CORE CASE 1 WORKSHOP

Petra Lewis MDProfessor of Radiology and OBGYN

Geisel School of Medicine at Dartmouth

Learning objectives Understand the meaning of the silhouette and sign signs Understand how these concepts can be applied in the

diagnosis and localization of pneumonias See how viral pneumonias differ in appearance Describe how pleural effusions appear on chest

radiographs on different views Understand how the appearance of effusions varies in

empyema and hydropneumothorax Understand the factors affecting the risks of medical

radiation and how they can be reduced. Calculate the risks to a real patient from his medical

radiation exposure during a single clinical episode

What questions/difficulties did you have arising from the case

Pneumonias

Silhouette sign

RLL pneumonia

Pleural effusions

Pleural Effusions How much fluid do you need to see on

A PA CXR?A lat CXR?A supine CXR?A CT scan?

How else can you visualize pleural fluid? Characteristics of fluid vs consolidation?

Small effusions

Small effusions

Decubitus views

Supine pleural effusions

Radiation Risk

Radiation risk What factors affect how much risk

patients are at from medical radiation?

Relative risks of examsAXR

Barium enema

Bone scan

CT abdomen/pelvis

CT head

CT pulmonary angio

CXR (PA )

CXR (PA and lat)

Low dose CT chest

Lumbar spine

Mammogram

Myocardial perf

PET FDG scan

UGI

Wrist radiograph

Radiation Equivalents Average background = 3mSv

Study Period natural radiationWrist radiograph 0.1 d

CXR (PA ) 2 d

CXR (PA and lat) 12 d

Mammogram 2 mAXR 3 mLumbar spine 6 mLow dose CT chest 7 mCT head 8 mUGI 1.7 yBone scan 2.0 yBarium enema 2.7 yMyocardial perfusion 3.1 yCT abdomen/pelvis 4.7 yPET FDG scan 4.7 yCT pulmonary angio 5.0 y

Met

ter e

t al.

2008

, 248

, 254

-263

.

Case study HT abdominal CT27 year old with complicated pancreatitis

HT Radiology Studies 12/7/06-2/6/07

CXR 28

KUB 11

CT chest 1

CT head 1

CT abdo-pelvis 19

Fluoro 1 minute

What is his increased risk of dying of a malignancy due to his radiation exposure during this hospital stay?

How much radiation did HT receive?Scan # Exposure/scan

mSvTotal

CXR 28 0.02

KUB 11 1

CT chest 1 8

CT head 1 2

CT A/P 19 10

Fluoro 1 minute 0.1 /min

TOTAL

So our patient received an estimated dose of ? mSv

Cancer induction rates 8% fatal cancers per Sv (1000 mSv)

= % fatal cancers risk for HT

Fractionation reduces risk by 50%= % fatal cancers risk for HT

Younger patient (<40) doubles risk(much higher for young children)= % fatal cancers risk for HT

Cancer induction rates Lifetime risk of fatal cancer

24% males, 20% females= /24 x 100% increased risk of dying of a

cancer from his hospital exposure=

Note – his risk of developing any type of cancer is about twice this (fatal and non-fatal)

How can we reduce risk?

Appendix

Learning Objectives from CORE 1 Review CXR anatomy including the location of the lobes of the lung and their relationship to fissures Be introduced to the American College of Radiology (ACR) appropriateness criteria for imaging Learn the indications for chest imaging in patients presenting with upper respiratory tract infection

symptoms. Learn the radiographic presentations of typical alveolar pneumonias in different lobes of the lung. Understand the concepts of “silhouette sign” and “spine sign” and how they can be used to localize

abnormalities on chest radiographs. Understand the term “air bronchograms” and the significance of this sign. Learn how some tumors can appear similar on imaging to pneumonia. Be introduced to the typical radiographic appearance of PCP pneumonia, and other opportunistic and

atypical pneumonias and how they differ radiographically from typical bacterial and lobar pneumonias Understand the meaning and appearance of “ground glass” opacities on chest radiographs and CT

scans. Understand the use and limitations of portable radiographs in the ICU. Learn the imaging features of ARDS Acquire a basic understanding of patient radiation doses from common examinations and how we can try

to limit them. Learn the common imaging features of various types of pleural effusion including simple,

hydropneumothorax, empyema and loculated pleural fluid collections (“pseudotumors”). Understand how pleural fluid appears differently on erect and supine radiographs. Learn when image guidance can help in the drainage of pleural fluid.