deviation-policy creation presentation
TRANSCRIPT
QA Project #4Deviation/Policy Creation
Beth Ann McKinney04/04/2014
Deviation DetailsCBCT misaligned to the wrong vert body Date/Time: 08/16/2013 2:24 pmMachine: SL2Treatment Site: Left Lower Lung
◦Fraction 31Dose: 200 cGy daily x 37 fx = 7400 cGy
◦Dose Spec: VolumeModality: 6x PhotonsTechnique: IMRT (8 field)
DocumentationThe error was discovered by the imaging
specialist while reviewing images from the previous day
A deviation report was filled out by the imaging specialist who discovered it◦No med tech note was made since it was
discovered at a later time◦No further documentation by the therapist(s) is
necessary
Brief Patient History71 y/o male with hx of stage IIB Squamous Cell
Carcinoma of the Rt. upper lung treated surgically with Rt. Upper lobectomy in 2006 and post op chemotherapy
43 yr hx of smoking 1-2 packs/day, quit in 2006 during previous CA diagnoses
Routine imaging studies were negative until abnormal chest x ray and f/up CT scan in March 2013 showed a lobulated necrotic mass in the left lower lobe of the lung
New primary stage IIIA Squamous Cell Carcinoma in left lower lobe of lung (N2 M0)
Curative treatment with IMRT and concurrent chemotherapy
Images Before Automatic Correction
After automatic correction
Possible Reasons This Error OccurredTherapists may have set up to a freckle
instead of the tattooWhat was included in the clip box may have
thrown off the automatic registration◦If the arm is too high and it is included in the clip
box, the software may try to line up with the bony anatomy of the arm The problem is that this is a “moveable” structure and
should not be considered when aligning the patient for treatment
Imaging specialist was not consulted
Correct Moves
Red FlagsYou are off by more than a cmYou see lots of purple and greenMoves that have been consistent suddenly change
◦In this case the patient’s moves were consistently in the negative direction through out his treatment, but this day, the moves were suddenly in the positive direction
If you can clinically see that your patient is flat on the table but x-axis rotation is still off by 10 degrees or more◦You are probably off by a vert body
Dose Deviation This was an IMRT case, so dose deviation is measured in terms of volume,
not C/A Basically, you are looking to see if the gross tumor volume is still falling
within the planned treatment volume In this case, most of the GTV was still contained in the PTV During this particular fraction, the volume did not get the full dose it was
intended to get However the deviation in dose was so small that it did not need to be made
up for Even if the entire gross tumor volume had fallen outside of the planned
treatment volume, it would only have missed 2.7% of the total dose planned 200 cGy/7400 cGy= 0.027 x 100 = 2.7%
In this particular case, the patient was getting a very high dose (7400 cGy total), similar cases might only get 6000 cGy total, so this is another reason why the dose did not need to be made up for
The greater concern is the treatment of normal tissue/structures
Similar Case- Complex Sim Day
After Automatic Correction
Moves that should have been made
Policy Recommendations If the clip box is throwing off your alignment, adjust its position or size so that it
doesn’t include unnecessary anatomy If you can see the image is way off (lots of purple and green) click on manual
method and drag the image to superimpose it on the initial scan, click back on bone, and then click automatic registration and convert to correction
Look for something on each patient’s scan that stands out (usually something unique about one vert body compared to the rest) once identified, see if it corresponds to the location on the sim day
Don’t just look at one structure, look at all surrounding anatomy to be sure everything is lined up correctly
If you have a move greater than 0.9 cm in any direction, call the imaging specialist, if the imaging specialist is out or unavailable, call physics (this is part of the current policy!)
In the words of Shannon: “Don’t just bone and go!”◦ Review your image carefully in all planes, don’t just click automatic registration, convert,
and accept w/o looking!
SourcesShannon Prausa
◦Imaging SpecialistLisa Benedetti
◦PhysicsAngela Schick
◦Radiation TherapistKerry Jeffries
◦Radiation Therapist