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Original Article

Progress in Medical Physics 2017; 28(4): 197-206

Published online December 31, 2017 https://doi.org/10.14316/pmp.2017.28.4.197

Copyright © Korean Society of Medical Physics.

Proposal on Guideline for Quality Assurance of Radiation Treatment Planning System

Yoonjin Oh*, Dong Oh Shin, Juhye Kim*, Nahye Kwon*, Soon Sung Lee§,ΙΙ, Sang Hyoun ChoiΙΙ, Sohyun Ahn, Dong-wook Park#, Dong Wook Kim

*Research Institute of Clinical Medicine, Kyung Hee University Hospital at Gangdong, Department of Radiation Oncology, Kyung Hee University Hospital at Gangdong, Department of Radiation Oncology, Kyung Hee University Hospital, §Department of Radiological & Medico Oncological Sciences, University of Science and Technology, ΙΙDivision of Medical Radiation Equipment, Korea Institute of Radiological and Medical Sciences, Department of Radiation Oncology, School of Medicine, Yonsei University, Seoul, #Department of Radiation Oncology, Inje University Ilsan Paik Hospital, Goyang, Korea

Correspondence to:

Dong Oh Shin (ohsd32@gmail.com)
Tel: 82-2-958-9467 Fax: 82-2-958-9469

Received: November 16, 2017; Revised: December 18, 2017; Accepted: December 19, 2017

This is an Open-Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/4.0) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.

We develop guidelines for the quality assurance of radiation treatment planning systems (TPS) by comparing and reviewing recommendations from major countries and organizations, as well as by analyzing the AAPM, ESTRO, and IAEA TPS quality assurance guidelines. We establish quality assurance items for acceptance testing, commissioning, periodic testing, system management, and security, and propose methods to perform each item within acceptable standards. Acceptance includes tests of hardware and network environments, data transmission, software, and benchmarking as specified by the system supplier, and apply the IAEA classification criteria. Commissioning includes dosimetric and non-dosimetric items for assessing TPS performance by applying the AAPM classification criteria and the latest technical items from the IAEA. Periodic quality assurance tests include daily, weekly, monthly, yearly, and occasional items by applying the AAPM classification criteria. System management and security items include the state and network connectivity of TPS, periodic data backup, and data access security. The guidelines for TPS quality assurance proposed in this study will help to improve the safety and quality of radiotherapy by preventing incidents related to radiotherapy.

KeywordsRadiation treatment planning system, Acceptance test, Commissioning, Quality assurance

Because of the rapidly aging population, the number of cancer patients has increased continually by 5.5% each year.1) In the U.S., approximately 50% of cancer patients receive radiation therapy, and in Korea, which has fewer cancer patients than the U.S, approximately 25% patients receive radiation therapy, with an annual increase of 6.2%.2) Radiation therapy plays an important role in cancer treatment, and with the rapid development of medical technology and high-precision radiation therapy methods, the quality of life of cancer patients is gradually improving. Currently, in every medical institution, in order to safely perform high-precision, high-dose radiation therapy such as intensity-modulated radiation therapy, stereotactic body radiation therapy, and stereotactic radiosurgery, a systematized and periodic quality assurance and control (QA) approach for use with therapy equipment is very important.

The WHO reported that between 1976 to 2007, personnel training and improvements to treatment environments did not keep up with the rapid development of radiation therapy technology, leading to 55% of the deleterious causes of radiation therapy on patients to be related to radiation treatment planning.3) For example, in England’s North Staffordshire Royal Infirmary, a new treatment system was introduced, but owing to discord between the new and existing systems, from 1982 to 1991, there were over 1,000 instances of patients receiving the wrong radiation treatment.4)

The key reasons behind the incidents related to radiation treatment planning included an insufficient understanding of the radiation treatment planning system (RTPS), a lack of commissioning, and no verification of independent calculations, and that educational training and quality assurance processes were not properly managed.5,6) Currently, according to examinations of a domestic radiation therapy quality assurance organization, the Nuclear Safety & Security Commission, and published technical reports of the Korean Society of Medical Physics,79) quality assurance experts are available, and quality assurance performed mechanical dosimetry is recommended. However, currently quality assurance guidelines for RTPS do not exist. Thus, in this research, to improve the quality assurance of treatment planning, which when poorly executed is one of the causes behind main radiation therapy incidents and accidents, the current state of international quality assurance is analyzed, and RTPS quality assurance guidelines are proposed.

1. Current state of foreign radiation treatment planning quality assurance

Radiation treatment planning and the current state of QA from related foreign organizations were analyzed and organized, from which relevant standards and procedures were prepared. Several quality control items and methods were separated by type, compared, and evaluated. These include the proposed RTPS (radiation treatment planning system) described in “Quality assurance for clinical radiotherapy treatment planning (TG-53)”10) from the AAPM (American Association of Physicists in Medicine), “Commissioning and Quality assurance of computerized planning systems for radiation treatment of cancer”5) from the IAEA (International Atomic Energy Agency), and “Quality assurance of treatment planning systems. Practical examples for non-IMRT photon beams”6) from ESTRO (European Society for Radiotherapy & Oncology).

2. Radiation treatment planning system quality assurance items and procedures

The goal of this study was to prepare integrated RTPS QA guidelines by referring to the relevant information for radiation treatment planning systems from developed countries and international organizations, and to deduce them in order to prepare implementation procedures. Guidelines were divided into RTPS acceptance tests and commissioning, periodic quality control, and system management and security, and the QA items and methods such as tolerances were checked.

1. Current state of foreign quality assurance related radiation treatment planning

When purchasing and setting up a RTPS, as well as when performing updates, a clinically qualified medical physicist (CQMP), performs acceptance tests and commissioning in a manner similar to that needed for the use of radiation treatment machines, and the RTPS needs to be managed in part with periodic quality assurance. The AAPM proposed items and detailed information on the construction of a structure, acceptance tests, commissioning, and periodic quality control, for the QA of a RTPS. In addition, the IAEA and ESTRO guidelines for RTPS QA were proposed.

The RTPS vendor and the CQMP perform an acceptance test using the specifications, along with an inspection of the hardware and related equipment, algorithms, DVH, software, and a check of the system input and output during normal operations. For these items, the AAPM and IAEA propose hardware, software, and benchmarking inspection items. The ESTRO and IAEA recommend investigating network connections and data transmission (Table 1). The ESTRO does not describe acceptance test items for hardware and related equipment, but does recommend that during inspections of software and related items that the RTPS vendor and medical physicist roles and responsibilities should be separated.

For commissioning, the CQMP, after investigating various benchmarks, compares and verifies calculation results and measured values during clinical operations to check whether usage is within an error tolerance. The AAPM divides such items into two categories: those that are related to dose and those that are not (Tables 2, 3). In particular, as a supplement the IAEA recommends comprehensive quality control items including asymmetric jaws, multi-leaf collimator (MLC), and similar new technologies.

For periodic quality assurance tests, the job of the CQMP is to check via acceptance tests and commissioning whether expected system functions are maintained in the clinic. The AAPM recommends investigating management items daily, weekly, monthly, and yearly, and the IAEA recommends the same at any time, but monthly and yearly. The ESTRO recommends that periodic QA based on acceptance tests and commissioning items be performed, but does not propose an inspection frequency for each quality assurance item, instead recommending that QA be performed to suit the conditions of each organization (Table 4).

System management and security are operations that include activities such as system maintenance and data backup and security of system use. The AAPM designates a system administrator and a computer system administrator, and recommends that system management and security operations be performed. For data management, development and maintenance of documented policies and procedures for patient data records and readouts are recommended. Moreover, to prevent data loss, every 5 to 10 years, records and important backup data should be stored separately. The IAEA recommends frequent data backup restorations as part of periodic QA operations, and the ESTRO restricts system access to those who have sufficient authorization, and recommends that valid inspection items be designed in the related departments according to their use.

2. Proposed guidelines for quality assurance of radiation treatment planning systems

1) Acceptance test

An acceptance test is an examination as to whether the RTPS is operated according to specifications. Based on the specification standard provided by a vendor, acceptance tests include the introduction and repair of instruments, verification of the hardware and network environment during updates, data transmission, software functions and operations, and examinations that check accuracy, and benchmark tests (Table 5). The results of acceptance tests are documented and stored while the system is used, and are consulted during system maintenance.

2) Commissioning

Commissioning is an operation that verifies items found to be insufficient in the acceptance test, and evaluates whether the accuracy and measured values are within the allowed tolerances of an instrument by evaluating the RTPS performance and comparison measured data under various conditions. This is performed during the introduction of the system and during software version upgrades. When restoring the hospital network and related instruments, operations are divided into those that do and do not depend on dose.

(1) Non-dosimetric commissioning

Non-dosimetric commissioning includes procedures for checking the RTPS installation, checking that items suit user-oriented use cases, acquiring patient image data, creating, transmitting, and recording anatomical structures, outline formation, three-dimensional structure formation, field selection, and beam data entry. Checking data transmission and display functions through a connected machine and the network, and checking connections with the linear accelerator are important. Non-dosimetric commissioning items are in Table 6, and the procedures are defined as follows.

First, to check the system installation and user environment, server instruments, and majority of the terminal equipment and peripheral devices, the whole system is assessed, and early parameters are determined. Second, to check the transmission and record of patient anatomical data, a phantom is used, wherein CT data is transmitted and its geometric data verified, and a check is made as to whether any problems arose with the CT image-related tools. Additionally, apart from the manual operation and CT images, other image modalities such as outline formation functions are verified, and patient data is confirmed to have been correctly entered and used. Third, to check the structural outline, whether by manual or automatic means, the outline functions that use CT images, 3D structure drawing functions, outline formation through interpolation, and automatic margin functions are checked to be within allowed errors. The relativistic electron density is manually set up, and whether or not changes in the density and MU value density reflections occurred for each pixel is checked. Additional checks include whether, the MU value changed with regard to the bolus function, points or lines exist, normal marks from markers are shown, and dose output is correct. Fourth, in order to check the beam data, the accuracy of data entry into the radiation treatment machine is checked. A check is also performed to verify that the field size and table field angle cannot be entered so as to exceed the regulated range of system parameters. Additionally, elements of the apparatus are examined, including the collimator and jaw, shielding block, MLC, automatic field, SAD and SSD, gentry, collimator, treatment table angle, and wedge. Finally, the beam and DRR target values are confirmed to lie within the allowed range.

(2) Dosimetric commissioning

The goal of dosimetric commissioning is to understand the dose calculation algorithms embodied in a RTPS, assess dose accuracy, minimize the uncertainty in dose calculations, and avoid inappropriate clinical use, while clearly delineating the clinically-allowed use range. The items in dosimetric commissioning are in Table 7, and the procedures are as follows.

First, to verify the beam model, measured and modeled beam data are compared to evaluate the modeling accuracy. Comparisons are performed with the deviation δ proposed by Venselaar et al.11) (Fig. 1), and the allowed standard is as seen in Table 8. The parameter δ1 refers to a region that is a high-dose region, located above the beam’s central axis, and exceeding the maximum dose depth. A region with a small dose angle, δ2, refers to the neighboring boundary where an increased dose and penumbral, inhomogeneous region exists. δ3 refers to a region in a field exceeding the maximum dose depth, i.e., a high dose region with a small dose angle. δ4 refers to a region outside the field, such as a penumbral region, with a low dose region and small dose angle. δ(RW50) refers to a field’s size deviation, and δ50–90 refers to the deviation of a beam’s edge profile.

Second, to prevent errant investigations, a water phantom, 0.6-cc ion chamber, and 0.1-cc ion chamber were used as standard electrometers. With open square fields of 5×5, 10×10, 20×20, 30×30, 40×40, 5×20, 20×5 cm2 and rectangular-wedge-shaped fields of 5×5, 10×10, 15×15 cm2, the relative and absolute dose distributions were investigated. The relative dose distribution was analyzed by selecting a one- or two-dimensional comparison. In one dimension, in a cross-section passing through the isocenter, at least one standard-depth PDD, with a maximum depth of 10 cm, and in some cases, two depth profiles were compared. Absolute dose verification was performed at a standard depth and at several other depths, doses were evaluated, and dosimeters were placed in the isocenter. The tolerances are shown in Table 5. For the calculated value with a wedge and the MLC-combined beam, a higher tolerance was allowed than with the open beam.

Third, in clinical settings, minimizing dose calculation uncertainty and avoiding inappropriate use of calculation algorithms requires several pieces of equipment. A water phantom and 0.6-cc ion chamber, 0.1-cc ion chamber, standard electrometer, tissue-equivalent solid phantom, film, micro ion chamber, solid-state dosimeter, glass dosimeter, and thermoluminescence dosimeter (TLD) were used. As shown in Fig. 2, dose testing was investigated under various conditions. Implementation of the test was performed under various SSD conditions with a 10×10 cm2 field, and 80-, 100-, 130-cm SSDs, as shown in Fig. 2a. These conditions included an open oblique arrangement of a 10×10 cm2 incident field, 100 cm SSD, and 30° gentry angle (Fig. 2b), and a wedged-oblique inclination of a 10×10 cm2 incident field size, 100 cm SSD, 30° gentry angle. At the wedge angle frequently used, and at a wedge angle where algorithm errors are easily generated (Fig. 2c), the PDD and profile, and absolute dose above the beam central axis were evaluated. Within the incident field, the tissue loss condition was tested in a 20×20 cm2 incident field (Fig. 2d); field conditions included an open off-axis field and wedged off-axis field (Fig. 2e, 2f), and the indeterminate field condition was with respect to the MLC (Fig. 2g). Evaluations of the PDD and profile in each field, and of the absolute dose above the beam central axis, were performed. The buildup region condition was an inhomogeneous compensation condition using a rectangular inhomogeneous model phantom and a mock human phantom, and the dose distribution and above-beam-center absolute dose according to the field size were evaluated.

3) Periodic quality assurance test

A periodic QA test checks whether the evaluated system performance and accuracy has been maintained and is reproducible, with respect to the RTPS acceptance test and commissioning during ordinary radiation treatment. Its goal is to check the stability and security of the treatment data files, verify the accuracy and function of peripheral devices used for data entry, check the security of the TPS software and output instruments, and verify software operations and accuracy. Periodic QA tests are performed often—daily, weekly, monthly, and yearly (Table 9), and the data is organized and stored so that changing trends in the results over time can be checked.

Daily operations are performed to examine and repair errors and changes in records. Every week, examination of computer file security, re-examination of clinical treatment planning, and problem-solving operations are performed. Every month, examination of the security of the RTPS CT data entry is performed, and the status of all RTPS equipment is examined. The correspondence between the measured and calculated doses is checked, and data accuracy and input/output devices are examined, with important software operations performed yearly. Finally, mechanical updates and fixed-time beam are checked, and checks and resulting restarts of the system software, including the operating system, are performed.

4) System management and security

A RTPS is comprised of computer hardware and software, related equipment, and RTP software. A combined system has networked and divided graphical workstations and servers and associated equipment which require maintenance to ensure nominal system functions. For this, monthly software and hardware checks and daily, weekly, or monthly data backup operations are required.

To support software management, the RTPS server and its backup log are checked monthly. Hardware management is also performed monthly by examining the server and storage devices, uninterruptible power supply (UPS), workstation LEDs denoting their operational state, and network connectivity. New and modified files are backed up daily, all files related to treatment plans are backed up weekly, and the entire system, including the system software and RTP software, beam data files, and treatment plan files, is backed up monthly.

In radiation treatment, the quality assurance of a RTPS is a very important in preventing radiation treatment accidents and qualitatively improving treatment. Such QA is divided into acceptance tests and commissioning, periodic tests, and system management and security. The verification and maintenance of RTPS performance and dose precision and accuracy are necessary for patient and equipment data management. Through this research, the key QA items from international reports by the AAPM, IAEA, and ESTRO on RTP QA are assembled and recommended, confirming that different QA items are recommended by each organization. Currently in Korea, reports from the Nuclear Safety and Security Commission examinations and the Korean Society of Medical Physicists are limited to the QA of radiation treatment items, and while their legal implementation and resulting recommendations are made, standards and procedures for RTP QA systems have not been prepared. The analysis of the current state of foreign QA guidelines in conjunction with the guidelines from this research can be used to establish an approach for RTPS QA, which will enhance radiation safety and improve treatment.

This work was supported by the General Researcher Program (NRF-2015R1D1A1A09056828), the Nuclear Safety Research Program (Grant No. 1603016) through the Korea Foundation of Nuclear Safety (KOFONS), and financial resources granted by the Nuclear Safety and Security Commission (NSSC) of the Republic of Korea.

Status of acceptance test.

ItemsAAPMESTROIAEA
HardwareCheck CPU, monitor, printer, and all peripheral instruments(Not described)Check CPU and memory, disk operation, input/output devices
Network environment(Not described)Network connectionNetwork connection
Data transmission(Not described)Data transmissionData transmission
SoftwareAccording to specification, mark as ‘exists/does not exist’Basic patient registration
System function check
Verification of system functions
Check calculation functions
Check utilities
Benchmark testMeasurement of accuracy of the dose calculation algorithm and calculation times under very specific circumstances with specific beam dataBasic treatment description
Verification of dose distribution
MLC field
Measurement of data for the photon beams of two machines (4 MV and 18 MV linear accelerators) and the results of a series of tests
Tests under standard fields

Status of non-dosimetric commissioning.

ItemsAAPMESTROIAEA
Check system installation(Not described)(Not described)Installation of system hardware
Software selection
Detailed parameter selection
Patient image dataPatient positioning and immobilization
Image acquisition
Image registration
Input of outline data
Collection of patient data
Input and transmission of anatomical data
Outline creationAnatomical descriptionDefinition of anatomical structure
Outline modification
Construction of volumes
Creation of the anatomical model
Beam data checksBeam arrangements and definition
Machine description, limits and readouts
Geometric accuracy
Field shape design
Wedge, compensator
Methodology, algorithms
Density corrections, etc.
Beam geometry
Beam display functions (BEV, beam location/shape, Block location in BEV, MLC field, Bolus location, etc.)
Beam parameters
Beam geometry
Field definition
Wedges, Beam modifiers
Normalizations
Plan output check
Parameter checks and documentation
SAD, SSD setup
BEV, field check
Portal image indicator

Status of dosimetric commissioning.

ItemsAAPMESTROIAEA
Beam data inputMeasurement of beam dataset
Transfer of measured data from water phantom
Manual data entry
Verification of input data
Data input
Documentation
Transfer of measured data from water phantom
Algorithm input data
Dose calculationSquare and rectangular field
Asymmetric fields
Blocked fields
MLC-shaped field
Wedged field
External surface variations
SSD variations
Inhomogeneity, etc.
Open field and rectangular field
Blocked fields
MLC-shaped fields
Wedged field
Off-axis field
SSD variations
Inhomogeneity
Missing tissue, etc.
Square and rectangular field
Asymmetric fields
Wedged field
SSD variations
Oblique incidence
Complicated surface formation
Build-up region
Density correction
Inhomogeneity correction
Compensator, etc.
Examination of dose calculations1-D comparisons
Difference between FDD (fractional depth dose) and TPR
2-D isodose curve
Color wash dose indicator
Dose difference indicator
DVH analysis
Distance maps
2-D and 3-D dose distribution
DVH
Beam dependence verification
Algorithms and clinical examination
1-D comparison: Depth dose differences according to field
2-D comparison: isodose curve
3-D comparison: Comparison of 3-D dose distribution and DVH
MU calculationMU calculation
MU calculation QA
Process Verification
MU calculationMU calculation
Process verification

Status of periodic quality assurance testing.

ItemsAAPMESTROIAEA
DailyError and change log(Refer to items for acceptance test)(Not described)
WeeklyComputer files
Review clinical planning
(Not described)
MonthlyCT data input
Problem review
Review of RTP system
CPU
Plan details
YearlyDose calculation
Data and I/O devices, critical software tools
MUs/time
VariableBeam parameterizationBackup recovery
CT (or other) scan transfer, geometry and density check
Patient anatomy
MUs/time

Items for acceptance test.

ItemsTest
HardwareCheck whether computer peripheral devices operate according to specifications
Network environmentCheck all network connections transmitting data in the RTPS and the network
Data transmissionCheck CT and MRI image data, treatment plan data transmitted by the RTPS, MLC data transmitted by the MLC control system, DRR data, and data transmitted by the compensator design device, simulation, and the radiation oncology management systems
SoftwareCT input and anatomical description, beam data input, dose calculations, dose indicators, dose volume histograms, document output accuracy checks
Benchmark testCheck calculation function using standard beam data

Items for non-dosimetric commissioning.

ItemsTest
System installation checks and user definitionHardware and software checks
System limits checks
Patient data checks
Data conversion of RTPS
Indicators and output devices installation checks
Treatment plan protocol checks
Conversion of CT number to electron density
Database checks
Patient anatomical description, transmission, and registrationCT image acquisition
CT image indicator related tools
Patient anatomical data formation from other non-CT image modalities and manual operations
Patient database
Structure outline creationManual outline formation using CT images
Automatic outline formation using CT images
3-D structure formation
Outline formation using interpolation
Automatic margin function
Set-up of relative electron density
Bolus formation
Points and line marker definition
Beam dataSystem parameter checks
System parameter limits
Collimator and jaw setup
Shielding block definition and formation
MLC
Automatic field formation
Beam installation checks
Gantry and collimator, treatment table angle
Wedge
Beam
DRR

Items for dosimetric commissioning.

ItemsTest
Verification of beam modelingComparison of measured and calculated beam data
Verification under simple conditionsRelative dose distribution and absolute dose verification
Verification in clinical conditionsVariation in SSD
Open oblique incidence field
Wedged oblique incidence field
Missing tissue
Open off-axis field
Wedged off-axis field
Irregular field
Build-up region
Inhomogeneity correction (Rectangular inhomogeneous model phantom or human body phantom)

Tolerance of assessing dose for external radiation treatment.

Dose evaluation region(1) Homogeneous, open field, symmetry beam(2) Simple inhomogeneous wedge, MLC-shaped field, asymmetry beam(3) Beam used by the combination of more than 2 types
δ12%3%4%
δ22 mm, 10%3 mm, 15%3 mm, 15%
δ33%3%3%
δ43% (30%)3% (40%)3% (50%)
δ(RW50)2 mm, 1%3 mm, 1%3 mm, 1%
δ50–902 mm3 mm3 mm

Items for periodic quality assurance test

ItemsTest
DailyReview error log
Review change log
WeeklyVerify computer files
Verify clinical plan
MonthlyVerify stability about CT data and CT value and relative electron density
Review problems of RTPS and prioritize resolution of problems
Review configuration and state of RTPS
YearlyCheck concordance between measured and calculated dose
Review accuracy of data and operation of I/O devices
Review important software
VariableCheck beam parameter and restart
Check software including OS and restart
  1. Whosaeng: Increased radiation therapy in cancer patients http://m.whosaeng.com/a.html?uid=94023.
  2. KEIT. PD Issue report. Technology trend and industry status of radiation therapy equipment. Korea Evaluation Institute of Industrial Technology 2017.
  3. WHO. Radiotherapy risk profile. World Health 2008.
  4. RPOP. Short case histories of major accidental exposure events in radiotherapy https://rpop.iaea.org/RPOP/RPoP/Content/InformationFor/HealthProfessionals/2_Radiotherapy/AccidentPrevention.htm.
  5. IAEA. Commissioning and quality assurance of computerized planning systems for radiation treatment of cancer. Vienna: International Atomic Energy Agency. Technical Reports Series no. 430 2004:430.
  6. ESTRO. Booklet no. 7. Quality assurance of treatment planning systems. Practical examples for non-IMRT photon beams. European Society for Radiotherapy & Oncology 2004.
  7. AAPM. Radiation Therapy Committee Task Group 53. Quality assurance for clinical radiotherapy treatment planning. American Association of Physicists in Medicine 1998.
  8. NSSC. Notification no. 2015-005. Technological standards for radiation safety of medical field. Nuclear Safety and Security Commission 2015.
  9. KSMP. AAPM Task Group 142 report. Quality assurance of medical accelerators. Korean Society of Medical Physics 2016;142.
  10. Choi S, Park D, and Kim K, et al. Suggestion for Comprehensive Quality Assurance of Medical Linear Accelerator in Korea. Prog Med Phys 2015;26(4):294-303.
    CrossRef
  11. Venselaar J, Welleweerd H, and Mijnheer B. Tolerances for the accuracy of photon beam dose calculations of treatment planning systems. Radiother Oncol 2001;60(2):191-201.
    Pubmed CrossRef

Article

Original Article

Progress in Medical Physics 2017; 28(4): 197-206

Published online December 31, 2017 https://doi.org/10.14316/pmp.2017.28.4.197

Copyright © Korean Society of Medical Physics.

Proposal on Guideline for Quality Assurance of Radiation Treatment Planning System

Yoonjin Oh*, Dong Oh Shin, Juhye Kim*, Nahye Kwon*, Soon Sung Lee§,ΙΙ, Sang Hyoun ChoiΙΙ, Sohyun Ahn, Dong-wook Park#, Dong Wook Kim

*Research Institute of Clinical Medicine, Kyung Hee University Hospital at Gangdong, Department of Radiation Oncology, Kyung Hee University Hospital at Gangdong, Department of Radiation Oncology, Kyung Hee University Hospital, §Department of Radiological & Medico Oncological Sciences, University of Science and Technology, ΙΙDivision of Medical Radiation Equipment, Korea Institute of Radiological and Medical Sciences, Department of Radiation Oncology, School of Medicine, Yonsei University, Seoul, #Department of Radiation Oncology, Inje University Ilsan Paik Hospital, Goyang, Korea

Correspondence to:

Dong Oh Shin (ohsd32@gmail.com)
Tel: 82-2-958-9467 Fax: 82-2-958-9469

Received: November 16, 2017; Revised: December 18, 2017; Accepted: December 19, 2017

This is an Open-Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/4.0) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

We develop guidelines for the quality assurance of radiation treatment planning systems (TPS) by comparing and reviewing recommendations from major countries and organizations, as well as by analyzing the AAPM, ESTRO, and IAEA TPS quality assurance guidelines. We establish quality assurance items for acceptance testing, commissioning, periodic testing, system management, and security, and propose methods to perform each item within acceptable standards. Acceptance includes tests of hardware and network environments, data transmission, software, and benchmarking as specified by the system supplier, and apply the IAEA classification criteria. Commissioning includes dosimetric and non-dosimetric items for assessing TPS performance by applying the AAPM classification criteria and the latest technical items from the IAEA. Periodic quality assurance tests include daily, weekly, monthly, yearly, and occasional items by applying the AAPM classification criteria. System management and security items include the state and network connectivity of TPS, periodic data backup, and data access security. The guidelines for TPS quality assurance proposed in this study will help to improve the safety and quality of radiotherapy by preventing incidents related to radiotherapy.

Keywords: Radiation treatment planning system, Acceptance test, Commissioning, Quality assurance

Introduction

Because of the rapidly aging population, the number of cancer patients has increased continually by 5.5% each year.1) In the U.S., approximately 50% of cancer patients receive radiation therapy, and in Korea, which has fewer cancer patients than the U.S, approximately 25% patients receive radiation therapy, with an annual increase of 6.2%.2) Radiation therapy plays an important role in cancer treatment, and with the rapid development of medical technology and high-precision radiation therapy methods, the quality of life of cancer patients is gradually improving. Currently, in every medical institution, in order to safely perform high-precision, high-dose radiation therapy such as intensity-modulated radiation therapy, stereotactic body radiation therapy, and stereotactic radiosurgery, a systematized and periodic quality assurance and control (QA) approach for use with therapy equipment is very important.

The WHO reported that between 1976 to 2007, personnel training and improvements to treatment environments did not keep up with the rapid development of radiation therapy technology, leading to 55% of the deleterious causes of radiation therapy on patients to be related to radiation treatment planning.3) For example, in England’s North Staffordshire Royal Infirmary, a new treatment system was introduced, but owing to discord between the new and existing systems, from 1982 to 1991, there were over 1,000 instances of patients receiving the wrong radiation treatment.4)

The key reasons behind the incidents related to radiation treatment planning included an insufficient understanding of the radiation treatment planning system (RTPS), a lack of commissioning, and no verification of independent calculations, and that educational training and quality assurance processes were not properly managed.5,6) Currently, according to examinations of a domestic radiation therapy quality assurance organization, the Nuclear Safety & Security Commission, and published technical reports of the Korean Society of Medical Physics,79) quality assurance experts are available, and quality assurance performed mechanical dosimetry is recommended. However, currently quality assurance guidelines for RTPS do not exist. Thus, in this research, to improve the quality assurance of treatment planning, which when poorly executed is one of the causes behind main radiation therapy incidents and accidents, the current state of international quality assurance is analyzed, and RTPS quality assurance guidelines are proposed.

Materials and Methods

1. Current state of foreign radiation treatment planning quality assurance

Radiation treatment planning and the current state of QA from related foreign organizations were analyzed and organized, from which relevant standards and procedures were prepared. Several quality control items and methods were separated by type, compared, and evaluated. These include the proposed RTPS (radiation treatment planning system) described in “Quality assurance for clinical radiotherapy treatment planning (TG-53)”10) from the AAPM (American Association of Physicists in Medicine), “Commissioning and Quality assurance of computerized planning systems for radiation treatment of cancer”5) from the IAEA (International Atomic Energy Agency), and “Quality assurance of treatment planning systems. Practical examples for non-IMRT photon beams”6) from ESTRO (European Society for Radiotherapy & Oncology).

2. Radiation treatment planning system quality assurance items and procedures

The goal of this study was to prepare integrated RTPS QA guidelines by referring to the relevant information for radiation treatment planning systems from developed countries and international organizations, and to deduce them in order to prepare implementation procedures. Guidelines were divided into RTPS acceptance tests and commissioning, periodic quality control, and system management and security, and the QA items and methods such as tolerances were checked.

Results and Considerations

1. Current state of foreign quality assurance related radiation treatment planning

When purchasing and setting up a RTPS, as well as when performing updates, a clinically qualified medical physicist (CQMP), performs acceptance tests and commissioning in a manner similar to that needed for the use of radiation treatment machines, and the RTPS needs to be managed in part with periodic quality assurance. The AAPM proposed items and detailed information on the construction of a structure, acceptance tests, commissioning, and periodic quality control, for the QA of a RTPS. In addition, the IAEA and ESTRO guidelines for RTPS QA were proposed.

The RTPS vendor and the CQMP perform an acceptance test using the specifications, along with an inspection of the hardware and related equipment, algorithms, DVH, software, and a check of the system input and output during normal operations. For these items, the AAPM and IAEA propose hardware, software, and benchmarking inspection items. The ESTRO and IAEA recommend investigating network connections and data transmission (Table 1). The ESTRO does not describe acceptance test items for hardware and related equipment, but does recommend that during inspections of software and related items that the RTPS vendor and medical physicist roles and responsibilities should be separated.

For commissioning, the CQMP, after investigating various benchmarks, compares and verifies calculation results and measured values during clinical operations to check whether usage is within an error tolerance. The AAPM divides such items into two categories: those that are related to dose and those that are not (Tables 2, 3). In particular, as a supplement the IAEA recommends comprehensive quality control items including asymmetric jaws, multi-leaf collimator (MLC), and similar new technologies.

For periodic quality assurance tests, the job of the CQMP is to check via acceptance tests and commissioning whether expected system functions are maintained in the clinic. The AAPM recommends investigating management items daily, weekly, monthly, and yearly, and the IAEA recommends the same at any time, but monthly and yearly. The ESTRO recommends that periodic QA based on acceptance tests and commissioning items be performed, but does not propose an inspection frequency for each quality assurance item, instead recommending that QA be performed to suit the conditions of each organization (Table 4).

System management and security are operations that include activities such as system maintenance and data backup and security of system use. The AAPM designates a system administrator and a computer system administrator, and recommends that system management and security operations be performed. For data management, development and maintenance of documented policies and procedures for patient data records and readouts are recommended. Moreover, to prevent data loss, every 5 to 10 years, records and important backup data should be stored separately. The IAEA recommends frequent data backup restorations as part of periodic QA operations, and the ESTRO restricts system access to those who have sufficient authorization, and recommends that valid inspection items be designed in the related departments according to their use.

2. Proposed guidelines for quality assurance of radiation treatment planning systems

1) Acceptance test

An acceptance test is an examination as to whether the RTPS is operated according to specifications. Based on the specification standard provided by a vendor, acceptance tests include the introduction and repair of instruments, verification of the hardware and network environment during updates, data transmission, software functions and operations, and examinations that check accuracy, and benchmark tests (Table 5). The results of acceptance tests are documented and stored while the system is used, and are consulted during system maintenance.

2) Commissioning

Commissioning is an operation that verifies items found to be insufficient in the acceptance test, and evaluates whether the accuracy and measured values are within the allowed tolerances of an instrument by evaluating the RTPS performance and comparison measured data under various conditions. This is performed during the introduction of the system and during software version upgrades. When restoring the hospital network and related instruments, operations are divided into those that do and do not depend on dose.

(1) Non-dosimetric commissioning

Non-dosimetric commissioning includes procedures for checking the RTPS installation, checking that items suit user-oriented use cases, acquiring patient image data, creating, transmitting, and recording anatomical structures, outline formation, three-dimensional structure formation, field selection, and beam data entry. Checking data transmission and display functions through a connected machine and the network, and checking connections with the linear accelerator are important. Non-dosimetric commissioning items are in Table 6, and the procedures are defined as follows.

First, to check the system installation and user environment, server instruments, and majority of the terminal equipment and peripheral devices, the whole system is assessed, and early parameters are determined. Second, to check the transmission and record of patient anatomical data, a phantom is used, wherein CT data is transmitted and its geometric data verified, and a check is made as to whether any problems arose with the CT image-related tools. Additionally, apart from the manual operation and CT images, other image modalities such as outline formation functions are verified, and patient data is confirmed to have been correctly entered and used. Third, to check the structural outline, whether by manual or automatic means, the outline functions that use CT images, 3D structure drawing functions, outline formation through interpolation, and automatic margin functions are checked to be within allowed errors. The relativistic electron density is manually set up, and whether or not changes in the density and MU value density reflections occurred for each pixel is checked. Additional checks include whether, the MU value changed with regard to the bolus function, points or lines exist, normal marks from markers are shown, and dose output is correct. Fourth, in order to check the beam data, the accuracy of data entry into the radiation treatment machine is checked. A check is also performed to verify that the field size and table field angle cannot be entered so as to exceed the regulated range of system parameters. Additionally, elements of the apparatus are examined, including the collimator and jaw, shielding block, MLC, automatic field, SAD and SSD, gentry, collimator, treatment table angle, and wedge. Finally, the beam and DRR target values are confirmed to lie within the allowed range.

(2) Dosimetric commissioning

The goal of dosimetric commissioning is to understand the dose calculation algorithms embodied in a RTPS, assess dose accuracy, minimize the uncertainty in dose calculations, and avoid inappropriate clinical use, while clearly delineating the clinically-allowed use range. The items in dosimetric commissioning are in Table 7, and the procedures are as follows.

First, to verify the beam model, measured and modeled beam data are compared to evaluate the modeling accuracy. Comparisons are performed with the deviation δ proposed by Venselaar et al.11) (Fig. 1), and the allowed standard is as seen in Table 8. The parameter δ1 refers to a region that is a high-dose region, located above the beam’s central axis, and exceeding the maximum dose depth. A region with a small dose angle, δ2, refers to the neighboring boundary where an increased dose and penumbral, inhomogeneous region exists. δ3 refers to a region in a field exceeding the maximum dose depth, i.e., a high dose region with a small dose angle. δ4 refers to a region outside the field, such as a penumbral region, with a low dose region and small dose angle. δ(RW50) refers to a field’s size deviation, and δ50–90 refers to the deviation of a beam’s edge profile.

Second, to prevent errant investigations, a water phantom, 0.6-cc ion chamber, and 0.1-cc ion chamber were used as standard electrometers. With open square fields of 5×5, 10×10, 20×20, 30×30, 40×40, 5×20, 20×5 cm2 and rectangular-wedge-shaped fields of 5×5, 10×10, 15×15 cm2, the relative and absolute dose distributions were investigated. The relative dose distribution was analyzed by selecting a one- or two-dimensional comparison. In one dimension, in a cross-section passing through the isocenter, at least one standard-depth PDD, with a maximum depth of 10 cm, and in some cases, two depth profiles were compared. Absolute dose verification was performed at a standard depth and at several other depths, doses were evaluated, and dosimeters were placed in the isocenter. The tolerances are shown in Table 5. For the calculated value with a wedge and the MLC-combined beam, a higher tolerance was allowed than with the open beam.

Third, in clinical settings, minimizing dose calculation uncertainty and avoiding inappropriate use of calculation algorithms requires several pieces of equipment. A water phantom and 0.6-cc ion chamber, 0.1-cc ion chamber, standard electrometer, tissue-equivalent solid phantom, film, micro ion chamber, solid-state dosimeter, glass dosimeter, and thermoluminescence dosimeter (TLD) were used. As shown in Fig. 2, dose testing was investigated under various conditions. Implementation of the test was performed under various SSD conditions with a 10×10 cm2 field, and 80-, 100-, 130-cm SSDs, as shown in Fig. 2a. These conditions included an open oblique arrangement of a 10×10 cm2 incident field, 100 cm SSD, and 30° gentry angle (Fig. 2b), and a wedged-oblique inclination of a 10×10 cm2 incident field size, 100 cm SSD, 30° gentry angle. At the wedge angle frequently used, and at a wedge angle where algorithm errors are easily generated (Fig. 2c), the PDD and profile, and absolute dose above the beam central axis were evaluated. Within the incident field, the tissue loss condition was tested in a 20×20 cm2 incident field (Fig. 2d); field conditions included an open off-axis field and wedged off-axis field (Fig. 2e, 2f), and the indeterminate field condition was with respect to the MLC (Fig. 2g). Evaluations of the PDD and profile in each field, and of the absolute dose above the beam central axis, were performed. The buildup region condition was an inhomogeneous compensation condition using a rectangular inhomogeneous model phantom and a mock human phantom, and the dose distribution and above-beam-center absolute dose according to the field size were evaluated.

3) Periodic quality assurance test

A periodic QA test checks whether the evaluated system performance and accuracy has been maintained and is reproducible, with respect to the RTPS acceptance test and commissioning during ordinary radiation treatment. Its goal is to check the stability and security of the treatment data files, verify the accuracy and function of peripheral devices used for data entry, check the security of the TPS software and output instruments, and verify software operations and accuracy. Periodic QA tests are performed often—daily, weekly, monthly, and yearly (Table 9), and the data is organized and stored so that changing trends in the results over time can be checked.

Daily operations are performed to examine and repair errors and changes in records. Every week, examination of computer file security, re-examination of clinical treatment planning, and problem-solving operations are performed. Every month, examination of the security of the RTPS CT data entry is performed, and the status of all RTPS equipment is examined. The correspondence between the measured and calculated doses is checked, and data accuracy and input/output devices are examined, with important software operations performed yearly. Finally, mechanical updates and fixed-time beam are checked, and checks and resulting restarts of the system software, including the operating system, are performed.

4) System management and security

A RTPS is comprised of computer hardware and software, related equipment, and RTP software. A combined system has networked and divided graphical workstations and servers and associated equipment which require maintenance to ensure nominal system functions. For this, monthly software and hardware checks and daily, weekly, or monthly data backup operations are required.

To support software management, the RTPS server and its backup log are checked monthly. Hardware management is also performed monthly by examining the server and storage devices, uninterruptible power supply (UPS), workstation LEDs denoting their operational state, and network connectivity. New and modified files are backed up daily, all files related to treatment plans are backed up weekly, and the entire system, including the system software and RTP software, beam data files, and treatment plan files, is backed up monthly.

Conclusion

In radiation treatment, the quality assurance of a RTPS is a very important in preventing radiation treatment accidents and qualitatively improving treatment. Such QA is divided into acceptance tests and commissioning, periodic tests, and system management and security. The verification and maintenance of RTPS performance and dose precision and accuracy are necessary for patient and equipment data management. Through this research, the key QA items from international reports by the AAPM, IAEA, and ESTRO on RTP QA are assembled and recommended, confirming that different QA items are recommended by each organization. Currently in Korea, reports from the Nuclear Safety and Security Commission examinations and the Korean Society of Medical Physicists are limited to the QA of radiation treatment items, and while their legal implementation and resulting recommendations are made, standards and procedures for RTP QA systems have not been prepared. The analysis of the current state of foreign QA guidelines in conjunction with the guidelines from this research can be used to establish an approach for RTPS QA, which will enhance radiation safety and improve treatment.

Acknowledgements

This work was supported by the General Researcher Program (NRF-2015R1D1A1A09056828), the Nuclear Safety Research Program (Grant No. 1603016) through the Korea Foundation of Nuclear Safety (KOFONS), and financial resources granted by the Nuclear Safety and Security Commission (NSSC) of the Republic of Korea.

Conflicts of Interest

The author(s) indicated no potential conflicts of interest.

Availability of Data and Materials

All relevant data are within the paper and its Supporting Information files.

Tables

Status of acceptance test.

ItemsAAPMESTROIAEA
HardwareCheck CPU, monitor, printer, and all peripheral instruments(Not described)Check CPU and memory, disk operation, input/output devices
Network environment(Not described)Network connectionNetwork connection
Data transmission(Not described)Data transmissionData transmission
SoftwareAccording to specification, mark as ‘exists/does not exist’Basic patient registration
System function check
Verification of system functions
Check calculation functions
Check utilities
Benchmark testMeasurement of accuracy of the dose calculation algorithm and calculation times under very specific circumstances with specific beam dataBasic treatment description
Verification of dose distribution
MLC field
Measurement of data for the photon beams of two machines (4 MV and 18 MV linear accelerators) and the results of a series of tests
Tests under standard fields

Status of non-dosimetric commissioning.

ItemsAAPMESTROIAEA
Check system installation(Not described)(Not described)Installation of system hardware
Software selection
Detailed parameter selection
Patient image dataPatient positioning and immobilization
Image acquisition
Image registration
Input of outline data
Collection of patient data
Input and transmission of anatomical data
Outline creationAnatomical descriptionDefinition of anatomical structure
Outline modification
Construction of volumes
Creation of the anatomical model
Beam data checksBeam arrangements and definition
Machine description, limits and readouts
Geometric accuracy
Field shape design
Wedge, compensator
Methodology, algorithms
Density corrections, etc.
Beam geometry
Beam display functions (BEV, beam location/shape, Block location in BEV, MLC field, Bolus location, etc.)
Beam parameters
Beam geometry
Field definition
Wedges, Beam modifiers
Normalizations
Plan output check
Parameter checks and documentation
SAD, SSD setup
BEV, field check
Portal image indicator

Status of dosimetric commissioning.

ItemsAAPMESTROIAEA
Beam data inputMeasurement of beam dataset
Transfer of measured data from water phantom
Manual data entry
Verification of input data
Data input
Documentation
Transfer of measured data from water phantom
Algorithm input data
Dose calculationSquare and rectangular field
Asymmetric fields
Blocked fields
MLC-shaped field
Wedged field
External surface variations
SSD variations
Inhomogeneity, etc.
Open field and rectangular field
Blocked fields
MLC-shaped fields
Wedged field
Off-axis field
SSD variations
Inhomogeneity
Missing tissue, etc.
Square and rectangular field
Asymmetric fields
Wedged field
SSD variations
Oblique incidence
Complicated surface formation
Build-up region
Density correction
Inhomogeneity correction
Compensator, etc.
Examination of dose calculations1-D comparisons
Difference between FDD (fractional depth dose) and TPR
2-D isodose curve
Color wash dose indicator
Dose difference indicator
DVH analysis
Distance maps
2-D and 3-D dose distribution
DVH
Beam dependence verification
Algorithms and clinical examination
1-D comparison: Depth dose differences according to field
2-D comparison: isodose curve
3-D comparison: Comparison of 3-D dose distribution and DVH
MU calculationMU calculation
MU calculation QA
Process Verification
MU calculationMU calculation
Process verification

Status of periodic quality assurance testing.

ItemsAAPMESTROIAEA
DailyError and change log(Refer to items for acceptance test)(Not described)
WeeklyComputer files
Review clinical planning
(Not described)
MonthlyCT data input
Problem review
Review of RTP system
CPU
Plan details
YearlyDose calculation
Data and I/O devices, critical software tools
MUs/time
VariableBeam parameterizationBackup recovery
CT (or other) scan transfer, geometry and density check
Patient anatomy
MUs/time

Items for acceptance test.

ItemsTest
HardwareCheck whether computer peripheral devices operate according to specifications
Network environmentCheck all network connections transmitting data in the RTPS and the network
Data transmissionCheck CT and MRI image data, treatment plan data transmitted by the RTPS, MLC data transmitted by the MLC control system, DRR data, and data transmitted by the compensator design device, simulation, and the radiation oncology management systems
SoftwareCT input and anatomical description, beam data input, dose calculations, dose indicators, dose volume histograms, document output accuracy checks
Benchmark testCheck calculation function using standard beam data

Items for non-dosimetric commissioning.

ItemsTest
System installation checks and user definitionHardware and software checks
System limits checks
Patient data checks
Data conversion of RTPS
Indicators and output devices installation checks
Treatment plan protocol checks
Conversion of CT number to electron density
Database checks
Patient anatomical description, transmission, and registrationCT image acquisition
CT image indicator related tools
Patient anatomical data formation from other non-CT image modalities and manual operations
Patient database
Structure outline creationManual outline formation using CT images
Automatic outline formation using CT images
3-D structure formation
Outline formation using interpolation
Automatic margin function
Set-up of relative electron density
Bolus formation
Points and line marker definition
Beam dataSystem parameter checks
System parameter limits
Collimator and jaw setup
Shielding block definition and formation
MLC
Automatic field formation
Beam installation checks
Gantry and collimator, treatment table angle
Wedge
Beam
DRR

Items for dosimetric commissioning.

ItemsTest
Verification of beam modelingComparison of measured and calculated beam data
Verification under simple conditionsRelative dose distribution and absolute dose verification
Verification in clinical conditionsVariation in SSD
Open oblique incidence field
Wedged oblique incidence field
Missing tissue
Open off-axis field
Wedged off-axis field
Irregular field
Build-up region
Inhomogeneity correction (Rectangular inhomogeneous model phantom or human body phantom)

Tolerance of assessing dose for external radiation treatment.

Dose evaluation region(1) Homogeneous, open field, symmetry beam(2) Simple inhomogeneous wedge, MLC-shaped field, asymmetry beam(3) Beam used by the combination of more than 2 types
δ12%3%4%
δ22 mm, 10%3 mm, 15%3 mm, 15%
δ33%3%3%
δ43% (30%)3% (40%)3% (50%)
δ(RW50)2 mm, 1%3 mm, 1%3 mm, 1%
δ50–902 mm3 mm3 mm

Items for periodic quality assurance test

ItemsTest
DailyReview error log
Review change log
WeeklyVerify computer files
Verify clinical plan
MonthlyVerify stability about CT data and CT value and relative electron density
Review problems of RTPS and prioritize resolution of problems
Review configuration and state of RTPS
YearlyCheck concordance between measured and calculated dose
Review accuracy of data and operation of I/O devices
Review important software
VariableCheck beam parameter and restart
Check software including OS and restart

Fig 1.

Figure 1.Location of dose calculation verification (solid line: measured profile, dot line: calculated profile).
Progress in Medical Physics 2017; 28: 197-206https://doi.org/10.14316/pmp.2017.28.4.197

Fig 2.

Figure 2.Verification in (a) SSD variation, (b) open oblique incidence field, (c) wedged-oblique incidence field, (d) missing tissue, (e) open off-axis field, (f) wedged off-axis field, (g) MLC-shaped field.
Progress in Medical Physics 2017; 28: 197-206https://doi.org/10.14316/pmp.2017.28.4.197

Table 1 Status of acceptance test.

ItemsAAPMESTROIAEA
HardwareCheck CPU, monitor, printer, and all peripheral instruments(Not described)Check CPU and memory, disk operation, input/output devices
Network environment(Not described)Network connectionNetwork connection
Data transmission(Not described)Data transmissionData transmission
SoftwareAccording to specification, mark as ‘exists/does not exist’Basic patient registrationSystem function checkVerification of system functionsCheck calculation functionsCheck utilities
Benchmark testMeasurement of accuracy of the dose calculation algorithm and calculation times under very specific circumstances with specific beam dataBasic treatment descriptionVerification of dose distributionMLC fieldMeasurement of data for the photon beams of two machines (4 MV and 18 MV linear accelerators) and the results of a series of testsTests under standard fields

Table 2 Status of non-dosimetric commissioning.

ItemsAAPMESTROIAEA
Check system installation(Not described)(Not described)Installation of system hardwareSoftware selectionDetailed parameter selection
Patient image dataPatient positioning and immobilizationImage acquisitionImage registrationInput of outline dataCollection of patient dataInput and transmission of anatomical data
Outline creationAnatomical descriptionDefinition of anatomical structureOutline modificationConstruction of volumesCreation of the anatomical model
Beam data checksBeam arrangements and definitionMachine description, limits and readoutsGeometric accuracyField shape designWedge, compensatorMethodology, algorithmsDensity corrections, etc.Beam geometryBeam display functions (BEV, beam location/shape, Block location in BEV, MLC field, Bolus location, etc.)Beam parametersBeam geometryField definitionWedges, Beam modifiersNormalizationsPlan output checkParameter checks and documentationSAD, SSD setupBEV, field checkPortal image indicator

Table 3 Status of dosimetric commissioning.

ItemsAAPMESTROIAEA
Beam data inputMeasurement of beam datasetTransfer of measured data from water phantomManual data entryVerification of input dataData inputDocumentationTransfer of measured data from water phantomAlgorithm input data
Dose calculationSquare and rectangular fieldAsymmetric fieldsBlocked fieldsMLC-shaped fieldWedged fieldExternal surface variationsSSD variationsInhomogeneity, etc.Open field and rectangular fieldBlocked fieldsMLC-shaped fieldsWedged fieldOff-axis fieldSSD variationsInhomogeneityMissing tissue, etc.Square and rectangular fieldAsymmetric fieldsWedged fieldSSD variationsOblique incidenceComplicated surface formationBuild-up regionDensity correctionInhomogeneity correctionCompensator, etc.
Examination of dose calculations1-D comparisonsDifference between FDD (fractional depth dose) and TPR2-D isodose curveColor wash dose indicatorDose difference indicatorDVH analysisDistance maps2-D and 3-D dose distributionDVHBeam dependence verificationAlgorithms and clinical examination1-D comparison: Depth dose differences according to field2-D comparison: isodose curve3-D comparison: Comparison of 3-D dose distribution and DVH
MU calculationMU calculationMU calculation QAProcess VerificationMU calculationMU calculationProcess verification

Table 4 Status of periodic quality assurance testing.

ItemsAAPMESTROIAEA
DailyError and change log(Refer to items for acceptance test)(Not described)
WeeklyComputer filesReview clinical planning(Not described)
MonthlyCT data inputProblem reviewReview of RTP systemCPUPlan details
YearlyDose calculationData and I/O devices, critical software toolsMUs/time
VariableBeam parameterizationBackup recoveryCT (or other) scan transfer, geometry and density checkPatient anatomyMUs/time

Table 5 Items for acceptance test.

ItemsTest
HardwareCheck whether computer peripheral devices operate according to specifications
Network environmentCheck all network connections transmitting data in the RTPS and the network
Data transmissionCheck CT and MRI image data, treatment plan data transmitted by the RTPS, MLC data transmitted by the MLC control system, DRR data, and data transmitted by the compensator design device, simulation, and the radiation oncology management systems
SoftwareCT input and anatomical description, beam data input, dose calculations, dose indicators, dose volume histograms, document output accuracy checks
Benchmark testCheck calculation function using standard beam data

Table 6 Items for non-dosimetric commissioning.

ItemsTest
System installation checks and user definitionHardware and software checksSystem limits checksPatient data checksData conversion of RTPSIndicators and output devices installation checksTreatment plan protocol checksConversion of CT number to electron densityDatabase checks
Patient anatomical description, transmission, and registrationCT image acquisitionCT image indicator related toolsPatient anatomical data formation from other non-CT image modalities and manual operationsPatient database
Structure outline creationManual outline formation using CT imagesAutomatic outline formation using CT images3-D structure formationOutline formation using interpolationAutomatic margin functionSet-up of relative electron densityBolus formationPoints and line marker definition
Beam dataSystem parameter checksSystem parameter limitsCollimator and jaw setupShielding block definition and formationMLCAutomatic field formationBeam installation checksGantry and collimator, treatment table angleWedgeBeamDRR

Table 7 Items for dosimetric commissioning.

ItemsTest
Verification of beam modelingComparison of measured and calculated beam data
Verification under simple conditionsRelative dose distribution and absolute dose verification
Verification in clinical conditionsVariation in SSDOpen oblique incidence fieldWedged oblique incidence fieldMissing tissueOpen off-axis fieldWedged off-axis fieldIrregular fieldBuild-up regionInhomogeneity correction (Rectangular inhomogeneous model phantom or human body phantom)

Table 8 Tolerance of assessing dose for external radiation treatment.

Dose evaluation region(1) Homogeneous, open field, symmetry beam(2) Simple inhomogeneous wedge, MLC-shaped field, asymmetry beam(3) Beam used by the combination of more than 2 types
δ12%3%4%
δ22 mm, 10%3 mm, 15%3 mm, 15%
δ33%3%3%
δ43% (30%)3% (40%)3% (50%)
δ(RW50)2 mm, 1%3 mm, 1%3 mm, 1%
δ50–902 mm3 mm3 mm

Table 9 Items for periodic quality assurance test

ItemsTest
DailyReview error logReview change log
WeeklyVerify computer filesVerify clinical plan
MonthlyVerify stability about CT data and CT value and relative electron densityReview problems of RTPS and prioritize resolution of problemsReview configuration and state of RTPS
YearlyCheck concordance between measured and calculated doseReview accuracy of data and operation of I/O devicesReview important software
VariableCheck beam parameter and restartCheck software including OS and restart

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June 2024

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