Radiation Oncology Peer Review in a Community Setting: The Value of Prospective Review.

Peer review is an important component of any radiation oncology continuous quality improvement program. While limited guidelines exist, there is no consensus about how peer review should be performed, and large variations exist among different institutions. The purpose of this report is to describe our experience with peer review at a busy Radiation Oncology clinic and to evaluate the difference between prospective and retrospective peer review. We also performed a failure modes and effects analysis (FMEA) of the peer review process. Starting in 2015, every peer review session was tracked, including recommended changes to treatment plans. We reviewed the frequency, types and severity of these changes. A team of physicians and physicists conducted an FMEA of the peer review process. Between April 2015 and June 2020, a total of 3,691 patients were peer-reviewed. Out of those, 1,903 were prospective reviews (51.6%). Plans reviewed before treatment were almost 4.5 times more likely to be changed by peer review than those reviewed after the start of treatment (0.9% vs 0.2%). Plan changes after the start of treatment had a higher severity than changes prior to the start of treatment. FMEA identified several critical components of peer review. While there is no national standard for peer review, it is evident that prospective peer review is preferable. There may be a subconscious reluctance to change plans already underway, which could be a barrier to improving plans with the peer review process. Rather than reviewing in a group setting, it would be ideal to individually assign review tasks that are embedded in the clinical flow, assuring prospective review for all patients prior to final physician approval. Individual review rather than group review may be more candid, due to interpersonal concerns about publicly disagreeing with colleagues.

Assessing the performance of an automated breast treatment planning software.

PURPOSE: To assess the dosimetric performance of an automated breast planning software. METHODS: We retrospectively reviewed 15 breast cancer patients treated with tangent fields according to the RTOG 1005 protocol and 30 patients treated off-protocol. Planning with electronic compensators (eComps) via manual, iterative fluence editing was compared to an automated planning program called EZFluence (EZF) (Radformation, Inc.). We compared the minimum dose received by 95% of the volume (D95%), D90%, the volume receiving at least 105% of prescription (V105%), V95%, the conformity index of the V95% and PTV volumes (CI95%), and total monitor units (MUs). The PTV_Eval structure generated by EZF was compared to the RTOG 1005 breast PTV_Eval structure. RESULTS: The average D95% was significantly greater for the EZF plans, 95.0%, vs. the original plans 93.2% (P = 0.022). CI95% was less for the EZF plans, 1.18, than the original plans, 1.48 (P = 0.09). D90% was only slightly greater for EZF, averaging at 98.3% for EZF plans and 97.3% for the original plans (P = 0.0483). V105% (cc) was, on average, 27.8cc less in the EZF breast plans, which was significantly less than for those manually planned. The average number of MUs for the EZF plans, 453, was significantly less than original protocol plans, 500 (P = 8 × 10-6 ). The average difference between the protocol PTV volume and the EZF PTV volume was 196 cc, with all but two cases having a larger EZF PTV volume (P = 0.020). CONCLUSION: EZF improved dose homogeneity, coverage, and MU efficiency vs. manually produced eComp plans. The EZF-generated PTV eval is based on the volume encompassed by the tangents, and is not appropriate for dosimetric comparison to constraints for RTOG 1005 PTV eval. EZF produced dosimetrically similar or superior plans to manual, iteratively derived plans and may also offer time and efficiency benefits.

Benchmarking failure mode and effects analysis of electronic brachytherapy with data from incident learning systems.

PURPOSE: Failure modes and effects analysis (FMEA) is a prospective risk assessment tool for identifying failure modes in equipment or processes and informing the design of quality control systems. This work aims to benchmark the performance of FMEAs for electronic brachytherapy (eBT) of the skin and for breast by comparing predicted versus actual failure modes reported in multiple incident learning systems (ILS). METHODS AND MATERIALS: Two public and our institution's internal ILS were queried for Xoft Axxent eBT-related events over 9 years. The failure modes and Risk Priority Numbers (RPNs) were taken from FMEAs previously performed for Xoft eBT of nonmelanoma skin cancer and breast intraoperative radiation therapy (IORT). For each event, the treatment site and primary failure mode was compared with the failure modes and RPNs from that site's FMEA. RESULTS: 49 events involving Xoft eBT were identified. Thirty-one (63.3%) involved breast IORT, and 18 (36.7%) involved the skin. Three events could not be linked to an FMEA failure mode. In 87.7% of events, the primary failure mode ranked in the FMEA top 10 by RPNs. In 83.3% of skin events, the failure modes ranked in the top 10 by RPN or severity. In 90.3% of IORT events, the failure modes ranked within the top 10 by RPN or severity. CONCLUSIONS: Evaluating FMEA failure modes against ILS data demonstrates that FMEA is effective at predicting failure modes but can be dependent on user experience. ILS data can improve FMEA by identifying potential failure modes and suggesting realistic occurrence, detectability, and severity values.

Hyper-dense foreign bodies found in the bowel during IGRT following brachytherapy.

A 28-year-old female with locally advanced adenocarcinoma of the cervix was undergoing treatment with external beam radiation therapy (EBRT), concurrent chemotherapy and high dose rate brachytherapy (BT). On-board imaging obtained prior to one of her external beam treatments revealed four radiopaque foreign bodies in her abdomen. The patient's treatment was delayed for further work-up of this new finding. Upon further investigation, it was discovered that the patient had recently started taking bismuth subsalicylate tablets (brand name: Pepto-Bismol, Procter & Gamble Co., Cincinnati, OH). A computed tomography (CT) scan of the tablets confirmed the size and Hounsfield Unit (HU) values coincided with the foreign object properties seen on the patient's scan. This unexpected finding is important to recognize as it consequently lead to a delay in treatment, additional imaging, and patient anxiety.

Lung Stereotactic Body Radiation Therapy (SBRT) dose gradient and PTV volume: a retrospective multi-center analysis.

BACKGROUND: The treatment of lung lesions with stereotactic body radiation therapy calls for highly conformal dose, which is evaluated by a number of metrics. Lung stereotactic body radiation therapy clinical trials constrain a plans gradient index. The purpose of this work is to describe the dependence of clinically achievable dose gradient on planning target volume. METHODS: Three hundred seventy-four lung stereotactic body radiation therapy treatment plans were retrospectively reviewed and selected for this study. The relationship between R50% and planning target volume size was observed and compared against the RTOG 0915 and 0813 constraints noting minor and major deviations. Then a least squares regression was used to determine the coefficients for a power functional form of the dependence of gradient measure (GM) on planning target volume size. RESULTS: Of the 317 peripheral lung SBRT plans, 142 exhibited no deviation, 135 exhibited a minor deviation, and 40 exhibited a major deviation according to the RTOG 0915 dosimetric. conformality and dose fall-off constraints. A plot of gradient measure versus planning target volume size for peripheral lesions, excluding RTOG 0915 major deviations, is fit with an power function of GM = 0.564 V0.215. CONCLUSIONS: Using the PTV size and GM relationship we have characterized, treatment plans with PTV < 85 cm3 can be evaluated subjectively to our previously plans, and given a percentile GM. This relationship and evaluation is useful for volumetric modulated arc therapy lung stereotactic body radiation therapy treatment planning and quality control.

Characterization of the HalcyonTM multileaf collimator system.

PURPOSE: To characterize the stacked and staggered dual-layer multileaf collimator (MLC) on the HalcyonTM system. METHODS: The novel MLC assembly was reviewed and compared to the widely used MillenniumTM 120-leaf MLC system. We investigated the MLC positioning stability over 70 days using Machine Performance Check (MPC) data. We evaluated the leaf transmission, penumbra, leaf end effect, and leaf edge effect. Leaf transmission through distal, proximal, and both MLC layers was measured with a Farmer chamber, by comparing an open and a closed field. Leaf penumbra was measured using film for three different MLC-defined field sizes. The leaf end effect was measured with sweeping gap fields of varying gap sizes defined by the distal MLC. The leaf edge effect was evaluated using the Electronic Portal Imaging Device (EPID) for the different banks, gantry positions, and collimator angles. Point dose measurements for 10 test plans were compared to dose predictions of two dose calculation model versions. RESULTS: From MPC data, the largest measured MLC positioning accuracy deviation was within 0.1 mm. The proximal MLC exhibited greater deviations compared to the distal MLC. The distal-and-proximal-combination had reduced inter-leaf and intra-leaf transmission compared to delivery with distal-only. The measured leaf transmission was 0.41% for distal-only, 0.40% for proximal-only, and negligible for distal-and-proximal-combination. The leaf end penumbra was wider compared to the leaf edge penumbra. The leaf end effect was measured to be -0.2 mm. The leaf edge effect showed minimal bank, gantry position, and collimator angle dependence. However, a systematic deviation between measurements and treatment planning system handling of the leaf edge effect was observed. The discrepancy between the measured and predicted dose in the 10 test plans improved with the latest version of the dose calculation algorithm. CONCLUSION: The characteristics of the stacked and staggered dual-layer MLC on the HalcyonTM system were presented.

Risk analysis of electronic intraoperative radiation therapy for breast cancer.

PURPOSE: To evaluate the process and improve safety of intraoperative radiation therapy (IORT) for early-stage breast cancers treated with electronic brachytherapy. METHODS AND MATERIALS: A multidisciplinary team conducted a failure mode and effects analysis (FMEA) for IORT breast cancer treatments by first developing a process map. This map was then used to identify failure modes for all steps in the treatment workflow. Risk priority numbers (RPNs) were assigned to each failure mode and were calculated as the product of the failure mode's probability of occurrence (O), severity (S), and lack of detectability (D). Corrective steps were implemented to address failure modes with the highest risk, and a revised process was generated. RESULTS: The steps with the highest risk failure modes were related to source calibration, use of correct plan and dwell times, and the correct site and intent. The introduction of a physician calibration check and an extended time-out checklist reduced the risk of these failure modes. The highest risk steps in the Xoft breast IORT treatment process are associated with source calibration and manual entry of dwell positions for each balloon size and volume combination. High-risk failure modes that could be mitigated with improved hardware and software interlocks were identified. CONCLUSION: High-risk failure modes are identified with FMEA and addressed with corrective steps. This application of FMEA can be used in principle for clinical processes throughout breast cancer care. This analysis demonstrates the importance of well-designed QC policies, procedures, and oversight in a Xoft electronic brachytherapy program for breast cancer IORT.

Evaluation of effective treatment depth in skin cancer treatments with electronic brachytherapy.

PURPOSE: To evaluate changes in the percent depth dose (PDD) and effective depth of treatment due to force applied by the applicator during treatments of nonmelanoma skin cancer with the Xoft electronic brachytherapy system. METHODS: To simulate compressible tissue, a 5-mm tissue-equivalent bolus was used. A soft x-ray ion chamber was used for output measurements, which were performed for all Xoft surface applicators with plastic endcaps in place. Output was first measured at 5 mm depth with minimal pressure from the applicator on the bolus and then repeated after applying uniform pressure on the applicator to calculate the change in PDD and effective treatment depth. RESULTS: For the 10-mm cone, a moderate force of 5 N changed the PDD by more than 20%. The effect was also pronounced for the 20-mm cone, while minimal for the 35- and 50-mm cones. Even when only a moderate force was applied, the effective prescription depth changed by several millimeters, on the order of a typical prescription depth. CONCLUSION: Based on the results of this simulation, excessive pressure applied on the skin by the applicator can drastically alter the PDD and effective treatment depth. The effect is most pronounced for the 10- and 20-mm cones, which tend to be used most frequently. Inappropriate applicator placement may therefore result in significant consequences such as excessive dose to the target, severe skin reaction, permanent discoloration, skin indentation, and poor overall cosmesis upon completion of treatment.

Improving the treatment planning and delivery process of Xoft electronic skin brachytherapy.

PURPOSE: To develop an improved Xoft electronic skin brachytherapy process and identify areas of further improvement. METHODS AND MATERIALS: A multidisciplinary team conducted a failure modes and effects analysis (FMEA) by developing a process map and a corresponding list of failure modes. The failure modes were scored for their occurrence, severity, and detectability, and a risk priority number (RPN) was calculated for each failure mode as the product of occurrence, severity, and detectability. Corrective actions were implemented to address the higher risk failure modes, and a revised process was generated. The RPNs of the failure modes were compared between the initial process and final process to assess the perceived benefits of the corrective actions. RESULTS: The final treatment process consists of 100 steps and 114 failure modes. The FMEA took approximately 20 person-hours (one physician, three physicists, and two therapists) to complete. The 10 most dangerous failure modes had RPNs ranging from 336 to 630. Corrective actions were effective at addressing most failure modes (10 riskiest RPNs ranging from 189 to 310), yet the RPNs were higher than those published for alternative systems. Many of these high-risk failure modes remained due to hardware design limitations. CONCLUSIONS: FMEA helps guide process improvement efforts by emphasizing the riskiest steps. Significant risks are apparent when using a Xoft treatment unit for skin brachytherapy due to hardware limitations such as the lack of several interlocks, a short source lifespan, and variability in source output. The process presented in this article is expected to reduce but not eliminate these risks.

Clinical and cosmetic outcomes in patients treated with high-dose-rate electronic brachytherapy for nonmelanoma skin cancer.

PURPOSE: To retrospectively analyze clinical and cosmetic outcomes in patients treated for nonmelanoma skin cancer (NMSC) with high-dose-rate (HDR) electronic brachytherapy (EBT) using surface applicators. METHODS AND MATERIALS: We identified 127 patients who had 154 NMSC lesions, 149 of which were basal cell carcinoma, treated with HDR EBT at our institution between July 2012 and March 2014. Lesions were treated to 40 Gy in 8 fractions. Local control, acute toxicity, late toxicity, and cosmetic outcomes were analyzed retrospectively. Acute and late toxicities were graded using the Common Terminology Criteria for Adverse Events, version 4.0. Cosmetic outcomes were graded using a standard scale based on the Radiation Therapy Oncology Group and European Organization for Research and Treatment of Cancer Late Radiation Morbidity Scoring Schema. RESULTS: Median (range) follow-up from completion of treatment was 16.1 (3.4-34.8 months). The overall crude recurrence rate was 1.3% (n = 2). Grade 0 to 1 acute radiation dermatitis was observed in 52.6% of treated lesions (n = 81), grade 2 in 34.4% (n = 53), and grade 3 in 13.0% (n = 20). No acute toxicity greater than grade 3 was observed and all acute toxic events resolved after treatment. Grade 0 to 1 late toxicity was observed in 94.2% of cases (n = 145), and grade 2 in 5.8% (n = 9). No late toxicity greater than grade 2 was observed. Across the 152 controlled lesions, cosmetic results were excellent in 94.2% of treated lesions (n = 145), good in 3.3% (n = 5), fair in 0.7% (n = 1), and poor in 0.7% (n = 1). CONCLUSIONS: HDR EBT confers promising local control, minimal toxicity, and excellent cosmesis in our institutional experience. It should be considered ideal for NMSC of the head and neck, particularly for basal cell carcinoma involving central facial locations where surgical cosmesis may be inferior.

Preliminary investigation of metal and metalloid contamination of homeopathic products marketed in Croatia.

BACKGROUND: Due to their popularity as a complementary therapy in many diseases, homeopathic products of animal, vegetable, mineral and chemical origin should be tested for the presence of contaminants to prevent eventual toxic effects. OBJECTIVE: Thirty samples of homeopathic products were analyzed to estimate possible contamination with potentially toxic elements: Pb, Cd, As, Hg, Cr, Ni and Zn, and to assess human exposure to these metals/metalloid as a consequence of their consumption. METHODS: Atomic absorption spectrometry was used to determine metal and metalloid concentrations. RESULTS: Most tested products had very low metal/metalloid levels (below the limit of quantification of the method), but the metal/metalloid levels in the remaining products were in the following ranges (in microg g(-1)): Pb 0.33-1.29 (6 samples), Cd 2.78 (1 sample), As 0.22 (1 sample), Hg 0.02-0.12 (24 samples), Cr 0.40-10.27 (10 samples), Ni 0.43-55.00 (19 samples), and Zn 2.20-27.80 (11 samples). In the absence of regulatory standards for homeopathic products, the obtained results were compared to maximum allowable levels (MALs) as proposed by USP Ad Hoc Advisory Panel. Some analyzed preparations had metal levels above MALs (Pb: 2 samples; Cd: 1 sample; Ni: 2 samples). However, estimated cumulative daily intakes from tested homeopathic products were in all cases lower than permitted daily exposures for all dosage forms. CONCLUSION: The risk of bioaccumulation of metals/metalloid from the homeopathic medicines seems to be rather low, due to small quantities of those products prescribed to be applied per day, as well as insignificant metal contamination of the majority of tested products. However, the fact that particular formulations were contaminated by metals above MALs indicates potential risk and points to the necessity of regular monitoring of homeopathic products for metal contamination, due to their frequent and mostly unsupervised use.

Wheat flour confectionery products as a source of inorganic nutrients: zinc and copper contents in hard biscuits.

Cereal-based confectionery products being consumed through whole human life are considered mainly to be a source of carbohydrates, that is energy, although cereals are a rich source of minerals as well. To evaluate some hard biscuits produced in Croatia as a source of different trace elements in nutrition, in this study Zn and Cu contents were determined in classic wheat flour biscuits and in dietetic biscuits enriched with whole wheat grain flour or whole wheat grain grits, soya flour and skimmed milk. Zn was determined by flame atomic absorption spectrometry (AAS); Cu was determined by inductively coupled plasma atomic emission spectroscopy (ICP-AES). The results show that the Zn content in different kinds of biscuits ranges from 5.89 up to 17.64 mg/kg and the Cu content ranges from 1.15 up to 2.79 mg/kg depending on the type of wheat milling products and mineral content of other ingredients used. Enriched dietetic biscuits produced from wheat flour type 850 and whole wheat grain flour and/or soya flour and skimmed milk were almost 200% and 150% higher in Zn and Cu, respectively, in comparison to classic white wheat flour biscuits and can be considered as good sources of Zn and Cu in nutrition.