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PubMed1998

Storage-phosphor computed radiography versus film radiography in the detection of pathologic periradicular bone loss in cadavers.

OBJECTIVES: The purpose of this study was to compare D-speed film, E-speed film, and the Soredex Digora system with respect to the detection of periradicular pathosis. STUDY DESIGN: Radiographic images of 100 cadaver jaws were made with E-speed film, D-speed film, and the Soredex Digora. Each set of 100 images was interpreted by four observers, with 30 days separating each of three viewing sessions from the next. The presence or absence of pathologic (inflammatory) periradicular bone resorption was determined by histologic examination of the samples. The observer performance was compared with the true histologic findings and evaluated with receiver operating characteristic and corrected receiver operating characteristic analysis. RESULTS: No statistically significant differences were found in diagnostic performance among the three radiographic techniques. In addition, no imaging technique was a good indicator of pathosis as determined by histologic analysis. CONCLUSION: Under the conditions of this study, it was determined that D-speed film, E-speed film, and the Soredex Digora were equivalent diagnostic imaging modalities with regard to the detection of pathologic periradicular bone resorption. No technique predictably indicated inflammatory resorption.

Alveolar Bone Loss↗

PubMed1998

A comparison of Kodak Ektaspeed Plus film and the Siemens Sidexis digital imaging system for caries detection using receiver operating characteristic analysis.

OBJECTIVE: To evaluate the accuracy of proximal caries detection comparing enhanced and unenhanced Siemens Sidexis CCD-based digital images with Ektaspeed Plus films utilizing receiver operating characteristic analysis. STUDY DESIGN: Sixty extracted teeth (24 posterior and 36 anterior) were imaged under identical standardized geometric and exposure conditions. Six observers, using a 5-point confidence scale, rated 120 proximal surfaces for the presence or absence of carious lesions by means of three image modalities: (1) observer enhanced and (2) unenhanced Sidexis displays, and (3) Ektaspeed Plus films. The ground truth was determined by microscopic analysis of ground sections. Receiver operating characteristic curves were generated with calculated areas (AZ) analyzed with analysis of variance for effect of reader, reading, and modality. RESULTS: Analysis of variance demonstrated significant differences among readers, readings and modalities (mean square values of 0.012, 0.005, 0.004, F ratios of 13.604, 5.329, 5.100; p = values of 0.001, 0.043, and 0.030, respectively). Post-hoc paired comparisons of modalities using Tukey's statistic demonstrated that only film and enhanced Sidexis images were different from each other (p = 0.024). AZ scores were 0.7650, 0.7499, and 0.8008 respectively, for unenhanced Sidexis, enhanced Sidexis, and Ektaspeed Plus film. CONCLUSION: Unenhanced digital Sidexis images were equivalent to film for the detection of proximal caries in this in vitro study. Observer enhanced Sidexis images exhibited a statistically significant lower diagnostic accuracy than the unenhanced digital and film images.

Analysis of Variance↗

PubMed1999

Two- and three-dimensional imaging modalities for the detection of caries. A comparison between film, digital radiography and tuned aperture computed tomography (TACT).

OBJECTIVES: To compare the diagnostic performance provided by two- (film and digital radiography) and three-dimensional imaging modalities (TACT slices and TACT pseudoholograms) in the detection of primary caries. METHODS: Forty-two extracted human posterior teeth were mounted and imaged with conventional film and direct digital radiography. Free-hand positioning of a dental X-ray source was used for all exposures. From the digital images, iteratively restored TACT slices and TACT pseudoholograms were generated. Film images were viewed on a viewbox. Digital format images were viewed on a high-resolution monitor. Eight observers used a five-point scale to score the presence or absence of occlusal and proximal caries using the four image modalities. Observers' assessments were compared with the histological examination of tooth sections. Possible differences in ROC curve areas among image modalities, observers, and surfaces were assessed by ANOVA. Intra- and interobserver reliability as indicated by intraclass correlation was also calculated. RESULTS: There were no statistically significant differences between the diagnostic performances of film, digital radiography, TACT slices and TACT pseudoholograms in the detection of caries (P = 0.310). Intraclass correlation indicated the highest concordance both within and between observers when film was used for the evaluation. CONCLUSIONS: Under the experimental conditions of this study, three-dimensional TACT images did not improve caries detection over film or digital radiography. Further research should investigate the effects of imaging variables on TACT's diagnostic efficacy.

Analysis of Variance↗

PubMed1999

Dosimetry of blood irradiation with radiochromic film.

It has been shown that radiochromic film is an ideal dosimeter for assessment and verification of delivered dose to irradiated blood products. Using a parallel opposing two-field technique on a medical linear accelerator, blood is irradiated to diminish the risk of transfusion-associated graft vs. host disease (TA-GVHD). The blood products are irradiated in a Perspex blood box to an applied dose of 29.5-31.7 Gy. Verification of applied dose has been performed with thimble ionization chambers and radiochromic film. Radiochromic film results have matched absorbed dose measurements from ionization chambers at all sites within the 'active' treatment volume within +/-6% for a 95% confidence limit. Using a sample of 100 in-vitro measurements, radiochromic film has measured the average applied dose to blood products to be 30.95+/-2.6 Gy for two standard deviations. Like currently available 'irradiated' film labels, the radiochromic film also serves as a visible reminder that the blood products have been irradiated.

Blood↗

PubMed2001

Image-receptor performance: a comparison of Trophy RVG UI sensor and Kodak Ektaspeed Plus film.

UNLABELLED: Objective. This study compares the physical characteristics of the RVG UI sensor (RVG) with Ektaspeed Plus film. STUDY DESIGN: Dose-response curves were generated for film and for each of 6 available RVG modes. An aluminum step-wedge was used to evaluate exposure latitude. Spatial resolution was assessed by using a line-pair test tool. Latitude and resolution were assessed by observers for both modalities. The RVG was further characterized by its modulation transfer function. RESULTS: Exposure latitude was equal for film and RVG in the periodontal mode. Other gray scale modes demonstrated much lower latitude. The average maximum resolution was 15.3 line-pairs per millimeter (lp/mm) for RVG in high-resolution mode, 10.5 lp/mm for RVG in low-resolution mode, and 20 lp/mm for film (P <.0001). Modulation transfer function measurements supported the subjective assessments. CONCLUSIONS: In periodontal mode, the RVG UI sensor demonstrates exposure latitude similar to that of Ektaspeed Plus film. Film images exhibit significantly higher spatial resolution than the RVG images acquired in high-resolution mode.

Analysis of Variance↗

PubMed2002

A comparison of D-, E-, and F-speed conventional intraoral radiographic films in endodontic measurement.

OBJECTIVES: We sought to compare observer measurement error and subjective ratings for International Standards Organization D-, E-, and F-speed direct exposure dental x-ray films used to determine endodontic working lengths. METHODS: Radiographs were exposed to achieve a standard background density of approximately 2.0. Three human maxillary posterior teeth for which No. 10 K-files had been placed at various lengths within 4 canals were studied in a cadaver section. A total of 30 radiographs were used (10 from each film type). Five licensed dentists excluding all authors viewed the radiographs independently and in random sequence. Distances from the file tips to the radiographic apices were measured and were compared with known lengths for error determination. The observing dentists also subjectively rated the images as desirable or undesirable. Statistical methods included a 3-factor ANOVA with Tukey honestly significant difference post hoc analysis to compare objective measurements and chi-square with respect to subjective ratings. RESULTS: No significant differences were attributable to film speed grouping or observers (P > .05); however, there was a specimen effect in that a significant difference was found in measurement accuracy among the 4 canals (P < .05). Differences in subjective ratings for the 3 film types were not statistically significant (P > .05). CONCLUSION: All 3 film types were similar in objective and subjective ratings. This being the case, the faster film is preferred to minimize the radiation dose to the patient.

Adult↗

PubMed1984

The suitability of diazochrome KBL film for UV dosimetry.

A promising material for use in a UV film badge dosemeter is diazo film. The optical density of this substance changes on exposure to ultraviolet radiation. The present paper reports some of the relevant factors in the processing of the film and also on its spectral sensitivity. It is evident from our results that development time and volume and concentration of ammonia solution should be standardised. However, after the film has been developed, it is not affected by subsequent UV exposure or by storage for up to one month. Although maximum sensitivity occurs at 405 nm, there is still an easily measurable response at 254 nm. It is concluded that provided procedures are standardised, Diazochrome KBL film is an inexpensive, convenient material for a UV film badge dosemeter with measurable sensitivity down to 254 nm.

Film Dosimetry↗

PubMed1997

Radiochromic film dosimetry for verification of dose distributions delivered with proton-beam radiosurgery.

In this work we studied the feasibility of radiochromic film for dosimetry verification of proton Bragg peak stereotactic radiosurgery with multiple beams. High-sensitivity MD-55 radiochromic film was calibrated for proton beam irradiation and the RIT 113 system was employed for film evaluation. Simulated stereotactic radiosurgery with a special phantom arrangement for film dosimetry was performed, following the same procedure as for a patient undergoing treatment. Five-beam irradiation was developed using a 3D treatment planning system. This plan was then delivered to the phantom in a one-day experiment. Planned and measured composite dose distributions were compared. Spatial accuracy of dose delivery to a region containing a simulated critical structure was evaluated for a single portal. Radiochromic film dosimetry validated the prescribed dose delivery within +/- 5%, one standard deviation, by comparing calculated doses with measured values. The alignment of apertures and boluses, as well as the alignment of the phantom with respect to the isocentre, was confirmed. Spatial accuracy of the method would have been able to detect possible misalignments greater than +/- 2 mm. We have demonstrated how radiochromic film dosimetry can be used to measure complex dose distributions in an irradiated phantom, thus enabling us to verify planned dose delivery of proton Bragg peak stereotactic radiosurgery with multiple beams. We assume that the dosimetric agreement between planned and measured dose distributions for the reported simulations will apply to patient treatments.

Calibration↗

PubMed1997

External audit of photon beams by mailed film dosimetry: feasibility study.

A feasibility study for mailed film dosimetry has been performed. The global reproducibility of the method is better than 2%. It is shown that the normalized sensitometric curve does not depend on photon beam quality in the range from Co-60 gamma-rays to 18 MV x-rays, although the dose per optical density decreases when the energy increases. The fading of the latent image before film processing is only 3% per month and the normalized sensitometric curve is not modified after a period of 51 days between irradiation and processing. Sets of films were mailed to three different institutes for irradiation and returned for processing and evaluation after more than two months in order to verify that mailing of irradiated and unprocessed films does not produce unwanted artefacts. Finally the feasibility of external audits with mailed film dosimetry is illustrated by comparison of beam profiles measured with films and ionization chambers in a polystyrene phantom.

Cobalt Radioisotopes↗

PubMed2002

The use of a reflective scanner to study radiochromic film response.

GafChromic MD-55-2 film response was studied using a flatbed, reflective Microtek ScanMaker E3 scanner, under different conditions to optimize its use. Irradiations were performed using 60Co gamma rays in a 0-300 Gy dose interval to produce a calibrated step wedge. A 24-bit colour-scale mode along with image splitting into its red, green and blue components is suggested as an improved dosimetry method over a 256 grey level (8-bit) mode, extending the dynamic range for this film. Diverse film orientation and positioning, a black or a white background, and individual step film scanning were evaluated. Unwanted normalization is overcome by adding reference black and white steps adjacent to the radiochromic film, ensuring reproducibility. The use of a red filter was found to be equivalent to the use of the red component of the image after image colour splitting. The useful range for MD-55-2 film is extended up to 300 Gy if colour components, other than red, are used to evaluate the response. Comparisons with optical density measurements show that inexpensive commercial scanners might be a good alternative to densitometers.

Calibration↗

PubMed2002

Effects of water light absorption properties of a radiographic film.

Photon beam dosimetry using Kodak extended dose range (EDR2) radiographic film can provide accurate and high spatial resolution information especially for areas such as IMRT dosimetry where a higher dose level (100-400 cGy) is often required to be delivered for verification. For such dosimetry checks, it may sometimes be useful to place the film in a tank filled with water during irradiation. The effects of water on the film when packaged and when removed from the packaging have been examined. Results have shown that the EDR2 film when supplied in the ready pack form is provided in water proof packages and no significant absorption effects are observed or measured on the film even after 48 h of soaking in a water bath. When the film is removed from the ready packs and exposed to water directly, various effects are seen. In the visible spectrum region, small variations (up to 3%) in recorded optical density (OD) are recorded using a fluorescent light densitometer. These effects become much larger in the infrared region (e.g. 7.5% at 900 nm and 12.5% at 1000 nm) and are wavelength dependent. The changes produced by the water are relatively independent of the exposure time to water from 5 s up to 1 h or whether the water exposure occurred.

Absorptiometry, Photon↗

PubMed2004

Surface dose extrapolation measurements with radiographic film.

Assessment of surface dose delivered from radiotherapy x-ray beams for optimal results should be performed both inside and outside the prescribed treatment fields. An extrapolation technique can be used with radiographic film to perform surface dose assessment for open field high energy x-ray beams. This can produce an accurate two-dimensional map of surface dose if required. Results have shown that the surface percentage dose can be estimated within +/-3% of parallel plate ionization chamber results with radiographic film using a series of film layers to produce an extrapolated result. Extrapolated percentage dose assessment for 10 cm, 20 cm and 30 cm square fields was estimated to be 15% +/- 2%, 29% +/- 3% and 38% +/- 3% at the central axis and relatively uniform across the treatment field. The corresponding parallel plate ionization chamber measurements are 16%, 27% and 37%, respectively. Surface doses are also measured outside the treatment field which are mainly due to scattered electron contamination. To achieve this result, film calibration curves must be irradiated to similar x-ray field sizes as the experimental film to minimize quantitative variations in film optical density caused by varying x-ray spectrum with field size.

Calibration↗

PubMed2005

A comparison of the performance of modern screen-film and digital mammography systems.

This work compares the detector performance and image quality of the new Kodak Min-R EV mammography screen-film system with the Fuji CR Profect detector and with other current mammography screen-film systems from Agfa, Fuji and Kodak. Basic image quality parameters (MTF, NPS, NEQ and DQE) were evaluated for a 28 kV Mo/Mo (HVL = 0.646 mm Al) beam using different mAs exposure settings. Compared with other screen-film systems, the new Kodak Min-R EV detector has the highest contrast and a low intrinsic noise level, giving better NEQ and DQE results, especially at high optical density. Thus, the properties of the new mammography film approach those of a fine mammography detector, especially at low frequency range. Screen-film systems provide the best resolution. The presampling MTF of the digital detector has a value of 15% at the Nyquist frequency and, due to the spread size of the laser beam, the use of a smaller pixel size would not permit a significant improvement of the detector resolution. The dual collection reading technology increases significantly the low frequency DQE of the Fuji CR system that can at present compete with the most efficient mammography screen-film systems.

Algorithms↗

PubMed2006

EPR dosimetry of radiotherapy photon beams in inhomogeneous media using alanine films.

In the current work, EPR (electron paramagnetic resonance) dosimetry using alanine films (134 microm thick) was utilized for dose measurements in inhomogeneous phantoms irradiated with radiotherapy photon beams. The main phantom material was PMMA, while either Styrofoam or aluminium was introduced as an inhomogeneity. The phantoms were irradiated to a maximum dose of about 30 Gy with 6 or 15 MV photons. The performance of the alanine film dosimeters was investigated and compared to results from ion chamber dosimetry, Monte Carlo simulations and radiotherapy treatment planning calculations. It was found that the alanine film dosimeters had a linear dose response above approximately 5 Gy, while a background signal obscured the response at lower dose levels. For doses between 5 and 60 Gy, the standard deviation of single alanine film dose estimates was about 2%. The alanine film dose estimates yielded results comparable to those from the Monte Carlo simulations and the ion chamber measurements, with absolute differences between estimates in the order of 1-15%. The treatment planning calculations exhibited limited applicability. The current work shows that alanine film dosimetry is a method suitable for estimating radiotherapeutical doses and for dose measurements in inhomogeneous media.

Alanine↗

PubMed2006

GafChromic RTQA film for routine quality assurance of high-energy photon beams.

Self-developing film offers many advantages over conventional radiographic verification film for routine radiotherapy quality assurance (QA). This paper presents results from an initial evaluation of a beam measurement system using GafChromic RTQA film and a flatbed scanner. Variability and energy dependence of the film calibration and accuracy of scanner readout are investigated in the context of QA measurements. For exposures of film between 2 and 4 Gy, the system is adequate for measurement of beam dimensions, as in multi-leaf collimator (MLC) offsets and secondary jaw calibrations, where agreement with conventional film measurements is within 0.5 mm. However, the measurement of absolute dose is subject to errors of about 25 cGy.

Calibration↗

PubMed1998

Reproducibility of cephalometric landmarks on conventional film, hardcopy, and monitor-displayed images obtained by the storage phosphor technique.

The aim of the present study was to evaluate and compare the reproducibility of cephalometric landmarks on (1) conventional films, and images acquired by storage phosphor digital radiography both on (2) hardcopy and (3) monitor-displayed versions. The material consisted of 19 cephalograms for each image modality. The phosphor plates were scanned in an image reader and the 10-bit normalized, raw data digital images were converted to 8-bit TIFF images for PC monitor-display. The digital hardcopies were produced in a laser printer. Six observers were asked to record 21 cephalometric landmarks on each conventional film, hardcopy, and monitor-displayed image. For the films and hardcopies, the landmark co-ordinates were recorded via a digitizing tablet. For the monitor-displayed images, the co-ordinates were recorded directly from the monitor using a dedicated Windows-based cephalometric program. Reproducibility was defined as an observer's deviation (in mm) from the mean between all observers. Differences between the image modalities and between the observers were tested by two-way analysis of variance for each landmark. There was a statistically significant difference between the reproducibility of film, hardcopy and monitor-displayed images in 11 of the 21 landmarks. There was no unequivocal trend that one modality was always the best. For a full cephalometric recording (the sum of all 21 landmarks), the monitor-displayed images (mean = 25.3 mm) had a lower precision than film (P < 0.005) and hard-copy (P < 0.02). There was no significant difference between film (mean = 21.8 mm) and hardcopy (mean = 22.8 mm). The lower reproducibility seen for the monitor-displayed images is most probably of little clinical significance.

Adolescent↗

PubMed1999

Radiotherapy review on national surgical adjuvant breast and bowel project (NSABP) phase III breast cancer clinical trials: is there a need for submission of portal/simulation films?

In all National Surgical Adjuvant Breast and Bowel Project (NSABP) breast cancer trials in which patients are treated with lumpectomy and postoperative breast irradiation, the quality assurance requirements dictate submission of a completed radiotherapy data form with the stated administered doses, the volumes treated, treatment prescription and daily treatment record sheets, dosimetry and calculation sheets, isodose distributions on the breast contour, photos of the patient in the treatment position, and portal or simulation films. A review of radiotherapy data on 1,982 patients who had lumpectomies accrued to seven recent NSABP breast cancer studies revealed only 2 patients who were judged to have inadequate fields. In both cases, a very small portion of the breast tissue was not included in the irradiated volume as demonstrated by the submitted films. On this basis, it was argued that submission of portal or simulation films for patients receiving postlumpectomy breast irradiation is not necessary. However, there was concern as to the incidence of patients with a possible excess amount of lung tissue included in the irradiated volume. To address this concern, the amount of irradiated lung was determined for the first 208 patients who had lumpectomies, with submitted data entered into the recent NSABP pathologic node-positive protocol B-28. Current NSABP radiation therapy guidelines suggest limiting the thickness of the irradiated lung in the portal beams to < or =3 cm. Only two patients (<1%) were found to have >3 cm of irradiated lung tissue in the treatment volume. Portal film submission is a considerable inconvenience to the individual institutions and is costly in terms of shipping, handling, and storage. These results indicate that submission of portal films is not a necessary part of quality assurance in NSABP breast cancer protocols. The NSABP has therefore eliminated the requirement for routine submission of portal films in protocols for which radiotherapy is not part of the test question.

Breast↗

PubMed1990

Radiotherapy verification film for estimating cumulative entrance skin exposure for fluoroscopic examinations.

Measurement of skin entrance exposures during fluoroscopic procedures is complicated by the use of automatic exposure control devices and the presence of contrast media. Due to variability in positioning spot films from patient to patient, standard dosimeters, such as thermoluminescent, cannot be properly placed on the skin prior to examination. Prepackaged film of the type used for portal verification in radiation therapy held next to the patient's skin in a specially modified patient examination gown was found to be useful for determining the entrance skin exposure from both fluoroscopy and spot films during air contrast barium enema exams. The usable sensitivity range of this film has been found satisfactory for exposure measurements at exposures and kVps typically used for gastrointestinal fluoroscopic procedures. Errors in exposure estimates due to changes in film speed and contrast with kVp are less than 5% for the range of kVps used. Errors from variations in beam quality due to the adjacency of scattering material are approximately 5%. Entrance exposures determined with film agreed with those determined from TLD measurements to within 21%, with an average difference of 9%.

Clothing↗