Stefan Both

Time course of mild arm lymphedema after breast conservation treatment for early-stage breast cancer.

PURPOSE Arm lymphedema is a potential consequence of the treatment for breast carcinoma. The objective of this retrospective study was to characterize the progression of mild arm lymphedema after breast conservation treatment for breast cancer. METHODS AND MATERIALS The study cohort was drawn from 1,713 consecutive Stage I or II breast cancer patients who underwent breast conservation therapy, including axillary staging followed by radiation. Arm lymphedema was documented in 266 (16%) of 1,713 patients. One hundred nine patients, 6% of the overall group and 40% of the patients with arm lymphedema, presented with mild arm lymphedema, defined as a difference of 2 cm or less between the measured circumferences of the affected and unaffected arms. RESULTS Among the 109 patients with mild arm lymphedema at the time of arm lymphedema diagnosis, the rate of freedom from progression to more severe lymphedema was 79% at 1 year, 66% at 3 years, and 52% at 5 years. The patients who were morbidly obese, had positive axillary lymph nodes, or received supraclavicular irradiation at the time of breast cancer treatment were at higher risk of progression from mild arm lymphedema to more severe edema. CONCLUSIONS Mild arm lymphedema, generally considered to be a minor complication after breast conservation treatment for breast cancer, was associated with a risk of progression to a more severe grade of arm lymphedema in a substantial fraction of patients.

Real-time study of prostate intrafraction motion during external beam radiotherapy with daily endorectal balloon.

PURPOSE To prospectively investigate intrafraction prostate motion during radiofrequency-guided prostate radiotherapy with implanted electromagnetic transponders when daily endorectal balloon (ERB) is used. METHODS AND MATERIALS Intrafraction prostate motion from 24 patients in 787 treatment sessions was evaluated based on three-dimensional (3D), lateral, cranial-caudal (CC), and anterior-posterior (AP) displacements. The mean percentage of time with 3D, lateral, CC, and AP prostate displacements>2, 3, 4, 5, 6, 7, 8, 9, and 10 mm in 1 minute intervals was calculated for up to 6 minutes of treatment time. Correlation between the mean percentage time with 3D prostate displacement>3 mm vs. treatment week was investigated. RESULTS The percentage of time with 3D prostate movement>2, 3, and 4 mm increased with elapsed treatment time (p<0.05). Prostate movement>5 mm was independent of elapsed treatment time (p=0.11). The overall mean time with prostate excursions>3 mm was 5%. Directional analysis showed negligible lateral prostate motion; AP and CC motion were comparable. The fraction of time with 3D prostate movement>3 mm did not depend on treatment week of (p>0.05) over a 4-minute mean treatment time. CONCLUSIONS Daily endorectal balloon consistently stabilizes the prostate, preventing clinically significant displacement (>5 mm). A 3-mm internal margin may sufficiently account for 95% of intrafraction prostate movement for up to 6 minutes of treatment time. Directional analysis suggests that the lateral internal margin could be further reduced to 2 mm.

A study to establish reasonable action limits for patient- specific quality assurance in intensity-modulated radiation therapy

An effective patient quality assurance (QA) program for intensity‐modulated radiation therapy (IMRT) requires accurate and realistic plan acceptance criteria—that is, action limits. Based on dose measurements performed with a commercially available two‐dimensional (2D) diode array, we analyzed 747 fluence maps resulting from a routine patient QA program for IMRT plans. The fluence maps were calculated by three different commercially available (ADAC, CMS, Eclipse) treatment planning systems (TPSs) and were delivered using 6‐MV X‐ray beams produced by linear accelerators. To establish reasonably achievable and clinically acceptable limits for the dose deviations, the agreement between the measured and calculated fluence maps was evaluated in terms of percent dose error (PDE) for a few points and percent of passing points (PPP) for the isodose distribution. The analysis was conducted for each TPS used in the study (365 ADAC, 162 CMS, 220 Eclipse), for multiple treatment sites (prostate, pelvis, head and neck, spine, rectum, anus, lung, brain), at the normalization point for 3% percentage difference (%Diff) and 3‐mm distance to agreement (DTA) criteria. We investigated the treatment‐site dependency of PPP and PDE. The results show that, at 3% and 3‐mm criteria, a 95% PPP and 3% PDE can be achieved for prostate treatments and a 90% PPP and 5% PDE are attainable for any treatment site. PACS Numbers: 87.53Dq, 87.53Tf, 87.53Xd, 87.56Fc

A Study to Quantify the Effectiveness of Daily Endorectal Balloon for Prostate Intrafraction Motion Management

PURPOSE To quantify intrafraction prostate motion between patient groups treated with and without daily endorectal balloon (ERB) employed during prostate radiotherapy and establish the effectiveness of the ERB. METHODS Real-time intrafraction prostate motion from 29 non-ERB (1,061 sessions) and 30 ERB (1,008 sessions) patients was evaluated based on three-dimensional (3D), left, right, cranial, caudal, anterior, and posterior displacements. The average percentage of time with 3D and unidirectional prostate displacements >2, 3, 4, 5, 6, 7, 8, 9, and 10 mm in 1-min intervals was calculated for up to 6 min of treatment time. The Kolmogorov-Smirnov method was used to evaluate the intrafraction prostate motion pattern between both groups. RESULTS Large 3D motion (up to 1 cm or more) was only observed in the non-ERB group. The motion increased as a function of elapsed time for displacements >2-8 mm for the non-ERB group and >2-4 mm for the ERB group (p < 0.05). The percentage time distributions between the two groups were significantly different for motion >5 mm (p < 0.05). The 3D symmetrical internal margin (IM) can be reduced from 5 to 3 mm (40% reduction), whereas the asymmetrical IM can be reduced from 3 to 2 mm (33% reduction) in cranial, caudal, anterior, and posterior for 6 min of treatment, when ERB is used. Beyond 6 min, the symmetrical 3D and asymmetrical cranial, caudal, anterior, and posterior IMs can be reduced from 9, 4, 7, 7, and 8 to 5, 2, 5, 3, and 4 mm, respectively (up to 57% reduction). CONCLUSION The percentage of time that the prostate was displaced in any direction was less in the ERB group for almost all magnitudes of motion considered. The directional analysis shows that the ERB reduced IMs in almost all directions, especially the anterior-posterior direction.

Current Status of Diversity by Race, Hispanic Ethnicity, and Sex in Diagnostic Radiology

PURPOSE To assess the diversity of the U.S. diagnostic radiology physician workforce by race, Hispanic ethnicity, and sex in the context of the available pipeline of medical students. MATERIALS AND METHODS Institutional review board evaluation and exemption were granted for the study, as primary data were obtained from publicly available registry sources, with no identifiable private or protected information. Publicly available American Medical Association, American Association of Medical Colleges, and U.S. census registries were used to assess differences for 2010 among diagnostic radiology practicing physicians, academic faculty, residents, subspecialty trainees, residency applicants, medical school graduates, and U.S. population by using binomial tests; with adjustment for multiple comparisons among different groups, differences with P < .001 were considered significant. Significant differences in diagnostic radiology resident representation were evaluated for academic years 2003-2004 to 2010-2011 and for 2010, compared among the 20 largest residency training programs. RESULTS Females and traditionally underrepresented minorities in medicine (URM)-blacks, Hispanics, American Indians, Alaskan Natives, Native Hawaiians, and Pacific Islanders (AI/AN/NH/PI)-are underrepresented as practicing physicians (23.5% and 6.5%, respectively), faculty (26.1%, 5.9%), and diagnostic radiology residents (27.8%, 8.3%), compared with the U.S. population (50.8%, 30.0%) (all P < .001). Although they are increased in percentage as residents compared with practicing physicians, females and URMs remain underrepresented at the resident trainee level, compared with their proportions as medical school graduates (48.3%, 15.3%, respectively). During the past 8 years, there was no significant increase in female or URM resident (all P > .01) representation, suggesting no dramatic change in future representation as practicing physicians. Moreover, diagnostic radiology ranks 17th in female and 20th in URM representation among the 20 largest residency training specialties. CONCLUSION Females and URM remain underrepresented in the diagnostic radiology physician workforce despite an available medical student pipeline. Given prevalent health care disparities and an increasingly diverse society, future research and training efforts should address increasing resident diversity with program directors and department chairs.

Proton beam versus photon beam dose to the heart and left anterior descending artery for left-sided breast cancer

Abstract Purpose. The purpose of this study was to compare the dose to heart, left anterior descending (LAD) artery and lung between proton and photon beam irradiation for left-sided early stage breast cancer. Material and methods. Ten women with early stage left-sided breast cancer were treated with breast conserving surgery and radiation. Whole breast radiation was delivered for actual treatment via a tangential technique with deep inspiration breath hold (DIBH) utilizing inverse planned intensity-modulated radiation therapy (IMRT). Each patient was replanned on an Institutional Review Board (IRB)-approved prospective study using en face proton beam radiation with both uniform scanning (US) and pencil beam scanning (PBS) techniques. Results. Both PBS (0.011 Gy) and US (0.009 Gy) proton plans resulted in a significantly lower mean heart dose compared to IMRT (1.612 Gy) (p < 0.05 for PBS vs. IMRT and US vs. IMRT). The Dmean, Dmin, Dmax, and D0.2cm3 of the LAD with either proton technique were significantly lower (p = 0.005) compared to IMRT. Both US and PBS reduced the mean dose to the lungs compared to IMRT. The coverage of the breast planning target volume was comparable between photon and proton plans. Conclusions. The dose to whole heart was relatively low in this study of patients treated under conditions of DIBH. However, proton beam radiation was associated with lower minimum, maximum, and dose to 0.2 cm3 of the LAD, which is the critical structure for late radiation therapy effects, compared to even the most optimized photon beam plan with DIBH and IMRT.

Concurrent segmentation of the prostate on MRI and CT via linked statistical shape models for radiotherapy planning.

PURPOSE Prostate gland segmentation is a critical step in prostate radiotherapy planning, where dose plans are typically formulated on CT. Pretreatment MRI is now beginning to be acquired at several medical centers. Delineation of the prostate on MRI is acknowledged as being significantly simpler to perform, compared to delineation on CT. In this work, the authors present a novel framework for building a linked statistical shape model (LSSM), a statistical shape model (SSM) that links the shape variation of a structure of interest (SOI) across multiple imaging modalities. This framework is particularly relevant in scenarios where accurate boundary delineations of the SOI on one of the modalities may not be readily available, or difficult to obtain, for training a SSM. In this work the authors apply the LSSM in the context of multimodal prostate segmentation for radiotherapy planning, where the prostate is concurrently segmented on MRI and CT. METHODS The framework comprises a number of logically connected steps. The first step utilizes multimodal registration of MRI and CT to map 2D boundary delineations of the prostate from MRI onto corresponding CT images, for a set of training studies. Hence, the scheme obviates the need for expert delineations of the gland on CT for explicitly constructing a SSM for prostate segmentation on CT. The delineations of the prostate gland on MRI and CT allows for 3D reconstruction of the prostate shape which facilitates the building of the LSSM. In order to perform concurrent prostate MRI and CT segmentation using the LSSM, the authors employ a region-based level set approach where the authors deform the evolving prostate boundary to simultaneously fit to MRI and CT images in which voxels are classified to be either part of the prostate or outside the prostate. The classification is facilitated by using a combination of MRI-CT probabilistic spatial atlases and a random forest classifier, driven by gradient and Haar features. RESULTS The authors acquire a total of 20 MRI-CT patient studies and use the leave-one-out strategy to train and evaluate four different LSSMs. First, a fusion-based LSSM (fLSSM) is built using expert ground truth delineations of the prostate on MRI alone, where the ground truth for the gland on CT is obtained via coregistration of the corresponding MRI and CT slices. The authors compare the fLSSM against another LSSM (xLSSM), where expert delineations of the gland on both MRI and CT are employed in the model building; xLSSM representing the idealized LSSM. The authors also compare the fLSSM against an exclusive CT-based SSM (ctSSM), built from expert delineations of the gland on CT alone. In addition, two LSSMs trained using trainee delineations (tLSSM) on CT are compared with the fLSSM. The results indicate that the xLSSM, tLSSMs, and the fLSSM perform equivalently, all of them out-performing the ctSSM. CONCLUSIONS The fLSSM provides an accurate alternative to SSMs that require careful expert delineations of the SOI that may be difficult or laborious to obtain. Additionally, the fLSSM has the added benefit of providing concurrent segmentations of the SOI on multiple imaging modalities.

CLINICAL TOXICITIES AND DOSIMETRIC PARAMETERS AFTER WHOLE-PELVIS VERSUS PROSTATE-ONLY INTENSITY-MODULATED RADIATION THERAPY FOR PROSTATE CANCER

PURPOSE To assess whether whole-pelvis (WP) intensity-modulated radiation therapy (IMRT) is associated with increased toxicity compared with prostate-only (PO) IMRT. METHODS AND MATERIALS We retrospectively analyzed all patients with prostate cancer undergoing definitive IMRT to 79.2 Gy with concurrent androgen deprivation at our institution from November 2005 to May 2007 with a minimum follow-up of 12 months. Thirty patients received initial WP IMRT to 45 Gy in 1.8-Gy fractions, and thirty patients received PO IMRT. Study patients underwent computed tomography simulation and treatment planning by use of predefined dose constraints. Bladder and rectal dose-volume histograms, maximum genitourinary (GU) and gastrointestinal (GI) Radiation Therapy Oncology Group toxicity grade, and late Grade 2 or greater toxicity-free survival curves were compared between the two groups by use of the Student t test, Fisher exact test, and Kaplan-Meier curve, respectively. RESULTS Bladder minimum dose, mean dose, median dose, volume receiving 5 Gy, volume receiving 20 Gy, volume receiving 40 Gy, and volume receiving 45 Gy and rectal minimum dose, median dose, and volume receiving 20 Gy were significantly increased in the WP group (all p values < 0.01). Maximum acute GI toxicity was limited to Grade 2 and was significantly increased in the WP group at 50% vs. 13% the PO group (p = 0.006). With a median follow-up of 24 months (range, 12-35 months), there was no difference in late GI toxicity (p = 0.884) or in acute or late GU toxicity. CONCLUSIONS Despite dosimetric differences in the volume of bowel, bladder, and rectum irradiated in the low-dose and median-dose regions, WP IMRT results only in a clinically significant increase in acute GI toxicity, in comparison to PO IMRT, with no difference in GU or late GI toxicity.

Gabapentin for the Treatment of Pain Syndrome Related to Radiation-Induced Mucositis in Patients With Head and Neck Cancer Treated With Concurrent Chemoradiotherapy

This retrospective study evaluated the efficacy of gabapentin for the treatment of pain syndromes related to radiation‐induced mucositis in patients with head and neck cancers treated with concurrent chemoradiation.

GABAPENTIN FOR THE TREATMENT OF PAIN RELATED TO RADIATION-INDUCED MUCOSITIS IN PATIENTS WITH HEAD AND NECK TUMORS TREATED WITH INTENSITY-MODULATED RADIATION THERAPY

This retrospective study evaluates the efficacy of gabapentin for the treatment of pain syndrome related to radiation‐induced mucositis in patients with head and neck tumors.