REVIEW ARTICLE

American College of Radiology (ACR) and American Society

for Radiation Oncology (ASTRO) Practice Guideline for
Intensity-modulated Radiation Therapy (IMRT)
Alan C. Hartford, MD, PhD,* James M. Galvin, DSc,w David C. Beyer, MD,z
Thomas J. Eichler, MD,y Geoffrey S. Ibbott, PhD,8 Brian Kavanagh, MD,z
Christopher J. Schultz, MD,# and Seth A. Rosenthal, MD**

PREAMBLE
Abstract: Intensity-modulated radiation therapy (IMRT) is a complex These guidelines are an educational tool designed to
technique for the delivery of radiation therapy preferentially to target
structures while minimizing doses to adjacent normal critical structures. It
assist practitioners in providing appropriate radiation oncology
is widely utilized in the treatment of a variety of clinical indications in care for patients. They are not inflexible rules or requirements
radiation oncology, including tumors of the central nervous system, head of practice and are not intended, nor should they be used, to
and neck, breast, prostate, gastrointestinal tract, and gynecologic organs, as establish a legal standard of care. For these reasons and those
well as in situations where previous radiation therapy has been delivered, set forth below, the American College of Radiology (ACR)
and has allowed for significant therapeutic advances in many clinical areas. cautions against the use of these guidelines in litigation in
IMRT treatment planning and delivery is a complex process. Safe and which the clinical decisions of a practitioner are called into
reliable delivery of IMRT requires appropriate process design and adher- question.
ence to quality assurance (QA) standards. A collaborative effort of the The ultimate judgment regarding the propriety of any
American College of Radiology and American Society for Therapeutic
specific procedure or course of action must be made by the
Radiation Oncology has produced a practice guideline for IMRT. The
guideline defines the qualifications and responsibilities of all the involved physician or medical physicist in light of all the circumstances
personnel, including the radiation oncologist, physicist, dosimetrist, and presented. Thus, an approach that differs from the guidelines,
radiation therapist. Factors with respect to the QA of the treatment plan- standing alone, does not necessarily imply that the approach
ning system, treatment-planning process, and treatment-delivery process was below the standard of care. To the contrary, a conscien-
are discussed, as are issues related to the utilization of volumetric modu- tious practitioner may responsibly adopt a course of action
lated arc therapy. Patient-specific QA procedures are presented. Successful different from that set forth in the guidelines when, in the
IMRT programs involve integration of many processes: patient selection, reasonable judgment of the practitioner, such course of action
patient positioning/immobilization, target definition, treatment plan is indicated by the condition of the patient, limitations of
development, and accurate treatment delivery. Appropriate QA procedures,
available resources, or advances in knowledge or technology
including patient-specific QA procedures, are essential to ensure quality in
an IMRT program and to assure patient safety. subsequent to publication of the guidelines. However, a prac-
titioner who employs an approach substantially different from
Key Words: intensity-modulated radiation therapy (IMRT), volu- these guidelines is advised to document in the patient record
metric modulated arc therapy (VMAT), quality assurance, safety, information sufficient to explain the approach taken.
dosimetry, practice guidelines, radiation oncology The practice of medicine involves not only the science,
but also the art of dealing with the prevention, diagnosis,
(Am J Clin Oncol 2012;35:612–617)
alleviation, and treatment of disease. The variety and com-
plexity of human conditions make it impossible to always
From the *Department of Medicine, Section of Radiation Oncology, reach the most appropriate diagnosis or to predict with cer-
Dartmouth Medical School, Hanover, NH; wDepartment of Radiation tainty a particular response to treatment. Therefore, it should
Oncology, Thomas Jefferson University, Philadelphia, PA; zArizona be recognized that adherence to these guidelines will not
Oncology Services, Scottsdale, AZ; yDepartment of Radiation Onco- assure an accurate diagnosis or a successful outcome. All that
logy, Thomas Johns Cancer Hospital, Richmond, VA; 8Department of
Radiation Physics, M.D. Anderson Cancer Center, Division of Radia- should be expected is that the practitioner will follow a rea-
tion Oncology, University of Texas, Houston, TX; zDepartment of sonable course of action based on current knowledge, available
Radiation Oncology, University of Colorado, Denver, Aurora, CO; resources, and the needs of the patient to deliver effective and
#Department of Radiation Oncology, Medical College of Wisconsin, safe medical care. The sole purpose of these guidelines is to
Wisconsin, WI; and **Radiation Oncology Centers, Radiological
Associates of Sacramento, Sacramento, CA. assist practitioners in achieving this objective.
The authors declare no conflicts of interest.
This guideline was revised according to the process described under the
heading “The process for developing ACR Practice Guidelines and
Technical Standards” on the ACR web site (http://www.acr.org/ INTRODUCTION
guidelines) by the Guidelines and Standards Committee of the ACR This guideline was revised collaboratively by the ACR and
Commission on Radiation Oncology in collaboration with the ASTRO. the American Society for Therapeutic Radiation Oncology
This report was previously published as ACR-ASTRO Practice Guideline
for intensity-modulated radiation therapy (IMRT), ACR Practice
(ASTRO). It is an updated version of the ACR-ASTRO Practice
Guidelines and Technical Standards CD, 2011. Guideline for intensity-modulated radiation therapy (IMRT)
Reprints: Alan C. Hartford, MD, PhD, P.O. Box 1797, Grantham, NH previously adopted in 2007.1 Separate, but complementary ACR-
03753-1797. E-mail: alan.c.hartford@hitchcock.org. ASTRO Practice Guidelines exist for stereotactic body radiation
Copyright r 2012 American College of Radiology (ACR) and American
Society for Radiology Oncology (ASTRO)
therapy and image-guided radiation therapy (IGRT).2,3
ISSN: 0277-3732/12/3506-0612 To achieve optimal patient care outcomes, a major goal of
DOI: 10.1097/COC.0b013e31826e0515 radiation therapy is the delivery of the desired dose distribution

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American Journal of Clinical Oncology  Volume 35, Number 6, December 2012 ACR and ASTRO Practice Guideline for IMRT

of ionizing radiation to target tissue while limiting the radiation QUALIFICATIONS AND RESPONSIBILITIES
dose to the surrounding normal tissues to an acceptable level. OF PERSONNEL
With the introduction of intensity-modulated radiation therapy See the ACR Practice Guideline for Radiation Oncology
(IMRT) in the early 1990s, it was recognized that dose dis- where qualifications, credentialing, professional relationships,
tributions could be significantly improved to better handle this and developments are outlined.11
class of treatment-planning problems. IMRT is different than the
older treatment technique of 3-dimensional conformal radiation
therapy that conforms each field to the beam’s eye view (BEV) Radiation Oncologist
outline of the target.4 Instead, IMRT irradiates subregions of the The responsibilities of the radiation oncologist must be
target to different levels, “painting” the dose so that isodose lines clearly defined and should include the following.
better conform around critical healthy tissues. To efficiently 1. Participate in and approve the immobilization/repositioning
generate the desired dose distribution for complex target and system in consultation with other members of the team.
critical structure geometries, a new treatment-planning techni- 2. Define the goals and requirements of the treatment plan,
que, called inverse planning, was introduced.5 including the specific dose constraints for the target(s) and
The process of care for IMRT consists of multiple steps for nearby critical structure(s).
treatment planning and delivery of radiation. Inverse planning 3. Delineate tumor and specify and approve target volumes,
should be used for IMRT. In this process, delineation of both the preferably using appropriate methodology of the Interna-
target volume and the surrounding tissues at risk is required to tional Commission on Radiation Units and Measurements.
decrease the dose to volumes of nontarget structures while ach- 4. Contour critical normal structures not clearly discernible on
ieving prescription doses to the target volume. An optimized cross-section.
treatment plan is developed that respects the target dose require- 5. Review and approve all critical structures contoured.
ments and the dose constraints of the surrounding dose-limiting 6. Perform final evaluation and approve the final IMRT plan
structures. IMRT treatment-delivery demands careful, day-by-day for implementation.
reproduction of the treatment plan within the patient. Throughout 7. Participate in peer review of IMRT treatment plans in
this complex process, quality assurance (QA) is necessary to conjunction with other members of the team.
achieve the preferred dose distribution with the accuracy and 8. Continue management of the patient throughout the course
reproducibility that distinguishes such precision treatment. of radiation therapy, including the ongoing acquisition,
IMRT has become widely used for a variety of clinical review, and verification of all treatment-related imaging.
indications, such as tumors of the central nervous system, head
and neck, breast, prostate, gastrointestinal tract, and gyneco- Qualified Medical Physicist
logic system, as well as sites previously irradiated.6–9 In gen- The responsibilities of the qualified medical physicist
eral, the ability of IMRT to deliver dose preferentially to target must be clearly defined and should include the following.
structures in close proximity to organs at risk and other non- 1. Perform acceptance testing, commissioning, and implemen-
target tissues makes it a valuable tool enabling the radiation tation of the IMRT treatment-planning system and all
oncologist to deliver dose to target volumes while minimizing subsequent upgrades, including the systems interface with
the dose to adjacent normal tissues. the treatment-delivery software and hardware.
This guideline focuses on multileaf collimator (MLC)- 2. Understand the limitations and the appropriate use of the
based IMRT techniques for photon treatment, such as multiple radiation therapy treatment planning (RTP) system, includ-
static segment (step-and-shoot) treatment, dynamic segment ing the characteristics of the dose optimization software, the
(sliding-window) treatment, volumetric modulated arc therapy precision of generated patient and beam geometry, and the
(VMAT), and binary-collimator tomotherapy. Compensator- applicability of dose calculation algorithms to different
based beam modulation is also used as a means of achieving clinical situations, including heterogeneity corrections.
IMRT. 3. Initiate and maintain a QA program for the entire IMRT
IMRT demands levels of precision and accuracy that system, to include the planning system, the delivery system,
surpass the requirements of conventional radiotherapy treat- and the interface between these systems.
ment planning and delivery techniques. The IMRT process 4. Act as a technical resource for the IMRT team.
requires a coordinated team effort between the radiation 5. Consult and participate with the radiation oncologist and
oncologist, the medical physicist, the medical dosimetrist, and other team members in implementing the immobilization/
the radiation therapist. In addition, it is important to have repositioning system for the patient.
appropriate process design with a well-managed balance 6. Participate in review of contours and anatomic structures for
between productivity and safety goals, careful attention to the IMRT plan.
maintenance of equipment and interfaces, and adequate train- 7. Review each patient’s IMRT plan for technical accuracy
ing and continuing education of team members, supervisors, and precision.
and managers—all designed to create and maintain a culture of 8. Provide physical measurements for verification of the IMRT
quality and safety within the radiation oncology department.10 plan.
This guideline describes a QA program for IMRT treatment
planning and delivery that includes (a) systematic testing of the
hardware and software used in the IMRT treatment planning Medical Dosimetrist
and delivery process; (b) review of each patient’s treatment The responsibilities of the medical dosimetrist or other
plan; and (c) review of the physical implementation of the designated treatment planner must be clearly defined and
treatment plan. should include the following.
This guideline supplements the ACR Practice Guideline 1. Contour clearly discernible critical normal structures.
for Radiation Oncology11 and the ACR Technical Standard for 2. Ensure proper orientation of volumetric patient image data
the Performance of Radiation Oncology Physics for External on the IMRT RTP system [from computed tomography
Beam Therapy.12 (CT) and other fused image data sets].

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3. Design and generate the IMRT treatment plan under the Medicine. It is recommended that the American Association of
direction of the radiation oncologist and medical physicist Physicists in Medicine Task Group 53 procedure for QA of
as required. treatment-planning systems be used.17
4. Generate all technical documentation required to implement
the IMRT treatment plan. System Log
5. Be available for the first treatment and assist with An ongoing system log should be maintained to record
verification for subsequent treatments as necessary. system component failures, error messages, corrective actions,
and hardware and software changes.
Radiation Therapist
The responsibilities of the radiation therapist must be
System Data Input Devices
clearly defined and should include the following.
1. Understand the proper use of the patient immobilization/ Input systems for image-based planning systems should
repositioning system and fabricate and understand the be checked for functionality and accuracy. There must be
proper use of devices for IMRT. correct anatomic registration: left, right, anterior, posterior,
2. Under supervision of the radiation oncologist and medical cephalad, and caudad from all the appropriate input devices. If
physicist, perform initial (planning) simulation of the fused or registered image data sets are used, the accuracy
patient and generate the medical imaging data appropriate should be verified.
for the IMRT RTP system.
3. Under supervision of the radiation oncologist and medical System Output Devices
physicist, perform verification (implementation) simulation The functionality and accuracy of all printers, plotters,
and verify that the IMRT treatment plan was correctly and graphical display units that produce, using digitally
imported for treatment. reconstructed radiographs or the like, a BEV rendering of
4. Implement the IMRT treatment plan under the supervision of anatomic structures and/or treatment aids should be assured.
the radiation oncologist and the medical physicist or of the There must also be checks to assure correct transfer of MLC
medical dosimetrist under the direction of the medical physicist. control point information along with the corresponding dose
5. Acquire periodic verification or IGRT images for review by for each field shape defined by these points (see the IMRT
the radiation oncologist. treatment plan implementation section).
6. Perform periodic evaluation of the stability and ongoing
reproducibility of the immobilization/repositioning system System Software
and report inconsistencies immediately to the radiation The system’s software should facilitate the following.
oncologist and the medical physicist. 1. Assuring the continued integrity of the RTP system’s
information files used for modeling the external radiation
Continuing Medical Education (CME) beams.
CME programs should include radiation oncologists, 2. Confirming agreement of the beam modeling to current
medical physicists, medical dosimetrists, and radiation therapists. clinical data derived from physical measurements.
The continuing education of the physician and qualified 3. Assuring the integrity of the system to render the anatomic
medical physicist should be in accordance with the ACR modeling correctly, including CT number consistency for
Practice Guideline for CME.13 conversion to relative electron density.
4. Assuring the consistency of dose optimization software.
QA FOR THE IMRT TREATMENT-PLANNING 5. Confirming the accuracy of the system-generated dose
SYSTEM volume histograms and other tools for plan evaluation.
6. Confirming the accuracy of the calculated monitor units.
IMRT RTP systems are complex. The starting point of the
IMRT process is a description of the desired dose distribution in
terms of dose volume constraints for the delineated target tis- IMRT TREATMENT PLAN IMPLEMENTATION
sue(s) as well as for the delineated surrounding organs at risk and Conforming the dose distribution to the target tissues with
nontarget tissues. On the basis of the dose constraints and on a high degree of precision and accuracy requires a greater
imaging data, a treatment plan is generated that shows the complexity, not only in the planning aspects but also in the
resulting dose distribution and the beam parameters required for implementation process. The planning process must include
its realization. If the dose distribution is not satisfactory, the inhomogeneity correction in optimization and dose calcu-
initial dose constraints are modified, and a new plan is devel- lations. The inhomogeneity correction algorithm should have
oped. This iterative process is continued until a clinically been validated for accuracy for a wide range of densities and
acceptable dose distribution has been found. In mathematical field sizes. It is important to point out that the use of Clarkson
terms, this plan is referred to as the optimized dose distribution. integration or pencil-beam algorithms has been shown to be
Documentation must exist indicating that the medical physicist unacceptable as a final calculation when treating in the thorax
has authorized the RTP system for the intended clinical use and region.18 Some systems use these algorithms for initial opti-
has established the QA program to monitor the delivery system’s mization. This practice is acceptable when a more accurate
performance as it relates to the inverse planning process.14–16 algorithm (eg, a Monte Carlo or superposition/convolution
It is recognized that various testing methods may be used, calculation) is used for a final calculation. The implementation
with equal validity, to assure that a system feature or component process may be defined as an accurate registration of the
is performing correctly. It is also noted that the commercial patient geometry with the dose delivery geometry of the
manufacturer may recommend specific QA tests to be performed treatment unit. The relationship between those 2 geometries is
on its planning systems. In this guideline, the important elements specified by the IMRT treatment plan that delineates patient
of the QA program for the IMRT RTP system are identified. anatomy relative to the external beam parameters of the
Information with more scientific detail may be found in appro- treatment unit. Implementation requires attention to detail and
priate reports of the American Association of Physicists in the combined skills of all members of the treatment team.

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Society for Radiology Oncology (ASTRO)
American Journal of Clinical Oncology  Volume 35, Number 6, December 2012 ACR and ASTRO Practice Guideline for IMRT

The following are required. localization and modeling of the MLC are also important for
VMAT dose delivery.
Correct Patient Positioning
The patient geometry must be reproducible and be in correct Segmental MLC and dMLC IMRT Delivery
registration relative to the treatment unit. Immobilization devices Small field sizes and short-term treatment pose particular
are necessary to assure accurate, reproducible positioning of the challenges. Inverse treatment planning can result in either
patient relative to the treatment unit. Specific organ-immobiliza- small field gaps for dMLC delivery or small apertures coupled
tion or motion-gating devices may aid in reproducible treatment with a small number of monitor units for dose delivery using
delivery. Many modern treatment delivery systems include IGRT the segmental MLC technique. Both situations are problematic,
capabilities. These systems work together with good patient and special attention is needed to avoid delivery errors. Non-
immobilization to guarantee reproducible patient positioning.2,19 linearity within this region can have a significant impact on the
An important aspect of daily target localization is the accurate dose delivered. An evaluation of beam stability at beam-on and
implementation of positioning instructions when the reference within the first few monitor units is important.
point used during simulation differs from the isocenter specified
during treatment planning. This shift information must be verified VMAT
daily during the treatment course and with special attention VMAT makes it possible to deliver IMRT using arc
during the initial patient setup. rotation techniques.20,21 The dose rate and speed of gantry
rotation may vary in addition to the MLC leaf positions
Correct Beam Delivery Parameters throughout the delivery of therapy. The added variable relative
All beam delivery parameters of the IMRT plan must be to fixed gantry IMRT introduces the need for special QA con-
correctly transferred to the treatment unit and verified. This siderations when using VMAT. For example, QA procedures
means using the approved treatment plan specifications: beam must guarantee that the dose rate, collimator leaf positions, and
energies, jaw settings, treatment aids, collimator position, gantry angle are properly coordinated at each point in time. Leaf
gantry position and motion, treatment table settings, treatment calibration and modeling are equally important for the VMAT
distance, and isocenter location. In particular, MLC position- dose delivery technique. In this case, it is harder to determine
ing and motion with the appropriate monitor unit settings must that the MLC leaves track properly with the rotating gantry and
correspond to the approved settings of the treatment plan. the changing dose rate. Various tests specific to the use of
VMAT delivery are discussed in 2 recent publications.22,23
These tests are similar to the ones suggested for dMLC IMRT
IMRT DELIVERY SYSTEM QA delivery, but add the rotating gantry to the test procedures.
IMRT is often delivered with a standard MLC, a binary
MLC, multiple pencil beams, or milled compensating filters. Compensator-based System
Typically, the leaves of these collimators project to a nominal For gantry-mounted accelerators, beam modulation can be
beam width of r1 cm at the treatment unit isocenter. The accomplished by substituting a solid beam attenuator or com-
delivery methods include, for example, multiple static segment pensator for the MLC approach.24,25 Relative to the use of the
treatment (step-and-shoot), dynamic segment treatment (sliding- MLC, compensators have advantages and disadvantages. How-
window), binary-collimator tomotherapy, sequential pencil-beam ever, a major advantage of this approach is that gantry-mounted
treatment, and high-resolution, milled compensator-based sys- treatment equipment that does not include an MLC can be used
tems. The volume arc delivery techniques also use a standard for IMRT. Although some QA requirements for compensator-
MLC. The precision and reproducibility of an IMRT treatment based IMRT may be different than the tests detailed in this
require the delivery system to accurately carry out the treatment document, it is recommended that a verification testing proce-
as planned. A fundamental difference with IMRT dose delivery dure be used to guarantee that the correct compensator is inserted
relative to conventional therapy is the mechanical accuracy of for each gantry angle (see the Patient-specific QA section
the MLC. The accuracy of the delivered dose depends on the below). Furthermore, other testing must be modified to apply to
accuracy of individual leaf position and the leaf gap width. this technology. For example, the equivalent to the localization
Incorporating routine QA of the MLC into the facility’s ongoing of the MLC leaf end is a test that guarantees that the compen-
QA program is essential. sator is securely locked on the treatment head in the correct
position relative to the beam center axis.
MLC Leaf Position Accuracy
Leaf position accuracy affects the dose at the edges of a Benchmark End-to-End Testing
conventional static treatment field, but with IMRT VMAT This test is recommended both for commissioning newly
delivery it affects the dose within the target, because the leaves delivered equipment and as a routine QA tool, a means for
build the dose as they move to different positions across the verifying performance from CT simulation to treatment of a
target volume. A 1 to 2 mm leaf position tolerance may be single process. The end-to-end test includes CT simulation,
acceptable for conventional fields, but submillimeter tolerance inverse treatment planning, transfer of the treatment plan
is necessary for accurate IMRT dose delivery. As part of a parameters to the delivery system, and actual dose delivery.26,27
routine QA process, MLC test patterns should be created to It is not intended as a replacement for individual component
verify precise modeling of the penumbra for each leaf and its testing, but rather as a supplement to assure that the separate
localization in space. These patterns should be executed at components work together to yield the desired dose dis-
different collimator and gantry combinations and over the tribution. A simple version of the end-to-end test uses a block
entire range of travel for all leaf pairs. These tests should be phantom containing a calibrated internal dosimetry system. The
performed periodically and after each service or repair. Precise phantom is imaged on the CT-simulation device. Treatment
localization and modeling of the MLC leaf end are equally fields are established using the inverse planning system, and the
important for both segmental and dynamic MLC (dMLC) plan is sent to the delivery device. The block phantom is placed
delivery. As discussed in the VMAT section below, precise on the treatment couch with laser triangulation or IGRT

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Hartford et al American Journal of Clinical Oncology  Volume 35, Number 6, December 2012

imaging used for positioning, and the treatment plan is deliv- Before the start of treatment and using all of the parameters of
ered to the phantom. The dosimeters may then be used to verify the patient’s treatment plan, the accuracy of dose delivery
the delivery of the radiation dose as planned. should be documented by irradiating a phantom containing a
calibrated dosimetry system to verify that the dose delivered is
PATIENT-SPECIFIC QA the dose planned. Multiple points in the delivered distribution
Patient-specific QA must be performed before clinical should be compared against the planned distribution, as can be
treatment begins. Further QA procedures are then continued accomplished, for example, using film dosimetry within the
throughout the IMRT treatment process. Such patient-specific phantom.26–29 This testing procedure has been termed “patient-
treatment verification is linked to implementation; it may be specific end-to-end testing.”
considered the confirmatory phase of the IMRT treatment Acceptable alternative tests provide equivalent or even
process, assuring compliance with the aforementioned sections more detailed verification. It is the responsibility of the medical
for the individual patient. Through a process that starts before physicist to assure the equivalence or superiority of an alternative
the initiation of treatment and then continues throughout the testing procedure. For example, one such method uses a
course of treatment, verification data confirm the correctness of 2-dimensional detector array to verify intensity patterns of
the administered dose using transfer of both the technical setup individual fields and the summed pattern for the entire IMRT
and the dose delivery data. The radiation oncologist must plan. This technique may be considered to provide equivalent
remain available to adjust, modify, and revise any aspects of information for IMRT-fixed gantry angle delivery, as long as the
the initial plan as the clinical situation warrants. pattern for each gantry position is verified together with the
Verification of the patient treatment plan includes doc- summed pattern, and as long as the treatment-planning system
umentation of all of the elements associated with imple- provides the necessary analogous information for comparison.
mentation as well as images of treatment ports and physical
dose measurements. Each facility should develop its own
Backup Monitor Unit Calculations
policies and procedures to achieve daily correlation between Backup monitor unit calculations are strongly recom-
the IMRT plan and dose delivery. Treatment verification ele- mended. These repeat the process that is performed by the
ments are described below. treatment-planning system, using an independent software
system. Data are gathered and input into the software package,
Treatment Unit Verification Data including basic treatment unit commissioning information and
Correct verification of the IMRT plan in the actual clin- information from the treatment-planning system, such as the
ical setting requires proper understanding, interpretation, field apertures selected for the patient’s plan and the depth to
transfer, and documentation of all aspects of the patient’s the calculation point. Of note, although it is a useful supple-
clinical setup, positioning, and immobilization, as well as ment, the backup monitor unit calculation is not a replacement
treatment unit parameters such as jaw setting, treatment aids, for the patient-specific end-to-end test.
gantry angle, collimator angle, patient support table angle and
position, treatment distance, and MLC setting. Record-and- DOCUMENTATION
verify systems allow for ongoing verification of the patient- Reporting should be in accordance with the ACR Practice
specific treatment parameters on the dose delivery unit and Guideline for Communication: Radiation Oncology.30–31
capture details of the actual treatment unit parameters in a Documentation of delivered doses to volumes of target
computer record for each patient. and nontarget tissues, in the form of dose volume histograms
and representative cross-sectional isodose treatment diagrams,
Image-based Verification Data
should be maintained in the patient’s written or electronic
In addition to documentation of treatment unit data, con- record. As noted above, various treatment verification meth-
gruence between portal images and approved simulator films or odologies, including daily treatment unit parameters, images
digitally reconstructed radiographs is necessary for accurate confirming proper patient positioning, and records of physical
treatment delivery. This method involves a comparison between measurements confirming treatment dosimetry, should also be
the simulated images and actual images obtained with the incorporated into the patient’s record.
treatment unit. Traditionally, this method used pretreatment
images recorded on film, which, when approved by the radiation
oncologist, assured that the subsequent treatment delivered is QUALITY CONTROL AND IMPROVEMENT,
properly administered to the designated clinical volumes. SAFETY, AND PATIENT EDUCATION
Although each facility establishes its own provisions for Policies and procedures related to quality, patient educa-
initial and ongoing portal imaging throughout the treatment tion, infection control, and safety should be developed and
process, consideration should be given to the use of 2 different implemented in accordance with the ACR Policy on Quality
BEV images, such as concurrent lateral and anteroposterior Control and Improvement, Safety, Infection Control, and Patient
views, to delineate the correct placement of the beam’s iso- Education appearing under the heading “Position statement on
center relative to patient anatomy. Such confirmation of patient QC & improvement, safety, infection control, and patient edu-
positioning should be performed initially and then periodically, cation” on the ACR web site (http://www.acr.org/guidelines).
at least weekly, throughout the course of the patient’s treat-
ment. Verification images for each field should be acquired for Patient and Personnel Safety
each treatment field to verify the orientation of the MLC Because of the larger number of monitor units needed to
arrangement for that field. deliver IMRT treatments relative to those used in conventional
treatment plans, room shielding issues must be addressed,
Dose Delivery Verification by Physical including primary barrier and secondary barrier require-
Measurement ments.32 Beam leakage and secondary scatter should also be
The medical physicist should assure verification of actual documented at the time of IMRT commissioning and peri-
radiation doses being received during treatment delivery. odically monitored over the equipment’s lifespan.

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Continuing Quality Improvement media/ACR/Documents/PGTS/guidelines/CME.pdf. Accessed

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