State of Michigan Computed Tomography Regulations

1
State of MichiganComputed Tomography
Regulations
Radiation Safety Section

• Don Parry, CHP

2
Radiation Safety Section

• Scope of Authority Regulates use of machine
  produced ionizing radiation.
• Ionizing Radiation Rules of the State of Michigan
• Part 15. Computed Tomography Installations
• Effective June 8, 2011
• Rules, Guidance Document, and FAQs available at
• www.michigan.gov/rss

3
Why all of the regulatory scrutiny of Computed
Tomography?

• Two things have contributed to the increased
  attention to CT.
• 1. The utilization of computed tomography has
  increased over the years
• II. Publication of Recent CT Medical Events

4
Patient dose from CT was 3 of all medical
exposure in 1980s
5
It increased to 49 in 2006
6
CT is 17 of the studies, but contributes to 49
of patient dose
7
II. Recent Medical Errors
8
Topics of the New CT Rules

• Medical Physicist Requirements
• CT Operator Requirements
• Conditions of Operation
• Enclosures
• Report and notification of a CT medical events
• Quality control program

9
Rule 705 CT Operators

• Initial qualifications. Before beginning to
  perform CT examinations independently, a
  technologist shall meet both of the following
• Be currently registered by the American registry
  of radiologic technologists (ARRT) or by the
  Canadian association of medical radiation
  technologists (CAMRT). 

10
Rule 705 CT Operators

• Document at least 20 hours of training and
  experience in operating CT equipment, radiation
  physics, and radiation protection or have the
  advanced certification in computed tomography
  from the ARRT.

11
Rule 705 CT Operators

• Continuing education. A technologist shall be in
  compliance with the ARRT requirements for
  continuing education for the imaging modality in
  which he or she performs services. The
  continuing education shall include credits
  pertinent to CT.

12
Rule 713 Conditions of Operation

• (1) Six months after the effective date of these
  rules, the CT facility shall establish scanning
  protocols in consultation with a medical
  physicist.

13
Rule 713 Conditions of Operation

• (2) The CT operator shall check the display
  panel before and after performing each scan to
  make sure the amount of radiation delivered is
  appropriate for the technique and individual
  patient. This may be accomplished by reviewing
  dose indicator devices if available or dose
  indices such as the technique factors. Dose
  indicators or indices outside of expected values
  shall be documented and reviewed by an
  interpreting physician or medical physicist.

14
(No Transcript)
15
Notification Values
16
Computed Tomography Dose Index (CTDI)
17
CT Dosimetry Phantoms
18
Dose Indices

• CTDI100 -CTDI with integration limits of /- 50
  mm
• CTDI w (1/3 CTDI100 )center (2/3 CTDI100
  )periphery
• CTDI vol CTDIw / Pitch

19
Dose Length Product
20
Dose Length Product
21
ACR CTDI Reference Values

• CTDIvol is NOT patient dose
• CTDIvol is reported in units of mGy for either a
  16-cm (for head exams) or 32-cm (for body exams)
  diameter acrylic phantom
• For the same technique settings, the CTDIvol
  reported for the 16-cm phantom is about twice
  that of the 32-cm phantom

22
Rule 713 Conditions of Operation

• (6) Only individuals whose presence is necessary
  are allowed in a fixed CT scanner room during
  exposure. Each individual, except the patient,
  shall be protected by at least a 0.5 millimeter
  lead equivalent apron or a whole body protective
  barrier.

23
Rule 711(4) Enclosures

• The control panel for a fixed CT scanner shall be
  shielded by a protective barrier that cannot be
  removed from a protective position between the
  operator and the radiation source during machine
  operation.

24
Good example
25
Bad example
26
(No Transcript)
27
Rule 715 Report and notification of a CT medical
event

• Rule 715. (1) A CT facility shall report any CT
  medical event.

(c) CT medical event means an unintended event
where a physician determines that actual damage
has occurred to an organ or a physiological
system of an individual due to or suspected to be
due to exposure to diagnostic radiation from a CT
scanner
28
Alert Values
Alert Threshold - CTDIvol 1 Gy (half skin
injury dose) - FDA suggested
29
Rule 717 Quality control program

• (2) Evaluations and tests shall be performed
  following written procedures and methods.
  Corrective action shall be taken and documented
  according to instructions provided by the medical
  physicist if the results of an evaluation or test
  fall outside the control limits.

30
(No Transcript)
31
Example of Corrective Action

• If either the mean CT number or the noise
  (standard deviation) is not within the criteria
  limit for 3 days in a row or 3 times within a
  7-day period, corrective action should be taken
  by reporting the problem to service
  representatives.

32
Rule 717 Quality control program

• (3). An on-site CT radiologic technologist
  shall be identified to be responsible for the
  ongoing quality control testing. The tests shall
  be performed by this technologist or by other
  personnel qualified by training and experience
  following written procedures and methods under
  subrule(2) of this rule.

33
FAQs

• Question 8 To become certified with the ARRT in
  Radiography, the radiography education program I
  completed included training in radiation physics
  and radiation protection. Will this training
  cover the radiation physics and radiation
  protection portion of the required 20 hours of
  training?

34
FAQs

• If you are ARRT registered in Radiography,
  ARRT(R), and do not have the advanced certificate
  in CT, we will assume that you have had training
  in radiation physics and radiation protection but
  you will still need to document 20 hours of
  training and experience in operating CT
  equipment.

35
FAQs

• Question 9 We use a team of two technologists to
  perform CT scans. Do both technologists need to
  be qualified under the CT rules?

36
FAQs

• No. Only one technologist needs to be qualified.
  If a team approach is used where only one
  operator meets the qualifications under the
  rules, the qualified operator must be in the CT
  room during the examination. This is to provide
  reasonable assurance that any mistakes made by
  any technologist who does not meet the
  qualification requirements are corrected before
  patients are irradiated or harm is done to the
  patient.

37
Quiz

• Q1What percentage of medical exposures were from
  computed tomography in 2006?
• A 49
• Q2A patient undergoes a CT scan at a technique
  of 120 mAs, pitch of 0.7 and 120 kVp for a scan
  length of 10 cm and the patient dose is 10 mGy.
  What is the dose for a 20 cm scan length at the
  same technique?
• A 10 mGy

38
Quiz

• Q3The displayed CTDIvol for a pediatric abdomen
  was 15 mGy using a pitch of 1.0. What would the
  CTDIvol be at a pitch of 1.5?
• A 10 mGy
• The displayed CTDIvol for a pediatric abdomen was
  5 mGy for a 32 cm phantom. Approx. what would it
  be for the 16 cm phantom used to set reference
  levels by the ACR?
• A 10 mGy

39
QUESTIONS?

• Contact Information
• Donald E. Parry, MHP, CHP
• Region Physicist-Radiation Safety Section
• MIOSHA
• Phone [phone]
• e-mail parryd_at_michigan.gov
• rssinfo_at_michigan.gov
• www.michigan.gov/rss