**1. Introduction**

Because of its low incidence, the risk of patient exposure to ionizing radiation is often underestimated—and underappreciated—as a patient safety (PS) threat across various healthcare settings. Consequently, the Joint Commission mandates that hospitals prepare for managing radiation-related risks in terms of protecting patients from unnecessary exposure, limiting any associated potential damage, monitoring the types and extent of radiation, and maintaining proficiency in decontamination procedures in cases of direct radioactive isotope contact [1, 2]. In terms of everyday healthcare facility functioning, there is a dual focus to ensure that radiation safety standards are met: (a) avoidance of unnecessary exposure including improper dosing and (b) assurance that radioactive material will be properly handled and disposed [2].

approximate incidence of adverse effects at various levels of radiation exposure (measured in Rads). In addition, comparative descriptions of alternative radiation units of measure are provided for the reader in the lower section of **Table 1**. The latter measure is intended to reduce the confusion often encountered due to multiple naming conventions in this area of science. An important distinction must be made between radiation exposure and radioactive contamination. Radiation exposure refers to a person receiving energy in the form of waves or particles from an external source or from internal contamination [9, 10]. To prevent harm to the patient, the duration of exposure is carefully controlled. To prevent harm to the radiology technician, distance and shielding from source are employed [11, 12]. In contrast, a contaminated person has radioactive material on (or inside) the body secondary to ingestion, inhalation or deposition on the body surface. Thus, contamination can be classified as internal or external. Most patients exposed to radiation are not contaminated [13]. Radiation can be measured in SI unit Gray (Gy), which represents the absorption of one joule of radiation energy per kilogram of matter. In order to reflect the degree of radioactive contamination in human tissue, the unit of Sievert (Sv) us usually employed. The following clinical vignettes will illustrate both radiation exposure (#1) and contamination (#2 and #3). For the purposes of our chapter, the reader should be familiar with the three general types of radiation, including the associated energetic characteristics and shielding capacity (**Table 2**). In addition, various levels of radiation exposure (measured in millisieverts) including the

Fundamentals of Medical Radiation Safety: Focus on Reducing Short-Term and Long-Term…

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57

Over a period of months, numerous patients who underwent computed tomography (CT) perfusion scans of the brain at different hospitals across a wide geographic area reported vague complaints of oddly shaped patterns of unexpected hair loss. Reportedly, the mostly band-like areas of alopecia appeared within 1–2 weeks following each patient's CT study. Some patients began complaining of new onset memory loss and/or difficulty keeping balance while walking. Given the unusual pattern of clinical signs and symptoms, as well as the isolated nature of occurrences, it took months before the connection was made between CT perfusion scans and what turned out to be significant radiation overdoses. When the true scope of the problem became evident, hundreds of patients were identified as having received approximately eight times the expected levels of radiation. It appeared that the root cause for the above occurrences may be faulty programming of CT scanner devices. A nationwide statement of caution was issued by the FDA, urging hospitals across the US to

**Type of radiation Penetrating energy Penetrating capacity in human body Shielding capacity** Alpha (α) Low Epidermis Dissipates in air Beta (β) Intermediate Soft tissue Sheet of paper

**Table 2.** Types of ionizing radiation, with corresponding levels of penetration and preferred shielding characteristics.

Gamma (γ) High Bones and organs Lead

typical associated contextual settings are shown in **Figure 1**.

**1.1. Clinical vignette #1**

Regardless of the details or the mode of delivery, the intent of the treating team should always be the reduction in both short- and long-term radiation exposures [3]. It has been recommended by different organizations and authors that radiation exposure reduction (RER) efforts encompass both pre-procedural and procedural phases of treatment [4, 5]. The use of radiation for diagnostic or therapeutic indications (RDTI) has clear benefits when appropriately directed and supervised. However, serious errors, prolonged or repeated exposures, and lack of supervision can be associated with significant adverse consequences, including the risk of acute radiation sickness, malignancy, and death [6–10]. **Table 1** [top section] lists the


**Table 1.** Approximate incidence of adverse effect at different radiation exposures measured in Rads.

approximate incidence of adverse effects at various levels of radiation exposure (measured in Rads). In addition, comparative descriptions of alternative radiation units of measure are provided for the reader in the lower section of **Table 1**. The latter measure is intended to reduce the confusion often encountered due to multiple naming conventions in this area of science.

An important distinction must be made between radiation exposure and radioactive contamination. Radiation exposure refers to a person receiving energy in the form of waves or particles from an external source or from internal contamination [9, 10]. To prevent harm to the patient, the duration of exposure is carefully controlled. To prevent harm to the radiology technician, distance and shielding from source are employed [11, 12]. In contrast, a contaminated person has radioactive material on (or inside) the body secondary to ingestion, inhalation or deposition on the body surface. Thus, contamination can be classified as internal or external. Most patients exposed to radiation are not contaminated [13]. Radiation can be measured in SI unit Gray (Gy), which represents the absorption of one joule of radiation energy per kilogram of matter. In order to reflect the degree of radioactive contamination in human tissue, the unit of Sievert (Sv) us usually employed. The following clinical vignettes will illustrate both radiation exposure (#1) and contamination (#2 and #3). For the purposes of our chapter, the reader should be familiar with the three general types of radiation, including the associated energetic characteristics and shielding capacity (**Table 2**). In addition, various levels of radiation exposure (measured in millisieverts) including the typical associated contextual settings are shown in **Figure 1**.

#### **1.1. Clinical vignette #1**

**1. Introduction**

56 Vignettes in Patient Safety - Volume 4

disposed [2].

Because of its low incidence, the risk of patient exposure to ionizing radiation is often underestimated—and underappreciated—as a patient safety (PS) threat across various healthcare settings. Consequently, the Joint Commission mandates that hospitals prepare for managing radiation-related risks in terms of protecting patients from unnecessary exposure, limiting any associated potential damage, monitoring the types and extent of radiation, and maintaining proficiency in decontamination procedures in cases of direct radioactive isotope contact [1, 2]. In terms of everyday healthcare facility functioning, there is a dual focus to ensure that radiation safety standards are met: (a) avoidance of unnecessary exposure including improper dosing and (b) assurance that radioactive material will be properly handled and

Regardless of the details or the mode of delivery, the intent of the treating team should always be the reduction in both short- and long-term radiation exposures [3]. It has been recommended by different organizations and authors that radiation exposure reduction (RER) efforts encompass both pre-procedural and procedural phases of treatment [4, 5]. The use of radiation for diagnostic or therapeutic indications (RDTI) has clear benefits when appropriately directed and supervised. However, serious errors, prolonged or repeated exposures, and lack of supervision can be associated with significant adverse consequences, including the risk of acute radiation sickness, malignancy, and death [6–10]. **Table 1** [top section] lists the

**Side effect Frequency Minimum exposure amount (Rads)**

Hyperpigmentation/erythema >50% 50–200 Mild fatigue >50% 50–200 Mild myelosuppression >50% 50–200 Skin desquamation <10% 100 Mild nausea/vomiting/diarrhea <10% 100–400 Intractable vomiting/diarrhea 90% >400

**Comparison of alternative units of measure Conversion factor**

1 Millicoulomb/kg 3.876 Roentgen\* 1 Microcoulomb/kg 0.003876 Roentgen\*

**Table 1.** Approximate incidence of adverse effect at different radiation exposures measured in Rads.

1 Tissue Roentgen 1 Roentgen

kg = kilogram; Sv = Sievert; \* = same applies for Parker and Rep units.

1 Rad 0.01 Joule/kg; 0.01 Gray; 0.01 Sv

1 Millirad 0.00001 Joule/kg; 0.00001 Gray; 0.00001 Sv 1 Milligray; 1 Centigray; 1 Decigray; 1 Dekagray 0.1; 1; 10; 1000 Rads, etc. (respectively) 1 Coulomb/kg 3876 Roentgen; 3875 Parker; 3875 Rep

Over a period of months, numerous patients who underwent computed tomography (CT) perfusion scans of the brain at different hospitals across a wide geographic area reported vague complaints of oddly shaped patterns of unexpected hair loss. Reportedly, the mostly band-like areas of alopecia appeared within 1–2 weeks following each patient's CT study. Some patients began complaining of new onset memory loss and/or difficulty keeping balance while walking. Given the unusual pattern of clinical signs and symptoms, as well as the isolated nature of occurrences, it took months before the connection was made between CT perfusion scans and what turned out to be significant radiation overdoses. When the true scope of the problem became evident, hundreds of patients were identified as having received approximately eight times the expected levels of radiation. It appeared that the root cause for the above occurrences may be faulty programming of CT scanner devices. A nationwide statement of caution was issued by the FDA, urging hospitals across the US to


**Table 2.** Types of ionizing radiation, with corresponding levels of penetration and preferred shielding characteristics.

of the highly radioactive cesium-137 was accidentally smashed, along with its lead enclosure, liberating "shiny bluish dust which glowed in the dark" [17]. Unaware of the danger, numerous individuals associated with the scrap metal yard owner came into contact with the radioactive powder. The most seriously affected victims developed alopecia, cutaneous burns, vomiting and diarrhea. The governmental response was slow at first, due mainly to the lack of recognition of the magnitude and the urgency of the situation. Experts from the Soviet Union and the US were involved in the subsequent management and containment of the radioactive risk. The incident was thought to be the most serious of its kind at the time, with 240 documented cases of contamination, 20 hospitalizations, and 4 fatalities [17, 18].

Fundamentals of Medical Radiation Safety: Focus on Reducing Short-Term and Long-Term…

http://dx.doi.org/10.5772/intechopen.85689

59

In 1992, an unexpected discovery of radioactive waste was made by a regional disposal company in Indiana, Pennsylvania [9, 19]. Subsequent investigation by the US National Regulatory Commission (NRC) found that in November of 1992, a local clinic in Indiana, Pennsylvania treated a patient with high-dose brachytherapy using an iridium-192 radioactive source [20]. It was determined that the treatment was not completed due to equipmentrelated issues. Unknown to the operators, the source wire became fractured and remained in the patient. Investigators discovered that the required radiation survey at the end of the treatment was not performed. The patient was discharged to a nursing home and died 5 days later. Unaware of the danger, nursing home staff removed the source-containing catheter and disposed of it as biohazardous waste [9]. The source was identified during routine radiation surveillance by the waste disposal company. In addition to being a contributor to the index patient's death, more than 90 individuals may have been exposed to the radioactive material,

Difficult to identify at the time of the initial exposure, radiation injury tends to present in a delayed fashion. Radiation injury also tends to be low on a typical differential diagnosis list as most cases tend to involve unintentional (and unrecognized) exposure. As demonstrated by our three vignettes, the uncommon occurrence of harmful medical radiation exposure (HMRE) can originate as a result of various types of PS error; both of omission and of commission [21]. In addition, radiation-related PS issues can result from lack of adequate oversight at both institutional level (e.g., absent safety procedures) and governmental level (e.g., lack of

Complexities associated with HMRE prompted an important discussion regarding the nature and the content of the informed consent process, specifically as it relates to medical radiation exposure [24]. The true gravity of such considerations is exemplified by the known association between cumulative radiation exposure and the incremental risk of malignancy following repeated CT imaging episodes [25]. Moreover, compared to the adult population, the

**1.3. Clinical vignette #3**

with doses ranging from <0.05 to >2.55 rem [20].

**2. The magnitude of the "silent" problem**

applicable laws, regulations, or enforcement) [9, 22, 23].

overall risk is significantly greater for pediatric patients [26].

**Figure 1.** Different levels of radiation exposure, measured in millisieverts (mSv) and the associated biological manifestations.

review institutional CT scan logs to check radiation dosage levels and data regarding applicable adherence to established dosing protocols [14, 15]. In response to the above events, the first state law in the US aimed at protecting patients from excessive radiation exposure during CT scans was signed into law by Gov. Arnold Schwarzenegger of California [16]. In addition to providing an accreditation mandate for CT scanners, the bill also requires that radiation dose be recorded on the scanned image in a patient's medical record, and that radiation overdoses be reported to patients, treating physicians, and the state Department of Public Health [16].

#### **1.2. Clinical vignette #2**

In 1987, improperly abandoned hospital radiation equipment in Goiania, Brazil, led to the contamination of a large number of people. During the post-incident review, it was discovered that an unused irradiation machine was left behind when a privately owned healthcare facility moved. The device was subsequently stolen by a group of young men who sold it to a scrap metal dealer. During the disassembly of the medical equipment, a broken capsule of the highly radioactive cesium-137 was accidentally smashed, along with its lead enclosure, liberating "shiny bluish dust which glowed in the dark" [17]. Unaware of the danger, numerous individuals associated with the scrap metal yard owner came into contact with the radioactive powder. The most seriously affected victims developed alopecia, cutaneous burns, vomiting and diarrhea. The governmental response was slow at first, due mainly to the lack of recognition of the magnitude and the urgency of the situation. Experts from the Soviet Union and the US were involved in the subsequent management and containment of the radioactive risk. The incident was thought to be the most serious of its kind at the time, with 240 documented cases of contamination, 20 hospitalizations, and 4 fatalities [17, 18].

#### **1.3. Clinical vignette #3**

review institutional CT scan logs to check radiation dosage levels and data regarding applicable adherence to established dosing protocols [14, 15]. In response to the above events, the first state law in the US aimed at protecting patients from excessive radiation exposure during CT scans was signed into law by Gov. Arnold Schwarzenegger of California [16]. In addition to providing an accreditation mandate for CT scanners, the bill also requires that radiation dose be recorded on the scanned image in a patient's medical record, and that radiation overdoses be reported to patients, treating physicians, and the state Department

**Figure 1.** Different levels of radiation exposure, measured in millisieverts (mSv) and the associated biological manifestations.

In 1987, improperly abandoned hospital radiation equipment in Goiania, Brazil, led to the contamination of a large number of people. During the post-incident review, it was discovered that an unused irradiation machine was left behind when a privately owned healthcare facility moved. The device was subsequently stolen by a group of young men who sold it to a scrap metal dealer. During the disassembly of the medical equipment, a broken capsule

of Public Health [16].

58 Vignettes in Patient Safety - Volume 4

**1.2. Clinical vignette #2**

In 1992, an unexpected discovery of radioactive waste was made by a regional disposal company in Indiana, Pennsylvania [9, 19]. Subsequent investigation by the US National Regulatory Commission (NRC) found that in November of 1992, a local clinic in Indiana, Pennsylvania treated a patient with high-dose brachytherapy using an iridium-192 radioactive source [20]. It was determined that the treatment was not completed due to equipmentrelated issues. Unknown to the operators, the source wire became fractured and remained in the patient. Investigators discovered that the required radiation survey at the end of the treatment was not performed. The patient was discharged to a nursing home and died 5 days later. Unaware of the danger, nursing home staff removed the source-containing catheter and disposed of it as biohazardous waste [9]. The source was identified during routine radiation surveillance by the waste disposal company. In addition to being a contributor to the index patient's death, more than 90 individuals may have been exposed to the radioactive material, with doses ranging from <0.05 to >2.55 rem [20].
