Therapeutic Radiologic Procedures Research Articles

მაიონებელი გამოსხივების ზემოქმედება სამედიცინო პერსონალზე და მისი კონტროლი კლინიკურ პრაკტიკაში

Ionizing radiation (IR) has been used for more than a century in clinical practice. It forms the basis for diagnostic and preventive radiology. However, medical professionals who work under constant radiation are at huge risk of developing different types of chronic or acute diseases such as malignant tumors, chronic dermatitis, hyperthyroidism, etc.  Depending on clinical practice, nurses are at higher risk of being influenced by ionizing radiation, caused by their specific job of being close to the patients who are under performing of some diagnostic or therapeutic radiological procedures. By the influence of constant ionizing radiation, at the expense of oxidation, the structure of DNA damages, which can cause carcinogenesis, chromosome instability etc. Historically, control of the effects of  IR started at the beginning of the 20th century when the impact of exposure was more harmful.  Nowadays, the world’s leading countries as well as the Republic of Georgia have the appropriate legislation that obligates hospitals to create safe working space for employees, and medical professionals to follow all guidelines to protect each other from exposure effects. Despite that fact, how the control of low-dose constant radiation performs is questionable. This opinion is proven by some official statistical data about radiation-caused diagnoses in medical professionals. Despite the revolutionary development of radiology through the past century, ionizing radiation effects on medical professionals remain one of the biggest problems and require specific attention.   &nbsp

MANAGEMENT OF HEMORRHAGE IN LAPAROSCOPIC COLORECTAL SURGERY

Abstract Introduction Laparoscopic colorectal surgery (LCRS) offers similar oncologic outcomes to the open approach along with early postoperative recovery but is not without complications, with bleeding being uncommon but with variable impact and technical resource demand. Methods A descriptive and retrospective study of bleeding in patients undergoing elective LCRS in our center between 01/012018 and 31/12/2021. The data analysis was performed using the SPSS statistical software. Results Out of 945 LCRS, 45 patients (4.8%) presented some hemorrhagic event. The main diagnosis was colorectal cancer (35), followed by diverticular disease (6). The procedures most frequently associated with bleeding were sigmoidectomy (13), TATME (7) and right hemicolectomy (7). Five patients presented moderate (4) or severe (1) intraoperative bleeding, controlled during surgery. The most commonly used hemostatic devices were biopolar energy (29.5%) and combined (34.1%). The diagnosis of postoperative bleeding was clinical in 20 cases (45.5%), 17 by CT angiography (38.6%) and 7 by endoscopy (15.9%). In 36.4% the origin of hemorrhage was in the anastomosis, demonstrated by endoscopy or radiological study. Eleven patients (25%) required reintervention: seven by open approach and four by laparoscopy (two conversions). Therapeutic endoscopy was performed in 7 patients (15.9%), in 1 patient interventional radiology-surgery was combined, and in another patient endoscopy-surgery. There was no mortality due to this cause. The mean length of stay after surgery was 19.52 days. Conclusions Hemorrhage in LCRS is a rare but potentially serious complication that requires early diagnosis and staged multidisciplinary approaches, including advanced therapeutic endoscopy and interventional radiology procedures.

Safety and effectiveness of vascular closure devices in interventional radiological procedures.

Although it is well known that vascular closure devices (VCD) are commonly used in therapeutic interventional radiological procedures, standard use in diagnostic procedures is not as well studied. The aim of this study was to determine the real-world safety and effectiveness of the VCD in both diagnostic and therapeutic interventional radiological procedures. A retrospective, single center study included all patients where VCDs were used for either a diagnostic or therapeutic interventional procedure. Various demographic and clinical risk factors were recorded and examined for any significant association with successful deployment and complications. A total of 2072 patients were included. VCDs were successfully deployed in 95.2% of the patients with 4.8% of perioperative complications, which included minor oozing from the puncture site, small hematoma less than or equal to 5 cm, large hematoma greater than 5 cm, pain, and loss of vascular access. Therapeutic (vascular interventional radiology (VIR) and neuro-interventional radiology (NIR)) procedures (OR 3.03, 95% CI 1.51-6.09, p = 0.002), use of Angioseal (OR 5.26, 95% CI 3.13-8.33), p < 0.001), and no use of antiplatelet medications (OR 0.47, 95% CI 0.22-0.97, p = 0.041) were independently associated with successful deployment of VCDs when controlled for other risk factors. Smoking (OR 3.50, 95% CI 2.00-6.05, p = <0.001), use of antiplatelet (OR 2.01, 95% CI 1.04-3.87, p = 0.037) and use of heparin (OR 1.78, 95% CI 1.10-2.86, p = 0.018) were independently associated with higher complication rates. VCD's were successfully deployed in 95.2% of the patients with 4.8% of perioperative minor complications.

Institutional Diagnostic Reference Levels and Peak Skin Doses in selected diagnostic and therapeutic interventional radiology procedures.

Institutional (local) Diagnostic Reference Levels for Cerebral Angiography (CA), Percutaneous Transhepatic Cholangiography (PTC), Transarterial Chemoembolization (TACE) and Percutaneous Transhepatic Biliary Drainage (PTBD) are reported in this study. Data for air kerma-area product (PKA), air kerma at the patient entrance reference point (Ka,r), fluoroscopy time (FT) and number of images (NI) as well as estimates of Peak Skin Dose (PSD) were collected for 142 patients. Therapeutic procedure complexity was also evaluated, in an attempt to incorporate it into the DRL analysis. Local PKA DRL values were 70, 34, 189 and 54Gy.cm2 for CA, PTC, TACE and PTBD respectively. The corresponding DRL values for Ka,r were 494, 194, 1186 and 400mGy, for FT they were 9.2, 14.2, 27.5 and 22.9min, for the NI they were 844, 32, 602 and 13 and for PSD they were 254, 256, 1598 and 540mGy respectively. PKA for medium complexity PTBD procedures was 2.5 times higher than for simple procedures. For TACE, the corresponding ratio was 1.6. PSD was estimated to be roughly 50% of recorded Ka,r for procedures in the head/neck region and 10% higher than recorded Ka,r for procedures in the body region. In only 5 cases the 2Gy dose alarm threshold for skin deterministic effects was exceeded. Procedure complexity can differentiate DRLs in Interventional Radiology procedures. PSD could be deduced with reasonable accuracy from values of Ka,r that are reported in every angiography system.

Radiation Hazard, Safety, Control and Protection

The field of Radiology and Nuclear medicine has advanced from era of X-rays to today's modern imaging techniques, most of which use the ionizing radiation. With the benefits of better diagnosis and treatment, it has caused manifold increase in radiation exposure to the patients and the radiology and nuclear medicine personnel. Many studies done till date have clearly documented the harmful effects of ionizing radiation from radiation exposure, especially cancer. This is more important in paediatric population as their tissues are more radiosensitive, and they have more years to live. Diagnostic and therapeutic radiological procedures including nuclear medicine are integral part of modern medical practices, exposing both patients and medical staff to ionizing radiation. Without proper protective measures, this radiation causes many negative health effects. Hence, proper knowledge and awareness regarding the radiation hazards and radiation protection is mandatory for health professionals, especially the nuclear medicine and radiology professionals. International Commission on Radiation Protection (ICRP) has recommended two basic principles of radiation protection, justification of the practice and optimization of protection.&#x0D; Faridpur Med. Coll. J. Jul 2019;14(2): 100-103

Safety and Functional Integrity of Continuous Glucose Monitoring Components After Simulated Radiologic Procedures.

Background:We investigated wearable components of the Dexcom G6 continuous glucose monitoring (CGM) System in simulated therapeutic and diagnostic radiologic procedures.Methods:G6 transmitters were loaded with simulated glucose data and attached to sensors. Sets of sensor/transmitter pairs were exposed to x-rays to simulate a radiotherapeutic procedure and to radiofrequency (RF) and magnetic fields to simulate diagnostic magnetic resonance imaging (MRI). The x-ray simulation provided a cumulative dose of 80 Gy. The MRI simulation used RF fields oscillating at 64 or 128 MHz and magnetic fields of 1.5 or 3 T. During the MRI simulation, displacement force, induced heating, and induced currents were measured. After the simulations, bench tests were used to assess data integrity on the transmitters and responsiveness of sensors to various concentrations of aqueous glucose.Results:Glucose concentrations reported by sensor/transmitter pairs after undergoing x-irradiation or a simulated MRI exam were similar to those from control (unexposed) devices. During the 3 T MRI simulation, the devices experienced a displacement force of 306 g, which was insufficient to dislodge the sensor/transmitter from the substrate, RF-induced heating of <2°C, and an induced current of <16 pA. Data stored on the transmitters prior to the MRI simulation remained intact.Conclusion:Wearable components of the G6 CGM System retain basic functionality and data integrity after exposure to simulated therapeutic and diagnostic radiologic procedures. The devices are unlikely to be affected by x-irradiation used in typical imaging studies. Simulated MRI procedures create displacement force, minimal heating, and current in sensor/transmitter pairs.

Patient Radiation Dose in Neurointerventional Radiologic Procedure: A Tertiary Care Experience.

PurposeNeurointerventional radiology procedures often require a long time to perform. Patient radiation dose is an important issue due to the hazards of ionizing radiation. The objective of this study was to measure the peak skin dose (PSD) and effective dose to estimate the deterministic and stochastic effects of a therapeutic interventional neuroradiologic procedure.Materials and MethodsThe cumulative dose (CD) and dose area product (DAP) were automatically recorded by a fluoroscopic machine and collected prospectively between April and November 2015. The study included 54 patients who underwent therapeutic neurointerventional radiology procedures. The CD of each patient was used to estimate the peak skin dose and the DAP was also calculated to estimate the effective dose.ResultsThe average estimated peak skin dose was 1,009.68 mGy. Two patients received radiation doses of more than 2 Gy, which is the threshold that may cause skin complications and radiation-induced cataract. The average effective dose was 35.32 mSv. The majority of patients in this study (85.2%) who underwent therapeutic neurointerventional radiologic procedures received effective doses greater than 20 mSv.ConclusionNot all therapeutic neurointerventional radiology procedures are safe from deterministic complications. A small number of patients received doses above the threshold for skin complications and radiation induced cataract. In terms of stochastic complications, most neurointerventional radiology procedures in this study were quite safe in terms of radiation-induced cancer.

ESTIMATION OF RADIATION EXPOSURE TO THE PATIENTS IN DIAGNOSTIC AND THERAPEUTIC INTERVENTIONAL PROCEDURES.

The present work reports data of the radiation exposure to the patient in various diagnostic and therapeutic interventional radiological (IR) procedures. The study includes 260 diagnostic and 195 therapeutic exposure data in 455 IR procedures. All the IR procedures were performed on a biplane angiographic machine in a tertiary care hospital. The radiation exposure was estimated from dose-area product (DAP), fluoroscopy time (FT), number of fluoroscopic runs, number of images and cumulative dose (CD) value recorded during the procedure. The data reported in the present study show significant variability in DAP values in diagnostic and therapeutic IR procedures. In diagnostic procedures, the minimum median DAP value is 8.93 Gy cm2 for upper limb angiography with mean FT of 2.7 min and maximum DAP value is 108.8 Gy cm2 for inferior vena cava angiography with mean FT of 12.55 min. For therapeutic procedures, the median value of DAP ranges from 2.43 Gy cm2 for sclerotherapy with mean FT 0.65 min to 267.23 Gy cm2 for coiling of cerebral aneurysm with mean FT of 60.52 min. The DAP value for each procedure was also correlated with FT, number of fluoroscopic runs, number of images and CD. The reported DAP values in this study are within the range of earlier published results which suggest that our finding provides at least approximate applicability to other hospitals. The third quartile DAP values of the procedures having significant number of patient data (n ≥ 10) serves as provisional reference values for the optimization of procedure protocols.

Entrance surface dose and induced DNA damage in blood lymphocytes of patients exposed to low-dose and low-dose-rate X-irradiation during diagnostic and therapeutic interventional radiology procedures

The ionizing radiation received by patients and health workers due to radiological imaging may increase the risks of radiation effects, such as cancer and cataracts. We have investigated the dose received by specific areas around the head and related this to DNA damage in the blood lymphocytes of subjects exposed to interventional imaging. The entrance surface doses (ESD) to the forehead, neck, and shoulder were measured with a thermoluminescence dosimeter (CaSO4 disc or polycrystalline powder of lithium tetraborate doped with Mn) and compared with that of dose area product (DAP). DNA damage was measured by γ-H2AX, p53ser15, chromosomal aberration (CA), and micronucleus (MN) assays in lymphocytes of patients (n=75), before and 2 and 24h after exposure. The measured ESD values were 230.5±4.9, 189.5±3.55 and 90.7±3.4mGy for the forehead, neck, and shoulder, respectively. The DAP varied from 1.8 to 2047 Gy*cm2, showing a correlation with fluoroscopy time (r=0.417). Received doses did not increase early markers of DNA damage (γ-H2AX and p53ser15 assays), but residual damage (CA and MN frequencies) showed a significant (p<0.001) increase at 2 and 24h post-exposure compared to pre-imaging, despite poor correlation with DAP (r=0.1). Our results show that interventional imaging procedures deliver significant radiation doses and induce measurable DNA damage in lymphocytes of subjects, highlighting the need for rigorous patient safety protocols.

Commentary: Minimising intraoperative exposure of ionising radiation to anaesthesiologists.

The anaesthesiologists and radiologists constitute the high-risk personnel getting exposure to radiation during diagnostic and therapeutic radiological procedures.[1] It has become the need of the hour for the anaesthesia providers to be in close contact with the patient both inside and outside the operative room. The unit of radiation is known as grey (Gy) (1 Gy = 100 rad) and when absorbed that dose is termed as Sievert (Sv). The dose limit for the exposure stays in the range of 150Sv-500Sv/year.[2] Multiplying and metabolically active cells are most sensitive to radiation hazards. The exposure hazards range from the simplest skin injury and cataract to the most lethal hazard, malignancy.[3] The harmful effect of radiation is more pronounced in pregnant women when the exposure is continuous, and more intense with dose greater than 0.5 Gy.[4] Monitoring at the thyroid collar, inside and outside the protective gear of lead apron is advisable for all staff.[5] The education and awareness about the risk involved, care that needs to be exercised are to be highlighted to all the susceptible health care personnel. The infrastructure plan and safe positions so as to minimise the effects are to be understood.[6] The basic principle of prevention such as limiting the time of exposure keeping a safe distance and use of proper protective shield should be strictly adhered to.[7] Since the radiation beam is most often directed perpendicularly, the anaesthesiologists when standing at head end of the patient, may receive lesser dose of radiation. Hence proper positioning of anaesthesiologist is essential to minimize the risk of radiation. Anaesthesia workstation could be used as an additional shield by rotating it to 180° such that the back of the equipment is facing the operative field thus giving the anaesthesiologist an additional cover.[8]

Radiation Dose During Coronary Angiogram: Relation to Body Mass Index

Ionising radiation based diagnostic and therapeutic cardiology and radiology procedures are very common in present day medical practice and are one of the largest medical sources of radiation to humans. The risk to health from radiation has been extensively documented. Obesity is becoming epidemic not only in the western world, but also in developing countries. In the present study we investigated if a patient's Body Mass Index (BMI) has an effect on the radiation dose received by the patient and operator during diagnostic coronary angiography (CAG). We analysed data of 3678 consecutive patients who underwent CAG from September 2007 to April 2010 in our cardiac catheter laboratory. Trans-radial access was used in 622 patients, whereas 3056 patients underwent CAG through trans-femoral route. We calculated the radiation dose in dose area product (DAP) units and correlated it with body mass index, screening time, procedure time, contrast volume, vascular access route and individual operator. Among the explored parameters, body mass index had the most significant association with the radiation dose during the procedure. Despite having similar procedure times and contrast doses, patients with increased BMI received much higher radiation dose during CAG. We also found the left anterior oblique (LAO) caudal and LAO cranial views produced the biggest increase in radiation dose in patients with a high BMI. There was no inter-operator variability. Obese patients require more than double the radiation dose in comparison to those with normal BMI. The operator should be aware of the increased dose of radiation required when performing CAG in patients with increased BMI, and especially in LAO cranial and caudal views.

Delay to Therapeutic Interventional Radiology Postinjury: Time Is of the Essence

Hemorrhage remains a leading cause of early death in injured patients, and definitive control of bleeding remains a fundamental principle of trauma management. Therapeutic interventional radiology (IR) procedures have increasingly become essential in the acute management of traumatic injury. The importance of time to control of hemorrhage for therapeutic IR procedures has not been adequately characterized. A retrospective analysis was performed by using data derived from the National Trauma Data Bank, version 7.1. Inclusion criteria included the following: adult, hypotensive patients, scene admission, patients who underwent early therapeutic IR vascular occlusive procedures within in 3 hours of admission at a level I or II designated trauma center (n = 1,748). Exclusion criteria included intracranial or venous occlusion procedures, patients who underwent any abdominal, thoracic, vascular, or intracranial operative procedures throughout their entire hospital stay. Logistic regression analysis was used to analyze the independent mortality risk associated with DELAY to IR procedures after controlling for important confounders. The majority of patients who died did so within the first 48 hours from injury (80%). Regression analysis revealed that DELAY to IR was independently associated with more than a twofold higher risk of mortality (odds ratio 2.7, 95% confidence interval 1.6-4.9, p < 0.001). For every hour delay, the risk of mortality increased by 47%. These findings were independent of injury mechanism and most pertinent to level I trauma centers. In hemodynamically unstable trauma patients undergoing therapeutic catheter-based IR procedures, delay to IR was independently associated with more than a twofold higher risk of mortality. These results suggest that therapeutic IR procedures should be performed as expeditiously as possible and held to the same dogma as applied to definitive operative control of hemorrhage.

Controlling radiation exposure during interventional procedures in childhood cancer patients

Many pediatric cancer patients undergo multiple diagnostic and therapeutic radiologic procedures over the course of their illnesses and are therefore at high risk for radiation exposure. There are a variety of measures that radiologists can employ to reduce this risk. These include limiting the use of radiation whenever possible, using specific strategies to reduce radiation exposure during interventional procedures, using quality assurance programs to ensure compliance, and maintaining continuing staff radiation safety educational programs. Some of the diagnostic and therapeutic interventional radiologic procedures that are performed in pediatric oncology patients are discussed here, along with specific tips for managing radiation exposure.

Trends and future needs in clinical radiology: Insights from an academic medical center

Objective Advances in technology, expanding indications and defensive medical practice, in combination with population aging, have all contributed to a substantial increase in utilization of imaging and therapeutic radiology procedures in recent years. Moreover, the integration of education, innovation and research into high-volume workflow, although challenging, is a key requirement in teaching hospitals. Therefore, identifying forthcoming demand in the use of radiology services at a referral center might be of special interest and facilitate health policy planning in this context. Methods Data regarding conventional radiographic, ultrasonographic and computed tomography (CT) investigations, radiotherapy sessions, and interventional procedures were collected for a 5-year period (2000–2004). Based on these observations, we deployed appropriate models to forecast utilization rates in 2005–2009. Results Between 2000 and 2004, ultrasound examinations increased by 31.8%, mammography by 31.6%, CT scans by 17.4%, interventions by 14.5% and radiotherapy sessions by 13.9%, while conventional investigations decreased by 42.5%. We identified significant increasing trends for ultrasound, mammography, CT and interventions (all p < 0.001 for linear component). Compared to current levels, the workload for these modalities is expected to rise in the next 5 years by 43%, 31%, 20% and 14%, respectively. Radiotherapy sessions demonstrate an unstable, non-significant increasing trend ( p = 0.189), while utilization of conventional radiography declines rapidly ( p < 0.001 for linear trend, 5-year prediction −51%). Conclusions In forthcoming years, the demand for radiology services at referral centers will increase substantially. Advances in digital technology alone will not suffice to completely alleviate the need for additional resources and well-trained personnel.

Gastrointestinale Blutung

Modern imaging modalities such as (multislice) helical CT allow new diagnostic strategies for gastrointestinal hemorrhage. Today, interventional radiology with superselective transcatheter embolization or TIPS procedures allow minimally invasive therapeutic management which can support or replace surgery. This review is a synopsis of the possibilities and relative merits of diagnostic and therapeutic radiological procedures for gastrointestinal bleeding. Which of them to use should be decided collaboratively by gastroenterologist, surgeon, and radiologist depending on local availability, personal experience, and individual patient factors.

The role of interventional radiology for complications of cholecystectomy

Abstract This report summarizes diagnostic and therapeutic radiologic procedures in 45 patients who suffered major complications from cholecystectomy. Complications were divided into (1) bile duct injury or ligation and (2) a variety of pathologic fluid collections. Specific lesions were bile duct injury (n = 6), accidental bile duct ligation (n = 12), ductal stricture (n = 12), abscess (n = 11), biloma (n = 7), hematoma (n = 5), infected pancreatic pseudocyst (n = 3), and stones (n = 2). Presenting problems were sepsis, jaundice, and intermittent cholangitis. The patients underwent 104 interventional radiologic procedures including 29 percutaneous transhepatic cholangiograms, 21 percutaneous biliary drainages, 12 balloon dilatations of strictures, drainage of 11 abscesses, 8 bilomas, 5 hematomas, and 3 pancreatic pseudocysts. Stones were removed by baskets in 2 patients; 12 pressure and perfusion studies were performed. One hundred of 104 procedures were successful; there was one failed biliary drainage, one unsuccessful stricture dilatation, one unsuccessful hematoma drainage, and one recurrent biloma. Thirty patients were spared another operation. The percutaneous procedures were beneficial although not curative in 14 of 15 patients who underwent reoperation; in those patients the procedures helped to establish a diagnosis, improve the patient's preoperative status, or serve as a landmark for the surgeon to locate and repair the ligated or injured duct. One patient died after reoperation, a 2.2% mortality rate. Sectional imaging studies combined with interventional radiologic procedures help to diagnose promptly and effectively treat major complications of cholecystectomy. These interventional procedures either cure the complication and obviate reoperation or aid the surgeon by relieving sepsis and jaundice before reoperation and providing an intraoperative guide for bile duct reconstruction. (SURGERY 1990;W7:632–8.)

Utilization of Radiology Services in the United States: Levels and Trends in Modalities, Regions, and Populations

To assess the most recent available data for levels and trends in utilization of radiology procedures across populations, modalities, and geographic areas. Aggregated claims data from Medicare enrollees for all radiology procedures and from the Medical Expenditure Panel Survey (MEPS), a nationally representative survey of almost 25 000 Americans, for some radiology procedures, were used to calculate population-based utilization for the relevant age groups. Limited private insurer data also were obtained. All radiology utilization was measured and reported, irrespective of provider specialty. Average levels and percentiles of utilization were measured according to modality, and average annual rates of increase in utilization were compared across modalities, data sources, and regions. Rates of increase in utilization according to modality and state were compared for correlation with state characteristics and initial utilization levels. In 2001, 4176 diagnostic and 274 therapeutic radiology procedures were performed per 1000 Medicare non-managed care enrollees. Nearly one-half of diagnostic procedures (n=2057) involved radiography. The other half involved computed tomography (CT) (n=391), magnetic resonance (MR) imaging (n=114), ultrasonography (US) (n=921), interventional radiology (n=215), mammography (n=221), and nuclear medicine (n=249). On average, between 1998 and 2001, utilization per Medicare enrollee increased 16% per year for MR imaging and 7%-15% per year for CT, US, interventional radiology, and nuclear medicine, while that for radiography increased 1% per year. The proportion of diagnostic radiology procedures performed in ambulatory settings increased from 62% in 1992 to 68% in 2001. There was wide variation across states in utilization by Medicare enrollees. State totals for diagnostic radiology were 3038 in the 10th percentile and 4573 in the 90th percentile. In 1999, MEPS reported average utilization in ambulatory settings as follows: 64 MR imaging, 102 US, 73 mammographic, 326 radiographic, and 43 radiation therapy procedures per 1000 persons (all ages) in the U.S. population. Utilization of high-technology modalities increased rapidly, while that of radiography was relatively stagnant. Variation in utilization among states and census regions was substantial.

Emergency Management of Variceal

Variceal haemorrhage is a life-threatening condition requiring prompt emergency therapy. This paper summarises the key aspects of management of this condition in the acute setting, including airway management, fluid resuscitation, and pharmacotherapy. The value of therapeutic endoscopy, balloon tamponade and radiological shunt procedures are also highlighted.

The volume and cost of radiologic services in the United States in 1990.

Knowing the total number of radiologic services provided in the United States and their cost is important. This information can, for example, indicate the opportunities available to a radiology practice considering opening a new office or show whether high-technology radiology is, as is widely assumed, an important factor in United States health costs. However, neither the total number of procedures nor their cost is known. We developed two largely independent estimates of each total (one based principally on surveys of radiologists, the other on Medicare data) to cross-validate the estimates and provide an indication of their uncertainty. We estimate that 260-330 million radiologic procedures were performed in the United States in 1990 (including both diagnostic and therapeutic procedures and radiologic procedures performed by nonradiologists) and that payments for these services totaled $19 to $22 billion (including payments for technical components in the hospital setting). This total was approximately 3.5% of national spending on personal health care; high-technology radiology totaled less than half of this amount. The procedures numbered 1.0-1.3 per capita annually, an increase of some 10-40% since 1980. Of the spending total, $10 to $12 billion was paid to physician practices, with a substantial portion of this amount going ultimately to practice expenses, particularly in the office setting. Our results suggest that spending on high-technology radiology is too small to be a major explanation for the current level of health costs in the United States.

Development of radiation protection standards.

Radiation protection standards are based on the best available knowledge, caution, and perception. Dose limits for occupational exposure have decreased as knowledge was gained about radiation effects: from 0.6 Sv (60 rem)/year for 1900-1930 to 50 mSv (5 rem)/year in 1958 (the level still used as of 1990). Current dose limits for public exposure range from 1 mSv to 5 mSv, depending on frequency of exposure. For the embryo and fetus, dose limits are 0.5 mSv/mo and 5 mSv for the entire gestation. In the 1970s, the concept of acceptable risk and that of a non-threshold dose-response relationship became the basis for setting dose limits. Three principles of radiation protection are that (a) dose levels should not exceed acceptable levels, (b) optimal dose levels should be as low as reasonably achievable, and (c) radiation should not be used unless it produces a positive net benefit. Although no dose limits have been set for patients undergoing diagnostic and therapeutic radiologic procedures, such measures must provide a net benefit to patients at optimal dose levels.