Radiation Protection in Urology
X-rays have been used to diagnose diseases in the kidney and urinary tract for about a century to visualize urinary tract to highlight a kidney stone or tumour that could block the flow of urine. It was only couple of decades ago that urologists started using X-ray fluoroscopy in their operating rooms. Then came lithotripsy and now it is computed tomography (CT) that is increasingly being used. CT is currently the most sensitive and specific imaging test for urolithiasis. The improved diagnostic accuracy of newer generation of CT scanners coupled with speed and patient friendliness is making CT a useful tool in follow-up of cancer patients (such as testicular) and there are situations when a patient is subjected to more than 10 CT scans in a follow up period of 5 years. Urological procedures like intravenous pylography (IVP) or intravenous urography (IVU) are generally performed using radiography machines. These investigations may or may not have a direct involvement of the urologist. However, active involvement of the urologist with the use of radiological facilities is in cystography, retrograde pyelography, voiding cystourethrogram (VCUG) procedures where there is a need to administer contrast agents directly into the urinary system. A number of procedures like percutaneous nephrolithotomy (PCNL), nephrostomy, stent placement, stone extraction and tumor ablation require fluoroscopy machine in the operating room.
Due to the increased use of radiation during urological procedures, protection of patients from ionizing radiation is becoming increasingly important. With such usage, there is a need for adopting dose management techniques in every radiological examination without compromising on image quality and clinical purpose. Further, there is need to reduce the number of CT scans for surveillance. There is possibility of staff getting high exposure in fluoroscopy room if protection principles and tools are not employed.
Urological imaging procedures may include abdomino-pelvic CT, fluoroscopy for viewing and positioning for urological problems, radiographs of the kidney, ureters and bladder (KUB), excretory urograms (intravenous pyelogram-IVP) and retrograde urethrograms (micturating cysto urethrogram - MCU). These procedures involve exposure to ionizing radiations (X rays) whereas ultrasound waves and magnetic resonance imaging (MRI) involve non-ionizing radiations. This website is concerned with exposure to ionizing radiations.
Typical values in terms of effective dose are presented in Table 1 below:
Table 1. Typical radiation doses in urological procedures
|Procedure||Mean effective dose (mSv) values|
|Abdomen radiography (AP)||0.7 |
|Intravenous Urogram (6 films)||2.5 |
|Micturating cysto urethrogram||1.2 |
|Percutaneous nephrolithotomy (PCNL)||4.5 |
|Ureteric stenting||4.7 |
|CT abdomen||10 |
|Renal angiogram||2 to 30 [4,5]|
|Kidney stent insertion||12.7 |
Studies for an acute kidney stone episode may, in some situations, involve a range of radiological procedures which may include 1 or 2 plain Kidney Ureter Bladder (KUB) radiographs, 1 or 2 abdominopelvic CT exams, and an IVP during the first year of follow up. The total effective dose from such studies may be in the range of 20 to 40 mSv.
Yes. There are several methods recommended for reduction of patient doses for radiological procedures in urology. Specific methods are available for optimization in radiography, fluoroscopy and computed tomography. The experience shows that with the use of optimization techniques it is possible to achieve significant dose reduction, in some cases to the tune of 50%, without compromising on image quality. Avoiding unnecessary CT or fluoroscopy examinations can contribute to further reduction. Read more »
Yes. If children or young adults are subjected to CT scanning, paediatric protocols or optimised protocols (reduced exposure parameters compared to adult protocol) are recommended. It is important that children get as little radiation exposure as possible because they are more sensitive to radiation than adults and they have a longer life expectancy.
This depends upon the complexity of the procedure that will determine fluoroscopy time and number of images taken. Typically the radiation dose may lie in the range of 1 to 5 mSv, but procedures such as angiography and stent insertion may involve higher radiation doses in the range of 2 to 30 mSv [Table 1]
Fluoroscopy in Urology
The major source of radiation exposure to personnel in fluoroscopy procedures is exposure to scattered radiation from the patient. The exposure comes mainly from the entry surface of the beam into the patient. The main protection for the personnel is lead apron and leaded screens and flaps wherever feasible. Additionally, distance as much as practicable, shortest time of radiation use (intermittent fluoroscopy rather than keeping foot on pedal continuously) is advised. Read more »
Yes, there are numerous ways to minimize scatter exposure of fluoroscopy personnel
Hellawell et al. has estimated that for a typical uretheral fluoroscopy procedure, utilizing 70 kV and 2 – 3 mA that a surgeon receives about 12 µGy to the lower leg, about 6 µGy to the foot, 2 µGy to the eyes and 3 µGy to the hands. An annual caseload of 50 cases would limit the dose received to a few tenths percent of the annual personnel exposure limits. Radiation exposure during percutaneous nephrolithotomy (PNCL) would be somewhat higher, but would still be expected to be less than a few percent of permissible annual limits. [HELLAWELL, G.O., et al., 2005].