Intensity-Modulated Radiation Therapy Dose = Prescription, Recording, and Delivery: Patterns of Variability Among = Institutions and Treatment Planning Systems -- Das et al. 100 (5): 300 = -- JNCI Journal of the National Cancer Institute

Journal of=20 the National Cancer Institute Advance Access originally published online = on=20 February 26, 2008
JNCI=20 Journal of the National Cancer Institute 2008 100(5):300-307;=20 doi:10.1093/jnci/djn020

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=A9=20 2008 The Author(s).
This is an Open Access article distributed under = the=20 terms of the Creative Commons Attribution Non-Commercial License=20 (http://creativecommons.org/licenses/by-nc/2.0/uk/), which permits = unrestricted=20 non-commercial use, distribution, and reproduction in any medium, = provided the=20 original work is properly cited.

ARTICLES

Intensity-Modulated Radiation Therapy Dose Prescription, Recording, = and=20 Delivery: Patterns of Variability Among Institutions and Treatment = Planning=20 Systems

Indra J. Das, Chee-Wai = Cheng,=20 Kashmiri L. Chopra, Raj K. Mitra, Shiv = P.=20 Srivastava, Eli Glatstein=20

Affiliations of authors: Department of = Radiation=20 Oncology, University of Pennsylvania, Philadelphia, PA (IJD, EG); = Department of=20 Radiation Oncology, Morristown Memorial Hospital, Morristown, NJ (CWC);=20 Department of Radiation Oncology, Kennedy Health System, Sewell, NJ = (KLC);=20 Department of Radiation Oncology, Ochsner Clinic Foundation, New = Orleans, LA=20 (RKM); Department of Radiation Oncology, Reid Hospital & Health Care = Service, Richmond, IN (SPS)

Correspondence to: Indra J. Das, FACR, = Department of=20 Radiation Oncology, University of Pennsylvania, 2 Donner Bldg, 3400 = Spruce St,=20 Philadelphia, PA 19104 (e-mail: das{at}xrt.upenn.edu ).

Background: Intensity-modulated radiation therapy (IMRT) = is a=20 widely acceptedmethod for radiation treatment to provide a=20 prescribed and uniformdose to the target volume and a = minimum dose=20 to normal tissuesthat is dependent on the IMRT software and = the=20 treatment machine.We examined the variation in IMRT dose=20 prescription, treatmentplanning, dose recording, and dose = delivery=20 among cancer patientswho were treated with different = treatment=20 planning systems atdifferent medical institutions to assess=20 variability in patientcare.

Methods: We conducted a retrospective analysis of 803 patients who = were⁼²⁰treated with IMRT between October 2004 and July 2006 for = brain,⁼²⁰head and neck, or prostate cancer at five medical = institutions⁼²⁰that used different treatment planning systems. The = prescribed⁼²⁰dose to the target volume, as recorded in the chart or as = noted⁼²⁰in the electronic data management system, was extracted for⁼²⁰each patient. The planned dose that was delivered to the = patient,⁼²⁰as represented in the dose=96volume histogram, was acquired⁼from=20 each treatment planning system. The actual minimum, maximum,⁼median,=20 and isocenter doses to the target volume were normalizedto = the=20 prescribed dose and analyzed for each disease site and⁼²⁰institution.

Results: Of the 803 patients, 12% were treated for brain cancer, = 26%⁼²⁰for head and neck cancer, and 62% for prostate cancer. The = recorded⁼²⁰dose variability from prescription was widespread for the = minimum,⁼²⁰maximum, and isocenter doses. A total of 46% of the patients⁼²⁰received a maximum dose that was more than 10% higher than = the⁼²⁰prescribed dose, and 63% of the patients received a dose that⁼was more than 10% lower than the prescribed dose. At all five⁼institutions, the prostate cancer cases had the smallest = dosimetric⁼²⁰variation and the head and neck cancer cases had the largest⁼²⁰variation. The median dose to the target varied from the = prescribed⁼²⁰dose by =B12% in 68% of the patients, by =B15% in88% = of the=20 patients, and by =B110% in 96% of the patients.The recorded = isocenter=20 dose varied from prescription for alldisease sites and = treatment=20 planning systems.

Conclusions: Substantial variation in the prescribed and delivered = doses⁼²⁰exists among medical institutions, raising concerns about the⁼validity of comparing clinical outcomes for IMRT. The = isocenter⁼²⁰dose in IMRT is simply a point dose and often does not = reflect⁼²⁰the prescription dose that is specified by a selected isodose⁼line encompassing the target volume. This study suggests the⁼²⁰need for national and/or international guidelines for dose=20 prescription,planning, and reporting for a meaningful = clinical trial=20 in IMRT.

CONTEXT AND CAVEATS

Prior knowledge

Intensity-modulated radiation therapy (IMRT)is = widely used=20 to treat cancer because it provides a prescribedand = uniform=20 radiation dose to the target while minimizing the⁼radiation=20 dose to normal tissues. In IMRT, many factors, including⁼²⁰special software, are required to plan treatments and = control⁼²⁰the radiation dose during therapy. Variations in these = factors⁼²⁰can affect the dose and, consequently, the clinical outcome.

Studydesign

A retrospective analysis of treatment parameters for⁼803=20 patients who were treated with IMRT for brain, head and⁼neck,=20 or prostate cancer at five medical institutions that used⁼²⁰different treatment planning systems.

Contribution

In IMRT,the prescribed dose rarely corresponded to = the=20 planned, or delivered,dose. At all five institutions,=20 dosimetric variation was smallestfor the prostate = cancer cases=20 and largest for the head and neckcancer cases. The = recorded=20 delivered dose varied from the prescribeddose for all = disease=20 sites and treatment planning systems.

Implications

Thesubstantial variation in the prescribed and = delivered=20 dosesthat exists among medical institutions raises = concerns=20 aboutthe validity of comparing clinical outcomes for = IMRT.=20 Nationaland/or international guidelines for dose = prescription,=20 planning,and reporting in IMRT are needed.

Limitations

The medicalinstitutions differed with respect to = volume=20 delineation, theavailability of quality-assurance data = for the=20 treatment planningalgorithms, and the uniformity of = IMRT input=20 constraints. Onlyfive treatment planning systems from = five=20 institutions, someof which had limited IMRT planning = data in=20 certain disease sites,were included.

Manuscript received = August 29, 2007;=20 revised December 20, 2007; accepted January 14, 2008.

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Editorial about this Article

Clinically Relevant Standards for Intensity-Modulated = Radiation=20 Therapy Dose Prescription=20: John Willins and Lisa Kachnic
J Natl Cancer Inst 2008 100: = 288-290.=20 [Ex= tract]=20 [Full = Text]

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Clinically Relevant = Standards=20 for Intensity-Modulated Radiation Therapy Dose = Prescription
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				J. Willins and L. Kachnic Clinically Relevant = Standards=20 for Intensity-Modulated Radiation Therapy Dose = Prescription J=20 Natl Cancer Inst, March 5, 2008; 100(5): 288 - 290. = [Full = Text] [PDF]=20 =20

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Intensity-Modulated Radiation Therapy Dose Prescription, Recording, = and=20 Delivery: Patterns of Variability Among Institutions and Treatment = Planning=20 Systems