MEDRADSC 3V03 - Quality Assurance in Radiation Therapy

According to WHO guidelines, what is the primary goal of Quality Assurance (QA) in radiotherapy?

To ensure consistency of the medical prescription and the safe fulfilment of that prescription.

The WHO definition of QA in radiotherapy emphasizes maximizing the dose to the target volume while minimizing the dose to what?

Normal tissue.

What are the three main categories of an effective quality assurance program in radiation therapy?

Structure, Process, and Outcome.

What is the term for variations that occur during a single treatment session?

Intrafractional variations.

What is the term for variations that occur between one treatment session and the next?

Interfractional variations.

Patient respiration or swallowing during treatment are examples of _ variations.

intrafractional

Tumor shrinkage or patient weight loss over the course of treatment are examples of _ variations.

interfractional

What type of error results from variations in the daily setup of targeting the treatment volume?

Random error.

What type of error results from variations in translating the treatment from the planning stage to the treatment unit and, if uncorrected, remains constant throughout treatment?

Systematic error.

Using headrest 'C' for treatment when headrest 'B' was used and documented during simulation is an example of a _ error.

systematic

A patient moving due to discomfort during a single treatment fraction is an example of a _ error.

random

Which type of error, random or systematic, is generally considered more impactful if not corrected?

Systematic error.

Omitting a prescribed bolus or using the wrong thickness of bolus are examples of what general category of error?

Human error.

What is the purpose of a QA committee in radiation therapy?

To oversee the quality assurance program, review incidents, and ensure policies and procedures are followed.

What does the acronym RTQAC stand for in the context of radiation therapy quality assurance?

Radiation Therapy Quality Assurance Committee.

What three professional roles, at a minimum, must be part of an RTQAC?

A Radiation Oncologist, a Medical Physicist, and a Radiation Therapist.

Protocols that allow for verification imaging to take place prior to, during, or after treatment are known as _ protocols.

Image-Guided Radiation Therapy (IGRT)

Name three national or international organizations that recommend QA standards for radiation therapy.

WHO (World Health Organization), CPQR (Canadian Partnership for Quality Radiotherapy), and ICRU (International Commission on Radiation Units).

In the multidisciplinary radiation therapy team, who is primarily responsible for generating a safe radiation treatment plan?

A dosimetrist.

In the multidisciplinary radiation therapy team, who is primarily responsible for quality assuring the radiation treatment plan generated by the dosimetrist?

A medical physicist.

Who is primarily responsible for the prescription of radiotherapy, including target delineation and dose?

The Radiation Oncologist.

Who is primarily responsible for the daily delivery of radiotherapy and patient monitoring during treatment?

The Radiation Therapist (RT).

Who is responsible for the commissioning of treatment equipment and software, as well as dosimetry assurance?

The Medical Physicist.

The 'Structure' component of a QA program includes what five key elements?

Staffing, Education, Equipment, Commissioning, and Facility.

The 'Process' component of a QA program primarily involves what?

QA Policies and Procedures for all aspects of patient treatment.

The 'Outcome' component of a QA program involves monitoring what aspects of patient care?

Treatment results, patient throughput/wait times, and patient satisfaction.

The case of Lisa Norris at Beatson Oncology Centre highlighted a critical error where an inexperienced treatment planner omitted the _ procedure.

normalization

What were the three main causes cited for the tragic overexposure incident involving Lisa Norris?

Staffing pressures, lack of clear allocation of staff roles, and lack of education.

What is the first step in implementing a new piece of equipment, which ensures it meets performance specifications and safety standards?

Acceptance Testing.

What is the name for the process of calibrating a new treatment machine and obtaining all required beam data for treatment planning?

Commissioning.

What are the two main categories of checks performed during the commissioning of a new treatment machine?

Mechanical checks and dosimetric checks.

Checking for the mechanical coincidence of the collimator, field light, and central axis is an example of a _ check during commissioning.

mechanical

Verifying the mechanical accuracy of the isocentre during collimator and gantry rotations is an example of a _ check during commissioning.

mechanical

Measuring the beam energy by comparing the percent depth dose to published data is an example of a _ check during commissioning.

dosimetric

What is the acceptable tolerance for field flatness during a dosimetric check?

Within $\pm$3%.

During a dosimetric check for field flatness, the 'horns' must be no greater than what percentage?

105%.

Verifying that the light beam aligns with the x-ray beam is an example of a _ check during commissioning.

dosimetric

In the analogy of the Boeing 747 accident, a co-pilot being too intimidated to question a decision corresponds to what potential issue in radiation therapy?

A Radiation Therapist being confused by a dose prescription but too nervous to question the order.

In the QA process, staff members are seen as a chain, with the next staff member doing what to the previous staff member's work?

Quality assuring it.

What is the name of the alliance among CARO, COMP, and CAMRT that mandates high-quality and safe radiotherapy for all Canadians?

CPQR (Canadian Partnership for Quality Radiotherapy).

If an error is caught in a radiation therapy department, what type of report should be filed?

An incident report or safety occurrence report.

One of the key duties of the RTQAC is to review radiation treatment incidents and verify that necessary steps were taken to prevent what?

Incidents from recurring.

A comprehensive QA program should include a robust voluntary _ system to help reduce or eliminate errors.

error reporting

According to 'Table 17.1A', what is the minimum staffing requirement for a chief radiation oncologist per facility?

One per facility.

According to 'Table 17.1A', what is the approximate staffing guideline for medical dosimetrists?

Approximately 1 per 250 patients treated annually.

According to 'Table 17.1A', what is the approximate staffing guideline for radiation therapists?

Approximately 1 per 90 patients treated annually.

Staffing guidelines from Cancer Care Ontario (Ontario Health) aim to ensure centers can meet minimum treatment requirements and also maintain what?

A quality assurance program.

What is one example of ongoing education required for radiation therapy staff?

New staff orientation, education with new equipment/processes, or ongoing professional development requirements (e.g., 25 hours yearly).

Which professional group is responsible for facility design, including shielding calculations?

Medical Physicists.

Which professional group is responsible for patient follow-up after treatment is complete?

Radiation Oncologist.

When a beam interlock appears on a linear accelerator, an electronics staff member can be consulted, but who retains the ultimate responsibility for treatment delivery?

The radiation therapist.

What type of human error can occur related to tattoos used for patient setup?

Using incorrect/previous tattoos or making an incorrect shift from a reference tattoo.

What does the lecture identify as the most common charting errors in historical paper charting?

Numeric, addition, and transposition errors of the recorded dose.

The ability to conform a high dose to target volumes can be attributed, in part, to what type of protocols?

IGRT (Image-Guided Radiation Therapy) protocols.

In the sample calculation, when the shielding was forgotten, what became the 'unknown' factor in the Monitor Unit calculation?

The dose (Dose/fld/fx).

In the sample calculation, why did the dose delivered to the anterior field increase when the lead (pb) shielding tray was omitted?

There was less absorbing material in the path of the beam to attenuate it.

After an overdose of 5 cGy was delivered to the anterior field on Day 7, how can this error be corrected?

Deliver 5 cGy less on the anterior field on Day 8 and re-calculate the Monitor Units for that field.