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Radiation Oncology Resident In-Training Examination Sandra S. Hatch, MD, FACR,* Neha Vapiwala, MD,y Seth A. Rosenthal, MD, FACR,z John P. Plastaras, MD, PhD,y Albert L. Blumberg, MD, FACR,x William Small Jr, MD, FACR,jj Matthew J. Wenger, BBA,{ and Marie E. Taylor, MD, FACR, *University of Texas Medical Branch, Galveston, Texas; yUniversity of Pennsylvania, Philadelphia, Pennsylvania; zDepartment of Radiation Oncology, Sutter Cancer Center, Sacramento, California; xGreater Baltimore Medical Center, Baltimore, Maryland; jjStritch School of Medicine, Loyola University, Chicago, Illinois; {ITPG, Inc., Vienna, Virginia; and Baptist Memorial Hospital East, Memphis, Tennessee

Background We investigated factors associated with positive margins following mastectomy and the impact on outcomes. Methods We identified 240 patients with stage I–III invasive breast cancer who underwent mastectomy from 1999 to 2009. Data included patient and tumor characteristics, pathologic margin assessment, and outcomes. Margin positivity was defined as the presence of in situ or invasive malignancy at any margin. Descriptive statistics were used for data summary and were compared using χ2. Results Of the 240 patients, 132 (55%) had a simple mastectomy with sentinel lymph node biopsy and 108 (45%) had a modified radical mastectomy. Overall, 21 patients (9%) had positive margins, including 12 (57%) with one positive margin, 3 (14%) with two positive margins, and 6 (29%) with three or more positive margins. The most commonly affected margin was the deep margin (48% of patients). Eight of the 21 patients (38%) received adjuvant chest wall irradiation. There were no differences between patients who had a positive margin and those who did not with respect to patient age, race, percentage of in situ component, tumor size, tumor grade, lymphovascular invasion, or immunostain profile (P > 0.05 for all). None of the patients with positive margins experienced a local recurrence. Conclusions Positive margins following mastectomy occurred in nearly 10% of our patients. No specific patient or tumor characteristics predicted a risk for having a positive margin. Despite the finding that only approximately 40% of patients received adjuvant radiation in the setting of a positive margin, no local recurrences have been observed.

A double-blind placebo-controlled randomized phase II trial was performed to determine whether High Dose Vitamin D2 supplementation (HDD) in women receiving adjuvant anastrozole improves aromatase inhibitor-induced musculoskeletal symptoms (AIMSS) and bone loss. Patients with early breast cancer and AIMSS were stratified according to their baseline 25-hydroxy vitamin D (25OHD) level. Stratum A (20-29 ng/ml) received either HDD 50,000 IU capsules weekly for 8 weeks then monthly for 4 months or placebo. Stratum B (10-19 ng/ml) received either HDD for 16 weeks and then monthly for 2 months, or placebo. AIMSS was assessed by the Brief Pain Inventory-Short Form (BPI-SF), the Fibromyalgia Impact Questionnaire (FIQ), and the Health Assessment Questionnaire-Disability Index (HAQ-DI) at baseline, 2, 4, and 6 months. Bone Mineral Density (BMD) was measured at baseline and at 6 months. The primary endpoint of the study was the change-from-baseline musculoskeletal pain. The secondary endpoint was the percent change in BMD at 6 months. Sixty women were enrolled. Baseline characteristics were comparable between the groups. At 2 months, FIQ pain (P = 0.0045), BPI worst-pain (P = 0.04), BPI average-pain (P = 0.0067), BPI pain-severity (P = 0.04), and BPI interference (P = 0.034) scores were better in the HDD than placebo group. The positive effect of HDD on AIMSS was stronger across all time points in Stratum B than Stratum A (FIQ pain, P = 0.04; BPI average, P = 0.03; BPI severity, P = 0.03; BPI interference, P = 0.04). BMD at the femoral neck decreased in the placebo and did not change in the HDD group (P = 0.06). Weekly HDD improves AIMSS and may have a positive effect on bone health. Vitamin D supplementation strategies for breast cancer patients on AI should be further investigated.

Summary Background Treatment with bisphosphonates decreases bone loss and can increase disease-free survival in patients with breast cancer. The aim of our study was to assess the effect of zoledronic acid on clearance of disseminated tumour cells (DTCs) from the bone marrow in women undergoing neoadjuvant chemotherapy for breast cancer. Methods Patients were recruited for this open-label, phase 2 randomised trial between March 17, 2003, and May 19, 2006, at a single centre. Eligible patients had clinical stage II–III (≥T2 and/or ≥N1) newly diagnosed breast cancer, Eastern Cooperative Oncology Group performance status of 0 or 1, and normal cardiac, renal, and liver function. 120 women were randomly assigned, using allocation concealment, to receive 4 mg zoledronic acid intravenously every 3 weeks (n=60), or no zoledronic acid (n=60), for 1 year concomitant with four cycles of neoadjuvant epirubicin (75 mg/m 2 ) plus docetaxel (75 mg/m 2 ) and two cycles of adjuvant epirubicin plus docetaxel. The primary endpoint was the number of patients with detectable DTCs at 3 months. Final analysis was done 1 year after the last patient was enrolled. Analyses were done for all patients with available data at 3 months. This study is registered with ClinicalTrials.gov, number NCT00242203. Findings Of the 120 patients initially enrolled, one withdrew after signing consent and one patient's baseline bone marrow was not available. Both of these patients were in the control group. At 3 months, 109 bone-marrow samples were available for analysis. In the zoledronic acid group, bone marrow was not collected from one patient because of disease progression, one patient was taken off study because of severe diarrhoea, and two patients had not consented at the time of surgery. In the control group, bone marrow was not collected from two patients because of disease progression, one patient withdrew consent, and three patients were not consented at the time of surgery. At baseline, DTCs were detected in 26 of 60 patients in the zoledronic acid group and 28 of 58 patients in the control group. At 3 months, 17 of 56 patients receiving zoledronic acid versus 25 of 53 patients who did not receive zoledronic acid had detectable DTCs (p=0·054). The most common grade 3–4 toxicities were infection (five of 60 patients in the zoledronic acid group and six of 59 in the control group) and thrombosis (five of 60 in the zoledronic acid and two of 59 in the control group). There was one documented case of osteonecrosis in the zoledronic acid group. Interpretation Zoledronic acid administered with chemotherapy resulted in a decreased proportion of patients with DTCs detected in the bone marrow at the time of surgery. Our study supports the hypothesis that the antimetastatic effects of zoledronic acid may be through effects on DTCs. Funding Novartis Pharmaceuticals and Pfizer Inc.

This retrospective pilot study examined the relationship between psychological status at the time of breast cancer diagnosis and ratings of cosmetic outcome later. Sixty-three patients completed measures of depression, anxiety, and quality of life at the time of diagnosis. Following lumpectomy and radiation therapy, these patients and their radiation oncologists completed ratings of the quality of the cosmetic outcome (Cosmesis). The results indicated that both psychological distress and quality of life were related to patients' ratings of Cosmesis, while only patients' quality of life was related to physicians' ratings of Cosmesis. We conclude that Cosmesis is a multifaceted construct that incorporates both physical and psychological factors.

Depression is a significant problem for some breast cancer survivors after the end of treatment. This study assessed depression using the CES-D for 84 breast cancer patients at the conclusion of radiation treatment, and at 3 and 6 months post-treatment. Based on the pattern of CES-D scores, patients were divided into five groups: (1) Stay Depressed (scores above clinical cutoff for depression at all timepoints); (2) Recover (above threshold at baseline, but below at follow-up); (3) Become Depressed (below threshold at baseline, but above at follow-up); (4) Never Depressed (below threshold at all times); and (5) Vacillate (none of the above patterns). This study examined the relationships between depression groups and a variety of medical, demographic, and psychological measures, including anxiety and quality of life (QOL). Number of children at home significantly distinguished the groups, with the Become Depressed group having more children and the Vacillate group having fewer children. Anxiety levels were different among the groups, with Recover and Never Depressed groups having consistently lower anxiety scores. QOL scores also distinguished the groups in that Never Depressed patients demonstrated better QOL than all other groups. The findings have implications for understanding resilience in cancer patients. Copyright © 2005 John Wiley & Sons, Ltd.

The present study evaluated the outcome of salvage treatment for women with local or local-regional recurrence after initial breast conservation treatment with radiation for mammographically detected ductal carcinoma in situ (DCIS; intraductal carcinoma) of the breast. The study cohort consisted of 90 women with local only first failure (n=85) or local-regional only first failure (n=5). The histology at the time of recurrence was invasive carcinoma for 53 patients (59%), non-invasive carcinoma for 34 patients (38%), angiosarcoma for one patient (1%), and unknown for two patients (2%). The median follow-up after salvage treatment was 5.5 years (mean=5.8 years; range=0.2-14.2 years). The 10-year rates of overall survival, cause-specific survival, and freedom from distant metastases after salvage treatment were 83%, 95%, and 91%, respectively. Adverse prognostic factors for the development of subsequent distant metastases after salvage treatment were invasive histology of the local recurrence and pathologically positive axillary lymph nodes. These results demonstrate that local and local-regional recurrences can be salvaged with high rates of survival and freedom from distant metastases. Close follow-up after initial breast conservation treatment with radiation is warranted for the early detection of potentially salvageable local and local-regional recurrences.

Lymphedema, defined as the abnormal accumulation of protein rich fluid dysfunction of the lymphatic system, is a common sequela of cancer therapy. The incidence is highest among patients who have undergone resection and irradiation of a lymph node bed. Recently, increased attention has been focused on the modification of anticancer therapies in an effort to minimize lymphatic compromise. Sentinel lymph node biopsy is an example of a surgical procedure developed to preserve lymphatic function. Concurrent with the development of less invasive treatments, the field of lymphedema management has evolved rapidly over the past decade. Combined manual therapy, often referred to as complex decongestive physiotherapy (CDP), has emerged as the standard of care. CDP combines compression bandaging, manual lymphatic drainage (a specialized massage technique), exercise, and skin care with extensive patient education. Case series collectively describing a mean 65% volume reduction in over 10,000 patients attest its efficacy. Pneumatic compression pumps were historically widely used to control lymphedema. Their use as an isolated treatment modality is now rare. Reliance on pumps diminished with the recognition that they may exacerbate truncal and genital lymphedema, as well as injure peripheral lymphatics when applied at high pressures. Many noncompressive approaches, particularly the use of benzopyrone medications and liposuction, continue to be used abroad.

Purpose : To investigate the impact of radiographic parameter and radiation technique on the volumetric dose of lung and heart for intact breast radiation. Methods and Materials : Forty patients with both two-dimensional (2D) and computed tomographic (CT) simulations were enrolled in the study. Central lung distance (CLD), maximal heart distance (MHD), and maximal heart length (MHL) were measured under virtual simulation. Four plans were compared for each patient. Plan A used a traditional 2D tangential setup. Plan B used clinical target volume (CTV) based three-dimensional (3D) planning. Both plans C and D used a combination of a medial breast field with shallow tangents. Plan D is a further modification of plan C. Results : Under the traditional tangential setup, the mean ipsilateral lung dose and volume at 20, 30, and 40 Gy correlated linearly with CLD (R = 0.85∼0.91). The mean ipsilateral lung dose (Gy) approximated 4 times the CLD value (cm), whereas the percentage volume (%) of ipsilateral lung at 20, 30, and 40 Gy was about 10 times the CLD (cm). The mean heart dose and percentage volume at 20, 30, and 40 Gy correlated with MHD (R = 0.76∼0.80) and MHL (R = 0.65∼0.75). The mean heart dose (Gy) approximated 3 times the MHD value (cm), and the percentage volume (%) of the heart at 10, 20, 30, and 40 Gy was about 6 times MHD (cm). Radiation technique impacted lung and heart dose. The 3D tangential plan (plan B) failed to reduce the volumetric dose of lung and heart from that of the 2D plan (plan A). The medial breast techniques (plans C and D) significantly decreased the volume of lung and heart receiving high doses (30 and 40 Gy). Plan D further decreased the 20 Gy volumes. By use of the medial breast technique, the lung and heart dose were not impacted by original CLD and MHD/MHL. Therefore, the improvement from the tangential technique was more remarkable for patients with CLD ≥ 3.0 cm (p Conclusions : The CLD and MHD impact the volumetric dose of lung and heart. The application of 3D planning for tangential breast irradiation does not decrease heart and lung dose. Adding a medial breast port significantly decreases percentage volume (PV) of lung and heart receiving high doses, especially when the CLD is excessive.

Nuclear workers, oil well loggers, astronauts, air flight crews, and frequent fliers can be exposed to low doses of neutrons, but the long-term human health consequences of neutron exposure are unknown. While few of these exposed populations are suitable for studying the effects of neutron exposure, patients treated with neutron-beam therapy might be a source of information. To assess the feasibility of conducting a multi-center international study of the late effects of neutron therapy, we surveyed 23 cancer centers that had used neutron beam therapy. For the 17 responding institutions, only 25% of the patients treated with neutrons (2,855 of 11,191) were alive more than 2 years after treatment. In a two-center U.S. pilot study of 484 neutron-treated cancer patients, we assessed the feasibility of obtaining radiotherapy records, cancer incidence and other follow-up data, and of estimating patient organ doses. Patients were treated with 42 MeV neutrons between 1972 and 1989. Applying a clinical equivalence factor of 3.2 for neutrons, total average organ doses outside the treatment beam ranged from 0.14 to 0.29 Gy for thyroid, 0.40 to 2.50 Gy for breast, 0.63 to 2.35 Gy for kidney, and 1.12 to 1.76 Gy for active bone marrow depending upon the primary cancer treatment site. We successfully traced 97% of the patients, but we found that patient survival was poor and that chemotherapy was not confirmable in a quarter of the patients. Based on our findings from the international survey and the feasibility study, we conclude that a large investigation could detect a fivefold or higher leukemia risk, but would be inadequate to evaluate the risk of solid cancers with long latent periods and therefore would likely not be informative with respect to neutron-related cancer risk in humans.

Purpose: This study was performed to determine the long-term outcome for women with mammographically detected ductal carcinoma in situ (DCIS; intraductal carcinoma) of the breast treated with breast-conserving surgery followed by definitive breast irradiation. Methods and Materials: An analysis was performed of 422 mammographically detected intraductal breast carcinomas in 418 women from 11 institutions in North America and Europe. All patients were treated with breast-conserving surgery followed by definitive breast irradiation. The median follow-up time was 9.4 years (mean, 9.4 years; range, 0.1–19.8 years). Results: The 15-year overall survival rate was 92%, and the 15-year cause-specific survival rate was 98%. The 15-year rate of freedom from distant metastases was 94%. There were 48 local failures in the treated breast, and the 15-year rate of any local failure was 16%. The median time to local failure was 5.0 years (mean, 5.7 years; range, 1.0–15.2 years). Patient age at the time of treatment and final pathology margin status from the primary tumor excision were both significantly associated with local failure. The 10-year rate of local failure was 31% for patient age ≤ 39 years, 13% for age 40–49 years, 8% for age 50–59 years, and 6% for age ≥ 60 years ( p = 0.0001). The 10-year rate of local failure was 24% when the margins of resection were positive, 9% when the margins of resection were negative, 7% when the margins of resection were close, and 12% when the margins of resection were unknown ( p = 0.030). Patient age ≤ 39 years and positive margins of resection were both independently associated with an increased risk of local failure ( p = 0.0006 and p = 0.023, respectively) in the multivariable Cox regression model. Conclusions: The 15-year results from the present study demonstrated high rates of overall survival, cause-specific survival, and freedom from distant metastases following the treatment of mammographically detected ductal carcinoma in situ of the breast using breast-conserving surgery and definitive breast irradiation. Younger age and positive margins of resection were both independently associated with an increased risk of local failure. The 15-year results in the present study serve as an important benchmark for comparison with other treatment modalities. These results support the use of breast-conserving surgery and definitive breast irradiation for the treatment of appropriately selected patients with mammographically detected ductal carcinoma in situ of the breast.

Purpose: The results of breast-conservation therapy using breast irradiation and a boost to the tumor excision site with either electron beam or interstitial 19*Ir implant are reviewed. Methods and Materials: A total of 701 patients with histologically conkned Stage Tl and T2 carcinoma of the breast were treated with wide local tumor excision or quadrantectomy and breast irradiation. The breast was treated with tangential fields using 4 or 6 MV photons to deliver 48 to 50 Gy in 1.8 to 2 Gy daily dose, in five weekly fractions. In 80 patients the regional lymphatics were irradiated. In 342 patients with Stage Tl and 107 with Stage T2 tumors, boost to the primary tumor excision site was delivered with 9 MeV and, more frequently, with 12 MeV electrons. In 91 patients with Stage Tl and 38 patients with Stage T2 tumors an interstitial ‘=Ir implant was performed. Tumor control, disease-free survival, cosmesis, and morbidity of therapy are reviewed. Minimum follow-up is 4 years (median, 5.6 years; maximum, 24 years). Results: The overall local tumor recurrence rates were 5% in the Tl and 11% in the T2 tumor groups. There was no significant difference in the breast relapse rate in patients treated with either electron beam or interstitial ‘“Ir boost. Regional lymph node recurrences were 1% in patients with Tl and 5 % with T2 tumors. Distant metastases were recorded in 5% of the Tl and 23% of the T2 groups. The lo-year actuarial disease-free survival rates were 87% for patients with Tl and 75% for patients with T2 tumors. Diseasefree survival was exactly the same in patients receiving either electron beam or interstitial 19*Ir boost. Cosmesis was rated as excellent/good in 84% of patients with Tl tumors treated with electron beam and 81% of patients treated with interstitial implant, and 74 and 79%) respectively, in patients with T2 tumors. Conclusions: Breast-conservation therapy is an effective treatment for patients with Tl and T2 carcinoma of the breast. There is no signiilcant difference in local tumor control, disease-free survival, cosmesis, or morbidity in patients treated with either electron beam or interstitial 19*Ir implant boost. Clinical trials in progress will further elucidate this controversial subject. Breast-conservation therapy, Radiation therapy, Brachytherapy boost, Electron beam boost.

In vitro data demonstrate that heat-induced radiosensitisation is maximised if hyperthermia and radiotherapy are given simultaneously, with the radiation fraction delivered midway through a hyperthermia session, rather than sequentially. The long-term normal tissue toxicity of full-dose simultaneous thermoradiotherapy is unknown.Patients with locally advanced breast cancer (T3, T4 or more than three involved nodes or local recurrence), no prior radiotherapy, received between four and eight sessions of simultaneous thermoradiotherapy. Hyperthermia always included the primary tumour site. In addition an electively heated sector (EHS) was included. The EHS was randomised to either medial or lateral to the tumour site, with the other side an irradiated but unheated control. As per our usual practice, patients received surgery and/or chemotherapy prior to radiotherapy. Radiation doses were 46-50 Gy followed by a boost of ≤16 Gy at 1.8-2 Gy per fraction. EHS and control sectors received the same dose.A total of 57 evaluable cases with average follow-up of 79 months experienced two local and two nodal recurrences. There was no significant difference in ≥grade 2 toxicity for heated versus control sectors (LR χ(2 )= 0.78, p = 0.38) with no relationship between number of hyperthermia sessions and toxicity (LR χ(2 )= 2.90, p = 0.09).Simultaneous full-dose thermoradiotherapy for breast cancer is feasible and well tolerated, with no significant difference in late toxicity between electively heated and unheated control sectors. All patients had hyperthermia to the primary tumour site with excellent local control.

Background. Previous reports have shown low-dose-rate (LDR) afterloading Ir-192 endobronchial radiation therapy (EnBRT) to effectively palliate symptoms in patients with malignant airway obstruction. The authors retrospectively assessed the consequences of LDR EnBRT with or without neodymium yttrium aluminum garnet (Nd:YAG) laser resection in 37 patients, Methods. Between February 1986 and June 1991, 37 patients with malignant airway obstruction were treated with LDR EnBRT at The Cleveland Clinic Foundation. Inclusion criteria for LDR EnBRT with or without Nd:YAG laser resection were patients with recurrent, symptomatic endobronchial lesions treated previously with external beam irradiation

Inflammatory carcinoma of the breast has been associated with a poor prognosis. Several therapeutic approaches have been under investigation in an effort to improve outcome.This is a retrospective analysis of 179 patients with histologically confirmed inflammatory carcinoma of the breast: 33 treated with irradiation alone, 35 with combined irradiation and chemotherapy, 25 with irradiation and surgery, and 86 with a combination of three modalities.The 5-year disease free survival (DFS) rates were 40% for patients treated with three modalities, 24% for those treated with irradiation and surgery, and 6% for those treated with irradiation alone or in combination with chemotherapy without a surgical procedure. The 10-year DFS rates were 35%, 24%, and 0%, respectively. Cause specific survival (CSS) curves closely follow the same trends. A clearly superior locoregional tumor control was observed in patients who underwent a surgical procedure: 79% with three modalities, 76% with irradiation and surgery, and only 30% with irradiation alone or in combination with chemotherapy. Distant metastasis occurred in 57% of the group treated with triple-modality therapy, 60% of those treated with irradiation plus surgery, and 85% of the patients treated with irradiation alone or in combination with chemotherapy. There was no significant correlation between the type of mastectomy or doses of irradiation and locoregional tumor control or survival. The significant morbidity of the trimodal therapy (10%), although somewhat higher than that of other modalities (3.2%), was acceptable.The addition of mastectomy to irradiation significantly improved locoregional tumor control, DFS, and CSS; differences were statistically significant. The combination of chemotherapy, surgery, and irradiation had a significant impact on locoregional tumor control and incidence of distant metastases compared with surgery plus irradiation, and a lesser impact, although still statistically significant, on DFS and CSS. Further clinical trials are needed to optimize the management of patients with inflammatory breast cancer.

Purpose: To determine the incidence, pattern of regional nodal failure, and treatment sequelae as determined by the extent of lymphatic irradiation. Methods and Materials: The records of 511 patients with 519 Stage I and II breast cancers treated with breast conserving surgery with or without axillary dissection and irradiation were reviewed. The extent of nodal irradiation was at the discretion of the attending radiation oncologist and varied considerably over the years. Management of the axilla consisted of axillary dissection alone in 351, axillary dissection and supplemental irradiation in 74, irradiation alone in 75, and simply observation in 21 patients. Results: Overall, axillary recurrence was uncommon (1.2%), but was slightly more frequent after irradiation alone (2.7%) than after surgery alone (0.3%), p = 0.14. There was no benefit for supplemental axillary irradiation after an axillary dissection yielding negative or 1 to 3 positive nodes. In the 21 patients in whom the axilla was observed, axillary recurrence was not observed. Supraclavicular failures were rare in women with negative or 1 to 3 positive axillary lymph nodes (0.5%), and not significantly affected by elective irradiation. Internal mammary node recurrence was seen in only one patient, and was not significantly influenced by elective internal mammary irradiation. Both arm and breast edema were significantly more common in women having breast and nodal irradiation than after breast irradiation alone. These sequelae were not influenced significantly by the number of lymph nodes obtained in the axillary dissection specimen. Radiation pneumonitis was seen with increased frequency with more extensive nodal radiotherapy. Pneumonitis was not found to be affected by the administration or sequencing of chemotherapy. Conclusion: There is little justification for axillary or supraclavicular irradiation following an axillary dissection which yields negative or minimally involved (1 to 3 positive) lymp nodes. There were too few patients with extensive axillary node metastases (>- 4 positive) in our series to draw conclusions about the optimal extent of nodal irradiation in this subset. Elective internal mammary lymph node irradiation increases technical complexity, does not appear to be advantageous, and when combined with supraclavicular irradiation places the patient at highest risk for pneumonitis.

This summary focuses on the role of postoperative radiation therapy in patients treated with modified radical mastectomy for invasive breast cancer, particularly in patients receiving systemic therapy.

Background During the past 2 decades, breast conservation therapy (BCT) has become firmly established as a standard therapeutic approach for eligible women with early-stage breast cancer. Breast radiation after conservative surgery is an integral component of BCT, resulting in comparable local control and equivalent survival to mastectomy. Successful breast conservation relies on understanding key elements for patient selection, evaluation, treatment contraindications, radiation therapy methods, and integration with systemic therapy. Methods The Appropriateness Criteria Committee of the American College of Radiology convened an expert panel to examine BCT for early-stage breast cancer. By using a modified Delphi technique to generate consensus, the expert panel responded to questionnaires on 9 clinical cases that address various key elements of breast conservation. A literature review on BCT led to the generation of an evidence table to support the consensus and overview. Results Consensus for appropriateness criteria for BCT was produced for various clinical scenarios commonly encountered in practice. These topics include radiation oncology management issues related to young patient age, sentinel node biopsy, elderly patients, other histology, positive margins, extensive intraductal component, node-positive breast cancer, genetic breast cancer, partial breast irradiation, and systemic therapy. Radiation methods for BCT are reviewed. Conclusion The Breast Cancer Panel has generated a consensus of up-to-date guidelines for the appropriate use of radiation for BCT by using a modified Delphi process for the American College of Radiology Appropriateness Criteria.

Irradiation of the axillary nodes is often indicated in the clinical radiotherapy of patients with lymphoma and breast cancer. The relative location of the axillary nodes and the humeral head has historically been estimated based on lymphangiographic data. Since CT offers more precise definition, the axillary nodal region in relation to the humeral head was systematically studied in 61 patients undergoing CT simulation for breast conservation therapy. Differences in arm position (degree of abduction) significantly affected the location of the axillary nodal region in relation to the humeral head. With the arm abducted beyond 55 degrees, humeral head blocking would result in blocking of some of the axillary nodes.

This study investigated changes in psychological adjustment and quality of life among breast cancer patients following completion of radiation therapy.Ninety-four patients completed measures of depressed mood, anxiety, and quality of life via interview at five time points: the end of radiation therapy, 2 weeks posttreatment, the first radiation oncology follow-up appointment (4-6 weeks after treatment), 3 months posttreatment, and 6 months posttreatment.At the conclusion of radiation treatment, participants reported elevated levels of depression, low levels of anxiety, and diminished quality of life. By 2 weeks posttreatment, depression decreased significantly and overall quality of life improved significantly, as well as quality of life in the specific FACT-B domains of Physical and Functional Well Being and the Breast Cancer Subscale. Following that time, the only significant change involved further improvement in breast-cancer-specific concerns.Results suggest that the primary psychological changes associated with ending breast cancer treatment occur quickly following the conclusion of treatment. Thereafter, psychological status appears to stabilize. The implications of these findings for treatment and directions for future research are discussed.

The efficacy of post-operative radiation therapy in breast cancer management has been evident for several decades. In recent years there has been increasing interest in treating the internal mammary lymph nodes. In an attempt to simplify their localization for treatment planning purposes, the position of the internal mammary lymph nodes was systematically studied in 65 breast cancer patients undergoing CT simulation.

Background Novel approaches are needed for breast cancer patients in whom standard therapy is not effective. 2-Deoxy-2-[18F]fluoro-D-glucose (18F-FDG) was evaluated as a potential radiomolecular therapy agent in breast cancer animal models and, retrospectively, in patients with metastatic breast cancer. Methods Polyoma middle T antigen (PyMT) and mouse mammary tumor virus-NeuT transgenic mice with tumors 0.5–1 cm in diameter were imaged with 18F-FDG, and tumor to liver ratios (TLRs) were calculated. The radiotoxicity of 18F-FDG administration was determined in healthy mice. PyMT mice with small (0.15–0.17 cm) and large (more than 1 cm) tumors were treated with 2–4 mCi of 18F-FDG, and control C3H/B6 mice with 3 mCi of 18F-FDG. At 10 days after treatment the tumors and control mammary glands were analyzed for the presence of apoptotic and necrotic cells. Five patients with breast cancer and metastatic disease were evaluated and standardized uptake values (SUVs) in tumors, maximum tolerated dose, and the doses to the tumor were calculated. Results Doses up to 5 mCi proved to be non-radiotoxic to normal organs. The 18F-FDG uptake in mouse tumors showed an average TLR of 1.6. The treatment of mice resulted in apoptotic cell death in the small tumors. Cell death through the necrotic pathway was seen in large tumors, and was accompanied by tumor fragmentation and infiltration with leukocytes. Normal mammary tissues were not damaged. A human 18F-FDG dose delivering 200 rad to the red marrow (less than 5% damage) was calculated to be 4.76 Ci for a 70 kg woman, and the dose to the tumors was calculated to be 220, 1100 and 2200 rad for SUVs of 1, 5 and 10, respectively. Conclusion We have shown that positrons delivered by 18F-FDG to mammary tumors have a tumoricidal effect on cancer cells. The study of breast cancer patients suggests that the tumor and normal organ dosimetry of 18F-FDG makes it suitable for therapy of this malignancy.

Lymphedema is a common late toxicity of cancer therapy. This article describes the rationale and process utilized by the Lymphedema Working Group for the revision and expansion of the Common Toxicity Criteria version 2 (CTC v2.0) lymphedema criteria to produce the CTC v3.0 lymphedema criteria. Established clinician-based rating scales and quantitative instruments are reviewed in this article. None of the extant rating scales have been formally validated, nor has their reliability been assessed. Drawbacks of current scales were considered in formulating CTC v3.0 criteria. Most rely exclusively on volume to diagnose and grade lymphedema. This imposes significant clinical limitations, particularly in the assessment of toxicity in oncology clinical trials. Volume-based rating scales are of little value in rating the severity of bilateral limb and nonlimb edema. Problems with nonvolumetric staging systems (eg, CTC v2.0) include insufficient detail to permit useful discrimination of severity among the majority of lymphedema patients. Technologies for objectively quantifying lymphedema have been developed and validated. Although these are briefly reviewed, it is recognized that cost and access issues limit their widespread clinical utility and, as such, were not considered in developing the CTC v3.0 criteria. The CTC v3.0 lymphedema criteria adopted several innovations. Principle among these was the decision to generate separate criteria for volumetric increase, dermal changes, and subcutaneous fibrosis. We anticipate the use of the new CTC v3.0 lymphedema criteria to begin in mid-2003 for grading the key clinical features of this disorder in oncology clinical trials. The purpose of this article is to familiarize the reader with (1) background on the clinical features of lymphedema, (2) information on established lymphedema rating systems, (3) the consensus process and rationale of the Lymphedema Working Group, (4) the new CTC v3.0, and (5) quantitative techniques for assessment of lymphedema.

Irradiation is indicated for patients undergoing mastectomy as surgical management for breast cancer treatment when clinical or pathologic tumor and nodal features predict risk of local/regional recurrence. Such features include: tumor size >/= 5 cm, inadequate surgical margins; skin, facial, or skeletal muscle invasion; dermal lymphatic invasion; poorly differentiated tumor histology; four or more lymph nodes positive; gross extracapsular tumor nodal extension into soft tissues; and matted lymph nodes or enlarged lymph nodes > 2 cm. Patients who were treated with irradiation after mastectomy can develop local/regional recurrences despite such adjuvant therapy. General management for chest wall and nodal recurrences is structured on the extent and volume of local/regional disease, the absence of distant metastases, the general health of the patient, and the extent of prior local/regional therapies, especially irradiation. Management of local/regional recurrence in the setting of no prior irradiation includes tumor debulking by systemic or surgical treatment followed by comprehensive chest wall and regional lymphatic irradiation. Doses are selected by tissue tolerances and volume of remaining disease. The management strategy for the patient with a history of irradiation parallels the nonirradiated patient with respect to systemic and surgical therapies to debulk the tumor to maximal response or no gross clinical disease. Radiation field design is determined by prior therapies. Doses to these fields are adjusted to normal tissue tolerance. Irradiation is given with a sensitizer such as hyperthermia or 5-fluorouracil chemotherapy. Use of radiation sensitizers can allow for a more meaningful biologic tumor effect when normal tissue tolerances prohibit delivery of standard tumor doses. Hyperthermia has been used effectively to promote complete tumor responses with use of irradiation in re-treatment cases.

In vitro and animal studies indicate that a moderate temperature of 41 degrees C maintained for approximately 1 h will provide radiosensitization if radiation (RT) and hyperthermia (HT) are delivered simultaneously, but not with sequential treatment. A minimum tumour temperature of 41 degrees C is a more feasible goal than the goal of42 degrees C needed for sequential treatment.Forty-four patients with 47 recurrent superficial cancers received simultaneous external beam radiotherapy and superficial hyperthermia on successive IRB approved phase I/II studies. All lesions had failed previous therapy, 35 were previously irradiated (mean dose 52.7 Gy). Hyperthermia was delivered with 915 MHz microwave or 1-3.5 MHz ultrasound using commercially available applicators. The average dimensions of 19 lesions treated with microwave were 4.7 x 3.6 x 1.7 cm and the average dimensions of 28 lesions treated with ultrasound were 8.0 x 6.1 x 2.9 cm. The most common sites were chest wall (15 cases) and head and neck (21 cases). Temperatures were monitored at an average of six intratumoral locations using multisensor probes. The median number of hyperthermia treatments was three and the median radiation dose 30 Gy. Radiation dose per fraction was 4 Gy with hyperthermia and 2 Gy or 4 Gy (depending on protocol) on non-hyperthermia days.Six different measures of minimum monitored temperature and duration were found to be highly correlated with each other. There was nearly a one-to-one correspondence between minimum tumour time at or above 41 degrees C (Min t41) and minimum tumour Sapareto Dewey equivalent time at 42 degrees C (Min teq42). After four sessions 63% of cases had a per session average Sapareto Dewey equivalent time at 41 degrees C which exceeded 60 min in all monitored tumour locations. The complete and partial response rate in evaluable lesions were respectively 21/41 (51%) and 7/41 (17%) and were best correlated with site (chest wall showing best response). Toxicity consisted of 10/47 (21%) slow healing soft tissue ulcers which healed in all cases but required a median of 7 months. The most important predictors for chronic ulceration were cumulative radiation dose80 Gy and complete response to treatment.Minimum tumour temperatures maintained for durations compatible in vitro with thermal radiosensitization (if RT and HT are delivered simultaneously) are clinically feasible and tolerable for broad but superficial lesions amenable to externally applied ultrasound or microwave hyperthermia. The current in-house protocol is evaluating the impact of more than four hyperthermia sessions on the overall thermal dose distribution and toxicity.

Purpose: Host, tumor, and treatment-related factors influencing cosmetic outcome are analyzed for patients receiving breast conservation treatment. Methods and Materials: Four-hundred and fifty-eight patients with evaluable records for cosmesis evaluation, a subset of 701 patients treated for invasive breast cancer with conservation technique between 1969 and 1990, were prospectively analyzed. In 243 patients, cosmetic evaluation was not adequately recorded. Cosmesis evaluation was carried out from 3.7 months to 22.3 years, median of 4.4 years. By pathologic stage, tumors were 62% T1N0, 14% T1N1, 15% T2N0, and 9% T2N1. The majority of patients were treated with 4–6 MV photons. Cosmetic evaluation was rated by both patient and physician every 4–6 months. A logistic regression analysis was completed using a stepwise logistic regression. P -values of 0.05 or less were considered significant. Excellent cosmetic scores were used in all statistical analyses unless otherwise specified. Results: At most recent follow-up, 87% of patients and 81% of physicians scored their cosmetic outcome as excellent or good. Eighty-two percent of physician and patient evaluations agreed with excellent-good vs. fair-poor rating categories. Analysis demonstrated a lower proportion of excellent cosmetic scores when related to patient age > 60 years ( p = 0.001), postmenopausal status ( p = 0.02), black race ( p = 0.0034), and T2 tumor size ( p = 0.05). Surgical factors of importance were: volume of resection > 100 cm 3 ( p = 0.0001), scar orientation compliance with the National Surgical Adjuvant Breast Project (NSABP) guidelines ( p = 0.0034), and > 20 cm 2 skin resected ( p = 0.0452). Extent of axillary surgery did not significantly affect breast cosmesis. Radiation factors affecting cosmesis included treatment volume (tangential breast fields only vs. three or more fields) ( p = 0.034), whole breast dose in excess of 50 Gy ( p = 0.0243), and total dose to tumor site > 65 Gy ( p = 0.06), as well as optimum dose distribution with compensating filters ( p = 0.002). Daily fraction size of 1.8 Gy vs. 2.0 Gy, boost vs. no boost, type of boost (brachytherapy vs. electrons), total radiation dose, and use of bolus were not significant factors. Use of concomitant chemotherapy with irradiation impaired excellent cosmetic outcome ( p = 0.02). Use of sequential chemotherapy or adjuvant tamoxifen did not appear to diminish excellent cosmetic outcomes ( p = 0.31). Logistic regression for excellent cosmetic outcome analysis was completed for age, tumor size, menopausal status, race, type of surgery, volume of breast tissue resected, scar orientations, whole breast radiation dose, total radiation dose, number of radiation fields treated, and use of adjuvant chemotherapy. Significant independent factors for excellent cosmetic outcome were: volume of tissue resected ( p = 0.0001), type of surgery ( p = 0.0001), breast radiation dose ( p = 0.005), race ( p = 0.002), and age ( p = 0.007). Conclusions: Satisfactory cosmesis was recorded in 81% of patients. Impaired cosmetic results are more likely with improper orientation of tylectomy and axillary incisions, larger volume of breast resection, radiation dose to the entire breast in excess of 50.0 Gy, and concurrent administration of chemotherapy. Careful selection of treatment procedures for specific patients/tumors and refinement in surgical/irradiation techniques will enhance the cosmetic results in breast conservation therapy.

Treatment planning for breast cancer is a challenge for bridge separations greater than 24 cm. Protocols require dose homogeneity to the breast parenchyma to 10% while maintaining good cosmesis (skin sparing). Low-energy beams (6 MV or lower) may not achieve protocol specifications because of lateral or medial hot spots. The buildup region for high-energy beams (i.e., 18 MV) may lead to underdosing in the superficial regions. Adding bolus will pull the isodoses to surface, surrendering skin sparing. A spoiler will increase the contribution of scattered medium energy electrons and photons, thereby increasing superficial dosing and maintaining skin sparing due to displacement of the spoiler from the skin. We chose Lucite as the spoiler material for our 18-MV beam. Buildup measurements were performed with a parallelplate ionization chamber to find the optimal spoiler thickness of 18 mm at a spoiler-to-skin distance of 22 cm. A breast phantom was designed allowing thermoluminescent dosimeter measurements. The spoiler has increased the percent depth dose from the depths of 0.5 cm to 3.0 cm to mimic those delivered by a 6 MV beam, while the relative skin dose was held to 50%. Our treatment schema is typically 6-MV photons with customized compensation for half or more of the fractions and uncompensated 18-MV photons with the spoiler for the remaining fractions. The spoiler may be used in conjunction with thin bolus (1.0 cm) for therapeutic dosing to the skin (scars, inflammatory disease, etc.). The treatment plans have maintained dose homogeneity for large patients, without consequence of skin reaction.

Very small breast cancers are being diagnosed with increased frequency, and, until recently, little information regarding the incidence of axillary lymph node metastases in these most favorable tumors was available. Moreover, scarce data exist regarding axillary failure in this cohort as a function of initial treatment, be it surgery, radiation, or simply observation. In the present study, limited to women with invasive cancers measuring no more than 10 mm, the incidence of pathologically positive axillary nodes was 12.3%. The incidence of nodal metastases was influenced by tumor size (albeit not quite significantly, p = .08); not one patient with a tumor < or = 5 mm had axillary node metastases, compared to 14.7% in those with cancers 6 to 10 mm. The histologic grade and tumor location were also important in predicting nodal positivity. The incidence of positive nodes was 38% in those with poorly differentiated cancers, compared to 8% and 7% in women with well and moderately differentiated cancers, respectively, p = .03. Axillary nodal positivity was seen in 17% of outer quadrant vs 3% of central and inner quadrant primaries, p < .01. The axilla was managed with surgery alone (76%), radiation alone (6%), surgery and radiation (6%), or simply observation (10%). With a median follow-up of 55 months, not one patient has suffered a nodal recurrence, and in our experience, survival free of distant relapse was not adversely affected by the omission of axillary surgery.

Purpose: The purpose of the present study is to evaluate the outcome of salvage treatment for local recurrence in the breast following the initial treatment of ductal carcinoma in situ (intraductal carcinoma) with breast-conserving surgery and definitive breast irradiation. Methods and Materials: An analysis was performed of 42 local failures in the breast that occurred following the initial treatment of ductal carcinoma in situ (intraductal carcinoma) with breast-conserving surgery and definitive breast irradiation. At the time of the local recurrence, 23 cases (55%) showed invasive ductal carcinoma, and 19 cases (45%) showed intraductal carcinoma, one with associated Paget's disease. The surgical treatment at the time of local recurrence included mastectomy ( n = 39), excision ( n = 2), or other ( n = 1). Adjuvant systemic therapy at the time of local recurrence included chemotherapy ( n = 2), hormonal treatment ( n = 7), both ( n = 1), or none ( n = 32). The median follow-up after salvage treatment was 3.7 years (mean = 4.0 years; range=0.1–9.5 years). Results: The 5-year actuarial outcome following salvage treatment for the 42 local recurrences showed an overall survival rate of 78%) and a cause-specific survival rate of 84%. The 5-year actuarial rate of freedom from distant metastases was 86%. None of the patients with histology of the local recurrence of intraductal carcinoma or with detection of the local recurrence with mammographic findings only developed distant metastatic disease after salvage treatment. The 5-year actuarial rate of freedom from chest wall recurrence following salvage mastectomy was 92%. All three of the patients who developed chest wall recurrence following salvage mastectomy also developed distant metastatic disease. Conclusions: These results demonstrate that local recurrences following the initial treatment of ductal carcinoma in situ with breast-conserving surgery and definitive breast irradiation can be salvaged with high rates of survival, freedom from distant metastases, and freedom from chest wall recurrence. The results of salvage treatment support the use of breast-conserving surgery and definitive breast irradiation for the initial management of ductal carcinoma in situ of the breast.

The treatment of patients with locally advanced noninflammatory breast cancer has evolved substantially over the past 30 years. From 1968 to 1989, 281 women were treated at Mallinckrodt Radiation Oncology Center with four different treatment methods. Median follow-up was 6.2 years (range 3-22 years); no patient was lost to follow-up.Retrospective review of records and analysis of data on a computer file were carried out. Thirty-five patients were treated with irradiation alone, 33 with irradiation and adjuvant chemotherapy, 81 with mastectomy and irradiation, and 132 with mastectomy, irradiation, and chemotherapy (triple-modality).Actuarial 5- and 10-year disease free survival (DFS) rates were 45% and 36%, respectively, with triple-modality therapy, 31% and 10% with irradiation and chemotherapy, 32% and 19% with irradiation and mastectomy, and 19% and 11% with irradiation alone. Cause specific survival (CSS) paralleled DFS in the four groups. Locoregional tumor control at 5 years was 91% for irradiation, mastectomy, and chemotherapy, 80% for irradiation and mastectomy, 54% for irradiation and chemotherapy, and 31% for irradiation alone. Systemic therapy and/or irradiation given before mastectomy yielded better locoregional tumor control, DFS, and CSS (not statistically significant). No difference in results was noted with radical, modified radical, or total mastectomy. In the triple-modality group, no chest wall failures occurred with chest wall doses greater than 5040 cGy. Grade 2 or higher treatment sequelae were noted in 10-42% of patients, depending on treatment modality.Triple-modality therapy yielded improved locoregional tumor control, DFS, and CSS compared with other modalities. Patients treated with surgery had better locoregional tumor control than those who received irradiation alone or in combination with chemotherapy, but the impact on DFS and CSS was less impressive. Additional clinical trials are needed to define further the role and optimal use of the various therapeutic modalities in the management of locally advanced breast cancer.

Purpose: Definitive radiation therapy for breast cancer with regional nodal involvement often introduces treatment of adjacent abutted regions. Many methods describe techniques to achieve an effective transverse plane match. Our facility recently adopted a matching technique using asymmetric jaws to beam-split all portals along the central axis plane. Our technique uses one isocenter to treat the opposed tangential breast fields, the supraclavicular port and the posterior axillary field. Methods and Materials: Our linear accelerator has four collimator jaws capable of being set independently. The longitudinal (Y) jaws beam-split all the portals at the match plane, namely the upper border of the tangential beams and the bottom border of the nodal fields. The transverse (X) jaws define the lateral borders of the nodal fields, and in a near beam-split fashion in conjunction with customized Cerrobend, block the lung for the tangential beams. The unique isocenter is chosen along the mid-bridge through the tangential match plane. Dosimetric qualities and calculational techniques of the asymmetric beams were analyzed with ionimetric water scans, ion chamber studies, and film. The match-line is clinically confirmed with composite port films. Results: Our dosimetric studies show asymmetric jaws provide nearly equivalent field edge definition and superior absorption in comparison with Cerrobend blocks. The use of one isocenter results in a reduction of in-room treatment time by a factor of two. The burden of lifting heavy Cerrobend blocks has been removed. A composite port film, which includes the medial tangential and supraclavicular ports, shows a perfect match-line in all cases. Similar composite port films taken with our previous technique of geometric matching with collimator and table angulation exhibit slight overlap or underdose regions in many cases. Conclusion: Our treatment technique takes full advantage of dual asymmetric jaws to achieve a perfect match-line, necessitates only one isocenter and set-up point, and supplies more absorption in reference to lung and contralateral breast dose. The pure match-line is accompanied by the fact that the patient does not have to move in any direction.

Purpose: The primary objective of this study was to explore the possibility of using the exit detector data (EDD) for in vivo quality assurance of our clinical breast cancer patient (BC) treatments. Methods: Eleven clinical BC patients were evaluated for dose delivery accuracy using TomoTherapy's Delivery‐Verification software on a GPU platform. Evaluations consisted of reconstructed delivery verification sinogram (DVS) and subsequent dose computation on MV‐CT datasets. The DVS reconstructions and dose computations were calculated utilizing MV‐CT scans covering the complete length of the treatment volume and the EDD files collected on the same day. Leaf‐opening‐time (LOT) differences were analyzed to investigate the frequency and magnitude of the sinogram differences between planned and reconstructed. Reconstructed dose distributions of fraction‐deliveries were scaled and convolved to give an approximation of the composite dose distributions. Composite dose distributions were compared against the original plans. Summed doses were based on rigid‐registrations of the fraction‐doses and do not account for soft‐tissue and dose deformations. Reconstructed DVHs are based solely on planning structures.Results: Characteristic average LOT differences were ∼5msec‐eq. It can be noted that large differences between individual fractions are small for composite dose distribution. For the reconstructed summed fractions, both minimal dose (D99%) and dose inhomogeneity (D5%–D95%) of the PTV were found to be within ±0.8Gy of the planned. Ipsi‐lateral lung volume receiving >20Gy and contra‐lateral lung volume receiving >5Gy were decreased by 0.5Gy%±0.4% and 3.2%Gy±1.9%, respectively. The heart mean dose and volume receiving >35Gy were decreased by 0.3Gy±0.4 and 0.3%Gy±0.3%, respectively. Conclusion: The results of study indicate that the EDDs are useful for DVS reconstruction and dose computation which can translate into being a great tool for in vivo quality assurance of BC treatments. Currently further studies are being investigated to account for the deformation of soft‐tissue and dose distributions.

To evaluate the association between age and breast/regional nodal relapse following breast conserving surgery and irradiation.The results of treatment in 511 patients with 519 Stage I and II breast cancers treated at Mallinkrodt Institute of Radiology and affiliated hospitals between 1958 and 1988 were reviewed.Seventy women, of whom 96% had axillary dissections, were 39 years of age or younger. These young patients were more likely to have chemotherapy (p0.0001), and tumor bed reexcision (p0.01), and less likely to have an undissected axilla (p0.01), or estrogen receptor positive tumor (p = 0.02) than the older women (40 years). Although breast recurrence tended to appear earlier in the younger patients (12% at 5 years for those40 years vs. 6% at 5 years for those older), by 7 years the breast failure rate for the two groups was the same (12%), p = 0.13. In the 37 women 35 years of age or younger, the actuarial rate of breast recurrence was 9% at 7 years. Compared to other series in the literature, in which cancers were grossly excised without regard to the microscopic margins of resection, and reexcision was not routinely performed, young women treated with breast conserving surgery and irradiation at our institution frequently underwent reexcision of the tumor bed (57%), and had negative pathologic margins of resection (75%). Regional nodal relapse was in general uncommon, and not seen with increased frequency in the youngest cohort.Our experience suggests that young age is not a contraindication to breast conserving surgery and irradiation. Although breast cancers in this cohort may have certain features rendering them prone to local failure, we believe this risk can be mitigated by appropriate patient selection and optimal surgical resection.

Purpose: To evaluate modulated electron radiotherapy (MERT) planning for delivery with the photon multicollimator (xMLC) for treatment of bilateral post‐mastectomy chest wall treatment. Current techniques are complex, time consuming, and deficient in terms of target coverage and organ at risk (OAR) sparing. Conventional techniques require blocks and energy modifying bolus, while IMRT is volatile due to patient motion and provides unnecessary dose baths. Materials and Methods: An in‐house Monte‐Carlo‐based MERT planning system has been developed for planning bilateral chest wall (MERT‐biCW) treatment aided by previously developed in‐house MERT optimization tools. The MERT‐biCW planning was performed in three steps: 1) determine the number of portal fields needed to cover a PTV and partition the PTV into sub‐PTVs for corresponding portals; 2) each sub‐PTVs is then planned with MERT individually incorporating multiple energy assigned segments within each portal; 3) optimizing all portals to achieve the final plan. Several new features have been added to our MERT planning tools including; automatic selection of the best incident angle for each portal, whereby the distal surface of the tumor will be reached by selected energy and minimizing the air gap to