1887
banner image
No data available.
Please log in to see this content.
You have no subscription access to this content.
No metrics data to plot.
The attempt to load metrics for this article has failed.
The attempt to plot a graph for these metrics has failed.
oa
Effect of MLC leaf width on treatment adaptation and accuracy for concurrent irradiation of prostate and pelvic lymph nodes
Rent:
Rent this article for
Access full text Article
/content/aapm/journal/medphys/40/6/10.1118/1.4803499
1.
1. H. D. Kubo, R. B. Wilder, and C. T. E. Pappas, “Impact of collimator leaf width on stereotactic radiosurgery and 3D conformal radiotherapy treatment plans,” Int. J. Radiat. Oncol., Biol., Phys. 44, 937945 (1999).
http://dx.doi.org/10.1016/S0360-3016(99)00041-3
2.
2. J. E. Monk, J. R. Perks, D. Doughty, and P. N. Plowman, “Comparison of a micro-multileaf collimator with a 5-mm-leaf-width collimator for intracranial stereotactic radiotherapy,” Int. J. Radiat. Oncol., Biol., Phys. 57, 14431449 (2003).
http://dx.doi.org/10.1016/S0360-3016(03)01579-7
3.
3. J. B. Fiveash, H. Murshed, J. Duan, M. Hyatt, J. Caranto, J. A. Bonner, and R. A. Popple, “Effect of multileaf collimator leaf width on physical dose distributions in the treatment of CNS and head and neck neoplasms with intensity modulated radiation therapy,” Med. Phys. 29, 11161119 (2002).
http://dx.doi.org/10.1118/1.1481515
4.
4. M. S. Ding, F. Newman, C. H. Chen, K. Stuhr, and L. E. Gaspar, “Dosimetric comparison between 3DCRT and IMRT using different multileaf collimators in the treatment of brain tumors,” Med. Dosim. 34, 18 (2009).
http://dx.doi.org/10.1016/j.meddos.2007.04.001
5.
5. J. H. Chang, K. M. Yenice, K. L. Jiang, M. Hunt, and A. Narayana, “Effect of MLC leaf width and PTV margin on the treatment planning of intensity-modulated stereotactic radiosurgery (Imsrs) or radiotherapy (Imsrt),” Med. Dosim. 34, 110116 (2009).
http://dx.doi.org/10.1016/j.meddos.2008.06.002
6.
6. E. Abe, T. Mizowaki, Y. Norihisa, Y. Narita, Y. Matsuo, M. Narabayashi, Y. Nagata, and M. Hiraoka, “Impact of multileaf collimator width on intraprostatic dose painting plans for dominant intraprostatic lesion of prostate cancer,” J. Appl. Clin. Med. Phys. 11, 144154 (2010).
7.
7. J. Y. Jin, F. F. Yin, S. Ryu, M. Ajlouni, and J. H. Kim, “Dosimetric study using different leaf-width MLCs for treatment planning of dynamic conformal arcs and intensity-modulated radiosurgery,” Med. Phys. 32, 405411 (2005).
http://dx.doi.org/10.1118/1.1842911
8.
8. Z. van Kesteren, T. M. Janssen, E. Damen, and C. van Vliet-Vroegindeweij, “The dosimetric impact of leaf interdigitation and leaf width on VMAT treatment planning in Pinnacle: Comparing Pareto fronts,” Phys. Med. Biol. 57, 29432952 (2012).
http://dx.doi.org/10.1088/0031-9155/57/10/2943
9.
9. L. Wang, B. Movsas, R. Jacob, E. Fourkal, L. Chen, R. Price, S. Feigenberg, A. Konski, A. Pollack, and C. Ma, “Stereotactic IMRT for prostate cancer: Dosimetric impact of multileaf collimator leaf width in the treatment of prostate cancer with IMRT,” J. Appl. Clin. Med. Phys. 5, 2941 (2004).
http://dx.doi.org/10.1120/jacmp.2020.25266
10.
10. V. W. Wu, “Effects of multileaf collimator parameters on treatment planning of intensity-modulated radiotherapy,” Med. Dosim. 32, 3843 (2007).
http://dx.doi.org/10.1016/j.meddos.2006.11.005
11.
11. T. Bortfeld, U. Oelfke, and S. Nill, “What is the optimum leaf width of a multileaf collimator?,” Med. Phys. 27, 24942502 (2000).
http://dx.doi.org/10.1118/1.1319524
12.
12. E. Ludlum, G. W. Mu, V. Weinberg, M. Roach, L. J. Verhey, and P. Xia, “An algorithm for shifting MLC shapes to adjust for daily prostate movement during concurrent treatment with pelvic lymph nodes,” Med. Phys. 34, 47504756 (2007).
http://dx.doi.org/10.1118/1.2804579
13.
13. P. Xia, P. Qi, A. Hwang, E. Kinsey, J. Pouliot, and M. Roach, “Comparison of three strategies in management of independent movement of the prostate and pelvic lymph nodes,” Med. Phys. 37, 50065013 (2010).
http://dx.doi.org/10.1118/1.3480505
http://aip.metastore.ingenta.com/content/aapm/journal/medphys/40/6/10.1118/1.4803499
Loading

Figures

Image of FIG. 1.

Click to view

FIG. 1.

Prostate shifts in the longitudinal direction. (a) Daily prostate shifts for all fractions. (b) The means and standard deviations of patient specific shifts. Positive and negative shifts correspond to the prostate shifts in the inferior and superior directions, respectively.

Image of FIG. 2.

Click to view

FIG. 2.

Daily D99 of (a) the prostate and (b) pelvic lymph nodes. D99 is expressed as a ratio of the daily dose to the planned dose.

Image of FIG. 3.

Click to view

FIG. 3.

Average volume of (a) the prostate and (b) pelvic lymph nodes receiving the prescription dose for each patient. Error bar indicates one standard deviation.

Image of FIG. 4.

Click to view

FIG. 4.

Typical DVHs of the targets and OARs for one fraction of a patient. P for prostate, PLN for pelvic lymph nodes, B for bladder, and R for rectum.

Image of FIG. 5.

Click to view

FIG. 5.

Daily D5 of the (a) bladder and (b) rectum. D5 is expressed as a ratio of the daily dose to the planned dose.

Image of FIG. 6.

Click to view

FIG. 6.

Mean dose of the (a) bladder and (b) rectum as a ratio of the daily dose to the planned dose. Error bar represents one standard deviation.

Image of FIG. 7.

Click to view

FIG. 7.

Isodose line differences and absolute dose differences between the measured and calculated planar doses for the original and shifted plans corresponding to prostate movements of 2, 4, and 8 mm in the longitudinal direction for the Novalis TX machine.

Image of FIG. 8.

Click to view

FIG. 8.

Dose metrics, including (a) isodose line differences, (b) absolute dose differences (3%), (c) DTA (3 mm), and (d) gamma index (3%/3 mm) between measurements and calculations of the original IMRT plans from (A) 2.5 mm MLC and (B) 10 mm MLC. Areas in bright color indicate points in the planar dose that fail the criterion of each dose metric.

Tables

Generic image for table

Click to view

TABLE I.

Characteristics of three MLCs used in this study.

Generic image for table

Click to view

TABLE II.

The dosimetric comparison of D99 and of the prostate and pelvic lymph nodes for 2.5, 5, and 10 mm MLC shifted plans.

Generic image for table

Click to view

TABLE III.

The average volumes of the prostate and pelvic lymph nodes receiving the prescription dose for each patient.

Generic image for table

Click to view

TABLE IV.

Gamma passing rate (3%/3 mm) between the measured and calculated plans for the original IMRT plans and MLC shifted plans corresponding to prostate movements of 2, 4, and 8 mm in the longitudinal direction.

Generic image for table

Click to view

TABLE V.

The percentages of pixels with dose differences between the measurement and calculation being less than 3% and 5% of the maximum dose.

Loading

Article metrics loading...

/content/aapm/journal/medphys/40/6/10.1118/1.4803499
2013-05-06
2014-04-18

Abstract

The aim of the study was to evaluate the impact of multileaf collimator (MLC) leaf width on treatment adaptation and delivery accuracy for concurrent treatment of the prostate and pelvic lymph nodes with intensity modulated radiation therapy (IMRT).

Seventy-five kilovoltage cone beam CTs (KV-CBCT) from six patients were included for this retrospective study. For each patient, three different IMRT plans were created based on a planning CT using three different MLC leaf widths of 2.5, 5, and 10 mm, respectively. For each CBCT, the prostate displacement was determined by a dual image registration. Adaptive plans were created by shifting selected MLC leaf pairs to compensate for daily prostate movements. To evaluate the impact of MLC leaf width on the adaptive plan for each daily CBCT, three MLC shifted plans were created using three different leaf widths of MLCs (a total of 225 adaptive treatment plans). Selective dosimetric endpoints for the tumor volumes and organs at risk (OARs) were evaluated for these adaptive plans. Using the planning CT from a selected patient, MLC shifted plans for three hypothetical longitudinal shifts of 2, 4, and 8 mm were delivered on the three linear accelerators to test the deliverability of the shifted plans and to compare the dose accuracy of the shifted plans with the original IMRT plans.

Adaptive plans from 2.5 and 5 mm MLCs had inadequate dose coverage to the prostate (D99 < 97%, or < 99% of the planned dose) in 6%–8% of the fractions, while adaptive plans from 10 mm MLC led to inadequate dose coverage to the prostate in 25.3% of the fractions. The average of the prostate over the six patients was improved by 6.4% (1.6%–32.7%) and 5.8% (1.5%–35.7%) with adaptive plans from 2.5 and 5 mm MLCs, respectively, when compared with adaptive plans from 10 mm MLC. Pelvic lymph nodes were well covered for all MLC adaptive plans, as small differences were observed for D99, , and . Similar OAR sparing could be achieved for the bladder and rectum with all three MLCs for treatment adaptation. The MLC shifted plans can be accurately delivered on all three linear accelerators with accuracy similar to their original IMRT plans, where gamma (3%/3 mm) passing rates were 99.6%, 93.0%, and 92.1% for 2.5, 5, and 10 mm MLCs, respectively. The percentages of pixels with dose differences between the measurement and calculation being less than 3% of the maximum dose were 85.9%, 82.5%, and 70.5% for the original IMRT plans from the three MLCs, respectively.

Dosimetric advantages associated with smaller MLC leaves were observed in terms of the coverage to the prostate, when the treatment was adapted to account for daily prostate movement for concurrent irradiation of the prostate and pelvic lymph nodes. The benefit of switching the MLC from 10 to 5 mm was significant ( ≪ 0.01); however, switching the MLC from 5 to 2.5 mm would not gain significant ( = 0.15) improvement. IMRT plans with smaller MLC leaf widths achieved more accurate dose delivery.

Loading

Full text loading...

/deliver/fulltext/aapm/journal/medphys/40/6/1.4803499.html;jsessionid=x9qnfai45du5.x-aip-live-01?itemId=/content/aapm/journal/medphys/40/6/10.1118/1.4803499&mimeType=html&fmt=ahah&containerItemId=content/aapm/journal/medphys
true
true
This is a required field
Please enter a valid email address
752b84549af89a08dbdd7fdb8b9568b5 journal.articlezxybnytfddd
Scitation: Effect of MLC leaf width on treatment adaptation and accuracy for concurrent irradiation of prostate and pelvic lymph nodes
http://aip.metastore.ingenta.com/content/aapm/journal/medphys/40/6/10.1118/1.4803499
10.1118/1.4803499
SEARCH_EXPAND_ITEM