1. Chapter 17 Quality Assurance

2. An adequate QA program increased staffing and up-to-date equipment
can be expensive
the total cost of QA program in radiation therapy ~3% of the annual billing
are QA programs voluntary?
incentive for QA?
a desire to practice good radiation therapy or avoid malpractice suits

3. QA: Goals
the objective, systematic monitoring of the quality and appropriateness of patient care.
is essential for all activities in Rad Onc
Structure: staff, equipment and facility
process: the pre- and post-treatment evaluations and the actual treatment application
and outcome: the frequency of accomplishing stated objectives (TCP), and by the frequency and seriousness of NTCP
all of which can be measured

4. A comprehensive QA program
includes admin, clinical, physical, and technical aspects of rad onc
Operationally, no single personnel has the expertise to cover all these areas
teamwork is essential among admin, rad onc, nurses, med phys, and therapy techs
For an effective QA program , all the staff must be well coordinated and committed to QA.

5. Minimum Personnel Requirements for Clinical Radiation Therapy
Category
Staffing
Radiation oncologist-in-chief
One per program
Staff radiation oncologist
One additional for each patients treated annually; no more than patients under treatment by a single physician
Radiation physicist
One per center for up to 400 patients annually; additional in ratio of one per 400 patients treated annually
Treatment planning staff
dosimetrist or physics assistant
One per 300 patients treated annually
physics technologist (mold room)
One per600 patients treated annually
Radiation therapy technologist
supervisor
One per center
staff (treatment)
Two per megavoltage unit up to 25 patients treated daily per unit; four per megavoltage unit up to 50 patients treated daily per unit
staff (simulation)
Two for every 500 patients simulated annually
staff (brachytherapy)
As needed
Treatment aid
As needed, usually one per patients treated annually
Nurse
One per center for up to 300 patients treated annually and an additional one per 300 patients treated annually
Social worker
As needed to provide service
Dietitian
Physical therapist
Maintenance engineer/electronics technician
On per 2 megavoltage units or 1 megavoltage unit and a simulator if equipment serviced in-house

6. Additional personnel
These recommendations are for clinical service only, do not include staffing for research, teaching, or administrative functions.
Additional personnel required for
QA of modern imaging equipment (e.g., cone-beam computed tomography [CT] system, [EPID]), CT simulators, and (PET)/CT
Sophisticated and complex treatments (e.g., [IMRT], [IGRT], [HDR], prostate implants, SRS, tomo, proton therapy).

7. For example
if 800 patients/y with 3 linacs, one 60Co, an orthovoltage, and one TPS: 2-3physicists
A training program with eight residents, two tech students, and a graduate student: 1 to 1.5 full-time employees (FTEs).
Administration of this group would require 0.5 FTE
If the faculty had 20% time for research: a
total of 5-6 physicists for direct patient care.

8. Many of the clinical physics tasks that have been traditionally performed by
physicists can be delegated to dosimetrists or physics assistants. For example,
dosimetrists can assist in routine QA checks, computer treatment planning, and
monitoring unit calculations and brachytherapy source preparations. A physicist in
this case has a role in establishing the procedures, directing the activities, and
reviewing the results.
In treatment planning, Figure 17.1 illustrates how physics support is usually
organized in this country. Arrangement A, in which the physician practically works
alone or does not seek consultation from the physics team, is obviously not
appropriate and is contrary to the concept of a multidisciplinary approach to radiation oncology. Arrangement β is not satisfactory either but is prevalent in many
institutions. There may be several reasons why an essential member of the team, the
physicist, is excluded in this case from the clinical process. Economics is one reason,
as physicists are usually higher salaried than the dosimetrists. Other reasons may
include having physicists who lack clinical training or a well-defined role in the
clinic. Nonetheless, arrangement C is probably the best approach, as it involves
teamwork among personnel whose responsibilities are matched with their credentials.
The Blue Book recommendation on dosimetrist staffing is 1 per 300 patients treated
annually. In some institutions, dosimetrists perform physics work only, whereas in
others they also do simulations. The relative proportion of a dosimetrist's efforts to
various tasks is dictated by the individual needs of the department, the scope of the
physics activities, and the extent of other physics and technical support available.

9. Training education and training of physics staffing of
critical importance
The greatest weakness in this regard has been the physicist's training
Most physicists are hired with less than adequate clinical training
Structured clinical training programs have been traditionally nonexistent

10. Training Certification boards residency-type clinical training
nationally accredited residency programs before taking the board examinations or assuming independent clinical esponsibilitie
the certifying board for radiological physicists—has decided that “Beginning in 2014… candidates must be enrolled in or have completed a accredited residency program.”
CAMPEP [Commission on Accreditation of Medical
Physics Educational Programs]

11. Radiation oncology physicist: Qualifications
a M.S. or Ph.D. in physics, medical physics, or a closely related field and a certification in radiation oncology physics by the American Board of Radiology, the American Board of Medical Physics, or another appropriate certifying body.

13. Role of physicist: example
At the University of Minnesota the physicist's consultation is made as important as other consultations, such as those sought from the medical oncologist, the surgeon, or the radiologist
To prevent bypassing the physics consultation, each patient is assigned a physicist who is available at the time of simulation to assist the radiation oncologist in formulating the best possible treatment plan
Subsequent physics work is the designated physicist's responsibility,although he or she may be assisted by the dosimetrist or other technical personnel.
The final treatment plan is approved by the radiation oncologist after discussing the plan with the physicist. Also, the physicist is present at the time of first treatment and subsequent treatments, if needed, to ensure proper implementation of the plan.

14. Not all the clinical physics procedures performed by physicists
Many of the technical tasks: by dosimetrists so that physicists can devote time to developmental activities
Every rad onc department needs to develop new programs as well as revise the old ones to keep current with advancements in the field: Responsibility of the physicist

15. Acceptance Testing
To satisfy all the specifications and criteria contained in the purchase contract
To perform all the tests in accordance with the company’s procedure manual
Any equipment to be used for patients must be tested to ensure that it meets its performance specifications and safety standards

16. Radiation Survey
To evaluate the exposure levels outside the room will not exceed permissible limits, considering the dose rate output, machine on time, use factors and occupancy factors for the surrounding areas
A calibration of the machine output (cGy/MU)
Radiation protection survey
Head leakage
Area survey
Tests of interlocks, warning lights, and emergency switches

17. Coincidence Collimator axis, light beam axis and cross-hairs
The light field edges
The intersection of diagonals and the position of cross-hair images
Light beam with x-ray beam
AAPM guidelines  3% (2%)

18. Mechanical Isocenter
The intersection point of the axis of rotation of the collimator and the axis of rotation of the gantry
Collimator rotation
2 mm diameter circle
Gantry rotation
±1 mm

19. Radiation Isocenter Collimator2 mm diameter circle
Treatment table 2 mm diameter circle
Gantry 2 mm diameter circle

20. Multiple Beam Alignment Check
Focal spot displacement
Asymmetry of collimator jaws
Displacement in the collimator rotation axis or the gantry rotation axis
The split-field test 1 2 1 2

21. X-ray Beam Performance
Energy
A central axis depth dose distribution
A suitable ion chamber in a water phantom
Small chamber (<3 mm)
For a larger chamber, the depth dose curve should be shift to the left (toward the source) by 3/4r.
Suitable depths for comparing depth dose ratios are 10 and 20 cm.
1010, 100 cm SSD, and 10 cm depth  ±2%

23. X-ray Beam Performance
Field flatness
The variation of dose relative to the central axis over the central 80% of the field size at 10 cm depth
< ±3%
Within the region extending up to 2 cm from the field edge at a 10 cm depth
+3% ~ -5%
The diagonal flatness extending up to 2.8 cm from the 50% isodose curve in a plane at a 10 cm depth
+4% ~ -6%

25. X-ray Beam Performance
Field symmetry
To fold the profile at the field center and the two halves of the profiles to be compared
< 2% at any pair of points

27. Electron Beam Performance
Energy
TG-25
Rp  (Ep)0=C1+C2Rp+C3Rp2
< ±0.5 MeV
Flatness and symmetry
flatness±5% (± 3%)
symmetry < 2%

29. Wedges
1010
±2°

30. Miscellaneous Checks
Isocenter shift with couch motion up and down  < ±2 mm
ODI  < ±2 mm
Field size indicators  < ±2 mm
Gantry angle and collimator angles  < 1º
Laser lights aligned with the isocenter  < ±2 mm
Tabletop sag with lateral or longitudinal travel under a distributed weight of 180 lb  < 0.5 cm

31. Simulator Checking of the geometric and spatial accuracies
Performance evaluation of the x-ray generator and the associated imaging system
Table 17.5

32. Brachytherapy Intracavitary sources and applicators Source identity
Physical length, diameter, serial No.
Source uniformity and symmetry
The superposition of the autoradiograph and transmission radiograph
Source calibration
A well ionization chamber
5%
Applicator evaluation
Orthogonal radiographs
The ease of source loading and removal

33. Remote Afterloaders (1)
Operational testing of the afterloading unit
Radiation safety check of the facility
Checking of source calibration and transport
Checking of treatment planning software
Table 17.6

34. Remote Afterloaders (2)
Source positioning
The position of dummy sources and radioactive sources should correspond within ±1 mm.
Source calibration
A well ionization chamber
A cylindrical lead insert for a conventional well ionization chamber for calibrating HDR sources
Cylindrical ion chamber
A free air geometry
An interpolative method of obtaining exposure calibration factor

35. Commissioning
After all the necessary beam data have been acquired and adopted, the machine can be released or commissioned for clinical use.

36. Commissioning Data for a Linear Accelerator
Description
Calibration
Dose per MU calibration of all modalities and energies according to current protocol (TG21)
Depth dose
Central axis depth dose distribution for all modalities and energies, sufficient number of FS to allow interpolation of data and all available electron cones
Profiles
Tranverse, longitudinal, and diagonal dose profiles for all modalities and energies at dmax for electrons and selected depths for photons; all cones for electrons and selected FS for photons
Isodose distribution
Isodose curves for all modalities and energies, all cones for electrons and selected FS for photons, all wedge filters for selected field sizes
Output factors
Sc,p, Sc, and Sp factors as a function of FS for all photon energies: output factors for all electron energies, cones, and standard inserts; tray transmission factors and wedge transmission factors
Off-axis ratios
A table of off-axis ratios for all photon energies as a function of distance from central axis; these data may be obtained from those profiles for a 4040 cm field at selected depths
Inverse square law
Verification of inverse square law for all photon energies,virtual source position for all electron energies, and effective SSD for all electron energies and cones
TPR/TMR
Direct measurement of TPRs/TMRs for all photon energies and selected FS and depths for verification of values calculated from percent depth doses
Surface and buildup dose
For all photon energies and selected FS, percent surface dose for all electron energies for a 1010 cm cone
Treatment planning system
Beam data input, generation, and verification of central axis percent depth dose and TPR/TMR tables; sample isodose curves for unwedged, wedged, asymmetric and blocked fields; sample isodose curves for multiple field plans using rectangular and elliptical contours; electron beam depth dose data, isodose curves on rectangular and circular contours
Special dosimetry
Data for special techniques such as total body irradiation, total skin irradiation, stereotactic radiosurgery, intraoperative electron therapy, etc

37. Periodic QA of Linear Accelerator
Frequency
Procedure
Tolerence (±)
Daily
X-ray output constancy 3%
Localization lasers
2 mm
Operational parameters
recorded
Biweekly
Electron output constancy
Weekly
Light/radiation field coincidence
3 mm
X-ray flatness and symmetry
Electron flatness and symmetry
Monthly
X-ray output calibration 2%
X-ray energy
2% in fepth dose (2% in ionization ratio)
Electron energy
3 mm in R80 (2 mm in Rp)
Optical distance indicator
Field size indicators
Gantry angle indicator 1°
Collimator angle indicator
Cross-hair centering
1 mm
Annually
Full calibration
Isocenter shift
Collimator rotation
2 mm diameter
Gantry rotation
Couch rotation
Couch vertical travel
Tabletop sag

38. Periodic QA of Simulators
Frequency
Procedure
Tolerance (±)
Daily
Localization lasers
2 mm
Weekly
Light/radiation field coincidence
Monthly
ODI
FS indicator
Gantry angle indicator 1º
Collimator angle indicator
Cross-hair centering
1 mm
Annually
Isocenter shift
collimator rotation
2 mm diameter
gantry rotation
Couch rotation
couch vertical travel
Tabletop sag

39. Thank you for your attention!!