Study type: Therapeutical study (experimental study)

Intracavitary hyperthermia: construction and heat patterns of individualized vaginal prototype applicators med. app.

By: Valdagni R, Amichetti M, Cristoforetti L
Published in: Int J Hyperthermia 1988; 4 (5): 457-466
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Aim of study (acc. to author)

Patients with inoperable or previously irradiated cervical carcinoma recurrences pose a challenging problem to the clinician. Low-dose irradiation and hyperthermia seem to be a promising method for treatments in previously treated patients. In order to heat the vaginal apex, individualized prototype applicators utilizing microwave antennas were constructed and tested in muscle equivalent phantom. Preliminary data from clinical utilization are also included.

Endpoint

Exposure

Exposure Parameters
Exposure 1: 950 MHz
Exposure duration: 60 s
Exposure 2: 950 MHz
Exposure duration: 120 s
Exposure 3: 915–950 MHz
Exposure duration: once a week for a total of 4 sessions, each session lasting 30 min

Exposure 1

Main characteristics
Frequency 950 MHz
Type
Exposure duration 60 s
Exposure setup
Exposure source
Setup Muscle equivalent phantom (75% water, 2% NaCl, 10 % Tx-150 as gelling agent, 13% polyethylene powder, dielectric constant of 52.89 and electrical conductivity of 2.68 S/m) placed inside a plexiglas plastic container (20 cm x 20 cm x 10 cm)
Additional info Heating patterns were obtained with the following set-ups with the microwave power same for all of these set-ups: 1) a single and straight antenna in direct contact with phantom material 2) a single and straight antenna positioned within a cylindrical cellulose acetate support and in direct contact with the phantom material 3) a single antenna curved on the emitting region and positioned within a cylindrical cellulose acetate support with the support not filled with phantom material.
Parameters
Measurand Value Type Method Mass Remarks
power 17 W - unspecified - 0.9 W reflected power

Exposure 2

Main characteristics
Frequency 950 MHz
Type
Exposure duration 120 s
Exposure setup
Exposure source
Additional info The heating pattern was obtained with two antennas curved on the emitting regions and positioned at the proximal end of the personalized vaginal applicator
Parameters
Measurand Value Type Method Mass Remarks
power 14 W - - - reflected power 0.1 W

Exposure 3

Main characteristics
Frequency 915–950 MHz
Type
Exposure duration once a week for a total of 4 sessions, each session lasting 30 min
Exposure setup
Exposure source
Additional info The antenna used was similar to the one described in E2. Hyperthermia was applied to a patient who was suffering from vaginal stump recurrence. The applicator was filled with distilled water and two antennas were inserted in it and bent at the proximal end of the applicator. The desired temperature was 43°C.
Parameters
Measurand Value Type Method Mass Remarks
power 14 W - - - reflected power 0.1 W

Exposed system:

Methods Endpoint/measurement parameters/methodology

Investigated system:
Time of investigation:
  • during exposure
  • after exposure

Main outcome of study (acc. to author)

The preliminary data indicate that individualized vaginal applicators might potentially improve the delivery of the therapeutic hyperthermia to malignant lesions located in the apex of the vagina. Further development and characterization of this type of applicator is warranted.

Study character:

Study funded by