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