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Title: Portal imaging practice patterns of children's oncology group institutions: Dosimetric assessment and recommendations for minimizing unnecessary exposure

Abstract

Purpose: To determine and analyze the dosimetric consequences of current portal imaging practices for pediatric patients, and make specific recommendations for reducing exposure from portal imaging procedures. Methods and Materials: A survey was sent to approximately 250 Children's Oncology Group (COG) member institutions asking a series of questions about their portal imaging practices. Three case studies are presented with dosimetric analysis to illustrate the magnitude of unintended dose received by nontarget tissues using the most common techniques from the survey. Results: The vast majority of centers use double-exposure portal image techniques with a variety of open field margins. Only 17% of portal images were obtained during treatment, and for other imaging methods, few centers subtract monitor units from the treatment delivery. The number of monitor units used was nearly the same regardless of imager type, including electronic portal imaging devices. Eighty-six percent imaged all fields the first week and 17% imaged all fields every week. An additional 1,112 cm{sup 3} of nontarget tissue received 1 Gy in one of the example cases. Eight new recommendations are made, which will lower nontarget radiation doses with minimal impact on treatment verification accuracy. Conclusion: Based on the survey, changes can be made inmore » portal imaging practices that will lower nontarget doses. It is anticipated that treatment verification accuracy will be minimally affected. Specific recommendations made to decrease the imaging dose and help lower the rate of radiation-induced secondary cancers in children are proposed for inclusion in future COG protocols using radiation therapy.« less

Authors:
 [1];  [2];  [3];  [4];  [4]
  1. Department of Radiation Oncology, University of Southern California Keck School of Medicine and Childrens Hospital Los Angeles, Los Angeles, CA (United States). E-mail: aolch@chla.usc.edu
  2. Department of Medical Physics and Engineering Physics, University of Wisconsin, Madison, WI (United States)
  3. Department of Medical Physics and Human Oncology, University of Wisconsin, Madison, WI (United States)
  4. Division of Radiation Oncology, University of Texas M. D. Anderson Cancer Center, Houston, TX (United States)
Publication Date:
OSTI Identifier:
20944707
Resource Type:
Journal Article
Resource Relation:
Journal Name: International Journal of Radiation Oncology, Biology and Physics; Journal Volume: 67; Journal Issue: 2; Other Information: DOI: 10.1016/j.ijrobp.2006.10.004; PII: S0360-3016(06)03245-7; Copyright (c) 2007 Elsevier Science B.V., Amsterdam, Netherlands, All rights reserved; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
62 RADIOLOGY AND NUCLEAR MEDICINE; ACCURACY; CHILDREN; IMAGES; NEOPLASMS; PATIENTS; PEDIATRICS; RADIATION DOSES; RADIOTHERAPY; RECOMMENDATIONS; VERIFICATION

Citation Formats

Olch, Arthur J., Geurts, Mark, Thomadsen, Bruce, Famiglietti, Robin, and Chang, Eric L. Portal imaging practice patterns of children's oncology group institutions: Dosimetric assessment and recommendations for minimizing unnecessary exposure. United States: N. p., 2007. Web. doi:10.1016/j.ijrobp.2006.10.004.
Olch, Arthur J., Geurts, Mark, Thomadsen, Bruce, Famiglietti, Robin, & Chang, Eric L. Portal imaging practice patterns of children's oncology group institutions: Dosimetric assessment and recommendations for minimizing unnecessary exposure. United States. doi:10.1016/j.ijrobp.2006.10.004.
Olch, Arthur J., Geurts, Mark, Thomadsen, Bruce, Famiglietti, Robin, and Chang, Eric L. Thu . "Portal imaging practice patterns of children's oncology group institutions: Dosimetric assessment and recommendations for minimizing unnecessary exposure". United States. doi:10.1016/j.ijrobp.2006.10.004.
@article{osti_20944707,
title = {Portal imaging practice patterns of children's oncology group institutions: Dosimetric assessment and recommendations for minimizing unnecessary exposure},
author = {Olch, Arthur J. and Geurts, Mark and Thomadsen, Bruce and Famiglietti, Robin and Chang, Eric L.},
abstractNote = {Purpose: To determine and analyze the dosimetric consequences of current portal imaging practices for pediatric patients, and make specific recommendations for reducing exposure from portal imaging procedures. Methods and Materials: A survey was sent to approximately 250 Children's Oncology Group (COG) member institutions asking a series of questions about their portal imaging practices. Three case studies are presented with dosimetric analysis to illustrate the magnitude of unintended dose received by nontarget tissues using the most common techniques from the survey. Results: The vast majority of centers use double-exposure portal image techniques with a variety of open field margins. Only 17% of portal images were obtained during treatment, and for other imaging methods, few centers subtract monitor units from the treatment delivery. The number of monitor units used was nearly the same regardless of imager type, including electronic portal imaging devices. Eighty-six percent imaged all fields the first week and 17% imaged all fields every week. An additional 1,112 cm{sup 3} of nontarget tissue received 1 Gy in one of the example cases. Eight new recommendations are made, which will lower nontarget radiation doses with minimal impact on treatment verification accuracy. Conclusion: Based on the survey, changes can be made in portal imaging practices that will lower nontarget doses. It is anticipated that treatment verification accuracy will be minimally affected. Specific recommendations made to decrease the imaging dose and help lower the rate of radiation-induced secondary cancers in children are proposed for inclusion in future COG protocols using radiation therapy.},
doi = {10.1016/j.ijrobp.2006.10.004},
journal = {International Journal of Radiation Oncology, Biology and Physics},
number = 2,
volume = 67,
place = {United States},
year = {Thu Feb 01 00:00:00 EST 2007},
month = {Thu Feb 01 00:00:00 EST 2007}
}
  • Purpose: To evaluate the incidence and prognostic factors for regional failure, with attention to the in-transit pathways of spread, in children with nonmetastatic rhabdomyosarcoma of the extremity. Methods and Materials: The Intergroup rhabdomyosarcoma studies III, IV-Pilot, and IV enrolled 226 children with rhabdomyosarcoma of the extremity. Failure at the in-transit (epitrochlear/brachial and popliteal) and proximal (axillary/infraclavicular and inguinal/femoral) lymph nodes was evaluated. The median follow-up for the surviving patients was 10.4 years. Results: Of the 226 children, 55 (24%) had clinical or pathologic evidence of either in-transit and/or proximal lymph node involvement at diagnosis. The actuarial 5-year risk of regionalmore » failure was 12%. The prognostic factors for poor regional control were female gender and lymph node involvement at diagnosis. In the 116 patients with a distal extremity primary tumor, 5% had in-transit lymph node involvement at diagnosis. The estimated 5-year incidences of in-transit and proximal nodal failure was 12% and 8%, respectively. The in-transit failure rate was 0% for patients who underwent radiotherapy and/or underwent lymph node sampling of the in-transit nodal site but was 15% for those who did not (p = .07). However, the 5-year event-free survival rate did not differ between these two groups (64% vs. 55%, respectively, p = .47). Conclusion: The high incidence of regional involvement necessitates aggressive identification and treatment of regional lymph nodes in patients with rhabdomyosarcoma of the extremity. In patients with distal extremity tumors, in-transit failures were as common as failures in more proximal regional sites. Patients who underwent complete lymph node staging with appropriate radiotherapy to the in-transit nodal site, if indicated, were at a slightly lower risk of in-transit failure.« less
  • Purpose: The study was designed to determine whether response-based therapy improves outcomes in intermediate-risk Hodgkin lymphoma. We examined patterns of first relapse in the study. Patients and Methods: From September 2002 to July 2010, 1712 patients <22 years old with stage I-IIA with bulk, I-IIAE, I-IIB, and IIIA-IVA with or without doxorubicin, bleomycin, vincristine, etoposide, prednisone, and cyclophosphamide were enrolled. Patients were categorized as rapid (RER) or slow early responders (SER) after 2 cycles of doxorubicin, bleomycin, vincristine, etoposide, prednisone, and cyclophosphamide (ABVE-PC). The SER patients were randomized to 2 additional ABVE-PC cycles or augmented chemotherapy with 21 Gy involved field radiationmore » therapy (IFRT). RER patients were stipulated to undergo 2 additional ABVE-PC cycles and were then randomized to 21 Gy IFRT or no further treatment if complete response (CR) was achieved. RER without CR patients were non-randomly assigned to 21 Gy IFRT. Relapses were characterized without respect to site (initial, new, or both; and initial bulk or initial nonbulk), and involved field radiation therapy field (in-field, out-of-field, or both). Patients were grouped by treatment assignment (SER; RER/no CR; RER/CR/IFRT; and RER/CR/no IFRT). Summary statistics were reported. Results: At 4-year median follow-up, 244 patients had experienced relapse, 198 of whom were fully evaluable for review. Those who progressed during treatment (n=30) or lacked relapse imaging (n=16) were excluded. The median time to relapse was 12.8 months. Of the 198 evaluable patients, 30% were RER/no CR, 26% were SER, 26% were RER/CR/no IFRT, 16% were RER/CR/IFRT, and 2% remained uncategorized. The 74% and 75% relapses involved initially bulky and nonbulky sites, respectively. First relapses rarely occurred at exclusively new or out-of-field sites. By contrast, relapses usually occurred at nodal sites of initial bulky and nonbulky disease. Conclusion: Although response-based therapy has helped define treatment for selected RER patients, it has not improved outcome for SER patients or facilitated refinement of IFRT volumes or doses.« less
  • Purpose: To determine the patterns of radiotherapy practice for pancreatic cancer in Japan. Methods and Materials: A questionnaire-based national survey of radiotherapy for pancreatic cancer treated between 2000 and 2006 was conducted by the Japanese Radiation Oncology Study Group (JROSG). Detailed information on 870 patients from 34 radiation oncology institutions was accumulated. Results: The median age of all patients was 64 years (range, 36-88), and 80.2% of the patients had good performance status. More than 85% of patients had clinical Stage T3-T4 disease, and 68.9% of patients had unresectable disease at diagnosis. Concerning radiotherapy (RT), 49.8% of patients were treatedmore » with radical external beam RT (EBRT) (median dose, 50.4 Gy), 44.4% of patients were treated with intraoperative RT (median dose, 25 Gy) with or without EBRT (median dose, 45 Gy), and 5.9% of patients were treated with postoperative radiotherapy (median dose, 50 Gy). The treatment field consisted of the primary tumor (bed) only in 55.6% of the patients. Computed tomography-based treatment planning and conformal RT was used in 93.1% and 83.1% of the patients treated with EBRT, respectively. Chemotherapy was used for 691 patients (79.4%; before RT for 66 patients; during RT for 531; and after RT for 364). Gemcitabine was the most frequently used drug, followed by 5-fluorouracil. Conclusion: This study describes the general patterns of RT practice for pancreatic cancer in Japan. Most patients had advanced unresectable disease, and radical EBRT, as well as intraoperative RT with or without EBRT, was frequently used. Chemotherapy with gemcitabine was commonly used in conjunction with RT during the survey period.« less
  • Purpose: To determine local control according to clinical variables for patients with intermediate-risk rhabdomyosarcoma (RMS) treated on Children's Oncology Group protocol D9803. Patients and Methods: Of 702 patients enrolled, we analyzed 423 patients with central pathology–confirmed group III embryonal (n=280) or alveolar (group III, n=102; group I-II, n=41) RMS. Median age was 5 years. Patients received 42 weeks of VAC (vincristine, dactinomycin, cyclophosphamide) or VAC alternating with VTC (T = topotecan). Local therapy with 50.4 Gy radiation therapy with or without delayed primary excision began at week 12 for group III patients. Patients with group I/II alveolar RMS received 36-41.4 Gy. Local failure (LF) was definedmore » as local progression as a first event with or without concurrent regional or distant failure. Results: At a median follow-up of 6.6 years, patients with clinical group I/II alveolar RMS had a 5-year event-free survival rate of 69% and LF of 10%. Among patients with group III RMS, 5-year event-free survival and LF rates were 70% and 19%, respectively. Local failure rates did not differ by histology, nodal status, or primary site, though there was a trend for increased LF for retroperitoneal (RP) tumors (P=.12). Tumors ≥5 cm were more likely to fail locally than tumors <5 cm (25% vs 10%, P=.0004). Almost all (98%) RP tumors were ≥5 cm, with no difference in LF by site when the analysis was restricted to tumors ≥5 cm (P=.86). Conclusion: Local control was excellent for clinical group I/II alveolar RMS. Local failure constituted 63% of initial events in clinical group III patients and did not vary by histology or nodal status. The trend for higher LF in RP tumors was related to tumor size. There has been no clear change in local control over RMS studies, including IRS-III and IRS-IV. Novel approaches are warranted for larger tumors (≥5 cm).« less
  • Purpose: To verify feasibility and monitor progression-free survival and overall survival in children with high-risk medulloblastoma and noncerebellar primitive neuroectodermal tumors (PNETs) treated in a Phase II study with preradiotherapy chemotherapy (CHT) followed by high-dose, hyperfractionated craniospinal radiotherapy (CSRT). Methods and Materials: Eligibility criteria included age >3 years at diagnosis, medulloblastoma with either high M stage and/or >1.5 cm{sup 2} postoperative residual disease, and all patients with noncerebellar PNET. Treatment was initiated with five alternating monthly cycles of CHT (A [cisplatin, cyclophosphamide, etoposide, and vincristine], B [carboplatin and etoposide], A, B, and A) followed by hyperfractionated CSRT (40 Gy) withmore » a boost to the primary tumor (72 Gy) given in twice-daily 1-Gy fractions. Results: The valid study group consisted of 124 patients whose median age at diagnosis was 7.8 years. Eighty-four patients (68%) completed the entire protocol according to study guidelines (within 9 months), and the median time to complete CSRT was 1.6 months. Major reasons for failure to complete CHT included progressive disease (17%) and toxic death (2.4%). The 5-year progression-free survival and overall survival rates were 43% {+-} 5% and 52% {+-} 5%, respectively. No significant differences were detected in subset analysis related to response to CHT, site of primary tumor, postoperative residual disease, or M stage. Conclusions: The feasibility of this intensive multimodality protocol was confirmed, and response to pre-RT CHT did not impact on survival. Survival data from this protocol can not be compared with data from other studies, given the protocol design.« less