Effects of variable placement of superior tangential/supraclavicular match line on dosimetric coverage of level III axilla/axillary apex in patients treated with breast and supraclavicular radiotherapy

Initial Clinical Experience of Cherenkov Imaging in External Beam Radiation Therapy Identifies Opportunities to Improve Treatment Delivery

PURPOSE

The value of Cherenkov imaging as an on-patient, real-time, treatment delivery verification system was examined in a 64-patient cohort during routine radiation treatments in a single-center study.

METHODS AND MATERIALS

Cherenkov cameras were mounted in treatment rooms and used to image patients during their standard radiation therapy regimen for various sites, predominantly for whole breast and total skin electron therapy. For most patients, multiple fractions were imaged, with some involving bolus or scintillators on the skin. Measures of repeatability were calculated with a mean distance to conformity (MDC) for breast irradiation images.

RESULTS

In breast treatments, Cherenkov images identified fractions when treatment delivery resulted in dose on the contralateral breast, the arm, or the chin and found nonideal bolus positioning. In sarcoma treatments, safe positioning of the contralateral leg was monitored. For all 199 imaged breast treatment fields, the interfraction MDC was within 7 mm compared with the first day of treatment (with only 7.5% of treatments exceeding 3 mm), and all but 1 fell within 7 mm relative to the treatment plan. The value of imaging dose through clear bolus or quantifying surface dose with scintillator dots was examined. Cherenkov imaging also was able to assess field match lines in cerebral-spinal and breast irradiation with nodes. Treatment imaging of other anatomic sites confirmed the value of surface dose imaging more broadly.

CONCLUSIONS

Daily radiation therapy can be imaged routinely via Cherenkov emissions. Both the real-time images and the posttreatment, cumulative images provide surrogate maps of surface dose delivery that can be used for incident discovery and/or continuous improvement in many delivery techniques. In this initial 64-patient cohort, we discovered 6 minor incidents using Cherenkov imaging; these otherwise would have gone undetected. In addition, imaging provides automated, quantitative metrics useful for determining the quality of radiation therapy delivery.

Contouring workload in adjuvant breast cancer radiotherapy

PURPOSE

To measure the impact of contouring on worktime in the adjuvant radiation treatment of breast cancer, and to identify factors that might affect the measurements.

MATERIAL AND METHODS

The dates and times of contouring clinical target volumes and organs at risk were recorded by a senior and by two junior radiation oncologists. Outcome measurements were contour times and the time from start to approval. The factors evaluated were patient age, type of surgery, radiation targets and setup, operator, planning station, part of the day and day of the week on which the contouring started. The Welch test was used to comparatively assess the measurements.

RESULTS

Two hundred and three cases were included in the analysis. The mean contour time per patient was 34minutes for a mean of 4.72 structures, with a mean of 7.1minutes per structure. The clinical target volume and organs at risk times did not differ significantly. The mean time from start to approval per patient was 29.4hours. Factors significantly associated with longer contour times were breast-conserving surgery (P=0.026), prone setup (P=0.002), junior operator (P<0.0001), Pinnacle planning station (P=0.026), contouring start in the morning (P=0.001), and contouring start by the end of the week (P<0.0001). Factors significantly associated with time from start to approval were age (P=0.038), junior operator (P<0.0001), planning station (P=0.016), and contouring start by the end of the week (P=0.004).

CONCLUSION

Contouring is a time-consuming process. Each delineated structure influences worktime, and many factors may be targeted for optimization of the workflow. These preliminary data will serve as basis for future prospective studies to determine how to establish a cost-effective solution.

Current clinical coverage of Radiation Therapy Oncology Group-defined target volumes for postmastectomy radiation therapy

PURPOSE

The Radiation Therapy Oncology Group (RTOG) has published consensus guidelines for contouring relevant anatomy for postmastectomy radiation therapy (RT). How these contours relate to current treatment practices is unknown. We analyzed the dose-volume histograms (DVHs) for these contours using current clinical practice at University of Texas MD Anderson Cancer Center and compared them with the proposed treatment plans to treat RTOG-defined targets to full dose.

METHODS AND MATERIALS

We retrospectively analyzed treatment plans for 20 consecutive women treated with postmastectomy RT for which the treatment targets were the chest wall (CW), level III axilla (Ax3), supraclavicular (SCV), and internal mammary (IM) nodes. The RTOG consensus definitions were used to contour the following anatomic structures: CW; level I, II, and III axillary nodes (Ax1, Ax2, Ax3); SCV; IM; and heart (H). DVHs for these contours and the ipsilateral lung were generated from clinically designed treatment that had actually been delivered to each patient. For comparison regarding dose to normal tissue, new treatment plans were generated with the goal of covering 95% of the anatomic contours to 45 Gy.

RESULTS

The prescribed dose was 50 Gy in each case. The mean percent of volumes that received 45 Gy (V45) for the RTOG guideline-based contours were CW 74%, Ax1 84%, Ax2 88%, Ax3 96%, SCV 84%, and IM 80%. Mean heart V10 values were 11% for treatment of left-sided tumors and 6% for right-sided tumors. Mean ipsilateral lung V20 values were 28% for left-sided tumors and 34% for right-sided tumors. For the contour-based plans, mean V45 values were CW 94%, Ax1 95%, Ax2 97%, Ax3 98%, SCV 98%, and IM 85%. Mean heart V10 values were 14% for treatment of left-sided tumors and 12% for right-sided tumors. Mean ipsilateral lung V20 values were 32% for left-sided tumors and 45% for right-sided tumors.

CONCLUSIONS

Clinically derived treatment plans, which have proven efficacy and are the current standard, cover 74% to 96% of the anatomy-based RTOG consensus volumes to the prescription dose. This discrepancy should be considered if treatment planning protocol guidelines are designed to incorporate these new definitions.

How do I deal with the axilla in patients with a positive sentinel lymph node?

OPINION STATEMENT

Optimal management of the axilla in a patient with a positive sentinel node biopsy is not yet defined.These patients usually have Breast Conserving Surgery and receive adjuvant systemic therapy and whole breast radiation.Treatment options for the axilla include: no further surgery with or without radiation completion axillary nodal dissection with or without radiation Radiation options in addition to whole breast radiation include axillary and supraclavicular nodal irradiation regional nodal irradiationincludes supraclavicular and internal mammary nodes Completion axillary dissection has been standard practice in patients with positive sentinel nodes. the number of involved nodes provides prognostic information. theoretically improves local control, but may be obviated by systemic chemotherapy. but avoidance of dissection may not adversely affect locoregional control or survival. dissection has significant morbidity so safe avoidance is desirable. There is little worldwide concordance on the use of radiation: whole breast radiation (commonly used after breast conserving surgery) may radiate the lower axilla supraclavicular radiation is most commonly recommended for patients with four or more nodes but may confer a survival benefit on patients with lower risk disease. adding nodal irradiation reduces local recurrence with only modest toxicity. Adjuvant systemic therapy provides a survival benefit for patients with nodal disease. Most will receive cytostatic chemotherapy containing an anthracycline and a taxane. Hormone therapy is appropriate for estrogen receptor positive disease. The extent to which systemic therapy controls microscopic nodal disease is unknown. Node positive patients should generally receive adjuvant chemotherapy.A small group of patients benefit from specific nodal therapy. Further studies are needed to better identify these patients.

Comparison of three-dimensional versus intensity-modulated radiotherapy techniques to treat breast and axillary level III and supraclavicular nodes in a prone versus supine position

BACKGROUND AND PURPOSE

To determine the optimal method of targeting breast and regional nodes in selected breast cancer patients after axillary dissection, we compared the results of IMRT versus no IMRT, and CT-informed versus clinically-placed fields, in supine and prone positions.

MATERIALS AND METHODS

Twelve consecutive breast cancer patients simulated both prone and supine provided the images for this study. Four techniques were used to target breast, level III axilla, and supraclavicular fossa in either position: a traditional three-field three-dimensional conformal radiotherapy (3DCRT) plan, a four-field 3DCRT plan using a posterior axillary boost field, and two techniques using a CT-informed target volume consisting of an optimized 3DCRT plan (CT-planned 3D) and an intensity-modulated radiotherapy (IMRT) plan. The prescribed dose was 50 Gy in 25 fractions.

RESULTS

CT-planned 3D and IMRT techniques improved nodal PTV coverage. Supine, mean nodal PTV V50 was 50% (3-field), 59% (4-field), 92% (CT-planned 3D), and 94% (IMRT). Prone, V50 was 29% (3-field), 42% (4-field), 97% (CT-planned 3D), and 95% (IMRT). Prone positioning, compared to supine, and IMRT technique, compared to 3D, lowered ipsilateral lung V20.

CONCLUSIONS

Traditional 3DCRT plans provide inadequate nodal coverage. Prone IMRT technique resulted in optimal target coverage and reduced ipsilateral lung V20.

Radiation techniques and toxicities for locally advanced breast cancer

Radiation therapy is used in the management of locally advanced breast cancer in the postmastectomy or neoadjuvant chemotherapy and breast-conservation setting to improve local-regional control and survival. Using modern-day technology, the therapeutic ratio has increased and the potential morbidity has decreased. This article reviews the technical aspects of radiation therapy for locally advanced breast cancer with emphasis on 3-dimensional radiotherapy techniques and discusses potential toxicities and how to reduce them.