Radiotherapy Quality Assurance Program Research Articles

Abstract PO2-23-05: Practice patterns and outcomes in the ongoing neoadjuvant ATNEC trial: node marking, response to NACT and breast conservation rates

Abstract Background In ATNEC trial, cT1-3N1M0 patients receive NACT followed by SNB/TAD. If the sentinel nodes(SNs) have converted to benign(ypN0), patients are randomly assigned to Axillary Treatment vs no Axillary Treatment. The study promotes standardized node marking procedures and includes a radiotherapy quality assurance program. Objectives – This study prospectively evaluates practice patterns, NACT response, adoption of node marking, rates of marked node identification, and breast conservation rates in the ongoing ATNEC trial across 70 centers in the UK. The trial aims to recruit 1900 patients. Materials and Methods Data from 196 randomized patients (median age: 54 [range: 28-79] years; median BMI: 26.5 [range: 17.6-51.1]) from December 2021 to June 28, 2023, across 70 UK centers were analyzed. These patients presented with cT1-3N1M0 breast cancer, received NACT, and exhibited no residual nodal disease (ypN0) on SNB/TAD. Results Among the randomised patients 54%(106) were post-menopausal, 71%(140) underwent breast conserving surgery(BCS) and 29%(56) mastectomy. At presentation, 12% (23) had T3, 63% (124) had T2, and 23% (46) had T1 tumors. Grade 3 tumors accounted for 70% (138) of cases. Among the patients, 60% (117) were HER2 positive, 31% (61) were triple negative, and 9% (18) were HER2 negative (ER or PgR positive). Anthracycline and taxane-based NACT were administered to 57% (106), while 38% (71) received a platinum-containing regimen. During SNB/TAD, a median of 4 nodes (interquartile range, 3-5) were removed. Among 184 patients with node marking data, 74% (136) had the involved node marked. The marked node was successfully removed in 94% (128) of these patients. Clip/coil only, Magseed and black dye were the commonest techniques used for node marking. The marked node was the sentinel node in 83% (106) of cases. Among 185 randomized patients with post-NACT response data, 68% (125) achieved a complete pathological response (pCR) in the breast, while 8% (15) had DCIS only and 22% (41) had invasive cancer. Among 105 patients with complete breast tumor response on imaging, 15% (16) had residual DCIS or invasive cancer. In the subset of patients with partial response or stable breast tumors on imaging (69 patients), 46% (32) had no residual tumor on histology (ypT0). Furthermore, 14% (26) exhibited partial or stable disease in the axilla on imaging but achieved complete pathological response on histology. Conclusions HER2-positive and triple-negative breast cancer cases predominate among patients undergoing NACT in the UK. Although 68% achieved a complete pCR (ypT0) in the breast, rates of BCS remain low. Notably, around 75% of randomized patients underwent node marking, with an intra-operative identification rate of 94%, demonstrating the successful implementation of node marking in the UK through the ATNEC trial. Citation Format: Amit Goyal, Andrea Marshall, Sophie Nicholls, Natalie Hammonds, Beatrix Elsberger, Duncan Wheatley, Janice Rose, Helen-Teresa Edwards, Abeer Shaaban, Roeum Butt, Gareth Jackson, Tara Homer, Luke Vale, Samreen Ahmed, Shama Puri, Sophie Gasson, Julie Bruce, Helen Higgins, Janet Dunn. Practice patterns and outcomes in the ongoing neoadjuvant ATNEC trial: node marking, response to NACT and breast conservation rates [abstract]. In: Proceedings of the 2023 San Antonio Breast Cancer Symposium; 2023 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2024;84(9 Suppl):Abstract nr PO2-23-05.

Radiotherapy Quality Assurance in SIOP Ependymoma II – Experiences from Germany, Austria and Switzerland

<h3>Objectives</h3> Radiotherapy (RT) for pediatric ependymoma remains challenging due to the young age of the patients and the close proximity of the tumour to critical structures. In Germany, Austria and Switzerland, a Radiotherapy Quality Assurance (RTQA) program was implemented within the SIOP Ependymoma II trial to ensure patient safety and protocol compliance. <h3>Methods</h3> Pre-trial site approvals and prospective plan reviews for patients in stratum 1 and 2 were performed. Plans were submitted by the treating centres to the reference centres Essen and Leipzig, who evaluated the plans regarding compliance to the study protocol and the German RTQA guideline. Results were categorized as per protocol, acceptable variation, justified unacceptable variation or unacceptable variation, respectively. Unacceptable variations required plan modification and re-review. <h3>Results</h3> Between May 2019 and December 2021, 33 patients (median age 5.1 years) from 8 institutions were reviewed. Thirty patients in stratum 1 received conformal RT. Within stratum 2, 3 patients received an additional stereotactic boost. The majority (n=31) of the patients were treated with protons. Of the 33 conformal RT plans, 4 (12%) were reviewed as per protocol, 14 (42%) as acceptable variation, 4 (12%) as justified unacceptable variation and 11 (33%) as unacceptable variation. Six of the unacceptable plans were re-submitted after modification. Four of them were approved after re-submission (acceptable variation=1, justified unacceptable variation=3), whereas 2 plans still had unacceptable variations. Reasons for rejecting plans were target volume delineation (44%), uniformity of target volume (33%) and dose to organs at risk (22%). All stereotactic boost plans were accepted (acceptable variation=1, justified unacceptable variation=2). <h3>Conclusion</h3> The high rate of rejected initial RT plans underlines the importance of a rigorous RTQA program. Improving the quality of RT plans potentially impacts favourably on outcome and long term side effects although requiring a high effort.

Disadvantaged Subgroups Within the Global Head and Neck Cancer Population: How Can We Optimize Care?

Within the global head and neck cancer population, there are subgroups of patients with poorer cancer outcomes independent from tumor characteristics. In this article, we review three such groups. The first group comprises patients with nasopharyngeal cancer in low- and middle-income countries where access to high-volume, well-resourced radiotherapy centers is limited. We discuss a recent study that is aiming to improve outcomes through the instigation of a comprehensive radiotherapy quality assurance program. The second group comprises patients with low socioeconomic status in a high-income country who experience substantial financial toxicity, defined as financial hardship for patients due to health care costs. We review causes and consequences of financial toxicity and discuss how it can be mitigated. The third group comprises older patients who may poorly tolerate and not benefit from intensive standard-of-care treatment. We discuss the role of geriatric assessment, particularly in relation to the use of chemotherapy. Through better recognition and understanding of disadvantaged groups within the global head and neck cancer population, we will be better placed to instigate the necessary changes to improve outcomes and quality of life for patients with head and neck cancer.

Oligorecurrent nodal prostate cancer: Radiotherapy quality assurance of the randomized PEACE V-STORM phase II trial

PurposeAim of this study is to report the results of the radiotherapy quality assurance program of the PEACE V-STORM randomized phase II trial for pelvic nodal oligorecurrent prostate cancer (PCa). Material and methodsA benchmark case (BC) consisting of a postoperative case with 2 nodal recurrences was used for both stereotactic body radiotherapy (SBRT, 30 Gy/3 fx) and whole pelvic radiotherapy (WPRT, 45 Gy/25 fx + SIB boost to 65 Gy). ResultsBC of 24 centers were analyzed. The overall grading for delineation variation of the 1st BC was rated as ‘UV’ (Unacceptable Variation) or ‘AV’ (Acceptable Variation) for 1 and 7 centers for SBRT (33%), and 3 and 8 centers for WPRT (46%), respectively. An inadequate upper limit of the WPRT CTV (n = 2), a missing delineation of the prostate bed (n = 1), and a missing nodal target volume (n = 1 for SBRT and WPRT) constituted the observed ‘UV’. With the 2nd BC (n = 11), the overall delineation review showed 2 and 8 ‘AV’ for SBRT and WPRT, respectively, with no ‘UV’. For the plan review of the 2nd BC, all treatment plans were per protocol for WPRT. SBRT plans showed variability in dose normalization (Median D90% = 30.1 Gy, range 22.9–33.2 Gy and 30.6 Gy, range 26.8–34.2 Gy for nodes 1 and 2 respectively). ConclusionsUp to 46% of protocol deviations were observed in delineation of WPRT for nodal oligorecurrent PCa, while dosimetric results of SBRT showed the greatest disparities between centers. Repeated BC resulted in an improved adherence to the protocol, translating in an overall acceptable contouring and planning compliance rate among participating centers.

Differences of Ring Applicator Reconstruction Methods in Brachytherapy

Purpose: Analysis and comparison of existing reconstruction methods of the ring applicator, as well as the development of reconstruction method that is closest to the actual source path in dosimetric planning using brachytherapy.&#x0D; Material and methods: Evaluation of reconstruction methods was carried out on the basis of CT images, which were used for dosimetric planning of patient treatment. The obtained data on the positioning of the radiation source using X-ray images were transferred to CT images using matrix transformation methods. A method of reconstruction along the source path is proposed, in which the minimum discrepancies in the location of the source positions in comparison with the coordinates of the actual source positions were obtained. For comparison, the reconstruction of the applicator was performed by three different methods: the method using the manufacturer’s applicator libraries, along the source path, and the method proposed above.&#x0D; Results: The results were assessed using a dose-volume histogram. Dose characteristics were selected based on the recommended ICRU Report 89. To assess the presence of the effect of the reconstruction method on the dose characteristics, the Friedman criterion was used. The differences between the doses for different reconstruction methods turned out to be significant (the critical value of the significance level was considered p=0.05). The maximum deviations of the median values of the parameters of the dose-volume histogram were 7.8 % for the “lib” method, 8.6 % for the tracking method, and 7.9 % for the track_new method. We calculated the median values of the deviations of the source positions obtained using the previously described reconstruction methods from the actual stopping positions of the source found experimentally.&#x0D; Conclusion: The use of the proposed reconstruction method track_new increases the accuracy of determining the positions of the stop of the radiation source in the applicator and, as a consequence, the accuracy of dose delivery on the brachytherapy apparatus in comparison with the manual tracking method. The methods used in this study can be used when putting the applicators into clinical use as part of a radiotherapy quality assurance program. The obtained results will be useful to medical physicists if it is necessary to choose a technique for carrying out the reconstruction of the applicator in accordance with the available capabilities and imaging methods and, as a result, will increase the accuracy of dosimetric planning and dose delivery on brachytherapy afterloaders.

THE MEDICAL PHYSICIST - SCIENTIST BEHIND THE CURTAIN

Ionizing radiation has validated its existence and effectiveness in modern medicine for both diagnostic and therapeutic use. For the last decade rapid growth in medical radiation application has witnessed in India towards the betterment of mankind, for safe and quality clinical practice, radiation protection and quality assurance. At the end of the 19th century Physics brought paradigm shift in the field of radiation-based medical diagnosis and treatment and giving rise to the modern medical physicist profession and revolutionized the practice of medicine. Medical Physicists are the scientists with Post graduation / PhD degrees, and certified from A.E.R.B as Radiological Safety Officer, deals with utilization of Physics knowledge in developing not only lifesaving tools &amp; technology but also diagnosis and treatments of various medical conditions that help humans live longer and healthier. Medical Physicists are responsible to carry out the commissioning, establishment of entire Radiation facility and get the clearance of statutory compliances form authorities in order to start the clinical practice are also responsible for research, developing and evaluating new analytical techniques, planning and ensuring safe and accurate treatment of patients also provide advice about radiation protection, training and updating healthcare, scientific and technical staff , managing radiotherapy quality assurance program, mathematical modeling ,maintaining equipment ,writing reports, teaching ,laboratory management and administration. Now it’s a time to raise the curtain from the Medical Physics profession and utilize their services up to maximum extent in the field of scientific research, academic, teaching, diagnosis, treatment and safety.

Statistical process control in monitoring radiotherapy quality assurance program: An institutional experience

Introduction: Statistical process control (SPC) is a handy and powerful tool for monitoring quality assurance (QA) programs in radiotherapy. The potential reasons for an uncontrolled QA state monitored via SPC can be identified using the cause-and-effect diagram. This study explains the institutional experience in monitoring weekly output constancy of medical linear accelerator (Linac) and patient-specific quality assurance (PSQA) using SPC and cause-and-effect diagram. Material and methods: Prospective monitoring of output constancy has been demonstrated by the simultaneous usage of Shewhart’s I-MR charts and time-weighted control charts. Two hundred and forty-one PSQA results were retrospectively analysed in a combined γ and dose volume histogram (DVH) based analysis using control charts and process capability indices. A PSQA analysis method has been illustrated in which the site-specific action limits (AL) and control limits (CL) for γ and DVH based analysis were obtained using SPC. Results: The simultaneous use of different control charts indicated a systematic error in the output constancy of Linac as successive measurement points fell above the CL. The reason for failure in output constancy was found using a cause-and-effect diagram due to a faulty monitor ion chamber. The obtained AL and CL for γ and DVH based analysis were used to decide pass or fail criteria in PSQA. Among the analysed treatment plans, four Head and Neck (HN), two Central Nervous System (CNS), four Gastro-Intestinal (GI), and four Gastro Urinal (GU) plans failed the PSQA analysis. Cause-and-effect analysis of these failed treatment plans in PSQA pointed out six primary potential sources of errors in the results. Conclusions: SPC tools can be adopted among institutions for consistent and comparable QA programs. If the QA process monitored using SPC falls outside the CL, cause-and-effect diagrams can be used to extract all possible contributing factors that lead to such a process state.

Protocol for tumour-focused dose-escalated adaptive radiotherapy for the radical treatment of bladder cancer in a multicentre phase II randomised controlled trial (RAIDER): radiotherapy planning and delivery guidance

IntroductionDaily radiotherapy delivered with radiosensitisation offers patients with muscle invasive bladder cancer (MIBC) comparable outcomes to cystectomy with functional organ preservation. Most recurrences following radiotherapy occur within the bladder. Increasing...

Protocol for hypofractionated adaptive radiotherapy to the bladder within a multicentre phase II randomised trial: radiotherapy planning and delivery guidance

IntroductionPatients with muscle invasive bladder cancer (MIBC) who are unfit and unsuitable for standard radical treatment with cystectomy or daily radiotherapy present a large unmet clinical need. Untreated, they suffer...

Implementing an online radiotherapy quality assurance programme with supporting continuous medical education – report from the EMBRACE-II evaluation of cervix cancer IMRT contouring

Background and purposeEMBRACE-II is an international prospective study of IMRT and MRI-guided adaptive brachytherapy (IGABT) in locally advanced cervix cancer. An online radiotherapy quality assurance (RTQA) programme with minimal data transfer and supporting continuing medical education (CME) was implemented for IMRT contouring. Materials and methodsParticipant contours for six volumes-of-interest (VOIs) on one benchmark case were scored (2 = excellent, 1 = fair, 0 = revision required) against a consensus reference contour. For contours receiving a 0 or 1 score, additional qualitative comments were provided. The Jaccard conformity index (JCI) was retrospectively calculated. User interaction with CME content (pre-accreditation questionnaire, contouring atlas, practice cases, quizzes, internal target volume (ITV-T) guide) was analysed. Results78 clinicians submitted contours for evaluation. 41% passed at the first attempt, 44% after one revision and 6% after two or more revisions. 9% did not re-submit after failing. The lowest mean scores were for the elective nodal CTV (CTV-E) (1.01/2) and ITV-T (1.06/2). 60 different errors across the six VOIs were identified; five potentially had high impact on loco-regional control. A JCI cut-off of 0.7 would have identified 87% contours that failed expert assessment, but also excluded 54% of passing contours. 39 clinicians responded to the pre-accreditation questionnaire – 36% anticipated difficulties with the ITV-T and 13% with the CTV-E. 35% clinicians contoured on the practice cases, 17% answered a quiz, 96% used the atlas and 38% the ITV-T guide. ConclusionExpert evaluation with qualitative feedback improved contouring compliance. The JCI is not a reliable alternative to expert assessment. Moderate uptake of optional CME content limited evaluation.

Radiotherapy Quality Assurance for Head and Neck Squamous Cell Carcinoma.

The impact of radiotherapy (RT) quality assurance (QA) has been demonstrated by numerous studies and is particularly important for head and neck cancer (HNC) treatment due to the complexity of RT target volumes in this region and the multiple adjacent organs at risk. The RT planning process includes many critical steps including interpretation of diagnostic imaging, image fusion, target volume delineation (tumor, lymph nodes, and organs at risk), and planning. Each step has become highly complex, and precise and rigorous QA throughout the planning process is essential. The ultimate aim is to precisely deliver radiation dose to the target, maximizing the tumor dose and minimizing the dose to surrounding organs at risk, in order to improve the therapeutic index. It is imperative that RT QA programs should systematically control all aspects of the RT planning pathway and include regular end-to-end tests and external audits. However, comprehensive QA should not be limited to RT and should, where possible, also be implemented for surgery, systemic therapy, pathology, as well as other aspects involved in the interdisciplinary treatment of HNC.

An IAEA survey of radiotherapy practice including quality assurance extent and depth

Background: The IAEA recommends a quality assurance program in radiotherapy to ensure safe and effective treatments. In this study, radiotherapy departments were surveyed on their current practice including the extent and depth of quality assurance activities.Methods: Radiotherapy departments were voluntarily surveyed in three stages, firstly, in basic facility information, secondly, in quality assurance activities and treatment techniques, and thirdly, in a snapshot of quality assurance, departmental and treatment activities.Results: The IAEA received completed surveys from 381 radiotherapy departments throughout the world with 100 radiotherapy departments completing all three surveys. Dominant patterns were found in linac-based radiotherapy with access to treatment planning systems for 3D-CRT and 3D imaging. Staffing levels for major staff groups were on average in the range recommended by the IAEA. The modal patient workload per EBRT unit was as expected in the range of 21–30 patients per day, however significant instances of high workload (more than 50 patients per day per treatment unit) were reported. Staffing levels were found to correlate with amount of treatment equipment and patient workload. In a self-assessment of quality assurance performance, most radiotherapy departments reported that they would perform at least 60% of the quality assurance activities itemized in the second survey, with particular strength in equipment quality control. In a snapshot survey of quality assurance performance, again equipment quality control practice was well developed, particularly for the treatment equipment.Conclusions: The IAEA surveys provide a snapshot of current radiotherapy practice including quality assurance activities.

Application of computed radiography in the quality assurance of linear accelerators in radiotherapy

Introduction: The two mechanisms, optical and radiation fields, operate individually and independently in a Linear Accelerator and cause changes with respect to each other. The standard method for performing the quality assurance (QA) test in radiotherapy involves the irradiation of a radiographic film. In this study, we made an attempt to examine how we could maximize the benefit from an impending filmless environment in the radiotherapy QA program. Aim: The aim is to study the feasibility of using computed radiographs (CRs) in the radiotherapy QA program. Materials and Methods: In this study, the QA tests were performed in Linear accelerators Clinac 600c and Clinac iX, both from Varian Medical Systems, Palo Alto, CA, which was commissioned during September 2004 and July 2011, respectively, were used. Optical and radiation field congruence, radiation isocenter for the gantry, collimator, and couch rotational axis verification, in two linear accelerators were done using gafchromic (EBT3) films and CRs. The standard Gafchromic® EBT3 film, utilized for routine QA were used. The errors estimated were compared and analyzed. Results: The mean error estimated in the QA with both linear accelerators using both QA tools (CR and Film) ranged between 0.053 mm and 0.069 mm, and the standard deviation was estimated to be within 0.062-0.164 mm. Conclusion: The results infer that the QA done with CR is in good agreement with the film. This study poses new challenges to the researchers, task groups, and the regulatory bodies to estimate the frequency of QAs for the newer and the older machines and also, the onset of frequent QAs, once the machine becomes older.

A Multi-Institutional Estimation of Interobserver Variability in Glioblastoma Delineation in the EORTC-1709-BTG /CCTG CE.8 Trial

Standard of care for glioblastoma (GBM) is maximal resection, radiotherapy (RT) + temozolomide (TMZ) followed by adjuvant TMZ (EORTC / NCIC 26981-22981 trial). For years, RT for GBM is conformal/modulated, volume-based with rigorous delineation guidelines for target and organs at risk (OARs) based on imaging (CT-MR). It is expected that the interobserver variability in delineation/planning would be limited. The EORTC 1709-BTG/CCTG CE.8 trial is a multi-institutional international prospective trial exploring standard RT+TMZ +/- marizomib in newly diagnosed GBM patients. Participating Centers are subjected to RT quality assurance (RTQA) evaluation of delineation/planning of a benchmark case (BC). The aim of this study is to evaluate the magnitude of interobserver variability in delineation observed in BC evaluation and assess the effectiveness of the prospective RTQA program. In all participating Centers, the BC was contoured and an individual planning was designed by local team before being uploaded to EORTC for assessment. Variability in contouring to individual (i) GTV (iGTV), iCTV, iPTV and iOARs were analyzed and compared with the consensus (c) contouring (cGTV, cCTV, cPTV, cOARs) generated from the pool of previously submitted cases using the VODCA software package (DVH, DICE, etc.), representing gold standard contours. Extracted descriptive data was analyzed using Excel and Python. Until 01/2019, 31/93 Centers completed the BC procedure and 53% of these had to adjust contouring, mostly due to missing parts of GTV or including brainstem/bony structures in the CTV. Mis-contouring of OARs occurred mostly for cochlea, brainstem or lacrimal glands. For both individually planned target volumes and iOARs the volume spread, standard deviation, mean and variance decrease significantly after RTQA review. Example: Different estimations of iCTV, iPTV as well as well as their overlap with iOAR are heterogeneous and present appreciable variations across Centers. Individual volume distributions are skewed towards smaller volumes. Consensus volumes coincide with median of individual volumes for almost all structures. despite center experience, availability of guidelines and protocols, we see significant variability in delineation. These protocol deviations may have significance for patient outcome and trial results. Moreover, our study shows that a RTQA review considerably improves consistency of delineation, indicating prospective plan review can be a valid tool even for highly specialized Centers and for well-established RT techniques. The full data set is required to further comment, especially on shape and symmetry of volume distribution. Whether the observed variability translates to clinical outcome is the subject of a parallel work.Abstract 3431; Table 1VolumeStdDev before/after RTQA[cc]Volume range before/after RTQA [cc]PTV62 / 47236 / 187Optic Nerve PRV1.5 / 0.67.7 / 2.1Optic Chiasm PRV0.3 / 0.286.3 / 5.6Brainstem0.9 / 0.520.4 / 15.6 Open table in a new tab

Radiotherapy Quality Assurance for the CHHiP Trial: Conventional Versus Hypofractionated High-Dose Intensity-Modulated Radiotherapy in Prostate Cancer

AimsThe CHHiP trial investigated the use of moderate hypofractionation for the treatment of localised prostate cancer using intensity-modulated radiotherapy (IMRT). A radiotherapy quality assurance programme was developed to assess compliance with treatment protocol and to audit treatment planning and dosimetry of IMRT. This paper considers the outcome and effectiveness of the programme. Materials and methodsQuality assurance exercises included a pre-trial process document and planning benchmark cases, prospective case reviews and a dosimetry site visit on-trial and a post-trial feedback questionnaire. ResultsIn total, 41 centres completed the quality assurance programme (37 UK, four international) between 2005 and 2010. Centres used either forward-planned (field-in-field single phase) or inverse-planned IMRT (25 versus 17). For pre-trial quality assurance exercises, 7/41 (17%) centres had minor deviations in their radiotherapy processes; 45/82 (55%) benchmark plans had minor variations and 17/82 (21%) had major variations. One hundred prospective case reviews were completed for 38 centres. Seventy-one per cent required changes to clinical outlining pre-treatment (primarily prostate apex and base, seminal vesicles and penile bulb). Errors in treatment planning were reduced relative to pre-trial quality assurance results (49% minor and 6% major variations). Dosimetry audits were conducted for 32 centres. Ion chamber dose point measurements were within ±2.5% in the planning target volume and ±8% in the rectum. 28/36 films for combined fields passed gamma criterion 3%/3 mm and 11/15 of IMRT fluence film sets passed gamma criterion 4%/4 mm using a 98% tolerance. Post-trial feedback showed that trial participation was beneficial in evolving clinical practice and that the quality assurance programme helped some centres to implement and audit prostate IMRT. ConclusionOverall, quality assurance results were satisfactory and the CHHiP quality assurance programme contributed to the success of the trial by auditing radiotherapy treatment planning and protocol compliance. Quality assurance supported the introduction of IMRT in UK centres, giving additional confidence and external review of IMRT where it was a newly adopted technique.

Issues on VMAT QA Program with EBT3 Radiochromic Films: An improvement proposal

EBT3 radiochromic film is renowned in medical physics field due its dose verification for Quality Assurance (QA) program in intensity-modulated radiotherapy (IMRT). However, it is known that QA programs, which include these films, are expensive and relatively time-consuming. Furthermore, it was noted that dosimetry with EBT3 film has been suffering with lack of accuracy. In that way, it was evaluated its possible dosimetric inaccuracy, the time expenditure in the whole QA process, as well as the cost-benefit of such a program and it is suggested efforts to improve this process based on our institution expertise. A retrospective study was performed on VMATplans, rating how many cases got success by absolute dosimetric Gamma analysis. Furthermore, in order to verify the film intra-lot aging, the calibration curves were compared to the lot fabrication date. On the other hand, with single- and multi-channel dosimetric analyses, further trials were performed over the post-irradiationsaturation curves up to 35 h after irradiation. The retrospective Gamma analyses exhibited that about 23% of the total VMAT cases did not passed by absolute Gamma evaluation. It was seen that the fabrication date influences the dose response, which prerequisites a calibration curve for each film box. For the multichannelanalyses, as excepted, the red channel sensitivity was the highest for doses up to 5 Gy. Moreover, it was reinforced that the dose response is a direct function of dose level for both types of analyses. In that way, it was chosen a post-irradiation time interval of 12h-16h, with dose response variation criteria less than 2%. Finally, it was verified, based on our routine, that there were about 23h/month expended in a film QA program and directly costs bordering US$20,000.00/year.

OC-0608: Radiotherapy quality assurance program for the STAR-TReC trial; planning results of Dutch centers

OC-0608: Radiotherapy quality assurance program for the STAR-TReC trial; planning results of Dutch centers

The TRENDY multi-center randomized trial on hepatocellular carcinoma – Trial QA including automated treatment planning and benchmark-case results

Background and purposeThe TRENDY trial is an international multi-center phase-II study, randomizing hepatocellular carcinoma (HCC) patients between transarterial chemoembolization (TACE) and stereotactic body radiation therapy (SBRT) with a target dose of 48–54 Gy in six fractions. The radiotherapy quality assurance (QA) program, including prospective plan feedback based on automated treatment planning, is described and results are reported. Materials and methodsScans of a single patient were used as a benchmark case. Contours submitted by nine participating centers were compared with reference contours. The subsequent planning round was based on a single set of contours. A total of 20 plans from participating centers, including 12 from the benchmark case, 5 from a clinical pilot and 3 from the first study patients, were compared to automatically generated VMAT plans. ResultsFor the submitted liver contours, Dice Similarity Coefficients (DSC) with the reference delineation ranged from 0.925 to 0.954. For the GTV, the DSC varied between 0.721 and 0.876. For the 12 plans on the benchmark case, healthy liver normal-tissue complication probabilities (NTCPs) ranged from 0.2% to 22.2% with little correlation between NCTP and PTV-D95% (R2 < 0.3). Four protocol deviations were detected in the set of 20 treatment plans. Comparison with co-planar autoVMAT QA plans revealed these were due to too high target dose and suboptimal planning. Overall, autoVMAT resulted in an average liver NTCP reduction of 2.2 percent point (range: 16.2 percent point to −1.8 percent point, p = 0.03), and lower doses to the healthy liver (p < 0.01) and gastrointestinal organs at risk (p < 0.001). ConclusionsDelineation variation resulted in feedback to participating centers. Automated treatment planning can play an important role in clinical trials for prospective plan QA as suboptimal plans were detected.

Does Quality of Radiation Therapy Predict Outcomes of Pediatric Multicenter Cooperative Group Trials? A Systematic Review

Radiotherapy (RT) quality assurance (QA) programs aim to standardize RT delivered on multicenter clinical trials to minimize variables that may confound the validity of results. Our objective was to review available evidence for correlation of RT quality with clinical outcomes within pediatric multicenter clinical trials. A Medline, Embase, and Cochrane Central Register of Controlled Trials literature search was performed restricted to English but with no date limits. Candidate studies accrued children with age <21 years or median age <15, were led by any cooperative group, published in full, and described central subjective +/- objective assessment of RT protocol compliance (quality). Data abstracted included assignment of violations in relation to clinical outcomes (locoregional and/or distant failure, progression-free survival [PFS], overall survival [OS]). 27 multicenter studies described in 26 articles met inclusion criteria. Disease sites were medulloblastoma (M; 9 trials), rhabdomyosarcoma (RMS; 7), Hodgkin’s (H;4) Supratentorial Primitive Neuroectodermal tumour (SPNET; 3), Ewing’s (E; 3), and Acute Lymphocytic Leukemia (ALL; 1). Deviations were found in 0-77% of RT plans reviewed. 10/27 reported that dose and/or field deviations significantly affected clinical outcomes in the form of inferior overall survival (N=1), PFS (4), local PFS (1), local control (3), and any recurrence (1). One study suggested improved PFS with local field RT deviations versus without. Studies reporting a significant relationship between RT quality and clinical outcomes were: 4 M, 3 SPNET, 2 H, 1 E, and 1 RMS. Overall, the weight of the evidence suggests that suboptimal RT negatively impacts clinical outcomes in pediatric multicenter and cooperative group trials.

P-222 Analysis of tumour contours and radiotherapy planning of “on-trial” patients undergoing chemoradiotherapy (CRT) in SCALOP trial: does pre-trial Radiotherapy Quality Assurance (RTQA) improve the quality of “on-trial” radiotherapy?

The SCALOP trial tested the safety and efficacy of gemcitabine (Gem) versus capecitabine (Cap) based CRT following induction chemotherapy and showed that GemRT was associated with greater toxicity and worse survival1. The evaluation of investigator-delineated volumes and plan assessment from the pre-trial RTQA program using a single benchmark case showed considerable variation in gross tumour volume (GTV) outlining but no major deviations in other aspects of RT planning.