-area product. An experimental correlation between environmental dosimetric records and dose-area products in the centres studied was established. The study covered a sample of 83 procedures performed by 10 specialists in six laboratories. The radiologists and cardiologists monitored wore nine thermoluminescent chips next to eyes, forehead, neck, hands, left shoulder, left forearm and left arm during each single procedure. In addition, direct reading electronic devices for environmental dosimetry were placed in the C-arm of the X-ray system, to estimate roughly the occupational radiation risk level. Typical shoulder doses derived from electronic dosimetry range between 300 and 500 muSv per procedure, assuming no lead protective screens were used. Using these values and patient dose-area data from two laboratories, averaged ratios of 84 and 120 muSv per 1000 cGy cm2 are obtained for cardiology procedures. Finally, occupational dose reductions of approximately 20% when using highly filtered X-ray beams with automatic tube potential (kV) reduction (available in some facilities), and by a factor of about three when using ceiling mounted screens, have been found.

Lens injuries induced by occupational exposure in non-optimized interventional radiology laboratories

Several cases of ophthalmologically confirmed lens injuries, caused by occupational radiation exposure, have occurred in two X-ray rooms devoted to vascular and visceral interventional radiology procedures. Both laboratories were equipped with overcouch X-ray systems not designed for interventional radiology and without specific tools for radiation protection of the eyes. Typical workloads ranged from between two and five procedures per day. For the two radiologists affected, estimates for the dose to eye lens ranged from 450 to 900 mSv per year, over several years. Once the incidents had been detected, the X-ray systems in both rooms were removed and new equipment specifically designed for interventional radiology was installed, including suspended shielding screens. Since these lens injuries were only detected accidentally, measures to avoid similar occurrences in the future are discussed.

Radiation exposure to the orthopaedic surgical team during fluoroscopy: "how far away is far enough?"

OBJECTIVES

To correlate the amount of radiation exposure to members of the orthopaedic surgical team based on their relative positions during a simulated fluoroscopically assisted orthopaedic procedure.

DESIGN

Experimental study using commercially available fluoroscopic units and dosimetry badges designed to measure "eye" (ocular lens), "shallow" (hands/skin), and "deep" (whole-body) radiation exposure.

SETTING

Standard hospital operating room at a level one trauma center.

PARTICIPANTS

Dosimetry badge clusters at specified distances from a fluoroscopic x-ray beam. Represented positions were direct beam contact, surgeon (12 in/30.5 cm), first assistant (24 in/70 cm), scrub nurse (36 in/91.4 cm), and anesthesiologist (60 in/152.4 cm).

INTERVENTION

Dosimetry badges were systematically exposed by a protocol intended to maximize radiation scatter. A maximum time for continuous fluoroscope use was set at ten minutes.

MAIN OUTCOME MEASUREMENTS

Radiation exposure readings from dosimetry badges processed by a commercially available dosimetry service.

RESULTS

Maximum readings are reported. Direct beam contact resulted in approximately 4000 mrem/minute (40 mSv/min) of radiation exposure. Deep exposure for the surgeon and first assistant was 20 mrem/min (0.2 mSv/min) and 6 mrem/min (0.06 mSv/min), respectively. Superficial exposure was 29 mrem/min (0.29 mSv/min) for the surgeon and 10 mrem/min (0.1 mSv/min) for the first assistant. Eye exposure was 10 mrem/min (0.1 mSv/min) for the surgeon and 6 mrem/min (0.06 mSv/min) for the first assistant. At the scrub nurse position, no deep or eye exposure was detected. One positive badge for shallow exposure was noted at the scrub nurse position, reflecting a 2 mrem/min (0.02 mSv/min) exposure rate. After ten minutes of continuous exposure, badges assigned to the anesthesiologist position never registered any positive readings.

CONCLUSIONS

These results indicate that unprotected individuals working twenty-four inches (70 cm) or less from a fluoroscopic beam receive significant amounts of radiation, whereas those working thirty-six inches (91.4 cm) or greater from the beam receive an extremely low amount of radiation.

The interdependence of staff and patient doses in interventional radiology

Staff doses arising from the use of X-rays are principally due to scattered radiation. This is related to the dose received by the patient expressed as the dose-area product (DAP). Doses to patients in interventional radiology are generally higher than for other fluoroscopically guided procedures. Doses to interventional radiologists are, therefore, amongst the highest associated with the use of diagnostic X-rays. The results of staff dose monitoring normalized to DAP should provide an indicator of those procedures which are associated with particularly high radiation exposures to staff, and should help to identify those radiologists whose practice may result in unnecessarily high doses to themselves. A study has been made of patient doses in two X-ray rooms used for interventional procedures associated with vascular and liver diseases. Doses to radiologists in these rooms were normalized to DAP. It was found that the average doses to the body, neck and hands were 0.05, 0.89 and 2.45 microSv/(Gy cm2), respectively for those radiologists with no significant involvement in hepatobiliary procedures. Higher doses were found for one radiologist whose workload included biliary drainage. The whole body dose was 0.17 microSv/(Gy cm2) or 5.8 mSv per year. It was shown that the doses to the neck and hands for the biliary drainage work was 6.59 and 29.0 microSv/(Gy cm2), respectively. This study has demonstrated the value of DAP as a measure of radiologist workload in respect of its significance in terms of staff dose.

Vascular radiology in The Netherlands in 1992: a quantitative approach

A survey was held into methods and extent of vascular radiology in the Netherlands. For the year 1992, quantitative data on the number of patients, vascular radiological examinations and characteristics of angiography facilities were obtained from more than 80% of the Dutch hospitals with angiography rooms (120). The following estimates have been inferred: approximately 50,600 patients were referred for non-cardiac vascular radiology, including 32,100 patients for intra-arterial arteriography, 8900 for intravenous DSA arteriography, 4600 for phlebography and 5000 for interventional radiology. On average about two vascular examinations were carried out per patient referred for arteriography. In interventional radiology, the number of patients and the number of examinations are quite similar. The total number of angiography rooms in the Netherlands was 136. The average age of angiography X-ray systems was 7.1 years, of imaging equipment 5.7 years. In 56% of the hospitals, the X-ray tube was normally applied in the undercouch position, in 40% in overcouch position and in 4% there was no preferred position. An additional survey of occupational exposure conditions in angiography rooms (19 hospitals) showed that, in most hospitals, protective lead aprons of 0.5 mm Pb-equivalent were in use. Thyroid collars were used rather infrequently.

Hazard of ionizing radiation to trauma surgeons: reducing the risk

A study aimed to establish the level of radiation exposure to orthopaedic surgeons involved in the care of injured patients; parts of the body most at risk, and to establishing whether surgeon control of X-ray image intensification reduced the risk. This was conducted on five orthopaedic surgeons regularly involved in musculoskeletal care. Radiation dosage (in millisieverts (mSv) to the body, neck, eyes and hands, was measured by means of dosimeters applied to these areas, before and after surgeon-controlled use of X-ray image intensification. Although all doses measured were within current safety guidelines (1.25 mSv total body dose/month, 3.75 mSv eye dose/month and 12.5 mSv extremity dose/month), the hands were most at risk (maximum recorded dosage 3.95 mSv/month). Control by the surgeons of X-ray image intensification significantly reduced exposure of the hands (P < 0.05).

An investigation into the effect of protective devices on the dose to radiosensitive organs in the head and neck

A series of experiments were performed to determine the dose reduction afforded to radiosensitive organs in the head and neck by various protective devices. These included spectacles with plastic, standard glass, photochromic and lead-glass lenses, a thyroid collar and a lead-acrylic face mask. The measurements were performed using an anthropomorphic phantom loaded with lithium fluoride thermoluminescent dosemeters, in conditions realistic of clinical practice. Irradiations were performed using scattered radiation produced by a pelvic phantom, for X-ray beams generated at 80 kVp and 110 KVp. It was found that the reduction in dose to the lens of the eye ranged between 0% and 97%, whilst the dose to the thyroid and oesophagus was reduced by between 76% and 97%, and was dependent on the protective device and tube potential employed. A reduction in brain dose of up to 81% was also measured, for the lead-acrylic face mask. Also presented is the ratio of organ dose to dose to the bridge of the nose for thyroid, oesophagus, brain and sinuses, as measured for the case of no head or neck protection.

Exposure of the hands to ionizing radiation in the resuscitation room of an accident & emergency department

Exposure of the hands to ionizing radiation in the resuscitation room of an A&E department was measured in eight health care personnel over 3 consecutive months. The radiation levels did not exceed those limits currently recommended by the International Commission on Radiological Protection 1990. The level recorded in one individual did exceed the level set at the Lothian Health Boards investigation limit. In only five of 85 occasions were lead gloves worn by the doctor during cross table lateral cervical radiographs. Recommendations are made for reducing the radiation exposure to the hands.

Minimizing radiation dose to patient and staff during fluoroscopic, nasoenteral tube insertions

It is possible to reduce greatly fluoroscopic radiation dose if some image degradation is acceptable. Since the fluoroscopic image during nasoenteral tube placements is used for guidance and not for diagnosis, a lower contrast image with increased quantum mottle can be easily tolerated. The three methods to reduce the radiation dose rate that were investigated consisted of removing the antiscatter grid, increasing the diameter of the optical aperture controlling the percentage of light reaching the television camera from the image intensifier output phosphor, and setting the fluoroscopic mA to the minimum value so that the kVp could be maximized. Fluoroscopic frozen video frames of a clinical tube insertion comparing the images with and without the dose-saving techniques are presented. Measurements of the radiation dose rates using a Plexiglas phantom show that the dose for patient and staff during fluoroscopic-guided nasoenteral tube placements can be reduced by over a factor of 10 without significantly adversely affecting the actual placement procedure.

The dependence of the scattered radiation dose to personnel on technique factors in diagnostic radiology

The measurement and prediction of scattered radiation dose to staff in diagnostic radiology is particularly important, owing to the increased use and complexity of interventional radiology. The air kerma-area product and scattered radiation dose in the vicinity of the patient couch, for both overcouch and undercouch X-ray tube geometries, were simultaneously monitored. The scattered radiation distribution at the couchside was deduced at a range of tube potentials for both overcouch and undercouch X-ray tube geometries. The variation of scattered radiation with field size on both geometries was investigated, as well as the variation with focus-table distance on an overcouch tube geometry. It was discovered that the scattered radiation dose at a point correlated with the air kerma-area product and the result may be used for radiation protection purposes. A method of predicting the scattered radiation dose at a given position is described.

Extremity doses during interventional radiology

The radiation doses received by the unprotected parts of a radiologist undertaking biliary and renal interventional techniques using an overcouch X-ray tube have been measured with thermoluminescent dosimeters. Mean doses to the eyes, thyroid and fingers ranged from 0.27 to 1.29 mSv per examination. The results substantiate the need for such monitoring but the study demonstrates that the doses to the radiologist can be kept to an acceptable level with careful technique.

A review of occupational exposure in the North-Western Region

The Ionizing Radiations Regulations 1985 require employers to monitor all classified persons and to demonstrate that all non-classified persons who work in controlled areas do not exceed three-tenths (i.e. the classification level) of any relevant annual dose limit. A review of occupational doses was undertaken to ascertain whether any person needed to be designated as a classified person and to demonstrate compliance with the Regulation regarding non-classified staff working in controlled areas. The occupational-dose data for 1986 were compared with data for 1981 to identify any areas where changes in workload, equipment or techniques had led to increases in whole-body or organ doses. The results demonstrate that the level of whole-body occupational dose received by the vast majority of NHS employees in the North-Western Regional Health Authority is, as expected, extremely low. However, two specific areas were identified where occupational doses are relatively high and need to be carefully monitored. The review has also led to a number of operational changes being implemented by the Approved Dosimetry Service.

Estimation of effective dose equivalent to staff in diagnostic radiology

The irradiation of staff in diagnostic radiology was simulated for conditions commonly encountered in fluoroscopy. Scattered radiation distributions were produced from diagnostic x-ray beams generated at tube potentials in the range 60-120 kVp, using the abdomen sections of a Rando phantom. Doses to a number of organs in the head and neck were measured using a Rando phantom loaded with lithium fluoride thermoluminescent dosemeters. The torso sections were placed on a water phantom on top of a stand, with film badge dosemeters positioned on the surface of the phantom at the forehead, neck, chest and waist, and the phantom was placed in the radiation field. Doses to organs in the torso were calculated from the waist-level film badge dosemeter reading using normalised organ dose data. Radiation doses to organs below a lead apron, when worn, were estimated from the unshielded dose values using a transmission factor appropriate to the quality of the scattered radiation. The effective dose equivalent (EDE) to the phantom was calculated for various x-ray beam qualities and lead apron thicknesses and compared with the film badge doses. The results indicate that a dosemeter worn at the waist/chest level under a lead apron generally underestimates the EDE. Conversely, dosemeters worn at the forehead/neck tend to overestimate the EDE. It is recommended that a dosemeter is positioned under a lead apron, if worn.

An investigation into the levels of radiation exposure in diagnostic examinations involving fluoroscopy

In order to investigate the levels of radiation exposure resulting from fluoroscopic examinations, area-exposure product measurements were performed on 6532 patients whilst undergoing a variety of examinations at a large district general hospital. Results for both the same and different types of examinations, performed in two different X-ray rooms by a number of different radiologists, are compared in order to highlight some of the factors which influence the wide variations in patient exposure which frequently occur in radiological examinations. Variations in exposure of patients of different weights are also presented.

An investigation of the radiation dose to staff during cardiac radiological studies

Measurements of radiation distributions in the vicinity of the couch were undertaken for a number of projections commonly employed during cardiac radiological studies. Three types of investigations were considered; cardiac catheterisations, pacemaker implants and percutaneous transluminal coronary angioplasties. The radiation dose to staff involved in these procedures was estimated. For each group of staff, the maximum annual workload and the workload which would necessitate an individual becoming a classified radiation worker may be deduced from an expression given in the text.

Radiation exposure to patients during radiological examinations of the gastro-intestinal tract: intrahospital dose variations

Skin and gonad doses have been measured in 144 adult patients undergoing barium meal and barium enema examinations at a University Teaching Hospital. Intrahospital variations are discussed and their implications for national dose surveys considered. It is suggested that, due to differences in leakage and scattered radiation levels, overcouch tube machines may deliver higher doses to organs outside the useful beam than undercouch units. The study also points towards increased film consumption in GIT studies.

Occupational exposure in medicine--a review of radiation doses to hospital staff in north-west England

The personal monitoring service operated by the Regional Physics Department at the Christie Hospital and Holt Radium Institute, Manchester, monitors staff involved with the uses of ionising radiations at all hospitals and clinics administered by the North Western Region Health Authority in England. Monitoring results relating principally to exposure during 1981 have been collated and examined. The analysis indicates that the doses received by staff are for the most part very low and provide little reason for concern. The only area of work in which worthwhile and cost-effective dose reductions could probably be achieved is that involving the use of pre-loaded applicators in gynaecological intra-cavitary therapy. Some relatively high staff exposures result from the use of this technique, and very significant reductions in these doses are confidently expected from a programme which has now commenced for the increasing use of remotely-controlled after-loading equipment housed in shielded treatment rooms.