. 2015 Sep 8;16(5):14–34. doi: 10.1120/jacmp.v16i5.5768

Table 1.

Detectors suitable for TPS commissioning and validation of photon and electron beams

Detector	Use	Comments	Reference
Scanning ion chambers	Beam scanning for photons and electrons	Typical scanning chambers have an air cavity of $4 - 6 mm$ diameter, (minimum of 2 chambers for measurement and reference)	TG‐106 (Das et al. ⁽⁵⁾ )
Electron diodes and film	Beam scanning for electrons, output factors (film)	QMP must confirm the effective point of measurement	TG‐25 (Khan et al. ⁽⁴⁵⁾ ), TG‐70 (Gerbi et al. ⁽⁴⁶⁾ )
Small field detectors	• Small field scanning & output factors ^a ,	Carefully select the detector type and size to fit the application.	TG‐106 (Das et al. ⁽⁵⁾ ), TG‐120 (Low et al. ⁽¹⁸⁾ ) Yunice, et al. ⁽¹⁶⁾
	• IMRT/VMAT point measurement	When scanning for penumbra, diodes are recommended.
	• MLC intraleaf measurement & penumbra
Large ion chamber	Aggregate MLC transmission factors	Interleaf transmission	LoSasso et al. ⁽²⁰⁾
Film and/or array detector	2D dose distributions, including dynamic/virtual wedge and planar fluence maps, intraleaf measurements^b	• Absolute dosimetry preferred; relative dosimetry adequate.	TG‐106 (Das et al. ⁽⁵⁾ ), TG‐120 (Low et al. ⁽¹⁸⁾ ), IAEA TRS‐430 ⁽⁷⁾
Film and/or array detector		• Desirable if the device can be mounted on the gantry and/or in a phantom at different geometries

If a diode detector is used for small field measurements, a “daisy chain” approach is recommended to minimize the energy dependence effects; the diode is first cross‐compared with an ion chamber for a $4 \times 4 {cm}^{2}$ field and then is used to measure the smaller fields.

Using film for intraleaf transmission is usually less precise than interleaf transmission.