Institute for Advanced Radiation Oncology QA – LINAC Daily, Monthly, Annual Jack Yang, Ph.D., DABR Institute for Advanced Radiation Oncology Barnabas Health Long Branch, NJ 07740 New Technologies in Modern Radiotherapy, Chulabhorn Research Institute, Bangkok, Thailand, August 22-25, 2012

Outlines Definition of treatment delivery quality assurance for LINAC Assure that the 5% final dose discrepancy can be achieved with the site specific QA process Current QA protocols implemented in modern radiation oncology clinics with updated LINAC functionalities

Radiation Oncology Error Management Clinical experience has shown that variations of 10% or more in the delivered dose can sharply reduce the probability of local tumor control. ICRU Report 62 recommends that radiotherapy be delivered within 5% of the prescribed dose to ensure adequate tumor control. The global aim is to achieve the desired tumor control while maintaining toxicities to normal tissues to a minimum Are these endpoints achievable with current delivery technology? Fig., Connor et al, IJROBP 1975

Linac QA Components: Dosimetric accuracy Mechanical Accuracy Safety Frequency: Daily Monthly Annually

The Early QA report (1994) AAPM TG-40 report Comprehensive QA program QA of EXRT (External Beam Treatment) equipment QA of RTP (Information and IT tools) system Brachytherapy Clinical practice

Periodic QA of Linear Accelerator (TG-40) Frequency Procedure Tolerence (±) Daily X-ray & electron output constancy 3% Localization lasers 2 mm Safety interlocks (door) functional Monthly X-ray & Electron output constancy 2% Light/radiation field coincidence X-ray flatness and symmetry Electron flatness and symmetry X-ray energy 2% in depth dose (2% in ionization ratio) Electron energy 2 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

Radiation Isocenter Checks Collimator » 2 mm diameter circle Treatment table » 2 mm diameter circle Gantry » 2 mm diameter circle

Misadministration Definition in US For external beam (>3 fractions) No written directive Wrong patient Wrong site Weekly dose exceeds 30% Total dose exceed 20% Most of the LINACs are inspected and governed by the state government !!

Misadministration Definition in US For Stereotactic radiosurgery/radiotherapy (<= 3 fractions) No written directive Wrong patient Wrong site Total dose error exceeds 10%

Background of TG 142 Principles - TG-40 was the International Commission on Radiation Units and Measurements (ICRU) recommendation that the dose delivered to the patient be within ±5% of the prescribed dose. The goal of a QA program for linear accelerators is to assure that the machine characteristics do not deviate significantly from their baseline values acquired at the time of acceptance and commissioning.

Rationales for Developing TG 142 New Technology since TG 40 MLC, as Asymmetric Jaws, Dynamic & virtual wedges, EPIDs……. Imaging: kV and cone beam, Respiratory gating….. Clinical procedures not emphasized in TG 40 with new modalities such SRS, SBRT, TBI, IMRT…… TG50, TG58, TG76 TG106, TG104, TG100 for various LINAC QAs

TG 142 fro Linear Accelerator QAs What This Report Doesn’t cover (some special techniques) Describe the techniques for performing QA tests Accelerator beam data commissioning equipment and procedures – TG-106 QA for TomoTherapy –TG-148 QA for Robotic Radiosurgery – TG-135 QA for Non-Radiographic Radiotherapy Localization & Positioning Systems – TG-147 Does add Specific Recommendations / Supplements the Work of Basic Applications of Multileaf Collimators – TG-50 Clinical use of electronic portal imaging - TG-58 Management of Respiratory Motion– TG-76 Kilovoltage localization in therapy – TG-104

MLC QA TG 50 (2001) - Update

EPID QA TG 58 (2001) - Update

TG-142 Testing Standards Acceptance Testing Procedure (ATP) Standards Acceptance testing sets the baseline for future dosimetric measurements for beam performance constancy, verifies that the equipment is mechanically functional and operates within certain tolerances from absolute specified values. Tolerances and Action Levels Level 1 – Inspection Action Level 2 – Scheduled Action Level 3 – Immediate Action or Stop Treatment Action or Corrective Action With these 3 action levels, there is an institutional need to specify the thresholds associated with Levels 2 and 3. Level 1 threshold isn’t a critical requirement but can lead to improvements in the QA program.

TG-142 Daily

TG-142 Daily (Continued)

TG-142: Monthly

TG-142 - Monthly (Continued) Procedure Tolerance (non-IMRT machines) (IMRT Stereotactic machines

TG-142 - Monthly (Continued) Procedure Tolerance (non-IMRT machines) (IMRT Stereotactic machines

TG-142: Annual

TG-142 – Annual (Continued) Procedure Tolerance (non-IMRT machines) (IMRT Stereotactic machines

TG-142 – Annual (Continued) Procedure Tolerance (non-IMRT machines) Tolerance (IMRT machines) Tolerance Stereotactic machines

Wedge Verification (Not Physical)

MLC Verification

MLC - Annual Test

Imaging Equipment Test - Daily

Imaging Equipment Test - Monthly

Imaging Equipment Test - Annual

Conclusions LINAC QA protocols have become extensive through modern LINAC development and implementation. AAPM TG-40 report still function as the base lines. AAPM TG-142 has gradually emerging into modern clinical practice (some of those testing are tedious and maybe not applicable to a busy clinic). However, regulatory agencies still have hard time to follow due to manpower, training and budgeting constraints. Annual report should include but not limited to the following: . (1) Dosimetry, (2) Mechanical, (3) Safety, (4) Imaging, and (5) Special Devices/Procedures.