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Title: Online adaptive radiotherapy of the bladder: Small bowel irradiated-volume reduction

Abstract

Purpose: To assess the potential reduction of small bowel volume receiving high-dose radiation by using kilovoltage X-ray cone beam computed tomography (CBCT) and quantized margin selection for adaptive bladder cancer treatment. Methods and Materials: Twenty bladder patients were planned conformally using a four-field, 15-mm uniform margin technique. Two additional planning target volumes (PTVs) were created using margins quantized to 5 and 10 mm in the superior direction only. CBCTs ({approx}8 scans/patient) were acquired during treatment. CBCT volumes were registered with CT planning scans to determine setup errors and to select the appropriate PTV of the day. Margin reduction in other directions was considered. Outlining of small bowel in every fraction is required to properly quantify the volume of small bowel spared from high doses. In the case of CBCT this is not always possible owing to artifacts created by small bowel movement and the presence of gas. A simpler method was adopted by considering the volume difference between PTVs created using uniform and adapted margins, which corresponds to the potential volume of small bowel sparing. Results: The average small bowel volume that can be spared by this form of adaptive radiotherapy is 31 {+-} 23 cm{sup 3} ({+-}1 SD). Themore » bladder for 1 patient was systematically smaller than the planning scan and hence demonstrated the largest average reduction of 76 cm{sup 3}. The clinical target volume to PTV margins in other directions can be safely reduced to 10 mm except in the anterior direction where, like the superior direction, the bladder showed significant variation. Conclusions: Online CBCT-assisted plan selection based on quantized margins can significantly reduce the volume of small bowel receiving high doses for some bladder patients. CBCT allows the 15-mm margins used in some directions to be safely reduced to 10 mm.« less

Authors:
 [1];  [2];  [2];  [3];  [4];  [3];  [5];  [6];  [2]
  1. North Western Medical Physics, Christie Hospital NHS Trust, Manchester (United Kingdom). E-mail: nichola.burridge@physics.cr.man.ac.uk
  2. North Western Medical Physics, Christie Hospital NHS Trust, Manchester (United Kingdom)
  3. Cookridge Hospital, Leeds (United Kingdom)
  4. Wade Centre for Radiotherapy Research, Christie Hospital, Manchester (United Kingdom)
  5. Department of Clinical Oncology, Christie Hospital NHS Trust, Manchester (United Kingdom)
  6. Academic Department of Radiation Oncology, Christie Hospital, Manchester (United Kingdom)
Publication Date:
OSTI Identifier:
20850177
Resource Type:
Journal Article
Resource Relation:
Journal Name: International Journal of Radiation Oncology, Biology and Physics; Journal Volume: 66; Journal Issue: 3; Conference: 48. annual meeting of the American Society for Therapeutic Radiology and Oncology, Pennsylvania, PA (United States), 5-9 Nov 2006; Other Information: DOI: 10.1016/j.ijrobp.2006.07.013; PII: S0360-3016(06)01168-0; Copyright (c) 2006 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; BEAMS; BLADDER; COMPUTERIZED TOMOGRAPHY; ERRORS; IMAGES; IRRADIATION; NEOPLASMS; PATIENTS; PLANNING; RADIATION DOSES; RADIOTHERAPY; X RADIATION

Citation Formats

Burridge, Nichola, Amer, Ali, Marchant, Tom, Sykes, Jonathan, Stratford, Julie, Henry, Ann, McBain, Catherine, Price, Pat, and Moore, Chris. Online adaptive radiotherapy of the bladder: Small bowel irradiated-volume reduction. United States: N. p., 2006. Web. doi:10.1016/j.ijrobp.2006.07.013.
Burridge, Nichola, Amer, Ali, Marchant, Tom, Sykes, Jonathan, Stratford, Julie, Henry, Ann, McBain, Catherine, Price, Pat, & Moore, Chris. Online adaptive radiotherapy of the bladder: Small bowel irradiated-volume reduction. United States. doi:10.1016/j.ijrobp.2006.07.013.
Burridge, Nichola, Amer, Ali, Marchant, Tom, Sykes, Jonathan, Stratford, Julie, Henry, Ann, McBain, Catherine, Price, Pat, and Moore, Chris. 2006. "Online adaptive radiotherapy of the bladder: Small bowel irradiated-volume reduction". United States. doi:10.1016/j.ijrobp.2006.07.013.
@article{osti_20850177,
title = {Online adaptive radiotherapy of the bladder: Small bowel irradiated-volume reduction},
author = {Burridge, Nichola and Amer, Ali and Marchant, Tom and Sykes, Jonathan and Stratford, Julie and Henry, Ann and McBain, Catherine and Price, Pat and Moore, Chris},
abstractNote = {Purpose: To assess the potential reduction of small bowel volume receiving high-dose radiation by using kilovoltage X-ray cone beam computed tomography (CBCT) and quantized margin selection for adaptive bladder cancer treatment. Methods and Materials: Twenty bladder patients were planned conformally using a four-field, 15-mm uniform margin technique. Two additional planning target volumes (PTVs) were created using margins quantized to 5 and 10 mm in the superior direction only. CBCTs ({approx}8 scans/patient) were acquired during treatment. CBCT volumes were registered with CT planning scans to determine setup errors and to select the appropriate PTV of the day. Margin reduction in other directions was considered. Outlining of small bowel in every fraction is required to properly quantify the volume of small bowel spared from high doses. In the case of CBCT this is not always possible owing to artifacts created by small bowel movement and the presence of gas. A simpler method was adopted by considering the volume difference between PTVs created using uniform and adapted margins, which corresponds to the potential volume of small bowel sparing. Results: The average small bowel volume that can be spared by this form of adaptive radiotherapy is 31 {+-} 23 cm{sup 3} ({+-}1 SD). The bladder for 1 patient was systematically smaller than the planning scan and hence demonstrated the largest average reduction of 76 cm{sup 3}. The clinical target volume to PTV margins in other directions can be safely reduced to 10 mm except in the anterior direction where, like the superior direction, the bladder showed significant variation. Conclusions: Online CBCT-assisted plan selection based on quantized margins can significantly reduce the volume of small bowel receiving high doses for some bladder patients. CBCT allows the 15-mm margins used in some directions to be safely reduced to 10 mm.},
doi = {10.1016/j.ijrobp.2006.07.013},
journal = {International Journal of Radiation Oncology, Biology and Physics},
number = 3,
volume = 66,
place = {United States},
year = 2006,
month =
}
  • Purpose: To determine the advantages and disadvantages of daily online adaptive image-guided radiotherapy (RT) compared with conventional RT for muscle-invasive bladder cancer. Methods and Materials: Twenty-seven patients with T2-T4 transitional cell carcinoma of the bladder were treated with daily online adaptive image-guided RT using cone-beam computed tomography (CBCT). From day 1 daily soft tissue-based isocenter positioning was performed using CBCT images acquired before treatment. Using a composite of the initial planning CT and the first five daily CBCT scans, small, medium, and large adaptive plans were created. Each of these adaptive plans used a 0.5-cm clinical target volume (CTV) tomore » planning target volume expansion. For Fractions 8-32, treatment involved daily soft tissue-based isocenter positioning and selection of suitable adaptive plan of the day. Treating radiation therapists completed a credentialing program, and one radiation oncologist performed all the contouring. Comparisons were made between adaptive and conventional treatment on the basis of CTV coverage and normal tissue sparing. Results: All 27 patients completed treatment per protocol. Bladder volume decreased with time or fraction number (p < 0.0001). For the adaptive component (Fractions 8-32) the small, medium, large, and conventional plans were used in 9.8%, 49.2%, 39.5%, and 1.5% of fractions, respectively. For the adaptive strategy, 2.7% of occasions resulted in a CTV V95 <99%, compared with 4.8% of occasions for the conventional approach (p = 0.42). Mean volume of normal tissue receiving a dose >45 Gy was 29% (95% confidence interval, 24-35%) less with adaptive RT compared with conventional RT. The mean volume of normal tissue receiving >5 Gy was 15% (95% confidence interval, 11-18%) less with adaptive RT compared with conventional RT. Conclusions: Online adaptive radiotherapy is feasible in an academic radiotherapy center. The volume of normal tissue irradiated can be significantly smaller without reducing CTV coverage.« less
  • Purpose: To design and evaluate individualized nonadaptive and online-adaptive strategies based on a pretreatment established motion model for the highly deformable target volume in cervical cancer patients. Methods and Materials: For 14 patients, nine to ten variable bladder filling computed tomography (CT) scans were acquired at pretreatment and after 40 Gy. Individualized model-based internal target volumes (mbITVs) accounting for the cervix and uterus motion due to bladder volume changes were generated by using a motion-model constructed from two pretreatment CT scans (full and empty bladder). Two individualized strategies were designed: a nonadaptive strategy, using an mbITV accounting for the full-rangemore » of bladder volume changes throughout the treatment; and an online-adaptive strategy, using mbITVs of bladder volume subranges to construct a library of plans. The latter adapts the treatment online by selecting the plan-of-the-day from the library based on the measured bladder volume. The individualized strategies were evaluated by the seven to eight CT scans not used for mbITVs construction, and compared with a population-based approach. Geometric uniform margins around planning cervix-uterus and mbITVs were determined to ensure adequate coverage. For each strategy, the percentage of the cervix-uterus, bladder, and rectum volumes inside the planning target volume (PTV), and the clinical target volume (CTV)-to-PTV volume (volume difference between PTV and CTV) were calculated. Results: The margin for the population-based approach was 38 mm and for the individualized strategies was 7 to 10 mm. Compared with the population-based approach, the individualized nonadaptive strategy decreased the CTV-to-PTV volume by 48% {+-} 6% and the percentage of bladder and rectum inside the PTV by 5% to 45% and 26% to 74% (p < 0.001), respectively. Replacing the individualized nonadaptive strategy by an online-adaptive, two-plan library further decreased the percentage of bladder and rectum inside the PTV (0% to 10% and -1% to 9%; p < 0.004) and the CTV-to-PTV volume (4-96 ml). Conclusions: Compared with population-based margins, an individualized PTV results in better organ-at-risk sparing. Online-adaptive radiotherapy further improves organ-at-risk sparing.« less
  • Thirty patients who were undergoing pelvic radiotherapy had /sup 14/C-lactose breath tests performed in the first and fifth weeks of treatment. In Group I (21 patients), a significant portion of the small intestine was irradiated, and in Group II (9 patients), only a small portion of the small intestine was irradiated. In Group I, the average reductions in the excretion of ingested /sup 14/C between the first- and fifth-week tests were 41.5% at 1/2 hour postingestion (p less than 0.05), and 21.8% at 1 hour postingestion (p less than 0.05). In Group II, the percentage reductions were 11.8% and 3.7%more » at 1/2 and 1 hour, respectively (p greater than 0.05). The data suggest that lactose malabsorption is a factor in the etiology of the nausea, vomiting, and diarrhea experienced by patients who are undergoing pelvic radiotherapy, and that the amount of bowel included in the treatment volume significantly influences the degree of malabsorption.« less
  • Thirty patients who were undergoing pelvic radiotherapy had /sup 14/C-lactose breath tests performed in the first and fifth weeks of treatment. In Group I (21 patients), a significant portion of the small intestine was irradiated, and in Group II (9 patients), only a small portion of the small intestine was irradiated. In Group I, the average reductions in the excretion of ingested /sup 14/C between the first- and fifth-week tests were 41.5% at 1/2 hour postingestion (p<0.05), and 21.8% at 1 hour postingestion (p<0.05). In Group II, the prercentage reduction were 11.8% and 3.7% at 1/2 and 1 hour, respectivelymore » (p>0.05). The data suggest that lactose malabsorption is a factor in the etiology of the nausea, vomiting, and diarrhea experienced by patients who are undergoing pelvic radiotherapy, and that the amount of bowel included in the treatment volume significantly influences the degree of malabsorption.« less
  • The volume, distribution, and mobility of opacified pelvic small bowel (PSB) were determined by fluoroscopy and orthogonal radiographs in 150 consecutive patients undergoing pelvic irradiation. Various techniques including uteropexy, omental transposition, bladder distention, inclining the patient, and anterior abdominal wall compression in the supine and prone treatment position were studied for their effect on the volume and location of small bowel within the pelvis. Abdominal wall compression in the prone position combined with bladder distention was selected for further investigation because of its simplicity, reproducibility, patient comfort, and ability to displace the small bowel. Factors correlating with the volume ofmore » pelvic small bowel (PSB) included prior pelvic surgery, pelvic irradiation (XRT), and body mass index. After pelvic surgery, especially following abdominoperineal resection (APR), there was a greater volume of PSB which was also less mobile. The severity of acute gastrointestinal effects positively correlated with the volume of irradiated small bowel. Overall, 67% of patients experienced little or no diarrhea, 30% developed mild diarrhea, and no patient required treatment interruption. Late gastrointestinal effects correlated with the prior pelvic surgery and with the volume of small bowel receiving greater than 45 Gy. Small bowel obstruction was not observed in 75 patients who had no previous pelvic surgery. However, following pelvic surgery excluding APR, 2/50 patients and following APR, 3/25 patients developed small bowel obstruction.« less