Practical Radiation Oncology

Editor's Note

W. Robert Lee — 2012-01-01

Welcome to the first issue in the second volume of Practical Radiation Oncology (PRO). In previous issues I have used this space to highlight specific papers, but in this short note I want to focus on the process of peer review.

Quality and safety considerations in stereotactic radiosurgery and stereotactic body radiation therapy: Executive summary

2011-09-19

This executive summary briefly describes the overall goals and content of the report on safety consideration for stereotactic radiosurgery (SRS) and stereotactic body radiation therapy (SBRT), but is very limited in length and content. This abridged version is not intended to replace the full length report but rather to highlight key recommendations. All readers are referred to the full report published online only at www.practicalradonc.org.

Developing a national radiation oncology registry: From acorns to oaks

2011-07-15

Abstract: Purpose: The National Radiation Oncology Registry (NROR) is a collaborative initiative of the Radiation Oncology Institute and the American Society of Radiation Oncology, with input and guidance from other major stakeholders in oncology. The overarching mission of the NROR is to improve the care of cancer patients by capturing reliable information on treatment delivery and health outcomes.Methods: The NROR will collect patient-specific radiotherapy data electronically to allow for rapid comparison of the many competing treatment modalities and account for effectiveness, outcome, utilization, quality, safety, and cost. It will provide benchmark data and quality improvement tools for individual practitioners. The NROR steering committee has determined that prostate cancer provides an appropriate model to test the concept and the data capturing software in a limited number of sites. The NROR pilot project will begin with this disease-gathering treatment and outcomes data from a limited number of treatment sites across the range of practice; once feasibility is proven, it will scale up to more sites and diseases.Results: When the NROR is fully implemented, all radiotherapy facilities, along with their radiation oncologists, will be solicited to participate in it. With the broader participation of the radiation oncology community, NROR has the potential to serve as a resource for determining national patterns of care, gaps in treatment quality, comparative effectiveness, and hypothesis generation to identify new linkages between therapeutic processes and outcomes.Conclusions: The NROR will benefit radiation oncologists and other care providers, payors, vendors, policy-makers, and, most importantly, cancer patients by capturing reliable information on population-based radiation treatment delivery.

Implementation of a “No Fly” safety culture in a multicenter radiation medicine department

Louis Potters, Ajay Kapur — 2011-06-17

Abstract: Purpose: The safe delivery of radiation therapy requires multiple disciplines and interactions to perform flawlessly for each patient. Because treatment is individualized and every aspect of the patient's care is unique, it is difficult to regiment a delivery process that works flawlessly. The purpose of this study is to describe one safety-directed component of our quality program called the “No Fly Policy” (NFP).Methods and Materials: Our quality assurance program for radiation therapy reviewed the entire process of care prior, during, and after a patient's treatment course. Each component of care was broken down and rebuilt within a matrix of multidisciplinary safety quality checklists (QCL). The QCL process map was subsequently streamlined with revised task due dates and stopping rules. The NFP was introduced to place a holding pattern on treatment initiation pending reconciliation of associated stopping events. The NFP was introduced in a pilot phase using a Six-Sigma process improvement approach. Quantitative analysis on the performance of the new QCLs was performed using crystal reports in the Oncology Information Systems. Root cause analysis was conducted.Results: Notable improvements in QCL performance were observed. The variances among staff in completing tasks reduced by a factor of at least 3, suggesting better process control. Steady improvements over time indicated an increasingly compliant and controlled adoption of the new safety-oriented process map. Stopping events led to rescheduling treatments with average and maximum delays of 2 and 4 days, respectively, with no reported adverse effects. The majority of stopping events were due to incomplete plan approvals stemming from treatment planning delays. Whereas these may have previously solicited last-minute interventions, including intensity modulated radiation therapy quality assurance, the NFP enabled nonpunitive, reasonable schedule adjustments to mitigate compromises in safe delivery.Conclusions: Implementation of the NFP has helped to mitigate risk from expedited care, convert reactive to proactive delays, and created a checklist, process driven, and variance-reducing culture in a large, multicenter department.

Evaluation of a metal artifact reduction technique in tonsillar cancer delineation

2011-07-18

Abstract: Purpose: Metal artifacts can degrade computed tomographic (CT) simulation imaging and impair accurate delineation of tumors for radiation treatment planning purposes. We investigated a Digital Imaging and Communications in Medicine-based metal artifact reduction technique in tonsillar cancer delineation.Methods and Materials: Eight patients with significant artifact and tonsil cancer were evaluated. Each patient had a positron emission tomography (PET)-CT and a contrast-enhanced CT obtained at the same setting during radiotherapy simulation. The CTs were corrected for artifact using the metal deletion technique (MDT). Two radiation oncologists independently delineated primary gross tumor volumes (GTVs) for each patient on native (CTnonMDT), metal corrected (CTMDT), and reference standard (CTPET/nonMDT) imaging, 1 week apart. Mixed effects models were used to determine if differences among GTVs were statistically significant. Two diagnostic radiologists and 2 radiation oncologists independently qualitatively evaluated CTs for each patient. Ratings were on an ordinal scale from –3 to +3, denoting that CTMDT was markedly, moderately, or slightly worse or better than CTnonMDT. Scores were compared with a Wilcoxon signed-rank test.Results: The GTVPET/nonMDT were significantly smaller than GTVnonMDT (P = .004) and trended to be smaller than GTVMDT (P = .084). The GTVnonMDT and GTVMDT were not significantly different (P = .93). There was no significant difference in the extent to which GTVnonMDT or GTVMDT encompassed GTVPET/nonMDT (P = .33). In the subjective assessment of image quality, CTMDT did not significantly outperform CTnonMDT. In the majority of cases, the observer rated the CTMDT equivalent to (53%) or slightly superior (41%) to the corresponding CTnonMDT.Conclusions: The MTD modified images did not produce GTVMDT that more closely reproduced GTVPET/nonMDT than did GTVnonMDT. Moreover, the MTD modified images were not judged to be significantly superior when compared to the uncorrected images in terms of subjective ability to visualize the tonsilar tumors. This study failed to demonstrate value of the adjunctive use of a CT corrected for artifacts in the tumor delineation process. Artifacts do make tumor delineation challenging, and further investigation of other body sites is warranted.

Intensity modulated radiation therapy planning for patients with a metal hip prosthesis based on class solutions

Henrie van der Est, Paulette Prins, Ben J.M. Heijmen, Maarten L.P. Dirkx — 2011-06-06

Abstract: Purpose: With the aging of the population, an increasing number of patients with metallic hip implants are referred for radiotherapy treatment. Class solutions for intensity modulated radiation therapy (IMRT) treatment planning are generally not applicable for these patients due to the required avoidance of dose delivery through prostheses. In this work a new approach for IMRT planning is presented, allowing the use of a default beam setup.Methods and Materials: For IMRT planning, Monaco (Elekta; CMS Software, Maryland Heights, MO) was used. In addition to the target and organs at risk, so-called prosthesis avoidance volumes (PAVs) were delineated in the beam's eye view projection for beams in which the prosthesis was partially in front of the target. By putting strict constraints on these virtual organs at risk, entrance dose delivery through a prosthesis is avoided while exit dose delivery is allowed. In this way, uncertainties in the dose delivery to the target and organs at risk, as derived by the treatment planning system, are largely minimized. To show the advantages of this IMRT-PAV technique, for 2 prostate cancer patients, 1 with bilateral and the other with unilateral metallic hip prostheses, obtained IMRT plans were compared with conventional IMRT plans using a prosthesis-avoiding beam setup.Results: For both IMRT techniques a similar planning target volume coverage was achieved, but with the IMRT-PAV technique the mean doses to the bladder and the rectum were reduced by up to 25%. While the IMRT-PAV technique required more time for delineation, the time for treatment planning reduced because the default beam setup could be applied. The number of segments needed for dose delivery was comparable for both techniques.Conclusions: With the new IMRT-PAV technique IMRT class solutions can safely be applied for cancer patients with metallic hip prostheses, generally yielding a reduced dose delivery to organs at risk or improved target coverage.

Improving cardiac dosimetry: Alternative beam arrangements for intensity modulated radiation therapy planning in patients with carcinoma of the distal esophagus

2011-06-09

Abstract: Purpose: Radiation for carcinoma of the distal esophagus is associated with cardiac perfusion deficits and pericardial effusion. We performed a dosimetric analysis of alternative beam arrangements for use in intensity modulated radiation therapy (IMRT) planning, seeking to lower radiation dose to the heart.Methods and Materials: Treatment plans using 4 separate beam arrangements were generated and optimized for 12 patients. Hemispheric and butterfly beam arrangements were compared with plans with posterior and lateral beam entries. Radiotherapy was planned to 50.4 Gy in 28 fractions, using step and shoot IMRT with 6 MV photons. Mean heart dose and volumes of heart and lung receiving up to specified doses (V5-V40) were recorded. Isodose distributions were evaluated for target coverage and normal tissue exposure.Results: IMRT plans utilizing posterior-lateral beam arrangements significantly reduced mean cardiac doses (32.5 ± 3.9 Gy, 33.3 ± 3.2 Gy vs 24.3 ± 3.7 Gy, and 23.4 ± 4.2 Gy, P < .05, paired Student t test with post hoc Bonferroni correction) as well as the total heart volumes receiving at least 20 and 30 Gy. IMRT allowed the maximum cord dose to be limited to less than 40 Gy. While both posterior-lateral beam arrangements lead to improved cardiac dosimetry, mean lung doses as well as V5 and V20 were slightly higher, although within accepted limits. Target coverage, homogeneity, and conformality were similar or improved with the use of alternative beam configurations.Conclusions: The use of IMRT with posterior-lateral beams can significantly reduce radiation dose to cardiac structures with minimal increased dose to the lung. Future studies will assess the physiologic and clinical impact of cardiac sparing.

Analysis of suitable prescribed isodose line fitting to planning target volume in stereotactic body radiotherapy using dynamic conformal multiple arc therapy

2011-07-26

Abstract: Purpose: To assess the most suitable value of a relative prescribed dose in clinical treatment plans of stereotactic body radiotherapy (SBRT) using dynamic conformal multiple arc therapy to treat lung tumors.Methods and Materials: We retrospectively generated alternative SBRT plans for typical examples of 8 patients who had been treated with SBRT for a lung tumor with a prescribed dose of 50 Gy in 5 fractions. The prescribed dose had been defined as 80% of the maximal dose in the planning target volume (PTV) (“the 80% isodose plan”). Alternative 20%-90% isodose plans at 10% intervals were generated (64 plans; 8 plans for each of the 8 patients), and factors related to leaf margins, target volume, normal lung volume, and monitor units were compared using dose-volume histogram analysis.Results: We could generate all the 64 plans. Compared with the 80% isodose plan, the V20 and mean lung dose (MLD) were both lower in the 60% plan; the V20 was approximately 19% lower (4.72% vs 3.84%) and the MLD was 13% lower (4.0 Gy vs 3.5 Gy). Mean PTV and ITV doses were higher in the lower percentage isodose plans. Compared with the 80% isodose plan, in the 60% isodose plan the mean PTV was 19% higher (56.1 Gy vs 66.8 Gy) and the mean ITV was 30% higher (59.6 Gy vs 77.4 Gy). The mean total monitor units increased more steeply than did the mean homogeneity index. The mean conformity index values in the 60% and 70% isodose plans were less than 1.15.Conclusions: The 60% isodose plan was considered the best plan in this analysis because of the lower comparative dosimetric factors in normal lung tissue (including V20 and MLD) and the higher comparative mean PTV and internal target volume doses achieved, along with good conformity index values. In clinical use, accurate estimation and commissioning should be performed for the dose distribution prior to selecting a plan. Further investigation is warranted to determine whether the calculated dosimetric advantages result in improved outcomes.

Initial clinical experience with a frameless and maskless stereotactic radiosurgery treatment

2011-06-06

Abstract: Purpose: To evaluate the initial clinical experience with a frameless and maskless technique for stereotactic radiosurgery using minimal patient immobilization and real-time patient motion monitoring during treatment. We focus on the evaluation of the patient treatment process.Methods and Materials: The study considered the first 23 patients treated with this technique. Head positioning was achieved with a patient-specific head mold made out of expandable foam that conforms to the patient's head. The face of the patient is left open for maximal comfort and so that motion of a region of interest consisting of the forehead, nose, eyes, and temporal bones can be monitored during treatment using a video surface imaging system (VisionRT Inc, London, UK). Initial setup of the patient was performed with the surface imaging system using the surface of the patient obtained from the treatment planning computed tomographic (CT) scan. The initial setup was confirmed and finalized with cone-beam CT (CBCT) prior to treatment. The shifts for final setup based on the CBCT and the duration of all the steps in the treatment process were recorded. Patients were monitored during treatment with surface imaging, and a beam hold-off was initiated when the patient's motion exceeded a prespecified tolerance.Results: The average total setup time including surface imaging and CBCT was 26 minutes, while the portion corresponding to surface imaging was 14 minutes. The average treatment time from when the patient was placed on the treatment table until the last treatment beam was 40 minutes. Eight (35%) patients needed repositioning during the treatment. The average shifts identified from CBCT after initial setup with surface imaging were 1.85 mm in the anterior-posterior direction, and less than 1.0 mm in the lateral and superior-inferior directions. The longest treatment times (including beam hold-offs) happened for patients who fell asleep on the treatment table and were moving involuntarily.Conclusions: The frameless and maskless treatment using minimal immobilization and surface imaging has proven to be reasonably fast for routine clinical use. We observed that patient compliance is important. An additional degree of semi-rigid immobilization would be helpful for patients who fall asleep and involuntarily move during the procedure.

Primary radiotherapy for locally advanced skin cancer near the eye

Krishna Reddy, Tobin Strom, Changhu Chen — 2011-07-28

Non-melanoma skin cancers are the most common cutaneous malignancies, with over 1 million cases in the year 2010. Approximately 80% of non-melanoma skin cancers are basal-cell carcinomas, and 20% are squamous-cell carcinomas. Although the mortality rate is low with less than 1000 patients estimated to have died in 2010, non-melanoma skin cancers may be disfiguring when occurring in the facial skin. A variety of treatments exist. Appropriate use of electrodesiccation and curettage, excision, or cryosurgery can eliminate up to 90% of small (≤1 cm in diameter), well-defined primary lesions. Surgical excision and Mohs' surgery have often been used for patients with larger tumors at high risk for recurrence. However, there are cases where surgical resection may result in severe cosmetic and functional deficits due to large tumor size or close proximity to critical structures, such as the eyes. In this article, we report a case of locally advanced skin cancer that extended to the lateral canthus in which surgical management was contraindicated due to expected high morbidity-proximity to the right eye, and in which primary radiation therapy (RT) allowed excellent local control while achieving favorable functional and cosmetic results. We further review the literature regarding treatment of locally advanced periorbital skin cancers with primary RT.

Reviewer recognition

2012-01-01

Meeting Minder page

2012-01-01