Radiation exposure to patients during extracorporeal shock wave lithotripsy

Radiation exposure of patients during endourological procedures

PURPOSE

Considering the existing gaps in the literature regarding patient radiation dose (RD) and its associated risks, a systematic review of the literature on RD was conducted, focusing on percutaneous nephrolithotomy (PCNL), extracorporeal shock wave lithotripsy (SWL), and ureteroscopy (URS).

METHODS

Two authors conducted a literature search on PubMed, Web of Science, and Google Scholar to identify studies on RD during endourological procedures. Two thousand two hundred sixty-six articles were screened. Sixty-five publications met the inclusion criteria using the PRISMA standards.

RESULTS

RD was generally highest for PCNL, reaching levels up to 33 mSv, 28,700 mGycm2, and 430.8 mGy. This was followed by SWL, with RD reaching up to 7.32 mSv, 13,082 mGycm2, and 142 mGy. URS demonstrated lower RD, reaching up to 6.07 mSv, 8920 mGycm2, and 46.99 mGy. Surgeon experience and case load were inversely associated with RD. Strategies such as optimizing fluoroscopy settings, implementing ultrasound (US), and following the ALARA (As Low As Reasonably Achievable) principle minimized RD.

CONCLUSIONS

This is the first systematic review analyzing RD, which was generally highest during PCNL, followed by SWL and URS. There is no specific RD limit for these procedures. Implementation of strategies such as optimizing fluoroscopy settings, utilizing US, and adhering to the ALARA principle proved effective in reducing RD. However, further research is needed to explore the factors influencing RD, assess their impact on patient outcomes, and establish procedure-specific reference levels for RD.

Radiation doses to patients from extracorporeal shock wave lithotripsy

The aim of this study was to determine the radiation doses to patients during extracorporeal shock wave lithotripsy (ESWL) and compare them with the available bibliographical data. In this method localization of the renal stones is attained by the use of fluoroscopy, and thus ESWL is included among those medical practices associated with patient radiation exposure. The entrance surface dose was measured using 3-4 thermoluminescent dosimeters positioned on the patients' backs at the entrance surfaces of the two x-ray beams for 50 ESWL procedures. Fluoroscopy time and number of spot films were also recorded. The average entrance surface dose at the patient's side with the renal stone was estimated to be 76.5 mGy for the oblique x-ray beam and 44.5 mGy for the PA x-ray beam. The mean fluoroscopy time was 204 s while 4 spot films were acquired on average. The mean effective dose (E) was estimated as 1.63 mSv per patient. The mean entrance surface dose values recorded in this study are comparable to but smaller than the values reported in the literature for ESWL, while the mean fluoroscopy time is within the range of values reported by other authors. On the other hand, the estimated E value is relatively higher compared to the corresponding values given in the literature based on patient measurements. However, it is comparable to recent published data acquired using extended measurements in an anthropomorphic phantom.

Extracorporeal lithotripsy. Update on technology

The development of shock-wave lithotripsy was a serendipitous event. Fortunately, the significance of this accidental discovery was not overlooked by the engineers at Dornier and their medical counterparts. There are many components that make up a lithotripter, but the heart of the lithotripter is its energy source. These machines often are categorized by the type of shock-wave generator used, and each type of generator has its own advantages and disadvantages. Unfortunately, no quantitative value of a shock-wave generator can be correlated to its qualitative effect. Interestingly, each type of energy source delivers its shock-wave energy with such distinctiveness that even the crater pattern it leaves in a stone is unique. New technology and ideas have transformed lithotripters in form and function so that they bear little resemblance to the original HM-1 prototype. Ongoing research is attempting to improve ESWL in several different ways, and advances in shock-wave generation, shock-wave measurement, and stone localization should result in even more efficient lithotripsy. The application of the time-reversal process to lithotripsy ultimately may enable lithotripters to track stones and electronically steer shock waves toward the target. Advances like these herald a time when ESWL, fortunately or unfortunately, will become automated completely.

Fertility measures in women after extracorporeal shockwave lithotripsy of distal ureteral stones

Long-term effects of extracorporeal shockwave lithotripsy (SWL) on female fertility remain a concern. Thirty-nine women of childbearing age who were treated for distal ureteral stones were surveyed. The mean age of these women was 33 years, and the average stone size was 6.9 mm. The mean calculated radiation exposure to the ovaries and the uterus was 7.53 and 10.9 mSv, respectively. Ten women (26%) attempted to become pregnant. No fertility problems were noted in these women, and 11 healthy babies were delivered. These preliminary findings provide further information regarding the safety of SWL in the treatment of distal ureteral stones in women of reproductive age.

Early experience with extracorporeal shockwave Dornier lithotriptor "compact"

One of the latest developments in extracorporeal shockwave lithotripsy (SWL) is a combination of an electromagnetic energy source with an upgraded parallel online ultrasound imaging for localization. The device is compact, requiring no significant installation or site preparation. Furthermore, it increases the margin of safety of SWL by virtue of the continuous ultrasound monitoring. A hundred sessions of SWL were performed on 88 patients using the Dornier Compact machine. Ninety three renal units having an average of 1.7 stones were treated (two had upper ureteric stones). Of the 135 stones, 2 (1.5%) were radiolucent and 4 (3%) were of faint opacity. Intravenous sedation was used in all patients except one 13-year-old patient, who required general anesthesia. Patients received an average of 2409 shocks per session, and the maximum power setting ranged from 1 to 6 (average 4.7). A plain film was obtained immediately before and after treatment. Early adverse effects were uncommon, and all were mild. Patients were followed by plain films at 2 weeks and 3 months. In 35 sessions (25 solitary and 10 multiple stones), the stones were considered completely fragmented; in 63 sessions, the stones (43 solitary and 20 multiple) were judged to be partial fragmented; and 2 sessions (solitary stones) resulted in poor fragmentation. The mean (+/- SD) stone dimension in the group with complete fragmentation was 9 +/- 4.8 (range 2-24) mm, compared with 11 +/- 6.3 (range 2-38) mm in those with no or partial fragmentation (P = 0.0095). After 2 weeks, 23 of 69 systems (33%) were stone free, while 46 showed residual stones.(ABSTRACT TRUNCATED AT 250 WORDS)

In situ extracorporeal shock wave lithotripsy (ESWL) for the management of primary ureteric calculi in children

Lithotripsy was used to treat 19 children (3 to 16 years of age) with primary ureteric calculi. No attempts were made to mobilize the stones to the kidney. Stones were located in the upper ureter in seven patients, middle ureter in three, and lower ureter in nine. Stone size ranged from 5 to 25 mm (average, 10.4 mm). All treatments were performed in the outpatient unit. Two children required general anesthesia, and 17 received intravenous sedation. The mean amount of energy used was 17.8 kV, and the average number of shock waves was 5,489. Before commencement of lithotripsy, two patients needed ureteric catheterization, and two had placement of double pigtail catheters. Of the 18 children who had adequate follow-up, 17 (94.4%) were completely stone-free, without any complication. The authors conclude that in situ extracorporeal shock wave lithotripsy is a safe and effective method for the treatment of primary ureteric calculi in children.

Female fertility following extracorporeal shock wave lithotripsy of distal ureteral calculi

This study was prompted by a spontaneous abortion in a 21-year-old woman following extracorporeal shock wave lithotripsy (ESWL ) of a distal ureteral calculus. To our knowledge, it is the first clinical retrospective study on the possible adverse effects of ESWL to the female reproductive tract. We analyzed treatment data and radiation exposure of 84 women in the reproductive period, and surveyed the patients by questionnaire, to which 67 (79.8%) responded. After ESWL 57 women (85.1%) practiced some form of contraception, while 10 childless women attempted to become pregnant. Overall 7 children with no malformations or chromosomal anomalies were born to 6 patients. Miscarriages were noted in 3 patients (4.5%) but they occurred at least 1 year after ESWL. Our data suggest that ESWL of lower ureteral calculi is a safe and effective procedure, and does not affect female fertility or lead to increased teratogenic risk.

Clinical trials of the Northgate SD-3 dual-purpose lithotriptor for renal calculi

The Northgate SD-3 is a bathless, portable shock wave lithotriptor made in the United States. It uses ultrasound localization and spark-gap, electrode-generated shock waves to fragment calculi in the upper urinary tract. Since October 1987, 312 treatments have been performed on 281 patients (286 kidneys) with stone burdens less than 2 cm. during clinical trials at 6 investigational sites in the United States. A fragmentation rate of 94% was achieved. Of the treatments 78% were judged successful (stone-free or fragments of less than 5 mm. remaining in an asymptomatic patient) and a 3-month stone-free rate of 58% was noted. The retreatment rate was 9% and the ancillary procedure rate was 5%. The complications (hematuria, ecchymosis, pain, obstruction) were mild and not unlike those seen in patients undergoing lithotripsy with other devices.

Factors influencing radiation exposure during the extracorporeal shock wave lithotripsy

A prospective evaluation of 89 consecutive sessions of extracorporeal shock wave lithotripsy (ESWL) was undertaken to try and find the best way of minimising the amount of exposure to radiation. Forty-two patients were randomly allocated to undergo ESWL treatment by experienced surgeons (group A), and 47 to undergo the treatment by inexperienced surgeons (group B). The mean calculated entrance radiation exposure was 3.01 rads (group A: 2.64 (0.97) rads, range 1.00-4.48, group B: 3.38 (0.86) rads, range 1.11-5.75). Among factors that influenced radiation exposure, the tissue: air ratio should be borne in mind and the level of skill in controlling movement of gantry was the most important in reducing the exposure to radiation.

Radiation exposure during ureteroscopy

Use of fluoroscopy during ureteroscopy increases the risk of radiation exposure to the urologist and patient. Radiation entrance dosages were measured at skin level in 37 patients, and at the neck, trunk and finger of the urologist, and neck and trunk of the circulating nurse. Radiation exposure time was measured in 79 patients, and was related to the purpose of the procedure and the type of ureteroscope used, whether rigid or flexible. Exposure could be minimized by decreasing the fluoroscopy time. A portable C-arm fluoroscopy unit with electronic imaging and last image hold mode should be used to minimize exposure time. Lead aprons and thyroid shields should be used by the urologist and other personnel in the endoscopy room.

Initial EDAP LT-01 lithotripsy group experience in the United States

The initial United States cooperative experience with the EDAP LT-01 second generation piezoelectric extracorporeal shock wave lithotriptor using ultrasonic guidance is presented. Particular to the machine are lack of radiation exposure, no need for anesthesia, a purely outpatient procedure, no electrocardiographic problems, a high degree of safety and a paucity of complications. The equipment is described briefly. The same machine currently is being used to destroy renal and biliary stones. The results are encouraging and highly comparable to the initial experience with the earlier machines. Fragmentation rates are approximately 86%, with destruction rates of 63.4% over-all. Ultrasound localization and monitoring proved surprisingly easy to learn and were increasingly less of a problem as experience was gained. No serious complications were observed, and there were no renal losses and no deaths. Only 3 cases of steinstrasse were noted among 461 with 633 stones targeted during 595 treatments.

Radiation doses in extracorporeal shock wave lithotripsy

Patients undergoing lithotripsy on the Siemens Lithostar system are exposed to radiation in three modes: film radiography, electronic radiography and fluoroscopy. Radiation exposure techniques (kVp, field size, number of exposures and projection) were recorded for the first 125 patients undergoing treatment on a recently installed Lithostar unit at a Winnipeg hospital. These data were then used in conjunction with phantom-based radiation dose measurements to calculate entrance skin dose and total energy imparted for each patient. Values of 142 mGy and 53 mJ, respectively, were found. In the case of energy imparted, 20% of the total arose from film radiography, 30% from electronic radiography and the remaining 50% from fluoroscopy. The estimated effective dose-equivalent, HE, to the average patient undergoing lithotripsy was 0.75 mSv. This corresponds to an estimated radiation risk for the induction of fatal cancers and genetic defects (in the first two generations of offspring) of between 5 and 11 per million.

Clinical experience using the Wolf Piezolith device at 2 British stone centers

Machines using the principle of piezoelectric extracorporeal shock wave lithotripsy have been developed. This has allowed the prospect of painless treatment for renal and ureteral calculi. The experience with use of 2 Wolf Piezolith machines for 1 year is presented. Different second generation lithotriptors have varying techniques of production of shock waves and different imaging methods. The Wolf Piezolith device uses ultrasound imaging and piezoelectric crystals for shock wave generation. Between June 1987 and May 1988, 545 patients 5 to 84 years old were treated with the Wolf Piezolith device. Of these patients 2-month followup data are available for 367 (398 renal units). Outpatient treatment was used routinely. For renal calculi complete fragmentation (into particles less than 2 mm. in size) was achieved in 94 per cent of the patients, with 53 per cent being completely free of stone at 2 months. For ureteral stones treated in situ the best results were obtained in the upper and lower ureter. Over-all, 62 per cent of the patients required more than 1 treatment, with the number of treatment sessions required increasing with the size of the stone treated. Morbidity was low. Ultrasound imaging has proved to be as effective as x-ray imaging. Compared to Dornier HM-3 lithotripsy, installation and running costs were low. The machine offers a favorable alternative to first generation lithotriptors.

Extracorporeal shock-wave lithotripsy of renal calculi

Extracorporeal shock-wave lithotripsy (ESWL) is a noninvasive technique that utilizes focused shock waves to fragment stones into sand-sized particles, which then pass spontaneously with urination. The clinical use of this technique was introduced in 1980 in Germany by Chaussy and associates and has replaced most open surgery and percutaneous endoscopy for stone removal. The physics of shock waves, equipment, techniques, and patient selection in ESWL are discussed. Results of treatment of renal, upper ureteral, and lower ureteral calculi are reviewed and compared. Complications of treatment, including ureteral obstruction, hemorrhage, and tissue damage, are discussed. The advent of second-generation lithotripters has widened the parameters for patient selection in the treatment of ESWL and has increased the availability of this treatment modality.

Variations in fluoroscopic and spot film techniques during extracorporeal shock wave lithotripsy

The radiation techniques of different operators who performed extracorporeal shock wave lithotripsy of the kidney were evaluated retrospectively. The study was limited to 9 operators who each performed more than 100 procedures on the Dornier lithotriptor. The average fluoroscopic time and number of video spot films per procedure for all operators were 4.1 minutes and 6.5, respectively. However, the average fluoroscopic time per operator varied from 1.4 to 7.6 minutes and the average number of video spot films per operator varied from 3 to 13. The results illustrate the need for some operators to reduce fluoroscopic time and video spot filming.

Effectiveness of radiation control program for Dornier HM3 lithotriptor

Radiation exposure during extracorporeal shock-wave lithotripsy (ESWL) was calculated using a "worst-case method" in 135 randomly selected patients. The patients were divided into four groups according to body weight: small (less than 140 pounds), medium (141-180 pounds), large (181-220 pounds), and very large (greater than 220 pounds). Average skin exposure was found to be 15.2 R (from 1.2 to 95.6 R). After implementation of a "radiation awareness program" radiation exposure was calculated in 128 cases (matched for body weight and stone burden) and average exposure was 9.5 R (from 0.9 to 33.4 R) with a reduction of 20, 37, 33, and 62 percent for each group, respectively. Radiation exposure reduction was primarily due to a reduction in the number of radiographic "snapshots" taken as a result of preferential use of special-mode fluoroscopic "stills."

Urinary extracorporeal shock wave lithotripsy: equipment, techniques, and overview

Second generation urinary lithotriptors are characterized by extensive technical alterations and significant equipment improvement in the functional, logistical, and medical aspects of shock wave lithotripsy (SWL). These newer devices feature a water bath-free environment, a reduced anesthesia requirement, improved imaging, functional uses in addition to lithotripsy, or combinations thereof. Shock wave generation by spark gap, electromagnetic, piezoelectric and microexplosive techniques are related to their peak energy, frequency, and total energy capabilities which impacts on both anesthesia needs and the length and number of treatment sessions required to pulverize calculi. A master table summarizes the types of SW energy, coupling, imaging systems, patient transport, functional features, cost, and treatment effectiveness of 12 worldwide lithotriptors in various stages of investigative and clinical trials as monitored by the Food and Drug Administration (FDA) of America.