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Radiation Safety and Shielding in Radiotherapy

10.1 Introduction The National Council on Radiation Protection (NCRP) Report No. 116, Limitation of Exposure to Ionizing Radiation, outlines the goals and philosophies of radiation protection in Chapter 2 of that document. The specific objectives are: 1. “To prevent the occurrence of clinically significant radiation-induced deterministic effects by adhering to dose limits that are below the apparent threshold levels and 2. “To limit the risk of…

Proton Radiotherapy

9.1 Introduction First proposed by Robert Wilson in 1946, radiation therapy with proton beams quickly became a reality with the first patient treatments performed in 1954 at Lawrence Berkeley National Labs. Starting in 1961 the Harvard Cyclotron Lab began treating patients (and continued up to 2002), and in 1990 the first hospital-based system became operational at Loma Linda University Medical Center, California, which featured the first…

Brachytherapy

8.1 Introduction Brachytherapy is defined as the temporary or permanent application of small, sealed radioactive sources in close proximity to or within the target volume. The treatment dose distribution is characterized by localized high dose and a steep dose drop-off. Soon after radium was first chemically isolated by Marie and Pierre Curie, the effects of radiation damage on skin were observed and led to the earliest…

Image Guidance and Localization Technologies for Radiotherapy

7.1 Introduction A key component of safe and effective modern radiotherapy is the ability to align a patient with respect to the radiation beam during treatment. Current means of accomplishing this include 3D visualization of soft tissue structures (via computed tomography (CT) or ultrasound and soon magnetic resonance imaging (MRI)), 2D or 3D localization of bony landmarks or fiducials (planar kV/MV images or implanted marker tracking),…

Immobilization Techniques in Radiotherapy

6.1 Introduction Proper immobilization techniques accomplish a variety of clinical goals including the following: ▪ Reduce patient motion and improve day-to-day reproducibility of setup. External beam treatments typically require several tens of minutes to complete, and during this time the operator is essentially blind to any motion of the patient or tissue with notable exceptions (e.g., orthogonal fluoroscopic imaging, 3D surface mapping, or combination magnetic resonance…

Quality Assurance of Radiotherapy Dose Calculations

5.1 Introduction In modern radiotherapy the vast majority of dose calculations are performed by computerized systems. There may be minor exceptions such as radiopharmaceuticals used in nuclear medicine. The system may calculate all or some of the following: point doses, 2D isodoses, 3D isodoses, and doses to volumes. In addition, a whole host of nondosimetric information may be used to inform clinicians as to the quality…

Ten Great Cases

Challenge Each case tests your ability to apply the fundamental principles we have just gone over and over. Suggestions 1 Read the history. 2 Evaluate the x-ray with your routine scanning pattern (ATMLL—Are There Many Lung Lesions?), making all the pertinent observations. 3 Then, and only then, answer all questions before you turn to the answers. Beware of “satisfaction of search.” There is a tendency when…

Unknown Cases: The Ultimate Challenge—For Radiology Residents and Hard Chargers

These quizzes were set up in the prior edition to simulate the oral boards in radiology. The oral boards have been discontinued, but you may find it interesting to “work against the clock.” These cases are more difficult and should be a challenge for radiology residents. If you are not a radiologist, try them or go out for a beer. Instructions There are three sections (A,…

Interstitial Lung Disease: A Picture Book

This is an expanded version of material presented in earlier chapters. Interstitial disease is a difficult challenge for both radiologists and clinicians. Figure S2.1 Open full size image Open full size image Open full size image Open full size image Normal Comments Note that the pulmonary vessels are the only structures seen within the air-filled lung. They branch, taper, and are barely visible as they reach…

Nonskeletal Pediatric Imaging

Pediatric musculoskeletal imaging was covered in a special section at the end of Chapter 8 . Congenital cardiac lesions were covered in Chapter 5 . Table 9.1 shows the appropriate imaging tests for common pediatric problems. TABLE 9.1 Imaging of Pediatric Problems Suspected Problems Imaging Tests of Choice Neonatal hydrocephalus or intracranial hemorrhage Cranial US Seizure Neonatal Cranial US Uncomplicated febrile seizure No imaging needed Neurologic…

Skeletal System

Introduction Fractures and other abnormalities involving the skull and face were covered in Chapter 2 . Initial imaging studies for a number of clinical problems are presented in Table 8.1 . A few general comments should be made about the structure of bone. Most bones consist of a densely calcified cortex, or shell, that surrounds the medullary space. The medullary space contains either active (red) marrow…

Genitourinary System and Retroperitoneum

Anatomy and Imaging Techniques The urinary system may be imaged in a number of ways. The initial studies of choice for many suspected clinical problems are shown in Table 7.1 . Historically, the most common radiographic method was intravenous injection of an iodine-based contrast agent followed by a series of radiographs (intravenous pyelogram [IVP]). IVP has been replaced by computed tomography (CT) scanning, with or without…

Gastrointestinal System

Introduction Imaging Techniques and Anatomy The most common imaging study of the abdomen is referred to as a KUB, or plain image of the abdomen. The term KUB is historical nonsense. It stands for k idney, u reter, and b ladder, none of which is usually seen on a regular x-ray of the abdomen; nevertheless, the term remains widely used. A KUB is usually done with…