In order to initiate the use of a multileaf collimator (MLC) in the clinic, a set of technical procedures needs to be available sufficient to create MLC leaf settings and to deliver an accurate dose of radiation through the MLC-shaped field. Dosimetry data for clinical use of the MLC were measured. Dosimetric characteristics included central axis percent depth dose, output factors, and penumbra. In this paper, it has been concluded that a dose control monitor unit calculation procedure that has been applied to the use of conventional secondary field-shaping blocks can be applied to the multileaf collimator dosimetry. The multileaf collimator penumbra (20% to 80%) is only slightly wider (1-3 mm) than the penumbra of the conventional collimator jaws. Beam's-eye-view comparisons made between the isodose curves in fields shaped by conventional Cerrobend blocks and isodose curves in fields shaped by the multileaf collimator demonstrated that the 50% isodose line at 10-cm depth exhibited the discrete steps of the multileaf collimator leaves, but that the 90% and 10% isodose curves of the multileaf were close to those shaped by Cerrobend blocks.

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Conflict of interest: Lung Therapeutics Inc. (LTI) sponsored the trial. SI serves as a Founder and Chief Scientific Officer of LTI and a member of the Board of Directors of LTI, which provided funding for preparation of the drug product and for the trial. He has an equity position (first-tier conflict of interest) in the company, as does the University of Texas Horizon Fund and the UTHSCT. He has a conflict-of-interest plan acknowledging and managing these declared conflicts of interest through the UTHSCT and the UT System. He is an inventor on a patent (USPTO 7332469) held by the UT Board of Regents and licensed to LTI. AAK and GF have received funding from LTI for this study, and they and KS likewise have conflict-of-interest management plans at the UTHSCT. KPS has an equity position in LTI. AAK, GF, and SI are inventors on patent USPTO 10,175,255 B2. NR and YCGL serve as key opinion leaders for LTI, and NR is paid for input to the company. SS is a paid consultant for LTI, and JG received payment as medical monitor for the study from LTI. LB has a potential conflict of interest, having more than $50,000 funding support for personnel and laboratory work for this study from LTI. AMS received funding in the fiscal year prior to submission greater than $50,000 from GSK for 2 funded COPD trials. YCGL has led clinical trials for which Rocket Ltd. provided pleural drainage kits for patients without charge. YCGL has served as advisor to LTI and CareFusion/BD.

A routine diode in vivo dosimetry program based on a combination of entrance and exit dose measurements was clinically implemented in the radiation oncology department of Grace Hospital, Detroit, in January 1995. The delivered dose has been monitored by taking weekly measurements. The calibration of the diodes and the in vivo dosimetry protocol for this new, more effective type of dose verification is presented. The problems encountered within the program are discussed along with our solutions.

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